Geography of the Heavens and Class Book of Astronomy

THE

GEOGRAPHY OF THE HEAVENS, AND

CLASS BOOK OF ASTRONOMY,

A CELESTIAL ATLAS.

BY ELIJAH H. BURRITT, A. If.

REVISED AND CORRECTED

BY O. M. MITCHEL, A ••••

NEW YORK: PUBLISHED BY HUNTINGTON AND SAVAGE, 216 PEARL STREET.

CINCINNATI :-H. W. DERBY &. CO.

1849.

TABLE OF CONTENTS.

P~a&

Pre&ee to the lint edidlm, .. Mitehel'. edition,. PreIimiDary chapter, • • MagnitwIee of stan,". •

• 7 • • 11 • • 17 • • 18 UOll8t.ellatioos •• • • • • 19 Right..-naion and decIiDatiou, 20 Sidereal time,. • • . • • • 22 'rable b liDding meridian JIU" BlIp of objec&sin mean time, K Correction lOr mean from apparent time, • • • • • • • 28 DefinitioIII,. . • 28 Greek aIphabet,. M Andromeda, • • • • •• 87 PtllIIII1I8 et Caput Mem.., • 40 Triangulom, • • • • •• 44 CIIIBiopeia, •

BoO.., .. Draco,. • • • •

• • 110

ComaBezeaicea,.

• 1M • 138 • 138 • 139 • 140 • 141

.• 128 180

Canes Venatici,. COlODa BomaIis, • Leo minor, • The Lynx, • Libra,. • • Scorpia,.. Ur-.minor,"

CepheuB,

••

• • j 44 • 148 • 163

CameloperoWl, BagiUariWl,. • •

• 166 • 167

Scutum Sobielki, Hen:nles, • • • •

• 159 • 161

45 CygnWl, • • • • 51 Lyra, • • • . • •• 55 Aquila et AntinoWl,. 82 DelphinWl, • • • . ,

Piscea,. • • Aries, •

Cetus,. • • Tauma, ~ • Orion,. • Eridanus, • Auriga,. • Gemini, • • Cancer, • : Canis minor, Monoceros,. Canis major, Leo major,. 8e1ltaus, • Hydm, Virgo,. • Carvus, •

P~a&

Ur-. major, •

• • • • • •

• •

• 186

• 170 • 174 • 177

86 Vulpecula et Anser,. • • • 72 8erpentarius vel Ophiuchus,. 79 Pegasus,. • . • • . • • • 81 Equulus vel Equi 8ectio,. • 85 Aquarius, • • • • • • • •

179 181 188 189

190 90 Capricomus, • • • • • • • 194 93 Rising, culminating, and setting 95 of the Visible conateUatiOl\ll • 96 in each month, • • • • • 198 • 102 Filled stan, PIII1I11u,. • • • 201 • 107 Distances of the /hed stan, • 206 • 108 Mi1ky Way, . . • • • • • 208 • Cluaten md Nebula,. • • • 207 • 118 AatzaI.,.atem and central sun, 209

1181

"

(v)

TABLE OF CONTENTS,

8oIar.,...., . . The SuD, • • • • • • • •

PAS.. ,

PAS..

III I NeptaDe,

110

I

•

• • • sst

ComebI, • • • • • • • • • 186

Men:ury,. • • • • • • • • 116 ' TranIIati.oD of the IIQD tJuoush

1IpIIIlII,....... .. 198

Venlll, • • • • • • • • • 119 ' The Earth,. • • • • • • • 138 The Moon, • • • • • • • • Me Solar and lUJlet Eelipa, •• 163 EcIiJI- oCtile aun,. . • . t56 Ecli.- of the Moon,. • • • 168 Man, • • • • • • • • • • 181 ' The AIIIianJidI, • • • • • • 1184. Jupiter, • • • • • • • • • 170

AUrIeIiveandprojediletimlell, SOl ~,. • • • • • • • 308 Nutatlon, Ahcjrrati.ou,. • • • 304. ParalIu:,. • • • • • • • • 806 RefracIicm, • • • • • • • • 306 Tw.,. • • • • • • • . S07 The 8euoaI,. • • • • • • 811

8atum, • • • • • • • • • 176 t!nnUi at B...... • • • 181

QUIIItioDI, tabJe8, &co, • • • 8M

I

Law of grantation,. • • • • 198

AII&ronomiealIDltramlmll,. • 811

PREFACE TO THB PIRBT EDITION. I BAVB long felt the want of a Class Book, which should be to the starry heavens, what Geography is to the earth; a work that should exhibit, by means .of appropriate delineations, the scenery of the heavens, the various constellations arranged in their order, point out and classify the principal stars, according to their magnitudes and ·places, and be accompanied at the same time, with such familiar eiercise~ and illustrations, adapted to recitation, as should bring it within the pale of popular instruction, and the 8cope of juvenile understandings. Such a work I have attempted to supply. I have endeavored to make the descriptions of the stars so familiar, and the instructions for finding them so . plain, that the most" inexperience~ should not fail to understand them. In accomplishing this, I have relied but little upon globes and maps, or books. I very early discovered that it was an easy matter to sit down by a celestial globe, and, by means of an approved catRlogue, and the help of a. little graduated slip ofbrus, make out, in detail, a minute (vii)

viii

PREFACE ·TO THE FIRST EDITION.

description of the stars, and discourse quite fami..; liarly of their position, magnitude and arrangement, and that when all this was done, I had indeed given the pupil a few additional facilities for finding those stars upon the artificial globe, but which left him, after all, about as ignorant of their apparent situation in the heavens, as before. I came, at length, to the conclusion, that any descnption of the stars, to be practically useful, must be made from a careful observation of the stars themselves, and made at the time of observation. To be convinced of this, let any person sit down to a celestial globe or map, and from this alone, make out a set of instructions in regard to some favorite constellation, and then desire his pupil to trace out in the firmament, by means of it, the vari~us stars which he has thus described. The pupil will find it little better than a fancy sketch. The bearings and distances, and especially, the comparative brightness, and relative positions, will rarely be exhibited with such accuracy that the young observer will be inspired with much confidence in his guide. I have demonstrated to myself, at least, that the most judicious instructions to put on paper for the· guide of the young in this study are those which I have used most successfully, while in a clear evening, without any chart but the firmament above, I have pointed out, with my finger, to a group of listeners, the various stars which compose this and that constellation.

PRU'ACE TO THE ~IR8T EDITION.

ix

In this way, the teacher will describe the stars as they actually appear to the pupil- taking advantage of those obvious and more striking feature. th~t serve to identify and to distinguish them from all others. Now, if these verbal instruction8 be committed to writing, and placed in the hands of any other pupil, they will &nswer nearly the same enc. This is the method which I have pursued in this work. The descriptive part of it, at least, was notcomposed by the light of the sun, principally, n~r of a lamp, but by the light of the stars themselv.~. Having fixed upon the most conspicuous star,or group of stars, in each constellation, as it passu! the meridian, and with a pencil carefully Dotedall the identifying circumstances of position, beari~, brightness, number and distance - their geom4rical allocation, if any, and such other descripti'\e features as seemed most worthy of notice, I then lI3turned to my room to transcribe and classifY these nemoranda in their proper order; repeating the SaID observations at different hours the same evening,and on other evenings at various periods, for a ~ of year_; always adding such emendations 81 subsequent observations matured. To satisfY mYlelf of the applicability of theBe descriptions, I h_e given detached portions of them to different p~i1s, and sent them out to find the stars ; and I have ~nerally had the gratification of hearing them repo~that "every thing was just as I had described it., If a pupil found any difficulty in recognizin, .,star, I re-examined the description \

X

PREFACE TO TBE FIRST EDITION.

to see if it could be made better, and when I found it susceptible of improvement, it was made on the spot. It is not pretended, however, that there is not yet much 1:oom for improvement; for whoever undertakes to delineMe or describe every visible star in the heavens, assumes a task, in the accomplishment of which he may well claim some indulgence.

• PREFACE TO IU'OHEL'B EDITION. To extraordinary discoveries· :which have marked the History of Astronomy. during the last few years. demand corresponding changes in the· books designed for the instruction of those who seek a knowledge of this science. Feeling confident that nothing can be more important. than the furnishing of our schools with valuable eleinentary works in science. I have been induced to undertake the revision and the re-writing of a large part of the well known school book, The Geography of fJuJ Heavena. In consequence of the rapid advance in Astronomy. and the important change, which has recently commenced in our country, in the mode ofpros8Cuting its study, this revision has become absolutely necessary. When this work first appeared there were very few telescopes in the United Statee, and of these a very small proportion were employed in the schools and academies. as means of instruction. Hence, at that time, any dElscription of the telescopic objects, found within the (xi)

xii

PREFACE TO MITCHEL'S EDITION.

limits of the several constellations, would have been almost useless. Within the last six years a new era in A~tronomical science has daw~e.d on , our country. A zeal and ardor has been aroused in its behalf, which, at one time, was regarded as quite impossible, in consequence of the peQuliar nature of our govemment and institutions. The reproach cast upon us by Europeans, for our utter neg]ect of science, if ever just, is no longer so. Only a fe. years have p88Beci, since the first. elfort was made to arouse tIM American people to the importance of the cultiVation of Astrenomical loienC&, and. we now are able to point to no less than three fil'llt cl818 observatories, aU erected within the lut five yean, at points widely distant from each other. The. example thus set in the West and the East, basprampted to active ejfort in many parts of our e»aotry, and, at this time, there is scarcely a school or college of any rank, at which it has not been J'et!lolved to attempt the founding of an AstrOJu)JniceJ Observatory, of greater or leu magnitude. To meet these rapid changes. in the mode of conveying the truths of Astronomy, and to present,.in I.imple and intelligible form, the results of the recent important discoveries, win be the main objects of attention in the: revisidn of this work. A large put of the Mythological notices will be

PllEI'ACB TO MITCHEL'S EDITION.

xiii

omitted, lUI less important than the description of telescopic olUects found in the various constellations. These objects, consisting ofnebulm, clusters, double, triple, multiple and binary stars, rich fields and vacant spots, will be noticed, and described, their places given, and drawings of the more important objecta, with a note of the diameter of the olUect glass which will show them, and re~der their observation possible. Among the new topics treated, we may notice the following as some of the more important. The subject of the binary and double stars, their distances and periods of revolution, has engaged the attention and talent of many of the best Astronomers of the .world, for the last twenty years. Tliese revolving suns will be found to fill their appropriate places in the revised work. The enlarging of the limits of the solar system, by the discovery of a planet exterior to Uranus. the extraordin~ry means of its discovery, its subsequent history, aDd the elementa of its orbit, constitute a topic of deep interest; add to thi. the discovery of five new asteroids, within the last two years; and the perfection of the tables of all the old planeta l and we find most import&llt advances in our knowledge of the solar sy.tem. In the structure of the Sidereal HeaveDII, and onr lmowledge of the distribution of the stan in space,

d"

PAEtACE TO MITCHEL'S EDITION.

little had been done after tbe death of Sir W. Herschel, until ,within the" lut few years. The diacovery of the actual diatance of a fixed star, by Bes8el, gave a new impUlse to the inveetigation of these 'sublime sulUects. This triumph of Bessel was speedily followed by many others, of a like kind. M. Argelander demenmatea the motion of the lun and solar system in space, and fi~es the point towards whiQh it is moving; M.Otho Strive determines- its annual angular motion as seen from the fixed' stars .of the 1lrst magnitude; and, finally, M. Petera, of RU88ia, fixes the distance of the stars of the second magmtudf4 from the mean parallaX of some thirty stars, deduced from observation. With these ,data, iUld' the preceding investigations of, Sir W. Herschel, M. Strtive, ~f Pulkova, Russia, commences a disCUI!Ision of the distribution of the stars in space; the popUlousness of the Milky Way aad the heavens, generally, in stars; determines the relative distances' of the spheres of the fixed stars of the different magnitudes; and, ftnally, their absolute di8tances, and the actual velocity of the sun anti solar system through epaoe~ If We add to these topics the discoveries by Lord Rosse's great reflector, the' changes in the views hitherto entertained on the subject of LaPlace" nebular hypO. the.aI,' and MUter'. thbOty', 'the great eentml sun, we '.d:that tile "t, feW-year. 'have beel1i~"

or

,

.

PllEFACE TO MITCHEL'S EDITION.

xv

most wonderful, and the most trnitful, in the whole history of Astronomy since the time of Newton. The necessity of a new edition of the Geography of the Heavens need not be urged, after what has been said. To meet the demands, a new set of star charts have been prepared expressly for this work, and the text will be found to conform to these charts. MOVJrT ABU., .,l1t, IIKB.

TUE REVI8ED

GEOGRAPHY OF THE HEAVENS. PRELIMINARY CHAPTER. To phenomena of the heavens have excited the curiosity, and fixed the attention, of mankind, in all ages of the world. The beautiful. clustering of the bright stars, the moving plUlete, the extraordinary changes of the mOOD, the phenomena of the day and night, were themes for study at a period so remote, that neither "history nor tradition reach far enough back in the past, to tell us when or by whom, these researches were commenced, or prosecilted. From the earliest ages, do-.n to the present time, the science of astroRomy h.. presented problems, t&XiJlg the. highest powers of the human intellect, and requiring for their solution the most profound reasoning, the moet accurate observation, the most powerful instruments, a.nd an ardor, ~rse­ verance and devotion, which have signalized hUlnan effort in no other dtlpartment of scientifio research. "The heavens declare the glory of God," and the sllCC6asful examination of these ·same heavens, haa most perfectly demonstrated that other great truth, that man has been made" but a little lower than the angels." By the effort of hi8 genius, he has risen to a knowledge of the structure and law. of the universe, he has vindicated the wisdom of God, in the beautiful adjustments of the moving planets, and the harmonious revolutions of a multitude of worlds, linked together by a mysterioua bond. He 17

18

GEOGRAPHY OF THE HEAVENS.

has extended the dominion of law to the remote stars, and has computed the periods of' these far distant orbs. But these sublime results have not been obtained by any single individual, or by any one nation. The great problem of the universe has been given to the human race, and its solution haR been the progressive work of all nations, in all agee, for the last six or seven thousand y~ars. At the end of this ,'ast period, we gather the f'ruits of all . preceding effort, and condense into narrow limits that knowledge, to gain which, has required the highest intellectual activity of the best minds which have adorned the earth. In looking out, of a clear night, on the starry heavens, we find a multitude of brilliant objects, scattered over'the sky, without any law or order in their di~tribution. We readily remark a great difference in the brilliancy of the stars, and our attention is soon fixed upon certain groups of brighter objects, whose configurations, or relative positions, enable us to find them, readily, when they are in the visible heavens. The diversity' in brightness has occasioned the classification of the stars, in order of their brilliancy. The brightest occupy the first class, and are called 8tar8 tf tkeJir8t mognitrule. Of these there are only a few. From the brightest stars down to those just visible to the nalted eye, the scale has been 'so divided that it comprehends Biz mogni,tude8, the number of stars in each class increasing as the brightness of the class decreases. We have six magnitUdes visible to the naked eye, and then the telescopic stars carry the series down to the sixteenth magnitude, and even still lower. In the description of any· star, then, we must always give its magnitude, as one means of fixing its identity. But as there are many stars in each class, the magnitude, alone, would not serve to point out a particular stat. In the early ages

19

PRELIMINA.RY CHAPTER.

of astronomy, the hea,'ens were divided into certain subdivisions, or groups of stars, called ronatellation6 .. and the figure of some animal, or other object, was as!Jigned, whose outline would embrace all the stars in a given constellation. These subdivisions have been retained in modern times, and although attended with many inconveniences, they are too firmly fixed, and too intimately woven, in all works on astronomy, ever to be changed. There is no resemblance between the configuration of the stars, and the object, whose name is assigned to the group; yet when the limits of the constellation, as fixed by the outline of the object whoi1e name it bears, becomes accurately known and laid down on maps, these subdivisions, or constellations of stars, greatly assist in obtaining a knowledge of the heavens. We may even identify a star, by knowing it is the brightest of a given constellation. To render it possible to designate the stars of each constellation, they have been named after the letters of the Greek alphabet, until these are exhausted, calling the brightest star after the first letter, and so on down. In case the number of letters is insufficient to give names to all the visible stars in a constellation, the Roman alphabet is called into use, and after this is exhausted, the Arabic characters, 1,2, 3,&0., are employed. Thils we call the brightest star in the constellatioJ;l of the Swan, a. Cygni, or Alpha qf tJuJ Swan,' the next brightest in the same constellation is called f3 Cygni, or Beta of the Swan; Cygnus being the Latin for Swan, and Cygni, meaning rf tJuJ Swan. The same is true of the other constellations, the Latin names being always retained in the designation of the ~~.

.

If the constellations contained a very few stars, and those of marked difference of magnitude, this mode of designating them might be sufficient for

2,0

GEOGRAPHY

or

THE HEAVENS.

their. identifieation and description. But in, eonsequence of the multitude of stars: and the difficulty ot distinguishing them from each other by their magnitudes, it has become necessary to fix their positions in the heavens, as the places on the earth's surface are ~xed by their longitude and latitude. The corre~ponding term/il applied to heavenly l>odies, are right ascenaioR. and tleclination, which terms we proceed to define. To us ~he sun appears to move among the fixed stars, and in the course of one year to return again to the point o~ departure. If his track could be marked by leaving behind him a hright line of fire, this line.would be found to Qe a circle traced out among the fixed stars, and this track of the sun is called .', . the ediptic. There are two poin" in thill track of especial interest, from the fact that on the days when the sun occupies them; the length of the day and night is exactly the same, each being twelve hours. These points, on the ecliptic or 8un's track, are called the equi1UJCtial poinJ.s. The one through which the sun passes in the spring is called the 'VtJrnal equi7lOX, that occupied by the sUD in autumn is called the autu11l1l8l equi7lOX. ' Each day and night the sun, and other heavenly bodies, appear to describe circles in the heavens, called diunu.d circles. They are all parallel to· each other. That diurnal circle described by the sun, at either equinox, is called the t;elestiol equator, or the equi1UJCtioJ. If the equinoctial could be marked by a line of fire in the heavens, it woul«\. be found to cut the sun's. track, or the ecliptic, in two opposite points, which we have already called the equi1UJCtial points. To fix the place of a star, or other heavenly body, it is referred to the equi1UJCtial, or celestial equator. A star on the north side of the equinoctilll is in 1Wrtllern dec1iflll#un, and one on the south side of

PRELIMINARY CHAPTER.

21

the same circle is in soutJaern tlecli1UZtirm. To meas· ure the distance of any object in the heavens, north or south of the equator, an imaginary circle is drawn through the object perpendicular to the equator, and the distance measured on the circle thus drawn from the object to the equator is caned its decli1/lltion. Knowing the declination of a star, north or south of the equator, does not suffice to fix its place in the heavens. It o~ly locates it on the circumference of a small circle parallel to the equator, and distant from it by an amount equal to the known declination of the object. To fix the exact poirit of the object on this small circle, it is only necessary to know how far the circle, drawn through the object and perpendicular to the equator, cuts the equator from the vernal equinox. This distance measured on the 'equator, from the vernal equinox round eastward, is called the right ascension. Any circle drawn through a heavenly body, and perpendicular to the equator, is called a meridian. That meridian which passes through equinoctial points, is called the prime meridian, or the equinoctial colure. Any star, or heavenly body, situated on the prime meridian, has no right ascension, or its right ascension is equal to zero. In case the equator be divided into twenty-four equal parts, and meridians be drawn through the points of division, these meridians are called hour circles. A heavenly body situated on the first hour circle, east of the vernal equiaox, has one hour. of right ascension; if it be on the second hour circle, east, it will have two hours of right ascension, and so round, through the twentyfour hours of right ascension to the vernal equinox again. . That point in the heavens, directly above us, in which a perpendicular to the sUrface of still water, carried upward, would pierce the celestial sphere, is called the %CI/.ith. If the same perpendicular be

~2

GEOGRAPHY OF THE HEAVENS.

conceiv~ to pass downward and pierce 'the lower hemisphere, the point of piercing is ca.lled the 1IOdir. The circle perpendicular to the equator, and passing through the zenith of any place, is ca.lled the meridian of that place. All points on the earth's surface in the same lo~gitude, will have the same meridian. The instant when the vernal equinox reaches the meridian of any place on the earth's surface, i. the beginning of the sidereal day, which terminates when the vemal equinox shall have passed entirely round and returned to the meridian again. A clock, or watch, so regulated as to mark 0 hours at the instant when the vernal equinox is on the IJ).erWian of a given place, and to mark the hours from 0 to twenty-four houra, is called a sidereal clock, and keeps sidereal time. It will be found that the right ascension (marked R. A.) of each o~ect is given in this work. In case the right ascension of a star is 3 h. 12 Ol. 10 s., it tells us that it will reach the 'meridian 3 h. 12 m.' 10 s. after the vernal equinox has passed it. If the time, aB' shown by a sidereal clock, is less than the R. A. of a star, then the star has not yet reached the meridian; on the contrary, should the time indicated by the sidereal clock be greater than the R. A. of any object, then the o~ect; hb already p$8led the meridian, and is west of it by an amount equal to the difference between the sidereal time aud ,the R. A. To render this clear, , take the following examples. The R. A. of a star is 4 h. 26 m. 10 s., the sidereal time is 3 h. 15 m. 25 s. Is the star east or west of the meridj~? It is east of the meridian, and to find the amount by which it is east, .... L

FIOmtbeR.A.=41810 8libtraet 8 Iii iii the time.

Dia:= 1 10 til

PRELIMINARY CRAPTER.

In caSe the sidereal time is 6 h. 12 m. 20 s., then the star has already passed the me~dian, and il west by an amount found as follows:

=.

....

L

PIOm the time = 0 II 10 8ab&nIet the A. R. 18 10

Diit=o.a 10

Or the ltar i8 0 h. 46 m. 10 I. WAst of the meridian. Anyone p08l!essing a sidereal time piece, whether clock or chronometer, will.find no difficulty in fixing the place of a heavenly body, as to its angular distance east or west of the meridian, at any hour in the twenty-four. The declination of the object, shows its distance north or south of the equator, and combining tbe t.wo, the A. R. and the Declination, we have the exact position of .the object in question. It frequently happens that perlons are not provided with sidereal time pieces, but may possess very good solar clocks, chronometers or watches. Mean Bolar time is reckoned from the instant, that the center of the mean sun (or one moving with the mean motion of the true Bun), is on the meridian. It differs from sidereal time,by 3 m. 56.5554 B. in each twenty-four hours, or a sidereal clock gains that amount daily on a mean solar clock. Hence we perceive that mean solar and sidereal time seldom, if ever, agree. When any heavenly body is on the meridian of a given place, a well regulated sidereal clock will show the time exactly equal to the right ascension of the body. No such relation exists between mean StJar t';m8 and the right a8Ce1I.8itm. To find the instant that ali object, whose right ascension is given, reaches the meridia.n in mean solar time, or that .bOWD by ordinary clocks and watches, the following table has been computed:,. ••J. ...

-. .. ~

"

14

GEOGRAPHY OF THE liar. "'1"'. -a~l_ --·ib. ... b. .. h. ..... bolD.

HE~VEN8.

"-, ,..,. ...

IopL

Oct.

Now. Doe.

lao •• l!1~~h.m.it 11 ..20111 151:3b. 1911 31935131 2311110,11 1615 1113 1511 lr7 931 1lr7 ~

ID.

Ia,,,

Ill. . . . . . . . .

1i 11,5 315 46 614

14,3 01 OU 267 04 II 6a 00 2 49 6U 45

I I I 1 0

1223 08,z:j 04 13 0123 6193

1sl,21 15 III 11 21 or II 04,111

IV 19 16.17 1215 07 13 1211 114 9 27 112 16 18 12;17 0815 04 13 08 11 110 , 23 7 18 1211 08,'17 04 15 00 13 05 11 17 II 19 7 14

64 7:4 8'4 914 104

512 41 47 1I:rr 4112 33 3U ~ 3U 2S

0 63 23 0 4912 0 4622 0 4UIl 0:'" 12

00 21 66;21 113,21 49110 45110

!!'l111 04 16 11814 04 19 00 16 11614 OU 18 66 UI 5114 6818 61 18 4714 5218 47il11 43 14

11 4 124 131'4 14,4 164

29 2 26 III 2 1st 112

21 11 13 09 05

0 0 0 0 0

36112 31 22 27 ~ 24 I!! 20 22

42110 38!*I 34,20 31110 lr7 110

4818 « 18 41 18 :rr 18 33 18

16'4 114 18113 193 20,'8

03 2 041 69 I 58 I 61 I

01 111 M 50 (6

0 0 0 0 0

1622 1322 0912 06 22 02112

23/110 20 20 16110 1220 0820

lID 18 falf6 25 18 18 8 21 18 1416 1718 10 16 1318 06 116

4l1li3 38 23 34193 311'23 27 28

lIB III 55 lIS 61 21 4721 44 21

05110 01 lID 51110 113111 50 18

OIl 18 05 17 0117 11117 113 17

~

21 3 47 I 22'3 42 I 23 3381 24 3 1M I 15 3 3D I

4~

18

5813 5:.! 12 48 111 44 III 41111

01 11 11111 54 11 50 11 4710

139 111 1 09 9 11 7 06 8 or 1 Ol! 9 03 8 58 859 6

09 05 01 66

:rr III 33 12 21 III 110 II 22 12

43 10 55 8 66 8 3810 61 8 51 8 J6 10 47 8 41 6 31 10 43 8 43 II t9 10 40 838ft

41 4:1 39 34 30

1914 1614 11 14 or 14 11-114

18 III 14 II 11 III or 12 031111

26 10 36 8 21 10 32 8 1810 1!8 8 1410 25 8 1110 1118

35 6 30 6 116 6 22 6 18 6

26 21 16 111 08

S9 13 66 J3 51 13 47 n 4:1I3

119 111 66112 hill 48'11 45 11

or 10 03 10 0610 5810 113 10

14 6 09 5 05 5 01 6 S7 6

03 59 54 50 46

9118163 6 9 64 7 48 0 II 50 7 44 5 9 47 7 40 5 9 4:17 3Ii 5 938 5

41 3& 32 :!II 113 It

~

14 38 14 35 16 31 14 3118 17 14 27 .. ~ 14

ui

02 IS 67 15 41111 4915 4& III

110 3 is I 13 93 40 21 (619 4911 41'1& 213 111.1 19;93 3611 4218 46 IT 37 15 te3 17 I 1623 33 21 3819 4111 31 Iii 11113 1tll 1423 1121 35 19 31 11 28 15 30 3 09 •••• 28 25111 3119 3217 24 15 311306 .••• 12312. ····19 118 ••••• 16

3913 4111\ 49 3513 37 11 411 3113 34 11 42 27113 30 \I 38 23 13 116 11 35 1913231 ...••

17 8 138 10" 06 8

on

6'~

A few examples will 8uffice to explain the use of this table. Given the A. R. of Sirius = 6 h. 38 m. 07 8.required the apparent time of its meridian passage, on January 11th.

Ruu.- To 1M numlJer placed uppoaite 1M date, add 1M A. R. if 1M star, all fou/nIl in this work.

B." ..

'l'huI: A. R. of 8iriUII = 8 88 07 Tabular No.

Sam

, 19 00

11 07 08

PUI,I'MIlfAllY CIIAPT&L I

Or Sirius passes the meridian at 11 h. 07 m. 08 s. apparent time. ExAuLE.-Required the apparent time or the . . . . meridian pllSl$age of Vega, on May 30th. .. ..

L

A. R. of Vega = 18 31 M Tabular No. = 19 31 00

8um= 38 OIl M • 8abUaet 24 hours M 00 00 Merjdian pa-ae 14 03 M apparent time.

It will ~ noticed that the foregoing computations have been made for apparntI. time. This is slightly dift'erent from the time shown by clocks and watches, called mean time. .ApparenJ noon is the exact instant when the trae 8un's center is on the meridian. III consequence of the apparent irregular motion of the sun, there is a variable difference between o:pparent or tnuJ- time, or that shown by the sun, and 1IIIl'aR time, or that shown by the clock. Since we rely for our time on the clock, we here present a table which will exhibit the mean days in the year, on which a clock Or watch, regulated to mean time, will be an even number of minutes faster or slower than the sun. From thi8 table it is easy to reduce the apparent tWe of any metridian· PfP,sage, found by the preceding table, to mean or ~rock time. To be rigidly accurate, the correction should be taken from the nautical almanac, or other accurate ephemeris, but for Ol'dinary gazing these table. are quite sufticient. • In ease the IIDII produced by addins to the tabuJar number oppoaita . the given date the A. R. of the Itar, or other hea"f8llly body, be gJe8Iier thIpa &wenly-tOar bola, tiom the IIDII IUhIract bnIDty.6ar bo-. UId the NIIIIIIiDder will be the ~ time. of IIIIIIidiIIl ,......

C

26

GEOGRAPHY 01' THE HEAVENS.

Now, returning to the examples already given of the meridian passages of Sirius and Vega; the fiJ'8t of these stars was found to culminate or pass the meridian at 11 h. 07 m. 08 s. apparent time, on the 11th Jan. By the last table, on the 11th of January, the clock is 8 m. faster than the sun. Hence the culmination by the clock, will take place at 10h. 69 m. 08s. Again, Vega was found to cuhninate at 14 h. 03 m.· 34 s., on the 30th May, apparent time. By the preceding te.ble, on the 28th of May the clock was 3 m. slower' than the sun, and gaining one minute in 7 days, or about 9s. per day. On the 30th the clock will be slow, about 2 m. 42 s.; and hence Vega will culminate, by the clock, 14 h. 03 m. 34s .. 2m. 42s. = 14 h. 06 m. 16s. These approximations are sufficiently accurate for ordinary purposes. . The first te.ble will not be in error more than 1 m. for twenty years, when the stars will culminate about one minute later than shown by the te.ble. From all the foregoing considerations we deduce the following dtfinititm8 : The magnitude of a star is its brightness compared with any star IlRsumed as a standard. A star of the 1st magnitude is of the highest order of brightness.

+

PRELIMINARY CBAPTEIL.

'

27

All stars below the 6th mognittule are only rendered visible by telescopic aid. ' A cunstel1t.d:i.r, is a group of stars falling within the limits of the outline of any animal or object whose name it bears, and whose figure is conceived to be drawn in the heavens, and is actually drawn on globes and maps of the heavens. The ecliptic, is the path which the sun appears to describe in a year among the fixed stars. The erpuztor or the equinoctioJ, is a great circle cut &om the heavens by producing the plane of the earth's equator to meet the celestial sphere. The equi1llXl:eS are the points in which the celestial equator and the ecliptic cut each other. , DiurnoJ circles, are those circles which the heaven~ ly bodies appear to describe every twenty-four hours. They are all parallel to the equator. Meridio:ns, are great circles perpendicular to the celestiaJ.. equator, and meeting in the points 'called the 1I.01'tk and sUI.IiA poles of the heavens. Huur circles, are meridians, cutting the equator so as to divide it into twenty-four equal parts; the first point of division being at the vernal eqainox. The zenith, is the point in which a perpendicular to the surface of still water, pierces the celestial IiIphere above. The nadir, is where the same perpendicular pierces the celestial sphere below. ' The meridian of any place; is the great circle, perpendicular to the celestial equator, and passing through $e zenith of the place. The rigltJ, ascension of a heavenly body, is its distance east of the vernoJ equinox, reckoned on the celestial equator. The declination of a heavenly body, is its distance north or south of the eqnator, measured on a meridian passing through the heavenly body. The declination is expressed in degrees, minutes and seconds, of a great circle, and is expressed by

28

GlWGlUPBY OF THB HEAVENS.

these symbols,O ,I " . Thils we write 12 degrees, 17 minutes, 10 seoonds: 120 17' 10". . A Wlereol day, is the interval from the instant the vernal equinox is on the meridian of a given place, till ~t again reaohf>s the same meridian. A tf"U8 solar day, is the interval from th~ instant the oenter of the true SUD is on the meridian of a given place, till it again reaches the same meridian. A mean solarday,'is the interval from the instant that the center of an imaginary sun (moving with the mean daily.mo.tion of the true sun) is on the meridian of any given place, till it reaches again . the meridian of the same plaoe. The equi1UJCtiol colure, is a meridian passing through the equinoctial points. ParaJlels of declination, are small circles, north o.r so.uth of the e.quator, and parallel to it. The rationBl hori%07&, is a plane. passing through the oenter o.f the earth, and perpendicular to the radius dra.wn to any place on the earth's surface. It divides the heavens into two hemispheres, the upper being the 'Visihle, the lower the in..n.ilJle hemi. sphere. Any heavenly body is in the act of rising, when . it passes from below up through the plane of the ratiuruil horizon. It is setting, when in the act Df passing below this same plane. . The sensiJJle horizon, is the circle limiting :our view, Dr where the earth and sky appear to meet. Vertical circles, pass through the zenith, and per· pendioular to the horizon. . The prime tJertfcol, is the great oirole, which outs the horizoll in the east and west points. Before proceeding to an exploration of the heavens, it. will be necessary to acquire 80me knowledge of the classes Df olUects; the individuals of which will be hereafter described. The mO,st casual observer oannot fail, on the first examinat.ion

PRELIKINAllY CBAPT&L

of the heavens, to notice an irregular zone, of une- ' qual brightness, called the Milky Way, which is seen to sweep entirely round the celestial sphere. This bright zone is found to consist of millions of stars, scattered with rich, but irregular profusion, throughout its entire extent.. Nearly all its stars are below the sixth magnitude, and are, of course, invisible to the naked eye. But .the smallest telescopic aid reveals multitudes of stars; and as the power of the telescope is increased, the number of stftrs brought to view iucreases in a like proportion. Although, according to the investigations of modern science (to be more fully examined hereafter), we may not fix absolute bounds and limits to the millions of stars composing the Milky Way, yet if we confine our examinations to the richer or denser portions, we are able to assign a figure within whose limits the Milky Way will be confined. Were it possible to enclode all the stars composing the Milky Way in some opaque envelope which would shut them out from all space beyond, within this envelope and not very far from its center, our own sun, itself a fixed star, would be found. Having thus enclosed the stars of the Milky Way in imagination, it is found that the space on the outside. of this envelope is not void' space. Very far beyond this limit, the telescope has revealed objects of greater or less brightness, which, when examined with powerful instruments, are found to consist of millions of minute points, grouped together, and assuming all possible forms, among whioh the globular manifestly predominates. These. are called cluster8 of stars, and are in many instances so large, as to ocoupy as much, if not more space than that takeu up by the Milky Way, and containing,inall probability, as many stars. These naagnificent cluster8 are so remote, that the telescope may often grasp, at one view, their vast extent, and innumerable millions 02

80

GEOQaAPBY OF THB RUVENS.

of stars., Other bright objects are seen beyond the limits of the stars composing the Milky Way, whieh assume al~· possible shapes, and which, in many respects, resemble the clusters; with this diifereBC8, that no telescopic power has ever revealed' any stars within their limits. These are oalled 'Min4la, or faint luminous clouds. Among the nebula, some present characteristics which indicate ,the fact, that in case they could be examined with greater telescopic power, they would be found to be composed of stars too remote to be seeR separately, but whoee combined light reaebes us from their vast distances, and shows tlJ,em as faint luminous clouds. There are others which exhibit no such charaeteristiea, and which many astronomers believe consist of luminous matter, resembling that, composing the tails of comets. These are called irresolvolJUJ ~. In this class, the most remarkable are the planetary neImla, so called from the fact that they present disks, very like those of the planets, with a luminous surface of uniform brightness. They resemble the very distant. planets,of our systelu, and are, in some instances, only a little less bright. Among the stars we reckon the following classes, viz. : Single 8fo:ra, Juuhle alars, mvltiple stars, bi1llD'1l star., periodical' or varialJle stars, new 8tarB, and ~ Btars. ' Single stars, are those which, to the naked eye, and under telescopic examination, are found to consist of one individual star. DuuJile stars, are those which, to the naked eye, appear single, but which, under ,telescopic examination, are found to consist of two star.. Sometimes the component stars are equal, at other times they are very unequal, the relative magnitude and distance being diiferent in every set. . lWultiple star" are 'Such as are leen single, by the

81

nak.f!d eye, but which the teleacope 1lnda compoMd of three or more ~. Binary·stars, are double etan, in whioh ~ components have been fou.nd to be united in such .. way that they revolve around each other. These are suns revolving about BUDa, and not a pltlfllll. about a sun. Yariahle 8Io.~s, are those which are found to unde~ go certain fluctuations in brightneel. Sometim81 they are found tp 101e· their ·lightl and actually to become invisible. Then they regain their brilliancy, by slow degrees, and reach their original brightnesi. In some individuals these changes are accomplished in a certain fixed period; in other eases the fluctu· ations of light Me not governed by any known law. New stars, are those which have. suddenly blazed forth in some rf\gion of the heaveDB previoully blank or vacant. They generally die away and disappear in the course of one or two years. Nebvi.()'I.U stars, are luch as are surrounded by • faint halo, or luminous haze of nebulouamatter. It will be readily remarked that tlleee objects, except the single s~ars, are telelCOpk, IUld are invisible to the naked eye. . The region in the heavens about four degrees on each side of the ecliptic, or SUD'S path, is called the uxlioc, and is remarkable as the region in which the sun, moon, and large planets perform their revolutions among the fixed stars. The canstella.. tiond, into which the stars in the. region of the zodiac were divided, are doubtless among the most ancient in the heaven~. In consequence (If the apparent annual motion o(the SUD among the constellations of the zodiac, tlie stars of thes~ constellations will be successively lost in the 8uperior brilliancy of the 8un, and will become invisible while in the immediate vicinity of the sun. This remark is true of all the .constellations beyond the

all

82

GEOGB.APBY OF THE IlEAVENS.

limits of the zodiac, and near enough to the sun's track to be above the horizon with the sun, and to be extinguished by his light. As we approach the north pole of the heavens, we find certain groups of s~s or constellations which never sink below the horizon, and are consequently visible at all seasons of the year. Others, more remote from the north pole, sink below the horizon, and disappear for only Ii. short time. ' As the stars abont the south pole of the heavens never rise above the horizon of any place in our northem latitudes, they are never visible to us ; and to be seen to advantage, the spectator must travel to southern latitudes. The Atlas 'which aCCfompanies this work, contains detailed maps of 'all the principal constellations. involving the stars down to 'the sixth magnitude. inclusive, the principal clusters, nebulm, double stars, &c. The constellation exhibited on any map. is, in general, snrrounded by its bounding constellations, so as to show their relative positions. This necessarily occasions the repetition of certain con~ stellations on several maps. But the inap intended for use, in the study of each constellation, is referred to in the text describing the constellation. As "each judicious instructor will select his own method of teaching the constellations to his classes. it has been thought best not to arrange this work with reference to one invariable plan, which must be followed to render it useful. It is, in gener~. better to study a constellation, when it occupies a position in the heavens far enough above the horizon to render all its sta.rs visible. This can only occur at a eertain season of the year; and as clasl!les will commence the study of astronomy at any convenient time, this work is so arranged that the teacher clln commence at any constellation which may be favorably situated for examination at the

.:aaLUllNART CBAJITBlL

88

time when hilt elas. enterB upOn the study of the heavens. . . In toaehing the confltellatioilll, it ill tertaibly best to CO.lllln81lCe with some one in which the principal .tal'lt are large and brilliant, and thus eaei\y recognized; such as the sta1'8 in U1'8~ MajOl", or In Lyra, or in Orion, or in Tauttlil. Having adopted any point of departure'easily recogniled, it will not be difficult to refer the surrounding cbnstellations to this point, and gradttally to extend the examination until it embraces 'the whole visible beaventl. The mllps present, as nearly as may be, pictures of the heavens, as 88en with the naked eye. A faint outline of the ilgure whos~ name the cons tellatiGh bears, is found on the map; not so prominent 88 to become the striking object, but sufficiently distinct for all useful'pw-poses of reference. These outlines mUllt be retained, as the st~ $re most readily described, and their plac;es found, :by their positions in the constellation. Thus we epeak of the bright star Albireo, in the bill l!f 1M Srvtm; Aldebaran, in the eye l!f tile BvJl, &e.; and by the locality thue given, the eye seizes ·the obj~ on the map at a glance. The parallels of declination al'id the houi' circles have not been drawn on the map, to prevent confusion; but the degrees of declination are marked on the right and left of the map, and the hours of Right Ascension fit the 'top and 'bottom. Hence it is easy to determine, from the maps, the A. R. and Dec. of any object. , . The double stars are at once recognized, on the maps, by being duuble and rtlu:nd, while all other aws are stellated or 8tar-shaped. The nebnlm and clusters-are readily distingUished 88 small faint objects, on tho maps. . We commence with the con8tellation!! upon -and to the east of the prime meridian, &nd' shall trace

84

GEOGRAPHY OF TIlE BEAYENS.

them, in the orderln which they appear to reach the meridian, going e~tward ronnd the celestial sphere. Ali! Greek letters 80 frequently occur in catalogues and tnape of the. stars, and on the celestial globes, the Greek alphabet is here introduced for the ~se of those who are unacquainted with it. The capitals are seldom used for designating the stars, but are here giv.en for the sake of regularity. THB Q:aBBB:

A B,

r A E II B

e

I K A M N

• 0 D p

~

0

-a• 1

C

''I

~

•a. p II

..e •• , p

T T


X

%

• • 0

v

t

+ lot

ALPHABBT.

Alpha . Beta Gamma Delta

Epsilon Zeta Eta Theta Iota Kappa Lambda Mu Nu. Xi

Omicron Pi Rho

Sigma Tau Upsilon Phi Chi Psi Omega ,

a b

!e short z e IODg th i k I m n x oshon P r

s t

u ph ch . ps o long

To find in what,part of the heavens to look for a constellation, at any season of the year and hour of the night, examine the map, and note the meftll right ascension of the constellation in question. Then find by the rule (page 14) the meridian pas-

•

•

PULIMINARY CBA.PTU.

aage of the mean right aaeenaion of the conatellation on the given day. In case the time at which you Beek the constellation. is later than the time of meridian passage, then the center of the constellation has passed the meridian; on the contrary, should it be earlier, the colUltellation is east of the meridian, and its angular dietanC8 from the meri.. dian will be expressed by the differe'RC6 between the time uf meridia1l.1assage of the center point.of the constellation an the time .uf aiJmi1Ultitn&. ExAMPLE.- Where must we look for the constellation Andromeda, at ten O'clock, p. M., on the I flth of October? From Map No.1, the right ascension of the middle point of this constellation is about one hour•

•

• ... L

A. R. of the middle point, =

I 00 00 00

= 10 61 Bum = 11 61

Tab. Nb.. - - - - - - - -

00

Time, 10 o'clock, 1Ubt., - - - 10 00 00 1 61 00

1'he center of the constellation is, therefore, _Ih. 51m. east of the meridian; and as the mean declination, shown by the map, ia about. 40° north, its place may be readily found .in the heavens. It will be well for the student to fix in the heavens Bome standard of measure, in degrees and in hours. Each hour of right ascension contains fifteen degrees of arc. The distance from the zenith to the horizon is .90°, or one quarter of the whole circumference. If this distance be divided by the eye into six equal parts, each of these parts will be U;o. It should be remembered that hours of A. R. are always measured on the equator, and the hour circles' are just 15° apart at the equator, but converge to a point at either pole. Hence the space

•

GQW" O~ TPB JlUUNS.

0"

iBtel'Cepted the parallela of declination by two alijacent; hour circlee, grow smaller the farther the parallel is from the equater, either north or south. In the notices of the double and binary stars, the ~ of the oomponent8, and the angle formed by -a line drawn from the 'center of the larger COi!lponent through the 08nter of the smaner one, with the meridian. counting from the north to the east round the circle, are given, with the date or epoc~ at which the giV8Il cijstance and position· were observed. It is by means of measures of the distan08s and angles of position, that it becomes possible, after many years of observation, to compu~ the curves which the binary stan describe, in their orbituaI motion around their common center o( gravity. In the description of the coJDPonenis, the largest star is called - - - - - 4. The next in size, .,. - - B; and if there be .m~ components than two, as is the case with multiple stars, they are named A, B, C, D, &c., in the order of magnitude. In many instances ,there is a marked dift'erence ill the color of the oomponent8 of double, and multiple stan. Whenever this di1fert'nce is readily recognized, the COlOl8 are given in tJ,te description of the components.

CON8TELLA TlON

or

87

ANDILOIIEDA.

CHAPTER I. DIRECTIONS FOR TRACING THE CONSTELLATIONS MAP NO.1.

O~

AlmaoIRDA. PIWlEUS· BT CAPUT MEDUS&. TIlWfGULYM. CASSJOPBIA.

To TJU.UrGLB.

Favorahly Bilvaled for emmination in Nooem/Jer, ]),.. cemher, and Jan1llU'!J. AND ROM. E D A •

If we look directly over head at 10 o'clock, on the lOth of November, we shall see the constellation celebrated in fable, by the name of AImllOMEDA. It is represented on the map by the figure of a woman having her arms extended, and chained by her wrisbJ to a rock. It is bounded N. by Cassiopeia, E. by Perseus and the head of Medusa, and ·S. by the Triangle and the Nortbern Fish, It is situated between 20° and 50° of N. declination. Its mean right ascension is nearly 15°, or one hour E. of the equinoctial colure. It consists of 66 visible stars, of 'which two arc of the 2d magnitude, and two of the 3d; mOljlt of the rest are small. . I The stars directly in .the zenith are. too small to be seen in the presence of the moon, but the bright star Almaack, marked "I, of the 3d magnitude, in the left knee, may be seen 13° due E., and Merach; marked ./3, of the 2d magnitude, in the girdle,7° south of the zenith. This star is then nearly on the meridiaD, and with two others N. W. of it, form the girdle.

D

'

8~

. GEOGRAPHY

OF THI: HEAV~8.·

The three stars forming the girdle. are of the 2d, 3d, and 4th magnitude, situated in a row, 3° and 4C? apart, and are called,3, 1£. and to. . If a straight line, connecting 'Y with iJ be produced i'outhwestedy, SO farther, it will reach to a, a star of the 3d magnitude, in the left bre8.l:it. This star may be otherwise known by its forming a line. ·N. aud 8., with two smaller ones on either side of it; or by its constituting, with tWI) others, a very small triangle, S. of it. Nearly in a l~ne with 'Y, iJ and a, but curving a little to the N., 7° farther, is a lone star· of the 2d magnitude, in the head, called Alpheratz, or a.·Antltf1Tllella. This is the N. E. cornf\r of the great " Square of Pegasus," to be hereafter described. It will be well to have the position of Alpheratz lVell fixed in the mind, because it is but one minute W. oOhe great. equinoctial colure, or first meridian of ~e heavens, and forms nearly a right line with 0, in the wing of Pegasus, 14° South of it, and with fI, in Cassiopeia,300 N. of it. If a line, connecting these tru'f\e stars, be produced, it will terminate in the pole. These three guides, in connection with the North Polar Star, point out to astronomers the pOtlition of that great circle in the heavens from wnich the right as.cension of all the heavenly bodies is measured. Bode has registered 226 stars in Andromeda. TEL E 8 COP I.e 0 B J E C T 8.

A DOllBLB BT.t.B.-A.R.=Oh.lm.43L Dec.+2500t'2",OD the crown of Andromeda's head, in a coarae clulder. A 10, B 11 mag.. bo&h reported pale blue. According to Sir Williem Henchel, till. .tar .. eurrounded by extensive nebuloaity, exceedingly faint and ditfueecl. No outline has yet been given by even the moat powerful inatrumenl& POlIo 120° 0'. DiaL .".00.· Epoch 1886.81.

+

n AIIDBOXDB.-A. R. = 0 h. 2 m. 2.. Dec. .5° to' 9", a fine double .tar, in the Milky Way, between the left baud of Andromeda and the head of ~ A Ii, B 8 mapitude..

SlatiOllUY,' POlIo 8lio Ii'. Dia. 4".7.

Epech ,1886.

... Alf. .oxu.a.-A.R.=0b.28m.21 ..

Dec.==32°1i0'. A _ _

;iouble alar, 011 the left breast. of Andromeda. A 4i. B. 9 magnitude. S&altiOlUU')" POlIo 17SO 9'. DiaL 36".6. Epoch 1832.110.

TaR GBUT NtBl1L4 Jlf AlfDBO'llJ:D4.-A. R. = 0 b. 34 m. Ii .. Dec. -r 40° 23' 6". Known as fllr back as 905 A. D., and of COUI'llll di.;covered by the naked eye. Besides being the oldest nebula on record, it is the only one fairly visible without the aid of the teleacope; yet to _

+

it requires a keen eye. !!ond a pure atmOllphere. 11 was rediscovered by ~imon MariWl, with the unaided eye, and drst examined by him with the Io!lescope, 011 the 15th Dec., 1612. Owing to the variety in the power of the teleecopea IllIed by different obeervers, in the examination of thiI object, it baa received great diversity of description; IIOIDII call it round, others ovaL CaBBini thOUght it nearly triangular. Sir William Herschel considered this the neareat of all the great nehuIe; on what ground I know not, unlea it be its apperent magnitude. He considers its distance to be about two thouaand timea the distllnce of ~iriU8! and if iSiriU8 be as remote a8 61 Cygni. then would the light of this object require no 1_ than twenty thousand yeara, at twel!!, milliOil milee per minute of time, to reach U& Such periods and distllncea are not more overwhelming than the magnitude of the object undet examilllltion. Great as ~ above distance may appear. in case we are to reprd thia mv.ty ligld as an aggregation of milli0D8 of distant auns, we mUl& sink it ,vaet.ly deeper in epace, to reconcile the hypothelia with the fae& that the atllrs which compoee it have OlIver been revealed by the moat powerful instrumenL ' There is a small attendant, or companion. dilCOVered by I.e Jentil in Nov.. 1749. which baa been pertially resolved into IItars by Lord Ro.e'., three feet Reflector. The drawing was made while under inspection with the twelve inch Refractor of the Cincinnati Obeervstory. '

==

+

86 AlfDBoxu.II.-A. R. 0 b. 46 m. 24 II. Dec. 22D 46' 7". A very cloae double atar. in the right elbow of Andromeda. A 6, B 7 magnitude; both of a golden color. The measurea indicate a biliary ch.aracter. Poe. 3O~0(.' DiaL QI'.90 Epoch 1830.78 Be_hel. 1896.90 . Stri:'ve. 0.937 320 47 1843.12 ~myth. 1 .000 322 9 1 .050 1847.70 MitcheL 330 14 !£ AIfDROJIIllD ••- A . R. = 0 h. 47 m. 53': Dec. -I- 37 q 37' 8". A .. ide double star in the girdle of Andromeda. A 4, 'B 16 IDIlgIli.tude. Poe. 1100 28'. Pist. 49".19. Epoch 184267. Challi& ' 'fhis objtlct ia diJticult, in consequence of the minute size of the

companion.

+

55 A ~nBOIIIRn . .-A. R. ,= 1 h. 43 m. 42.. Dec. = 39'" 56' t". A delicate double star on the left. leg of Andromeda. A Iii, B, 18

40

GEOGUPHY OF THE HEAVENS.

mapitude. Diaovered by BencbeI, ad maJked .. "a IDe apeciJDOD of a nebulOUIIIIbu'." POB. 3600 0'. Dis&. 25".0. Epoch 1832.96.

==

+

" Aifn_ _ n••-A. R. 1 h. 54 m. 06.. Dee. == 4,1 0 33' 8". A magnificent triple IIbu' on the left knee of Andromeda. A 3i, B and C combined make a IIbu' of 6i magnitude. Thill IItar was known to lie double .. '&r back... 1778. The atar was examined and Dleasured .. double by all B\Jbaequent obeerverB down to SUe. Ye, who in 1842, with the great refractor of the Pulkova obIervatory, first divided the BlDafi star into two, making it 1l triple lilt. The distance between the dOlI<' green Itars cannot ellceed 0".4, and to it fairly double requires a moat powerful instrument I ob&ained many _res of this object, ami sucCeeded in dividing the IIlarII, clearly, showing a diflerence in the magnitude of the componentl. The meuures of ang1es of poaition, agree remarkably weD with esch other, and give the pose 11 0° 00'. Dist. 0".4 O. Epoch 1846.6. It is worthy of remark. that the firBt examination. of this object, IDIIIIe

.ee

by myaelf; were with a diminUhed apmure. Theae were imaucceaaful, and it was only after the fuU aperture was employed that the BlarII were desrly divided. This division requires a capital atmllsphere, and a maooth clock motion, for its IIIlCODlplishment. . POB. A to B,82° 9'. Dis&. 10".8. Epoch 1837.80.

+

==

A'JI EW'JI8.tTJIn N ..vu.-A. R. 2 h. III m. 31i.. Dee. == '10 36' 1H. On the right foot, a little above a line drawn from ~ Peraei to " AndrolllelhB, at about two-third. the diatance from the. first atar. It very IDueh reeemb\es an annulus E8Il very obliquely. It wu discovered by Kill Caroline Herachel, in August l783, with a very ordinary reftector, and • power of thirty timeI. The dark IIJIIIC8 along the greater ads, w.. clearly E8II by Sir William Henchel, and he reganIed the object .. an immen8e ring of myriads of IIlarII, 80 remote that their individUl!lliy _ . . WIlIer his greateIt apace-penetrati power. .

PER8EU~

ET CAPUT

MEDU8~.

PBsM is represented with a sword in his right ; hand, the head of Medusa in his left. It is 8itua-' ted directly N. of the Pleiade8 and the Fly. between Andromeda on the W. and Auriga on the E. Its mean declination i8 49° N. It i8 on the meridian the 24th of December. It contains, including the head of Medu8a, 59 8tars, one of which is of the 2d magnitude, and four of the 3d. According to Eu-' dosia, it contains, including the head of Medu8a, 67 stars.

CONSTULATION

or

PERSEU8.41

- - - - - " " p - D8Xt,

Brandiahes high in heaven his IWOrd of flame, And holds triumphant the dire Golgon'. head, Flasbing with fiery makes I the atara he eounta Are Nt~ " and two of theIIe he ~ N obi, refulgent in the aeOOnd rank. One. m his vest, one in Meduaa'. head... .

Tn HB-\D OF MJi:DUSA is nota separate constellation, but forms a part of Perseus. It ilt represented as the tnlDkle.8s head of a frightful Gorgon~ crowned with coiling snakes, instead of hair, which the victor Perseus holds in his hand. Th~re are, in all, about a dozen stars in the Head of, Meduta; two of the 4th magn~tude, and one, varying alternately from the 2d to the 4th magnitude. This remarkable star is called Algol, and marked jJ. It is situated 12° E. of 'Y, in the knee of A~drolJleda, and may be known by means of three stars of the .th magnitude, lying a few degrees S. W. of it, and forming a small triangle. It is on the meridian' the 21st of December; but 88 it continues above the horizon 18 bours out oC 24, it may be seen .every evening from. September to· May. It varies from the 2d to the 4th magnitude in about hours, and back again in the same time; after which it remains &'teadily brilliant for 2! days, when th~ same' changes recur. The periodical v~riation of Algol was determined in 1783, by John Goodricke of York (Eng.) to be 2 days, 20 hours, 48 minutes, and 56 seconds. Dr. Herschel attributes the variable appearance of Algol to spots upon its surfact', and thinks it hail a motion OB its axis similar to that of the m1l. He also observes, of variable stars generally :-" The rotary motion of stars upon their axes is a capital feature in their resemblance to the sun. It appears to me now, that we cannot refuse to admit such a motion, and that indeed it may be as evidently proved as th~diurnal motion of the earth. Dark IIIpots, D2 .

3,

D

GEOGRAPHY OF TIlE BEAVENS.

~r large portions of the surface less luminous than the rest, turned alternately in certain directions either towards, or from 08, will account for all the phenomena of periodical changes in the luster of the stars, 80 satisfactorily, that we certainly need not look out for any other cause." It is said that the famous astronomer Lalande, who died at Paris in 1807, was wont to remain whole nights, in his old age, upon the Pont Neuf, to exhibit to the CUriOO8 the variations in the brilfiaacy of the star Algol. ' ' Nine degrees E. by N. from Algol, is the bright star ~enib, marked A, of the 2d magnitude, in the side of Perseus, which with., Andromeda, makes a perfect right angle at Algol, with the open part towards Casiopeia. By means of this strikingly perfect figur~. the three stars, last mentioned may always be recognized without the possibility bf mill taking them. Algenib may otherwise be readily distinguished by its being the brightest and middle one of a number of stars l)ing four and five degrees apart, in a large semicircular form, \Curving towards Ursa Major. . Algenib comes to the meridian on the 21st December, 15 minutes after Algol, at ~bich time the latter is almost directly over head. When these 'two titars are on the meridian, that beautiful cluster, the Pleiades, is about half an hour E. of it; and in short, the most brilliant portion of the starry hf'a\'ens is, then visible in the eastern hemisphere., The glories of the sC)tlne are unspeakably magnificent; and the student who fixes hie eye upon those lofty mnnsions of being, cannot fail to covet a knowledge of their pr~er and relations, nnd to " reverence Him who Malle the Seven Stars and Orion." The Milky-Way around Perseus is very vivid, bei ng undoubtedly a rich stratum of fixed stars. presenting the most wonderful and sublime phenomenon of the Oreator's power and greatness. Koh-

CONIITELLATION 01' PERIlEUS.

"8

Jer, the .astronomer, observed a beautiful nebula Dear the face of Perseus; besides eight other nebulouscJusters in different parts of the constellation. Bode has registered 196 st8l'8 in this constellatioD. TELESCOPIC OBJECTS.

+

78 M. Paaul.-A. R. = 1 h. 32 m. 18 L .Dec = 50" 46' 5H , an Oftl white nebula, cloII8 to the toe of Andromeda, thougb in the limit. 01 p--. Diacovered by Meehain. Me.ier pIOIlOIlDIled it a com..-J duater; while Hencbel thought it a double me.oIvable nebula. With the Northumberland E9uatorial, Cambridge. E.ug. nhu a 'PfMIl/eil . . pttzrtmt:e. .PnJ( CbaIJia .y." the r.olution ia very doub&fuL"-

A M.... R'II'IC.!fT C£uana.-A. R. .=

• b. 07

m. 68

L

:0-

+ 68 24' 4". In the 8WOld bandle of P _ Tbia ia certainly one cl the m08l. brilliant and beautiful objecta in the heaftna; under _ _ 0

able circumstances, the field of view g10W8 and Iparldee 'With innUlJlllllo diamonds, em a ground dark. and rich .. the bIaekeIl velvet.-In the center, five ItarII are IUT8IIged in the fOrm of a bow IIlrongly bent, while a bright 8th mag. etar ia lituat.ed precileIy at the point where the thumb and fi~ would hold the arrow. Thill cluster ill COIlIidered by Sir W. HeracbeI, and with ~, .. a protuberant portion of the Milky-Way, Of vall stratum Of etIirI of which our own lun ill an indi"idual- With the fuU aperture of the I~ inch R.efractor, all bazDte. dilapJI8Brs, aild the beavena beyond are comp~ly dark and pure. ehowing that the vilion 11M ~rced entirely beyond the limit. of apace Occupied by these atan, and that the interval between them and the neareet group beyond ill 10 great .. to bide them abaolutely from the view. No drawing can give an., idea of the aplendOl' of dliI object. The one which IICCOmlJaniee diia de.:ription Wall taken with care, and givee a correct idea of poaition and relative magnitude, but not of the aparkling beauty of the stara. able

A.

ELOlfOATIID

NKllvu.-A. R. = I h. 30 m. 26

L

Dec.

+ 38° 21' Near the head of Med... Discovered by Herachel, J 788. Thill is probably one of thole ItupendoUl rings of ItarII f(liming

=

• ..,.me univeme, lib oar own, and _

under great obliquity.

/I. Pall.III.-A. R. = 2 h. 33 m. 8. Dec = 48" 32' 9", A Triple etar oil the ·Ieft moulder of P _ . A' 4, yellow; B J 3, violet; C. II, py.-No change in poaition aeema to have occUJ'ftld aince fin& djacovereci by Herachelin 1782. DiaL A to B = 1(/' • A.toC=!l7" • P ..IIIJ,-A. R. = 2 h. 39 m. 6&1.\ Dee. = 56° 13' 5". A double or rtther multiple &tar (IB the head of. PeraeUl. A 6, orange; B 8.\, blue. There are !DID..Y aIaIII in the tield. The principal one baa thrM amall etIirI on one aide, and one on the other, all nearly in the _ aUaight 1ine, and fOrming • miniature of Jupiter and hilllalellliw.

44

GEOGllPHY OJ' THE:REAVENS.

No chaD&e in positian, ,yet ~' .

+

~ PunI, AlgoL-'-A. R. = ~ h. 67 m. 46 I. Dee. = 40· 20' A C081'fIIi donble star in the head of Med\l8ll; on the shield of Pen.eus.A 2 to 4 mill!"' B. 11. Th~ is themllllt wOIIc1erfulllDloDg the Yal'iable BtarB. 1'he rapidity and .regularity of its changes; the great amount of change in brilliancy, and ita double ehamcter, IJl8.rk it as a most extraordinary objeeL-It diminishtis from the 211 to the 4th magnitude in about S~ hours, retains its diminished splendor about 18 minutes, and in 3i ho.urs resumes by degrees its former splendor•...:.Ita period is 2d. 20 11. 48 m. 66&. • PJ:BIBI.-A. R.

=

Herschel.

-t- 390 32' 4", a line' Si, B 9. Discovered by

3 h. 47 m. 08 I. Dee. =

double star near the left leg of Perseua.

A

• DiIt..== 8'.00 Ep. 1780.69 HerseheL A COJl[PBUnD G.ovp.-A. R. = 3 h. 68 m. lis. Dec. = + 49°

POI. = 8° 82'

ew in the left knee of Perseua.-First ~red by Herschel 1790.

TRIANGULUM •

. The Triangle is supposed to have derived its name from'the Egyptian Delta. li.'ormerly there was but one Triangle; a second was added by Hevelius, and is retained on the map. , The Triangles are situated between the head of Aries, on the south, and the knee of Andromeda, on the north. They contain one star of the third, and one of the fourth magnitude. The other' stars are small. Ptolemy reckoned, in this constellation, foui' lltars ; Hevelius, nine; Piazzi, twenty-fh'e; and Bode has registered thirty-three stars. Most of them are telescopic. . TELESCOPIC OBJE CTS .•

+

°

A L4aaJ: )'AIlIT N ..17U-A. R. = 111. 24 m. 611. Dec. 29 61' 03"; between the head of the Northern Fish and the TrlaDgle. Discovered by MtlIIier, 1764; IIlIIOIved by Herschel, 1783, into minute stus. He locates this object in the 334th order of distances, or reganIsit aa 334 au- more remote than BtarB of the tim magnitude.

CONSTELLATION 01' CASSIOPEIA,

"

+

• Tau.lf8I1LI.-A. ft.=1 h. 63 III. 88.. Dee= H" 30' INY', A eboe double II&ar on the triangle. A IIj, B III, mag. Diacmend '" 8tr~:-

Pc.. lU'o f1

Dial.

== (/'

Epoch 1881i.711 Smyth.

+

Tau.lfIJI1LI.--A. R. = 2 h. 8 III. 08.. Dec. = 29°SS', A ebe double 1I&ar, un. . the bue CJfthe triangle. A II~," topaz yellow," B 7, .. green." DiKoYend '" H8IICbeL a..-t _ u _ indicate hity in the compOnents. ' POll. 77" Iif1 Di8t. 80".1198 Epoch 1830.97 Struve. . I

=+""

A CWII: Douau &r.....~A. R. ==2 h. J9 III. th. Dee. 12' 05". Between the Fly and Triangle. A 61, B 10. Dia:overed '" 8&r'."ftI. ' POll. MOO 4f1 DiA. 1",808 Epoch 1882.86 &,uve.

CASSIOPEIA.

This consteJlation is situated 26° N. of Androm· eda, and midway between it and the North Polar Star. It may be seen; from our latitude, at all hours of the night, and may be traced out at almost anl season of the year. Its mean declination is 60 N. and its right ascension 12°. It is on our meridian the 22d November, but does not sen~ibly change its position for several days; ,for it should be remembered that the apparent motion of the stars becomes slower and slower as they approximate the poles. . Cassiopeia is a beautiful conl!tellation, contain· ing 55 stars that are visible to the naked eye; of which one is of the 2d and four are of the 3d mag· nitude, and so sit\1ated as to form, with one or two smaller ones, the figure of an inverted chair. ---,,---" Wide her atan. Dispened, nor imine with m1UUal aid impnrted i , Nor duzIe. brilliant with eomipouII8ame :

Their number fifty-Ave."

46

GEOGRAPHY: OF THE HEAVENS.

Caph, J3 Cft8siopeill, in the garland of the chair, is almost exactly in the equinoctial colure, 30° N. of Alpheratz, II Andromeda, with which, and the Polar Star, it forms a straigh.t line. Caph is therefore on the meridian the lOth of November, and one hQur past it on the 24th. It is the westernmost star of the bright ·cluster. Schedir, 0/ CasE!iopeia, in the breast, is the uppermost st!lr of the five bright ones, and is 5° S. E. of J3 : the other three bright ones, forming the chair, Bre easily distinguished, as they meet the eye at the fint glance. There is an importance attached to the position of J3 that concerns the manner and the surveyor. It is used, in connection with obilervations on the Polar Star, for determining the latitude of places, and for discovering the magnetic variations of the needle. It is generally supposed that the North Polar Star, so called, is the real immovable pole of the heavens; but this is a mistake. It is 80 near the true ~ole that it has obtained the appellation of the North Polar Star " but it is, in reality, more than a degretl and a half distant from it, and revolves about the. true pole every 24' hoUl'B, in 'a circle whose radius is 1°' 31'. It will ~onsequently, in 24 hours, be twice on the meridian" once ohove, and once heZOID the pole: and twice at its greatest elongation E. and W . . The polar Star not being exactly in the N. pole of the heavens, but 01Ie degree and 31 minutes on that side of it which is towards Caph, the. position of the latter becomes important, as it ~lways .shows on. ' which side of the true ,pole the polar star is . . There is another important fact in relation to the position of this star. It is equidistant from the pole, Hnd exactly qpposite another remarkable star in the .<;quare of the Great Bear, on the other side of the pole. It also serves to mark a spot in the litarry

C'ON8TELLATION OF C,uSIOPBIA.

47

heavens, ren~ered memorable 88 being the place of a lost star. Two hundred and sixty-six years ago, a bright star shone 5<> N. N. E. of Caph, where now is a dark void I On the 8th of November, 1572, Ty~ho Brahe and Cornelius Gemma.saw a star· in the constellation of Cassiopeia, which became all at once, so brilliant, that it surpassed the splendo.r of thp. brightest planets, and; might be seen even at noonday I Gradually, this grea.t brilliancy diminished, until the 15th of March, 1573, when,' without moving from its place, it became utterly extinct. . Its color, during this time, exhibited all the phe.nomena of a prodigious flame-first it was of a dazzling white, then of a reddish yellow, and lastly of an ashy paleness, in which its light expired. It is impossible, says Mrs. Somerville, tQ imagine any thing more tremendous than a conflagration that could be visible at such a distance. It was seen for eixteen months. Some a&tronomers imagined that it wo~ld reappear again after 150 years; but it has never heen discovered since. This phenomeno~ alarmed all the astronomers of the age, who beheld it; and many of them wrote dissertations concerning it. Rev. Professor Vince, one of the m08t learned and pious astronomers of the age, has this remark :"The disappearance of some stars may. be the destruction of that system at the time appointed by the DEITY for the probation of its inhabitants ; and the appearance of new stars·may bp. the formation of new systems, for. new races of beings then called into existence, to adore the works of their Creator." Thus, we may conceive the Deity to have been employed from all eternity, and thull he may continue to be employed for endless ages; forming' new systems of beings to adore him; and trans-

t8

GEOGRAPHY

or

THK HEAVENS.

planting beings already formed into happier regions, who will continue to. rise higher and higher in their elijoymeilts, and go on to oontemplate' system after system through the boundless univers~. LA. Puc. says :-" As·to those stars which suddenly shine forth with a very vivid light, and then immediately disappear, Uie extremely probable that great conflagrations, produoed by .extraordinary . oauses, ·take plaee on their surface. This coujecture, is confirmed by their change of oolor, .which is analogous to that presented to us on the earth by those bodies which are set on fire and then gradually extinguished." The late eminent Dr. Good. also observes that" Worlds and systems of worlds are not only perpetually creating, but also perpetually disappearing. ,It is an extraordinary fact, that within the period of the last century, not less than thi~een stars, in different constellations, seem to have totalJy perished,. and' ten new ones to have bee~ created.. In, many instances it is unquestionable, that ~he st81'8 themselves, the supposed habitation of other kinde or orders of intelligent beings, together with the different planets by which it is probable they were surrounded, have utterly vanished, and the spots which .th~y .Occupied in the heavens, have become blanks I What has befallen other systems, Will assuredly befall our own. Of the time and the manner we know nothing, but the fact is incontrovertible; it is foretold by revelation; it is inscribed in the heavens;. i.t i, felt thrOugh the earth, Such is the awful and daily text; what then ought. to be 'the comment?" The great and good Beza, falling in with the luperstition of hid age, attempted to prove that this was a comet, or the same luminous appearance. which conducted the magi, or wise men of the East,

,CONSTE1.LATION

49

OF CASSIOPEIA.

into Palestine, at· the birth of our Sav~our, and that it now appeared to announc~ his second coming I About 6° N. W. of Caph, the telescope reveals 10 us a grand' nebula of small stars, apparently compressed into one mass, or single blaze of light, with a great number of 100s6 stars surrounding it. TELESCOPIC OBJECTS.

LoqaJl CLveTu.-A. R. == 0 b. 18 m. 10.. Dec. + 70" 30' 3". RegiIItered by Sir Jno. Hencbel, and by bim regarded .. • good teet for the light and defining power of a teleecope. It ie lit-

=

A LU8J1

.Un!

WIled between the tOot.tocllllld the knee of CepheWl, .

.

A CLOBJI DouaLa BT.....-A. R. = 0 b. 38 m.68 e. Dee = 600 :w 2." Between Andromeda'1 knee and the heed of CBSBiopeiL A 7i

B I mag.

p_ 1470 2 146 25'

.

Diet. 2".3 2

.~

Epoch 1832.87 Smyth. IH47.60 Mitchel.

The reJatiOllBbip ie merely optical

+

• C.u.lOPIIU.-A. R.=O b. 39 m. 27.. Dee. 56° 57' 9". A binary ater in the CeetwI of CBSBiopei... A 4 peIe white,.B 7i purple, IMcovered by Henchel,' . . . 1779, when ita position was 620 04 Diet. 1\".27 1843.19 the meaIUI1lII.pve 95 08 9.1 Smyth. 1847.60 101 20 8 ·59 MitcheL M:idler tbinb the periodic time of this eyatem will be about 5¥2 yean. p. C.I.8IJOPJlu...-A. R.=O b. 57 m. 23.. Dee. MOO' 8". A COIIlIIII triple ater on the right elbow, ~ of an extraordinary proper m0tion, amounting to 5".8 in A. R. and 1".55 in Dec. per annum. In Cue we locate this ater at the distance fiom our system due to its magnitude, its hourly motion cannot be less than 125,000 milea I a quantity IBr exceeding the velocity of the ~ moving p1~

A Loon CLUIT...-A. R. = 0 h. 69 m. 19.. Decl. ' \f- 6()o 44' 0". below the right hip of CBSBiopeia, on the robe, one quarter way on the line joining ,. and .. It was discovered by Miss Caroline Herschel, in 1783, and ie deecqbed by Sir William as ~ a cluater of pretty COJIlIlla' Ed 1IIarIJ." .

=+

A SllolLL DoURLJlBT.lll.-A. R. = 1 b. 9m. 10 .. Dec. /i'/'O 1\6' 9", Between the right knee. and elbow of CBSBiopeia, A 9. B 10 magnitude.-'J'his oi!ject ill situated in the center of a brilliant_mblage of small &tara discovered by Henehel 1787• .,. C.I.88JOPJI'A.-A. R.

•

E

= 1 b. 14 m. 42..

Dec. -:

+ 6'/'0 17' fI'.

60

GEOGRAPHY OF THE HEAVENS.

A line triple star cbe to the 1 _ put of CIIIIiopaia'. throne. A 4, orange. B 9 blue. C 11 reddiIIb. DiscoveTed by !Strilve. 1020 01' Dis&. 81".9 Epoch 1836.28 Smyth. 262 36 2 .0 1836.:l8 Smyth. 102 37 30 .394 18~7. 70 . MitcheL 253 07 32 856 1837.70 . Mitchel. This oIiject may be found between the noith star and I CllSIIiopeia, at a little _ than' one-third of the distance which separates them nom the laUer 1Itar. ' Poe. A. B. B. C. A. B. B. C.

+

A.. 0 ... CL17I1TJ:R.-A. R. = 1 h. 18 m. 61.. Dec. = 61 0 27' 8". On the lady'. leg, half way wm I to 1" Deecribed as .. a pthering of amall and large etan, with gIim~ of star d\lllt of collllidarable extenL"

==

+

A CL17IT. ...-A. R. 1 h. 33 m. 06.. Dec. = 61 0 04' 9". JUIIt below the. right knee of Cuaiopeia. mid-way. between I and., Diseovered by Herachel. 1787. It is IIOID8 2' or 3' in diameter, and baa an 8! magnitude star in the center. 66

CU810PllB.-A.

R.

= 2 h. 2 m. 0 L Dec.

+ 65

0

46' 2".

A

star with two distant companion.-Iocated very near the position in the

heavens in which the celebrated r&tW ,tar of 1672 made ita BUdden and , brilliant appearance. The first.Bight of this moat extraordinary stranger, seems to have been caught by Schiler, of Wittemburgh. as early as the 6th of August, 1672. On the 11th ofNOVIlIIIber, following, the celebrated Tyeho BraM, on returning to his house wm his laboratory, was surprised to _ 80me peasants gazing up in the heavens. He lOOn discovered the oI!ject of their curiosity to be a IwiJIiIInt Btar, which he bad never before .en. His finely stocked observakllY, gave him an opportunity of obIlerWig the stranger with great aoouracy. He 'lOOn determined that it was located beyond the region of the planets, and even among the fixed stant, as it had no sensible parallax, and never changed its position during the time it remained visible. The brilliancy of this object increased from the time of ita diacoYel)', until it ~ that of Sirius, the brightest of all the fixed stan, and even came III be acarcely 1_ than that of VenUll, the moat brilliant planet. Having attained its maximum brilliancy, it began to decline by degrees, losing its splendor, until finally, in March 1574, nin~ teen montha after its discovery, it disappeared for ever from the sight. This being the first change in the region of the fixed atara, since the revival of letters in Europe, created a great sensation, and produced 8 great variety of pub1iabed accounts. Strange as it may appear, at this day, Tyebo was ashamed to pub1iab his o~tions, to the world, conBidering it .. a diegrace, for a nobleman, either to study 80eb subjects, or to publish them to t8e world!' ~ • These new and tempora.". stan, are among the inscrutable worb of God. No intellect, however great, no study. however profound, baa yet hemP able to tathom theirmyaterious coming and going. Some ha?e ~ the idea that they are moving in exC88lli.vely elongated orbit"t

•

61

CONSTELLATION OF CASSIOPEIA.

whose principal axee are tumed directly towards our own system, and Chat it ia only in their JleIII'I!IIt approach to the earth that they become ftIible. In COJl8elIuene8 of the ~ appearance of Dew Itar8, in the _ region, in 946 and 1264, BirJohn Herachel baa IIIggeIIted that thi8 may be a periodical star, with a retum after intervals of about thn!e

hundred YeaJII. . It C8II8 we estimate the ?elocity of thia IItar in ita orbit, by the dimipution of ita light, we IIhall find it moving at 110 ltupendous a rate as to lI&un the irnagination-and we are a1moet driven from a theory requiring lII1eh motion. If we yield to the suggeetion of Besee\, that there exist
+.

A BUUTlFlTI. TBTPLJ: &r.n.-A. R. = 2 h. 15 m.1i8 8. Dec. 66° 40' 7". Under CII8IIiopeia'. right foot, mid-way between /II. Pemei and ,. Cephi. A ti pale yellow B 7 lilac. C 9 blue. Poe. A. B. 2740 2 Diet.' 2".1 183483 Diet. 7.6 1834.83 A. C. 107 1 No change in poaition or distanee baa been remarked Bince the di8covery by Heracbel, in 1779.

+

A MULTlPLJ: BuB.-A. R. = 23 h. !l2 m. 40.. Dee. 670 40'. One of the stanI WIll diacovered to be clOIIIto double, by the Hm. W. R. Dawes, J840. " . Pos. 2220 DiaL 1".6

+

6 CA.8S10PJ:I~-A. R. = 23 b. 50 m. 56 8. Dec. = 6to 61', 8". A fine double star on the left elbow. A 6. B 8. magnitude. 'The large IItar is white, the emall'one blue, with colora said to be clear and distinct.

--DIRECTJONS FOR TRACING THE CONSTELLATIONS ON

MAP NO. II. PISCES.

THE FISHES.

Favorably sitUated for examination in October, NotJemher and December. . • THE FISHES.

THIS constellation is now the first in order, of the

52

GEOGRAPHY OF THE HEAVENS.

12 constellations of. the Zodiac, and is ul'ually represented by two fishes tied a considerable distance apart, at the extremities of a long undulating cord, or ribbon. It ~ccupies a large triangular space in the heavens, and its outline at first is somewhat difficult to trace. In consequence of ·the annual precession of the I!Itars, the constelloJ.i07l. Pisces has now come to OCPJlPY the sign Aries; each constellation having advanceu one whole sign in the order of the Zodiac. The sun enters the sign Pisces, while the earth enters that of Virgo, about the 19th of FebruarY, but he does not reach the constelloJ.iun. Pillces before the 6th of March. The Fishes, therefore, are now called the "Leaders of the Celestial Hosts." . That loose assemblage of small stars directly south of Merach, A, in the constellation of Andromeda, constitutes the Northern Fish, whose mean length is about 16°, and breadth, 7°. Its mean right ascension is 1 h, and its declination 25° N. Consequently, it is on the meridian the 24th of No~ vember; and, from its breadth, is more than a week in passing over it. The Northern Fish and its ribbon, beginning at II, Andromedre,may, by a train of small stars, be traced, in a S. S. easterly.direction, tor a distance of 33°, until we come to the star El Rischa, II Piscium, of the 2d magnitude, which is situated in the node, or .flexure of the ribbon. This is the principal star in the constellation, and is situated 2° N. of the equinoctial, and 53 minutes east of the prime meridian. From II Piscium the ribbon or cord makes a Hudden flexure, doubling back across the ecliptic, where .we meet with three stars of the 4th-magnitude situated in a row 3° and 4° apart, marked on the map " I, a. From a the ribbon runl' north and westerly along the Zodiac, and terminates at the tail of the Western Fish. The head of the fish may be

OONSTELUTION 0., PISCES.

recogniJled by the star IJ, 4th magnitude, 111'\ louth of .. Pegasi. . . This part of the ribbon, including the Western Fish at the end of it, has a mean declination of 5° N., and may be seen throughout the month of November, passing the meridian slowly to the W., near where the sun pasS611 it on the lBt of April. Twelve degrees W. of this Fish, there are four small stars situated in the form of the letter Y. The two Fishes, and the cord between them, make two sides of a large triangle, 30° and 40° in length, the open part of which is towards the N. W. When the Northern Fish is on'the meridian, the Western is nearly two hours past, it. This constellation il bounded N. by Andromeda, W. by Andromeda and Pegasus, S. by the Cascade, and E. by the Whale, the Ram and the Triangles. . When, to enable the pupil to find any star, its direction from another is given, the latter is always understood to be on the meridian. ' After a little experience with the maps, even though unaccompanied by directions, the ingenious youth will be able of himIJelf, to devise a great many expedients and facilities for tracing the constellations, or selecting out particular stars. TELESCOPIC OBJECTS. 179 P.

xxru

PiBcium.

==

==

23 h. 37 m, 49.. Dec. 0"'37' .".' Under the p..-Jing Fiah, mid-way between FOIIIIIhaux aDd ~ CBllliopeia. A 8i. B 15 magnitude. , Diaeovered by M. Str;:'ve. . Po& 2280 23' .Di&. r.417 Epoch 18:12.50 StriiYe. 230 00 3 .000 , 1833.79 Smyth. 227 33 '2 .702 1847.66 Mitchel. Theee, m~18I idIiml no evidence of change. Thoee of Smyth . . A DST.IC4TJ1 DOUBU BTAR_A. R.

-

mere eatimltiODll.

'

+

34 PI8CIU.":-A. R. = 0 h. 1 m. 63.. Dec. = 100 14' 8". 'A fine double star, Dell the wiDr of p..... A 8. B lSi mapitnde. DiBcovered by Striive.

52

54

GEOGRAPHY OF THE HEAVENS.

POll. 160" 08' .

DilL 8".87

Epoch 1828.73 &ril_.

+

38 PIICUI••-A. R. = 0 b. 9 m. 9 •. Dec. = '[069' Ir. A double liar on the &ip of the tail of the ~ Fiah. A 7!. B 8 magnitude. . ' Discovered by Herachel, 1782. POll. 244,0 67' DiaL = 4".00 Epoch 1782.68 235 64 . 4 .80 18:i7.89 19rnyth. 235 li9 4,646. 1847.65 . MilcheL These last o~ _ to decide the fixity of these sIarI. . .

=+

49 Prsc1I1•.-A. R. = 0 b. 22 m. 29 110 Dec. 160 09' 2". A' difficult d~e sIar, ·between the wing of P . - and the right hand of Andromeda. A 7. B 13 magnitude. . . .' Discovered by Struve, and thus messured by hilldn November 1828 • . Poa.: 1070 42' DilL 13".26

=

=+

0 b. 81 m. 31.. Dec. 200 33' 6". 65 PJICJu••~A. R. Be'tWeen the head and right band of. Aildromeda. A 6, orange. B 9, dee"p blue. Diacovered by Striiyeo POll. 1920 4f1' Diat. 6".37 Epoch 1830.22 StrUve. 191 52 7.014 1847.65 Mitchel. '!'here is no. evidence of binary character, and uw.·is doubtless all optical duplicity merely. . 65 Pllcun._A. R.

=

0 h. 4l m. 18 I. Dec.

=

+ 26" 50' 3".

A

dose double sIar on the right arm of Andromeda. A 6. B 7 magnitude. Discovered by Sir W. Herschel, who made the followipg measurea. POlIo 3000.57' .Diat. 4".00 Epoch 1783•.15 298 30 4 .60 1838.17 Smyth. 297 32 1847.65 Mitchel. Henchel thought there might be physical eonnection between the com ponents in ~ set. If 10 the period will be very greet. .

=

=+

., pJlcun• ..--A. R. I b. 5 m. 4 110 Dec. 23° 44' 1". lbe ventral fin of the Northern Fish. A 6, B 13 mag. DUicovered by Str'lve, and thus measured POlIo 2:17° '52'. Diet. 7".98. Epoch 1832.06.

OIl

+

{ PrscI1JJI.-A. R. = 1 b. .5 m. 21 110 Dec.::;: 60 43' 7". A _ _ double sIar on the bend of the band joining the two Fishes. M::d1er ranks this &n1ODg the IItanI in which there is a probable retrograde

.

~u~

POll. 670 23' 63° 31'

=

DiaL 22".187 23".226

Epoch 1781.88 Herschel. 1841.57 M;odler.

=+

A. R. 1 h: 27 m. 41.. Dec. 60 49' 6". A close double sIar in the space between the two Fishes aDd the curve of tke Ribbo~ A 6! ylillowish, B 8 psIe white. Diacovered by Herschel, 1792POI. 200 00' DiaL 1".467 Epoch 1830.13 Strr._

CONSTELLATION OF PISCES.

A. R. = 1 h. Um. 88L Dec. = 1° 03' r. A c10Ie double . . at the end of the Ribbon. A 7, B 71. . Diaccmnd by 8\ru ve, and thUl IIIIIIIIIUIed by him. POll. MO .1' DilL 1".282 Epoch 1831.'11.

=

=

" PI8cnn••-A. R I h. 63 m. ~6 L Dec. 10 59' 3". A clOlll doable IItar at the IIOUtheru extremity of the Ribbon; A 6, pale green. B 6, blue.

Poa. 3370 23' Dial Epoch 17S1.79 HeracheI. 3".775 1830.93 BeMeI. 3320 611' 331 0 W 3".733 1831.60 Miiodler 330° 03' 1847.66 Mitchel. . Mii.dIer, after a full m.cu..ion of all the ohlemationa, tbiub a retr0grade mo&ion ill probable. and a period of revolution amoUDting to about 6000 years. 'IiIMe lIIowly-revolving objecta require clOlll !,xamination ; my own _ go to confirm, in _ degree, Madler'. opinion.

+

NJ:BVLIo.-A. R. = 23 h. 06 m. 36 L Dec. = SO In the eye of the preceding or western Fish. Ita length is 4 , and ite breadth 1', according to ite diaco_. It is p..-Ied by a filinter nebula. Th_ ol!jecta are very difficult in any but the.JllOll powerful instrumente. Diaeovered by HencbeI, 1786. A'

39'

F.l.IlIT

or'.

DIRECTIONS FOR TRACING THE CONSTELLATIONS ON

MAP NO. '111.

AllIES. THE RAM. FatJ07'fihly situated for emmi7UZtion in Nooember, December, and Jan'ULl.T'!J. THE

R~M.

TWENTY-TWO centuries ago, as. Hipparchu8 informs us, this constellation occupied thefirst sign in the ecliptic,. commencing at the vernal equinox;. ' But as the constellations gain about 50" on the equinox, at every revolution of the heavens, they have advanced in the ecliptic nearly 31° beyond it, or more than a whole sign: so that the Fishes now

6.

GEOGRAPHY OF TH~ HEAVENS.

occupy the same place in the Zodiac, that Aries did, in the time of Hipparchus; whence the ctm8teUotiun, Aries is now in the sign Taurus, Taurus in Gemini, tt.nd Gemini in Cancer, and so on. . Aries is therefore now the second constellation in the Zodiac. It is situated next east. of Pisces, and is midway between the Triangles and the. Fly on the N. and the head of Cetus on the S. It contains 66 stars, of which, one is of the 2d, one of th~ 3d, and several of the 4th magnitudes. "First, from the east, the Ram conducts the yev:; Whom Ptol~my with twia nine stara adol1lB,

Or which tWo only claim the Second rank ; The rest,. when Cynthia lills the sign, are l~"

It is readily distinguished by means of two bright stars in the head, about 4° apart, the brightest being the most north-easterly of the two. The first, which is of· the 2d magnitude, situated in the right horn, is called .i Arietis, or simply Arietia; the other, which is of the 3d magnitude, lying near the left horli, is called Sheratan, j:J Arietis,' and may be known by another star of the 4th magnitude, in the ear, ItO S. of it, called Mesartkim, 'Y Arietili!, which is thefirst star in this constp.llation. . Arietis and Sheratan, are one instance out of many, where st.ars of more than ordinary brightness are seen together in pairs, as in the Twins, ~he Little Dog, &e., the brightest star being commonly on the east. The position of' Arietis affords important facilitie!!l to nautical science. Difficult to comprehend as it may be, to the unlearned, the skillful navigator who should be lost upon an unknown sea, or in the midst of the Pacific ocean, could, by measuring the distance between Arietis ·and the Moon, which often passes near it, determine at once not only the ~PDt he was in, but his true eourseand distance to any

known meridian or harbor on the earth.

CONSTELLATION OF ,ARIEl!.

&7

Lying along the moon's path, therl'l ftre nine conspicuous stars that are used by nautical men for determining their longitude at sea, thence called 'tUZfdicoJ stars. . These stars are Arietis, Aldebaran, Pollux, Regulv, Spica Vir:ginis, Antares, Altair, Fomollw.ut, and MarkolJ. The true p1at'f18 at tOO. slant, fur every day in. the year, are gi"en io the Nautical Almanac, a valuable work published anoually by the I nglilIh "Board of Admiralty.". to guide marinen in navigating the Sl.'a& They are usually publiahed two or three yean in advance, for the bene1ii of long voyages. . • That a man, .y. Sir John Herschel, by merely meuuring the mooo', appareot Ililqnee from a I&ar, with a little portable inatrwneot held in his hand, and applied to his eye, even with 80 unlllable a footing as the deck of a ship, sha1l .y positively within five miles. where he is, 011 a boUIl..... leas ocean, cannot but appear to persons ignorant of phyaical astronomy, an approach to the mimculous. And yet, .y. he, the alternatives of lilB and death, wealth and ruin, are daily and hourly stalr.ed, with perfect CQQfidence, on tOO. marvelous computations. Capt. Basil Hall, of the royal navy, relates that he had lIIiIed from San BIas, 00 the west COIIIIt of Mexico, and after a voyage of 8000 miles, ooc:upying eighty-nine days, arrived oft" Rio Janeiro, having in this inte~al ~ through the Pacific ocean, rounded Cape Hom, and ~ the South Atlantic without making any land or seeing a Iingle.1IIiI 00 the voyage. Arrived within a few day.' IIIiI of Rio, he took a set nf lunar obIervatiOll8, to aseertaio his true poaitiim. and the bearing of the harbor, and shaped his coune accordingly. "I hove to," ay. he, "at four in the morning, till the day should break, and then bore up; iIr although it was hazy, we could _ before us a couple of miles or 80. About eight o'clock it became 80 foggy that I did not 1iIte to stand in further. and was jwJt bringing the ~ the wind again before aending the people to bresk&at, when it y cleared oft; and I had the satisfiletion of _ jug the great Sugar-Iosf rock, which stand. 011 one side of the harbor'. mouth, 80 nearly right ahead that we had not to alter our coune above a point, in order to hit the entrance of Rio. 'I'his was the lint land we had seen for three months, after ClOIIIing 80 ID!lDY -.. and being set backward. and forwards by innumerable l:urrenta and foul winda."

Arietis comes to the meridian about twelve minutes after Sheratan, on the 6th December, near where the sun does in midsummer. Arietis, al~o, is nearly on the same meridian with Ahnaack, in the foot of Andromeda, 19° N. of itl and culminates only four minutes after it. The other stars in this constellation are quite small, constituting that 100S6

68

GEOGRAPHY OF THE HEAVENS.

cluster which we see between the Fly on the north, and the head of Cetus on the solith. : When Arietis is on the meridian, Andromeda and Cassiopeia are a little past the meridian, nearly over heQ.d" and Perseus with the head of Medusa, is as far to the east of it. Taurus and Auriga are two or three hours lower down; Orion appears m the S. E., and the Whale. on the meridian,just below Aries, while Pegasus and the Swan are seen half way over ,in the west.

The

manner in which the ancients divided the Zodiac Into twelve equal parts, was both simple and ingeniouS. Having no instrument that would meuu:re time exact1y, " They took a v_I, with a small hole in the bottom, and having filled it with water, IIUfi'ered the aame to distill. . drop by drop, into anoth.er ve.e\ set beneath to receive it, beginning at the moment when IIODI8 star rose, and continuing till it rose the next following night, when it would have performed one comp\et.e revolution in the heavens. The water fiilling down Into the receiver they divided into twelve equal parts: and having twelve other small v_Is in neaa, each of them capable of containing one part, they again poured aU the wat.er into the upper v~ and ohiIerving the rising of some star in the ,Zodiac. at the same time suftered the water to drop into one of the lInall vesaela. And aa soon aa it was full, they removed it, and set an empty one in its place. Jullt aa each _ I waa full, they took notice what &tar of the Zodiac roae at that time, and thus continued the proces8 through the the twelve _ I s were filled." , 'rhus the 'was divided into twelve equal porticms, corresponding to the twelve months of the year, commencing at the VfIJlal equinox. Each of these pomona served aa the vialble IIlJIr686ntative or Iign of· the month it appeared in. All those stars in the Zodiac which were observed to riee while the first vessel waa filling, were ClOI18Iellated and ~uded in the first sign, and called .Ariu, an animal held in great ellteem by the shepherds of Chaldea. All those stars in the Zodiac which roae while the second ve.e\ was filling; were· conIIteUated and included in the second sign, which for. similIl' reaaOna, waa denominated TIJIIfW; and all those staN which were observed to riee while the thUd _ I waa filling, were conatellated in the third aign, and called Gemini, in allusioD to the twira _ _ of the flocks. . ThUB each sign of BOO in the Zodiac, received a distinctive appellation, according to the limcy or supentiticm of the inventors; which names have ever sinee been retained, although the conatellationB themselves have aee left their nominal signs more than 30 0 behind. The sign A riea, therefore, included all the atara embraced in the 'first 300 of the Zodiac, and no more. The aign Taurus, in like manner, included all those stars embraced in the next 300 of the Zodiac, or those betwl!6n 300 and CillO,

ream-

C:til

CON~TELLATWN

OF PISCES.

59

and 80 of the rest. O! thoee who imagine that the twelve constellations of the Zodiac refer to the twelve tribes of Israel, lOme aacribe Aries to the tribe of Simeon, and others, to Gad. During the campaigns of the French anny in Egypt, General Dessaix discovered among the ruins at Demlera, near the banks of the Nile, the great temple suppoeed by lOme to have been dedicated to leis, tbe femate deity of the Egyptians, who believed that the rising of the Nile W88 OCC&Sioned by the tears which ahe continually shed for the 1088 of her brother Osiris, who was murdered by Typhon. Others suppoee this edifice W88 erected for astronomical purpoeea, from the circumstance that two Zodiau were discovered drawn upon the ceiling, on opposite sides. On both these Zodiacs the equinoctial pointe are in Leo, and not in Aries; from which it has been concluded, by thoee who pertinaciously endeavor to array the argumente of science against the chronology of the Bible and the validity of the Mosaic account, that these Zodiacs were constructed when the sun entered the'sign Leo, which must have been 9720 years ago, or 4000 years before the inspired account of the creation. The infidel writers in ,France and Germany, make it lU,OOO years before. But we may "llet to our aea!," that whatever ill true in fact and correct in inference on this subject will be found, in the end, not only col1sistent with the Mosaic record, but with the common meaning of the eJlpreSsions it uses. The discovery of Champollion has put this CJ.uestion for ev.er at rest; and M. Latronne, a most learned antiquary, has very IIIIl:isfiIctorily demonstrated that these Egyptian Zodiacs are merely the horoscopes of distinguished personages, or the precise situation of the heavenly bodies in the Zodiac at their' nativity. The idea that such was their purpose and origin, first suggeSted itself to this gentleman on finding, in the box of a mummy, a similar Zodiac, with II1,lch inscriptions and characters 88 determined it to be the horoaCope of the d~ person. Of all the diacoveries of the antiquary among the relics of ancient Greece, the ruins of Palmyra, the gigantic pyramids of Egypt, the temples of their gods" or the sepulchres of their kings, acarcely one 80 aroused and riveted the curiosity of the learned, 88 did the diacovery of Champollion the younger, which der:ipktn the hUrog(lJPhiu of ancient Egypt. 'rhe potency of thia invaluable diacovery has been signally manifested in settling a formidable controversy between the champions of infidelity and thoee who maintain the Bible account of the creation. It has been shown that the constellation PiM:u, since the days of Hipparchus, has come, by reason of the annual precession, to occupy the same apparent place in the heavens that Aries did two thousand yeam ago. The Christian ptronomer and the. infidell\l'8 perfectly agreed as to the fad, and the amount of this yearly gain in the apparent motion of the &lara. They both believe, and both can demonstrate, that the fixed IItara have gone forward in the Zodiac, about 50" of a degree in every revolution of the heavens since the creatiQll; 80 thAt were the world to 6ght upon any authentic inBcription or record of past agetI, which should give the true positiOIl. or longitude of any particular star at that time, it would be easy to Ai an unquestionable date to auch a record. Accord-

already

60

GEOGRAPHY OF THE HEAVEN8.

ingly, when the WnoUB .. Egyptian Zodiacs," which were IICUlptured OIl the walla of the temple at -nendera, were brought away en ""'11#, and exhibited in the Louvre at Parie, they enkindled a more ex citing intereat in the thOlllllUlds who laW them, than ever did the entrance of Napoleon• .. Educated men of every order, and those who had the vanity to think themselves sw:h," .YI the commentator of Champollion, .. rushed to t . hold the ZodiDu. These Zodiacs were immediately puhliahed and commented upon, with more or 1_ good faith and decorum. Science IIIruck out into lysteiDa very bold; and the Ipirit of infidelity, seizing upon the diacovery, lIattered. itaeIf with the hope of drawing from thence new 1Upport. It was .unju8t:ifiably taken for granted, that the ruina of Egypt furnished astronomy with monuments, containing observations that exhibited the state of the heavens in the IIIOIIt remote periods. Start:ini with this IUIIWJIpt:ion, a pretense was made of demonstrating, by means of calculations received as infallible, that the celeal.ial appearances assigned to these monuments extended back from forty to sixty-five centuriea ; that the Zodiacal system to which they must belong, dated back fifteen thousand years, and must reach far beyond the 1imita asaigned by Moaea to the exiatence of the world." Among those who stood forth more or 1_ bold as the adveraarieol of revelation, the IIlO8t prominent was M. Dupuis, the famous author of L'origine tk tow 1u Cultes. The infidelity of Dupuis was spread about by means of pamphlets, and the advocates of the MOIIIIic account were acandalimd "until a ne. Alexandt!r arose to cut the Gordian knot, which men had vainly lOught to untie. This was Champollion the younger, armed with his diacovery." The.hieroglyphica now apeak • language that all can understand, and no one gainlay. " The Egyptian Zodiacs, then," .ys Latronne, "relate in no respect to astronomy, but to the idle phantasies of judicial astrology, as connected with the destinies of the emperors who made or completed them." .

TELESCOPIC OBJECTS. A CLOIB DovaLa &ru.-~. R. = 1 h. 41 m. 19 I. Dec. =;fOn the hom of AIle&. A 6, yellow. B 8, blue. Diacoveied by Herschel Poe. 1720 26' DiaL 8".378 Epoch 1823.98 StrUve. 1836.11 Smyth. 2 .400 169 6'

11 0 28' 7 H •

=+

,. ARIKTII.-A. R. = I h. 44 m. '5 L Dec. ISO 30' 5". In the lower bend of the Ram'l hom. A 41. B 5. This ia the firal double star ever detected. Less than one hundred years have elapsed, and now they are numbered by thouaandL Diacovered by Dr. Hook 1764. M..dler thinks motion is probable. Poe. 1830 65' DiaL lOU.l7'~ .Epoch 1779.6a HerscheL . 179 30 8 .957 1831.79 Striive. 178 20 8 .8\9 1841.78 Miidler. 176 37 9 .184 1847.65 Mitchel It we are to receiva ~ obaenat:ionI as conclusive of periodic revolu-

81

CONSTELLATION OF PIICE&.

tiaa, die mighty year of a- two __ cumot &II mach Ibart of four tbou.nd of our y _ .

+

NlIBl1LA.-A. R. = I h. 60 m. Sf.. Dec. = 180 Following ,. OIl the neck of Arlee. It ill quite large but f'ainL

A Rovn

18' 6".

+

A Ql1.1.DRl1PLlI BTu_A. R. = I h. 110 m. .u.. Dec. = 200 16' 7". Under the ear of An... A 6, B 16, C 10. D 9 JDBgDitude. Measures of A and B only are given. The other distancea are great. A to B POI. = 630 83' DiaL 1".370 Epoch 1831.42 Btri:.ve.

=+

=

10 AauTI_A. R. 1 h. M m. 36.. Dec. 260 09' 7". Over the head of the Ram. A 61. B 81. I>iIIcmered by Struve. POI. 260 IT Diet. 1".98 Epoch 1833.06 Struve•

+

.. AauTII.-A. R. = " h. 40 m. 12.. Dec. Hlo 4T 8"'. On the haunch of Arlee. A beautiful triple lilt. A 6, B 81. 0 11 DlllgDitude. DiIIcovered by Sir W. HeneheJ. October 1782.AalaTll1.-A.R.= 20h.:IOm. 04 .. Dec. =

+ 200 41' OS"·

A very c1081l double i!&ar at the root of the teil of Aries. A 1\. B 61. DiIIcovered by StrUve, and reckoned by him ill among hill elmut, and III1IIbd ., pervicinm••, It _ ODe of the fimt teats employed after the erection of the Cincinnati Refractor, and 10 easily separated u to excite the BUBpicion thet the disttnce between the componenla hu been inCI'I!I1IIing. Thill ill confirmed by the following meaBUIeII.

POI. 1880 60' 196 11

DiaL 0".647 0.7640

Epoch 1830.16 Striive. 1841.87 M;;dler.

+

32 AalaTII.-A. R. = 2 h. 1i6 m. 06.. Dec. = 240 A triple Bet between the tail of Arlee and the Fly. A 6j, B mag. Diacovered by StrUve. , A to B POI. 2660 Sf' OS" Diet. 0".45 Epoch 1841.87 A to C 3S6 00 00 6.00 1886.88 A Cloon D011BLlI BTu_A.R.

=

~

F

M;;dler. Smyth.

3h. 14m. 06 .. Dec. = +200 .

13' 07". FoIlovring the t8il of Arlee. A 8, B 9. mag. by Striive. POI. 930 42' DilL 0".76

8T OT'. '. C 16,

Epoch 1827.16 8triive.

62

GEOGRAPHY OF THE HEAVENS.

DIRECTIONS FOR TRACING THE CONSTELLATIONS

O~

MAP NO. IV.

CETUs-THB WHALE. PART

OF

To RIvER

ERIDANU8-

Po.

Favorohly situated for examination in Octohcr, N~ her, Decemher, and January. THE WHALE.

As the whale is the chief monster of the deep, and the largest of the aquatic race, 110 ill it the largest constellation in the heavens. It occupieR a I"pace of SOo in length, E. and W., with a mean breadth of 20° from N. to S. It is situated below Aries and the Triangles, with a mean declination of 12° S. It is represented as making its way to the east, with its body below, and its head elevated above the equinoctial; and is six weeks in passing the meridian. Its tail comes to the meridian on the 10th of November; and its head leaves it on the 22d of December. ', This constellation contains ninety-seven stars; three of the 2d magnitude, nine of the 3d, and several of the 4th. The head of Cetus may be readily dil!tinguished, about 20° S. E. of Aries, by means of five remarkable stars, 4° and SO apart, and 'so situated as' to forma regular pentagon. The brightest of'these is Menkar, II Ceti, of the 2d magnitude, in the nose of the Whale. It occupies the S. E. angle of the figure. It is 3lo N. of the equinoctial, and ISO E. of EI Rischa, II Piscium, in the bight of the cord between the Two Fishel:!. It is directly 37° S. of Algol, and nearly in the same direction from the Fly. It makes an equilateral triangle with Arietis and the Pleiades, beinJt distant from

CONSTELLATION OF CETUS.

each about 23° S., and may otherwise be known by a star of the 3d magnitude in the mouth, SO W. ot' it, called "/, placed in the south middle angle of the ' . pentagon. ,'.' . ,; .... ls a sw of the 4th magnitude, 4° N. W. of "/, and these two constitute the S. W. side of the pentagon in the head of the Whale, and the N.E. side of a similar oblong figure in the neck. Three degree", S. S. W. of "/, is another star of the 4th magnitude, in the lower jaw, m,arked a, con-\. stituting the 'east side of the oblong pentagon; and 6° S. W. ofthis, is a noted star in the neck of the Whale, called Mira, marked 0, or the "wonderful.star of 1596," which for~ the S. E. side. This variable star was first noticed as such by Fabricius, on the 13th of August, 1596. It changes from a star of the 2d magnitude 80 as to become invisible once in 334 days, or about seven times in six years. Herschel makes its period 331 days, 10 hours, and 19 minutes; while Hevelius assures us that it once disappeared for four years; so that its true period, perhaps, has not been satisfactorily determined. The whole munbar of IIanI .-rtained to be variable, amounlB to only 15; while thole which are rmapected to be ~ amount to 37.

Mira is 7° S. S. E. of 0 Piscium, in the bend or knot of the ribbon which connects the Two Fishes. Ten degrees S. of Mira, are four small stars, in the . breast and paws, about 3° apart, which form.a square, the brightest being' on' the east. Ten degrees S. W. of Mira, is a star of the 3d magnitude in the heart, called Baten Kaitos, ~ Ceti, which makes 8 scalene triangle with two other 'stars of the same magnitude 7° and 10° west ofit; also, an equilateral triangle with Mira and the easternmost one in the Iilquare. A great number of geometrical figures may be formed fTom the stara In this, and in ID06t of the other COIIIItIllIationa, merely by refenmce to the

64

GEOGRAPHY OF THE HEAVENS.

maps; but it i. better that the lltudeut ehoaId ueJCiae his own ingenuity in &biB way with refimmce to the tItuII tbemIel-, for when once he baa oonstructed a group into any letter or figure of his own invention, he never will forget iL The teacher ahould tberefoIe require his cIaaa to colllllli& to writing the reauI.t of their own obaervaliona upon the relative poaition; magnitude IUld figurea of the principal tItuII in each coD8tellation. One evening's eXel" ciae in &biB way will diaclOll8 to the student a II1llprising multitude of _ , MJ1Ml"U, trianglu, _ and Idttra, by which he will be better able to identify and remember them, tlw1 by. any inatrudiona that could be given. For example: 0 and (, in the Whale, about 10° apart, make up the 8 ..E. or IIhorter Bide of an ilregular aquare, with " in- the node of the Ribbon, and another star in the Whale .. &r to the right of {, .. " is above 6. Again, There 111'8 three IIIalB of equal magnitude, formiq a straight line W. of Baten; from whi'ch, to the middle star is 100, thence to the W. one 121; and 8° or 9° S. of this line. in a triangular direction, is a bright star of the second magnitude in the coil of the tail, called Diphda, or "

TELESCOPIC OBJECTS.

=

=-

It CBTI.-.~. R. 0 h. tl m. 63 II. Dee. ,0 50' 06". A difficult double star. between the Whale'. tail and the Southern Fish. A 6, yellow; B l5, blue. Position end distance estimated .. fullowa, Dr the Bedford Catelogue: POI. 1800: 66' DiaL 6".5 Epoch 1837.89. A LOKD KnRO.... NuuL.I..-A. R.=Oh. 39m. 4611. Decl.=t60 10'. Near the boundary of the Apparstu. 8culptoria. Discovered by Miss Henc:bel, in 1783.

.

.

42 CBTI.-A. R.= I h. 11 m. 38 II. Dee. = _10 21', A clo.e double star,. between the whale'. back and the band of Piacee-A 6. B 8 mag. Discovered by StrUve and marked among his .. Vicime "Itan. POI. = 3340 30' Diat. 1".177 Ep. 18:J6.91 8trii.~e., 61 CBn.-A. R. = .1 h. 66 m. 37 II. Dee. = - 10 06' 6". A double star on the back of tie head of CetuL A 7, B 81 mag. Di. covered by Str" ve, who reports the following meuurea. POI. = t600 00' Diat. ....78. Epoch 183t.36~

• OItTI. MIU.-A. R. = t h. 11 m. 16 II. Dec. = - 30 'S' 3", A remarkable variable star, with a distant companion, on the middle of the whale's neck. It is the first of these wonderful objects ever discoveroo ell, and was noticed by David Fabricius .. early as 1596. It becomes .. bright as the IIeCOlld magnitude, and then decreases to invisibility. Herschel estimates its period at 331 days 10 hours 19 minutes. Its maximum brilliancy is. aUained about the first of October at this time. 'Ibe color olthis star is also ~ to vary with the magnitude. .

8i

CONSTELLATION OF CETUS.

A Pt..t.lIHABV NUVL4_A. R. = 2 h 19 m. 26 .. Dec. =_1 0 61' 6". In the iDiddle of the whale', neck.' Discovered by HeracheI, 1'186•

+

., CBTL-A. R. = 2 h. 27' m. 29 I. Dee. = 40 53' 5". A double IItar in the whale', eye.. A 4i, yeDow, B 1", blue.-Thia ill one of Struve'. " difficilea ". He leportB the following measures: Poe. 830 30' Diet. T'.726 Ep. 183l.9:I. 84 CJ:TJ..-A. R. = 2 b. 33 m. 02.. Dec. = - 10 22' T'. A cIifficult oiject like the preCeding, on the whale'. under jaw, Strilve, ita disco_ fumiahea th_ measuree : Poe. 3340 3T Diet. 4".866 Ep. 1831.90. A ROVB"D Nnvlo4. - A. R. == 2 h. 34 m. 30 ,. Dec. == - 00 41' 02". On the Whale',.lower jaw. Examined by HenK'hel, and placed in \he 910th order of diatancea; that is, 910 times more remote than the fixed IIlanI of the lilIIt magnitude. Diacovered by MII8Bier.

+

,. CJ:TT..-A. R. = 2 h. 81; m. 01". Decl. = 20 Sa' 01\". A beIlutiful cloae double atar, in the Whale'. mouth. The Bedfonl Catalogue regards the .. fixity" of the componentll as lllltabliabed; while M~dler thinks an increasing mOtion CIlrtain, with a period of about 569 yean. The following measures are reported ~ PO&. = 28:-40 I~' DiaL 2".liS/) .t:poch 18264~ StrUve. 2 .680 18:1...3 6 " 287 06 293 37 2 .946 . 1841.14 ... M:idler. All OVAlo NJ:RVL~.-A. R. = 2 h. as m 08 L Decl. = - 80 16' 1". On the breast of the Whale." It ill pale, thoqgh qi,stinct, and brightens at the center." . Dillcovered by Hemchel, 1785. '"

== -

94 CV.TT.-A. R; = 3 h. 04 m. 38 L DeeL difficult double 1Itar. in the top oftha Whale', tongue. Discovered by Sir John HencbeJ.

1'2

10 4T 09". A A 5j, B 16, Diag.

GEOGRAPHY OF THE HEAVENS.

DIRECTIONS

FOR TRACING THE

CONSTELLATIONS ON

MAP NO. V.

T AUllUS- Tn BULL. ORION.

PART

OF

.

ERIDANU8-THE Rrvn Po.

Favorably situated for ezami1U.l.twn in DecemlJer, JafI...zry, February and Marek.

.

TAURUS.

THE BULL is represented in an attitude of rage, if about to plunge at Orion, who seems to invite the on~et by provocations of assault and defiance. Only the head and shoulder-s of the animal are to be seen; but' these are so distinctly marked that they cannot be mistaken. Taurus is now the lIeC01IJl sign and tAird constellation of the zodiac; but anterior. to the time of Abraham, or more than 4000 years ago, the vernal equinox took place, and the year opened when the sun was in Taurus; and the Bun, for the space of 2000 years, was the prince and leader of the celestial host. The Ram suc(,eeded next, and now the Fishes lead the year. Tile head of Taurus sets with the sun about the last of May, when the opposite constellation, the Scorpion, is seen to rise in the S, E. It is situated between Perseus and Auriga on the north, Gemini on the east, Orion and Eridanus on the south, and Aries on the west, having a mean declination of 16° north. It contains 141 visibl6 stars, including two remarkable clusters, called the PLEIADES and HYADES. The first is now on the shoulder, and the latter in the face of the Bull. The Pleiades, according to fable, were the seven daughters of Atlas and the nymph Pleione, who M

CONBTELLA TION OF T AUBU8.

were tumed into stars, with their sisters the Hyades, on account of their amiable virtues and mutual aft'ection.

ancien..,

That! we everywhere 1l1li1 that the with all their barbari.n mel idolatry, entertained the belief that unblemiahed virtue and a rneritorioua iii!! would meet their rewud in the 1Iky. 'l'hU8 Virgil ~ta Mapu. Apollo u beDdiDg &om the IIky to ~ the youth IulU8_ II Made 110ft Wtulie paer: lie itur lid utra; Im. geait.e, et geuiture n-." .. Go on, ~ boy. in the patb8 of Wtue; it ia the way to the Itan; c6pring of the god_ thyaelf_ Ihak thou become the father of godL" Our diagu.t at their 8lIpen&i&ioIIII_y be in lOme IJI8IIIl11re mitigated, by aerioWlly ~, that bad .aIDe of the. ~ lived in our day. they bad been omamenta in the Chrialian ehureh, and mocIeIB of IOcial Wtue.

The names of the Pleiades are Alcyone, Merope, Maia, Electra, Tayeta, Sterope and Celeno. Merope was the only one who married a mortal, and on that aecount her star is dim among her sisterl5. Although but six.of these are visible to the naked eye, yet Dr. Hook informs us that, wit.h a twelve feet telescope, he saw 78 stars; . and Rheita affirms that he counted 200 stars in this tlmall cluster. The IDOIIt ancient autbora, BUCh u Homer, AUaJua, and Geminua, counted only ft::e' PIeilde8; but Simonidea, Varro, Pliny, Aratua, Hip' parcbU8. and Ptolemy. reckon them seven in number; and it wu .... aerted, that the seventh had been _ before the burning of Troy; but this difference might arise &om the difrerence in diat.inguiabing them with the naked eye.

The Pleiades ftre so called from the Greek word, to sail,. because, at this season of the year, they were considered" the star of the ocean" to the benighted mariner. .AlCJj01le, of the 3d magnitude, being the brightest star in this cluster, is sometimes called the light of the Pleimles. The· other five are principally of the 4th Rnd 6th magnitudes. The Pleiades,. or as they are more fnmiliarly termed, the seven mrs, come to the meridian 10 minutes before 9 o'clock, on the evening of the lBt 01 January, and may serve, i~ place of the sun, to ~fW, pleein,

G~RAPHY OF THE HEAVENS.

:68

indicate the time, and as a guide to the' surrounding stars. A~ to Heaiod, who wrote about 900 yean before the bi11h of our Saviour, the heliacal riaiug of tbe Pleiadell ,took place on the 11th of May, about the time of harvest.

.. When, Atta.bom, the PJeiad

BtarII arise BetOre the 8\ID above the dawning akies, 'Tia time to JeIIP: and when tbey link below The mom-illumin'd "eat, 'till time to lOW."

ThWl, ill all agee, have the BtarII been oo-ved by the hubandman. for "lignBand for_" ' Pliny say. that 'Fha", the MiletaD u&ronomer, determiDed the eo. micalBetting of the Pleiadell to be 2. da,.. after the autumnal equinox. 'I'hi. would make a, difference between the Betting at that time and the preaent, of 35 daya, and u a day an&We18 to about 59' of the ecliptic, th_ day. will make 34° So.,'. Thia, divided by tbe annual preceMion (1iOi"), 'will give 2465 yeal8 since the time of Thalea. Thus dOM utronomy become the parent of~. • If it be borne in mind that the stars UDifonaly rille, come to the meridian, and eel about fOur minutes earlier every lucceeding night". it will be very easy to determine at what time the seven BtalII pus the meridian on any night eubaequent or 8Iltllcedebt to'tIW 18& of January. }o'or exampie: at what time will the I8VlID BtalII qulmjnate on the 5th of January ! Multiply the live days by fOur, and take the reeuit from the time they culminate on the 1st, and it will give thirty miputes after eight o'clock in the evenina.

The Pleiades are also sometimes called VergilitlJ, or the" Virgins of spring;" because the sun entel"ll this cluster in the" season of blossoms," about the 18th of May. He who made them alludes to this circumstance when he demands of Job: "Canst thou bind the sweet influences of the Pleiades," &c.-[Job xxxviii, 31.] The Syrian name of the Pleiadee ia Sueeotla, or Suct:mh-&ootla, derived from a ChaIdaic word, which aignifieia "to speculate, to obsene," and tbe .. Men of' Succoth" (2 Kinga nii, 80), have been thence COJIIidered obIBrvera of the IIaJB.

The Hgades are situated 11 0 S. E. of the' Pleiades, in the face of the Bull, and may be readily dis- ' tinguished by means of five stars so placed as to form the letter V. The most brilliant star is on

CONSTELLATION 01' TAURUS.

eg

the left, in the top of the letter, and called N.tlelJa· ran, Go Tami, from which the moon's distance is computed . .. A lIIar of the liM magnitude Ulumell His radiant head; and of the IBCODd rank, Another beams not liar remote."

.Aldebaran. is of Arabie origin, and takes its name' from two words which signify, " He went before, or led the way "-alluding to that period in the history of astronomy when this star led up the starry host from the vernal equinox. It comes to the meridian at nine o'clock on the lOth of January, or 48l minutes aCter Alcyonej'l Tauri, on the Is.t. When Aries is about 270 high, Aldebaran is just rising in the east. So MAlfILJUS : .. Thus "hen the Ram hath doubled.ten degreee, And join'd _ mcxe, then riae the Hyadee. "

A line 15l o E. N. E. of Aldebaran 'will point out a bright star of the 2d magnitude iu the extremity of the northern horn, marked fJ or El Nath; (this' star is also in the foot of Auriga, and is common to both constellations.) From fJ in the northern horn, . to , in the tip of the southern horn, it is 8 0 , in a southerly direction. This star forms a right angle with Go and fJ. IJ and ',both, in the button of the horns, are in a line nearly north and south, 8° apart, with the brightest on the north. That 'Very bright star 1710 N. of fJ, is Capella Go, in the constel· lation .Auriga. This map contains the most brilliant, and on ftll accounts, the most interesting portions of the hf!l1vens. According to the investigations ofStriive, this region is nearer to our sun and system than any other portion of the celestial sphere, as will be more fully developed hereafter. Besides this, Al~y· one is regarded as the great center of the millions

'10

GEOGRAPHY 01' THE HEAVENS.

of stars elu~tered ,together and forming the Milky Way. This region, on account of its splendor, and the remarkable configurations of its stars, forms an admirable point in beginning the study of the heavens. 'fELESCOPIC

7 T.U1Rl.-A. R.

OBJECTS.

+ 2:\055' 4".

= 3 b. 24 m. 58 8. Dec. =

A

triple star on the back of Taurus. A 6, B 6i, C II magnitude. Discovered by Btr~ve, and two of the components are among bis .. vicinessemm,'~ or close stars. From his measures. compared with Mii.dler's, a retrograde movement in A and B seems to be certain. A to B Pas. 271 0 00' Diet. 0".fi3 Epoch 1827.16 fltruve. 264 36 0 .55 1841.80 Madler.

=

A

+ B to C

Poi!. 630 36 Di8t. 22".25 Epoch 1827.16 Struve. 601822.50 1841.80 ~dJer. The period of A about B, is probably about 680 or 690 yean.

-2-

+

80 TAuRT.-A. R. = 3 b. 39 m. 30 B. Dec. = 160 38' 8". A delicate double star on the left sboulder-blade of Taurus. A 6, " pale emerald." B 10, .. purple." Discovered bv Herscbel. Dist. 9".867' Epoch 1824.98 Struve. Poe. 680 46f A DoUBLJI STAll.-A.

R. = 3 b. 51 m.,27 8.

Dec..= 220

44' 7".

In the neck of Taurus; be\Wef!Il tbe Pleiades and Hyades. . A 7i, B 8 magnitude.

A distant companion of the 12 magnitude.'

Discovered by StrUve. Poe. 12:70 41'

Dist. 7".208

Epoch 1823.98

South.

+

80 Tuilll.-A. R. = "h. 21 m.Ol 8. Dec. = 150 17'. A close double star on the Dull's face, 1~0 BOUth west of Aldebaran. A II.

H 8i.·

Poe. 120 65' A CLOSE

Diet.

DOUBLE

. 1".74

Epocb 1831.18

SUll.-A. R. ~

5

15' 3". On the southern bom of·TalllUB. DiscoveJed by Btr;: ve. Poe. 171 0 13' Dis!. .2".327 /

Struve.

7 m. 23 8. Dec. A 8, B 8i.

h.

Epoch 1830.63

+ liP

Stri: ve.

=+

A DouBL~ STu.-A. R.=5b.8m.Oa .. Ike. 19057'2". In the,middle of the southern born of Taurus. A fI, B 11 magnitude. Discovered by Str;: ve. Dis!. 10".547 Epocb 1828.19 Btr"ve. Poe. 147° 33'

118 TAUlll.-A. R. = 5 b. 19 m. 25 8. Dec:. = Between tbetips of the Bull's borns. A 7, B 7j. . Poe. 1960 46'

Dist. 4".89

Epoch 18:l9.63

+ 25

0

Btl;: ve.

00'8"'.

CONSTELLATION OF TAURU8.

=

=+

A LA.Rln: NIIB17U.'--A. R. 6 b.' 2'm.1I1 .. Decl. 210 1i4' One degree N. W. (Tauri, on the tip of the Bull's southern hO!IL Discovered by MMBier, 1758, and is No. I ofhia great catalogue. It was IICcidentally picked up while obaerving the comet of that year, and induced Me&Iier to commence a search for BIlCh objects. It is reIOlved wi1h diftic:ulty by the best inBtruments, and Herschel reckOIlll its profundity of tile 980th order-that ia, 980 ~ more remote than stars of the firat magnitude. . . . (12".

or

+

• T.17•••-A. R. = 8b. 87 m. 69.. Deel. = lISO 86' 8". AIc:yone, \be prineipaI star In the P1eiadee, a IIIDIIll cluster visible to the eye In the necIt of Taurua. Thie little group has ever 00en remarkable, but recently a tenfold Interest has been given to it by the announcement of Dr. MiUJler of Dorpat, RUIIIIia, that its Chief star, Alc:yone, is the central au1l of om aMral ayllem. It is ablOlutely certain that the law of gravitation extends to tile fixed stars, as is abundantly shown by the orbitual revolution of &he doUble. stars, w.h~ periods and pIacee have 00en computed and predicted by the application of this law. This being eert8in. In the mighty group of millions of stars with which our own BUD is associated, there mil" be a «'flier of gravity; and it then remains to delentline whether tru. point is filled by a ponderous globe, of vast dimensions, and bearing the IIUIle relation in point of magnitude to the millions of suns by wbich it is surrounded, as our BUD does to the planets, satellites, and comets by which it is encireled. Analogy, in the solar system, taught the existence of such' a ponderous mass, but this analosy was broIr.en in· the revolving Btars; in whic)l it often occurs that the components are nearly equal in magnitude, moving round I common center of gravity. Again, in examining the heaveb8, such a mighty preponderating body would be detect.ed by the swifter propet motion o( the stars in its vicinity. A fter a laborious search, M"dler reached the conclusion that no BIlCh vast globe existed, and that the center or gravity, probsbly vacant, could only be found by a severe examination of tIil proper motions of the fixed Btars. By a beautiful trsin of reasoning and dll8ely conducted ~, he finally reached the conclusion that Alcyone, in the Pleiades, now holds the high rank of centralaun.. but that, in the course of ages, by the perpetual changes constantly going on among the components of our utral ay,tem, this rank may JlIlIIII to some other star. He computes roughly the distance of Alc:yone, and reckons it to be so great, that light, 8ying with ~ velocity of twelve milliOllB of miles a minute, csnnot resrh u. from that star in 1IlIIB than 537 years.' He further computes roughly, that our BUD revolve. about A1eyone in a period of 18,200,000, in an orbit inclinllll to the ecliptic under an angle of S4 0 00'. Should &his wonderful theory be confirmed, the proper motions of the fixed Btars assume a new and increased interest.-(See P!1iidler's Paper, "Centml 8un"-Mitehel's Sidereal M_ger, Nos. 4 and 5, Vol. L)

+

A NSB17J.0171 Sru.-A. R. = 8 b. 59 m. 86-.. DeeL 300 20 Olin. Over the neck of 'I·aurus. This object was discovered by tbII elder Heraohel, and was the final link in that long chain of obam:valio.

72

GEOGRAPHY 01' THE HEAVENS.

, which led to the adoption of the .. DebuIar tbeoJy,n The liar is perf'ectIy in the center of the I18bulOll8 atmoBphere which eunounda it, and He..' del arguee the nebuloeity of &his -mg almoepbere from tbe fact that, in cue each shining point is a &tar, wbat muat be the magnitude of the central oro, which exceed. &hem all in the eoormoua ratio of millions to one. Tbe8e 118bu10118 atan ... c:ertain1J moat wOllderful objects, and d.erve the moat rigid ICI'Iltiny. ,

+

X TAnl_A. R. = 4 b. IS m. lit.. »eeL = Jlio 14' or. A doUble &tar at'the back of the Bun'. ear. ,A 6, B 8, mag, Poe. 250 00' Dis&. 19".3 lfpoeb. 1831.91 Smyth.

ORION. WHOEVER looks Up to this constellation and learnl'! its name, will never forget it. It is too beautifully splendid to ne\ld a description. When it is on the meridian, there is then above the horizon the most magnificent view of the celestial bodies that the starry firmament dords; and it is visible to all the habitable world, because the equinoctial passes through the middle of the const.ellation. It is represented on celestial maps by the figure of a man in the attitude of assaulting a Bull, 'with a sword in his' belt, a huge club in his right hand, and the skin of a lion in his left, to serve for a shield. Manilius, a Latin poet, who compol!ed five boob on astronomy, a short time before the birth of our Saviour, thus describes its appearance:

" Firat next the Twins, - great Orion rille, Hia arms extended I!treteh o'er half the ekiee;

Hia stride as large, and with a steady pace He marchea on. and DltlII8UleII a vut ~; On each broad shoulder a bright &tar diaplay'cJ, And three obliquely grace hie banging blade. In hie ...at head, iuuners'd in bound1eea spheres, Three atara, 1_ bright, but yet u great,he 'be8nt, But fiuther off remo'fed, their eplendors JOlt; Th1l8 gJaC'd and arm'cJ, he Ieede the atarry hOll&."

The center of the constellation is midway between the poles of the heaven. and directly over the equa-

CONSTELLATION OF ORION.

'73

tor. It is also about SO W. of the solstitial colure, and comes to the meridian about the 23d of January. The whole number of visible stars in thi~ constellation is .seventy-eight ; of which two are of the 1st magnitude, four of the 2d, three of the 3d, and fifteen of the 4th. Those four brilliant stars in the form of a long square or parallelogram, intersected in the middle by the "Three Stars," or "Ell and Yard," about 25° S. of the Bull's horns, form the outline of Orion. The two upper stars in the parallelogram are about 15° N. of the two lower ones; and, being placed on each shoulder, may be called the epaulets of Orion. The brightel!lt of the two lower ones it! in the left foot, on the W., and the other, which .is the least brilliant of the four, in the right knee. To be more particular: Bellatrix,.y Orionis, is a star of the 2d magnitude on the W. shoulder; Betelguese, II Orionis, is a star of the lilt magnitude,7lo E. of Bellatrix, on the E. shoulder. It is brighter than Bellatrix, and lies a little farther· towards the north; ana comes to the meridian thirty minutes after it, on the 21st of January-. These two form the upper end of the parallelogram .. Rigel, ii Orionis, is a splendid. star of the Ist magnitude, in the left foot, on the W. and H,o S. of Bellatrix. &ipk, is fl star of the 3d magnitude, in the end 'of the sword scabbard, Bio E. of Rigel. These two form the lower endo£ the parallelogram. - - - - " .:Fint\ in l'IUJk The martial star upon hie ahoulliar ftamea:. A rival star illuminates hie foot ... ADd on hie girdle bMma a JUminuy Which, in 'ricinity of other . . Might claim the proudest bonOJ'l."

There is a little triangle of three small stars in the head of Orion, which forms a larger triangle with the two in his shoulders. In the middle of the . G

74

GEOGRAPHY OF THE HEAVENS.

parallelogram are three stars of the 2d magnitude, in the belt of Orion, that form a straight line about 3° in length from N. W. to S. E .. They are usually distinguished by the name of the Three 8t4r., because there are no other stars in the heavens that exactly resemble them in position and brightnel5s. They are sometimes denominated the Three.King., becaulle they point out the Hyades and Pleiades on one side, and Sirius, 01' the Dog-star on the other. In Job they are called the /Jmuh of Orion; while the ancient husbandmen called them JQIXJ/i. rod, and some times the Rake. The University of Leipsic, in 1807, gave them the name of Napoleun. But the more common appellation for them, including those in the sword, is the EU and Yard. They del'ive the latter name from the circumstance that the line which unites the" three stars tI in ·the belt measures just 3° in length, And is divided by the central 'Star into two equal parts, like a yard-stick; thus serving as a graduated sta.dard for measuring the distances of stars from each "'ther. When therefore any star is described as beiag SO.r.na.Dy degrees from another, in order to determine tile di .. tance, it is recommended to apply thill rule. It is'neceMaIY that the acholar douJd tuk his ingenuity only. h nerunga in applying such a standard to the IIIanI, before he will Jearn to judge of their relative distances with an accuracy that will aeldom ....,. a degree from the truth. .

The northernmost star in the belt, called Mintika, wh~n on the meridian, is almost exactly over the equator. It is on the meridian, the 24th of January. The" three stars tI are situated about 8° W. of the solstitial colure, and uniformly pass the meridian one hour and fifty minutes after the seven stars. There is a row of stars of the 4th and 5th magnitudes, S. of the belt,. running down obliquely towards Saiph, whieh forms the sword. This row i.e

a, is less than l O S. of the equinoctial, and

CONSTELLATION OF ORION.

75

31"'0 oalled the Ell, because it is once and a quarter the length of the Yard or belt. A very little way below Thabit, :. Orion is, in the sword, the,,<, is a nebulous appearan.ce, the most remarkable one in the heavens, With" good telescope an apparent opening is discovered, through which, as through a window, we seem to get a glimpse of. other heavens, and brighter regions beyond. A. the telescope extends our knowledge of the ItaJII and greatly inbehold hundJeda and thOUlllllltla, which, but for this almost divine improvement of our _on, had fore~ remain· . ·ed, unaeen by us, in an unfathomable void. A BtIIr in Orion'. aword, which appears Bingle to the UIIII8IIiated vision, is multiplied into six by the teleacope; and another into twelve. Galileo tound eighty in the belt., twenty-one in a nebulous BtIIr in the hBBLI, and about five hundred in another part of Orion, within the comp.1S8 of one or two degrees. Dr. Hook _ aeventy-eight atara in the Pleiades. and Rheita with a better teleBcope, about two hundred in the IIIUDB cluster and more than two thouand in Orion. peaBeII their visible number, we

.w

About go W. of Bellatrix,,),, are eight stars, chiefly of the 4tJt magnitude, in a curved line running N, a.nd S. with the concavity towards Orion; these point out the skin of the lion in his left hand. Of Orion, on the whole, we may remark with Eudosia: .. He who admires not, to the ItaJII is bIind." As the CODBtellation Orion, which rises at noon about the 9th day of Much, and seta at noon about the 21st of June, is generally BUp~ to be IUlCOmpanied, at ita rising, with great rains and storms, it became extremely terrible to marinel1l, in the early adventures of navigation. Virgil, Ovid, and Horace, with lOme of the Greek poets, make mention of this, Thus Eneas accounts for the storm which cast him on the AIi:ican cout on his way to Italy : -

.. To that blest shore we ateer'd our destined way, • When BUdden, dire ()riqn rous'd the sea: AII charg'd with temp!lStB rose the baleful Iter, And on our navy pour'd his wat'ry war." To induce him to delay his departure, Dido'. sister advises her to .. Tell him, that, charg'd with deluges of rain, ()riqn rages on the wintry main,"

76

GEOGRAPHY OF THE HEAVENS.

The II8ID8 of this CODIIteIIation is mentioned iri &be boob of Job aDd ADI08, and in Homer. The inspired prophet, 'penetrated like the paabnist of Israel, with the omniscience and power displayed in the celestial giorlee. uUenI this sublime injunction: .. Seek Him that maketh the aeven IItanI and Orion, and tumeth the abadow of death into morning." Job aJeo. with profound veneration, adores Hill awful majesty who '''oommandeth the .un and aeaJeth up the 1IbIJ8; who alone spreadeth out the heavellll, and maketb. Arcturus, Orion, and Pleiades,' and the cbambeJB of the BOUth : " And in another place, the Almighty demands of him-.' Knowest thou the ordinances of heaven t Canst than bind the BWeet inlIuences of the Pleiades, or 100II8 the bandB of Orion; canst thou bring forth M~ in his -.on. or canst thou guide Areturus with his BOna , " Calmet suppoES that Mozzarotk ill hr.re put ror the whole lIl'Iier of eeleslial bodies in the Zodiac, which by their appointed revolutiollll, pr0duce the various _ n a of the year, and the regular succe&8ion of day and night. .An:t_ ill the name of the principal star in Bootes, and ill here .put ror the constellation i_It The expression, hill WTUI, doubtle81 JeferB to Asterion and Char&, the two greyhounds, with which he _011 to be pIIlIIIIing the great bear around the North pole. TELESCOPlC

OBJ~CTS:

258 P. IV. OBIOIlU.-A. R. = 4 h. 49 m. 48 B. 115' 04". A double star ~ Orion'. right knee. Discovered by Henchel. . P08. 1740 51' Diet. 2".00 Epoch 1782.85 179 M 2 .M 1832.09

.Dee.'=

+1

0

A 8j, B 9, mag.

Herecbel. Str"ve.

+

t ORIO_IB.-A. R. = II h. 04 m. IiIi B. Dee. = 2° 39' 09". A double star between the right ann and thigh of Orion:. A 6, B 8j, the first orange, the aecond blue. P08. 630 28'· Diet. 7".05

Epoch 1832.05 Struve.

=...;.

/; OBIOlUB.-A. R. = II h. 6 m. 111.. Dee. 80 .23' 05". Rigel, a double star in the right foot of Orion. A I, "pale yellow," B 9, ....pphire blue." A third star has been recently added by artificial occultation. at the Cincinnati Observatory. It is of the 20th magnitude, and invisible without hiding the principal Btara. , The relative positions of the IIbIJ8 remain unchanged since their w.. covery, in 1781. Discovered by Henchel. Poe. 1990 46' Dist.9".14 Epoch 1831.113 StrUve.

=

=+

84 P. V. ORIO_IB.-A. R. 5 h. 16 m. 53 B. Dec. 10 46' 4". A close double star in Orion'B right side. A 8, B 10. The oomponenta ani fixed. Discovered by Herschel. Poe. 3230 13' DiIt. 2".61 Epoch 18.11.81.

=+

92 OlllO_II.-A. R.=5h. 22Il1019 •. Dec. 50 49' 03". A dose double star on the ~ ahoulder of Orion. A 5, 8 7, mag. A IlOIIl-

77

CONSTRLLATION OF ORION.

pariIun oflate meuurea with thOl8 of Herschel in 178l1, indicatea a IIow ietrograde uwtiOll, amounting to lOme 1()C' or 12° in half a century. Poe. 203° 45' DiaL 1".04 Epoch 1830.96 Struve.

=

=+3'1

S3 OaIOII'II.-A.R. lih. 22m. iii L Dec. 09'9"'. dose double star 00 the right shoulder. A 6, B 8, mag. POL 25'> 35' DiaL 1".87 Epoch 1831.22 StriAve..

A

== t

A OaIolI'ltI.-A. R. = Ii h. 18m. 19 a. Dec. 90 49' OS". A double .tar in the ear of Orion. A., .. pale white,' B 6, .wJet No ehaDge haa been detected. Discovered by HBlIICbel, 1779. Poe. 400 32' DiaL 4".M Eporb 1830.¥l Stri.ve.

=

/I OaIOII'II.-A. R. 5 h. 27 m. 25 L Dee.-IIo 30'. A lelltople .tar in the great nebula in the sword acabbsrd of Orion. A 6, B 7,

C 7i, D 8, E 15, F 16, mag. For more thsn fifty y _ this ol!jeet w .. regarded as only ~ple. After the mounting of the " Dorpat refrac:tor," Strr.ve addea a fifth star to the lour alresdy known; IIIld a tew yean since a Ili:i;th was discovered by Sir J IUJItl8 South. It is not certain that any change haa yet been detected among the components of this remarkable 1JI'OUp. Epoch 1832.1i3 Struve. Pos. A B, 311 0 14' DiaL 12".983 A C,

60 07

A D, 342

10

13 .467 18 .780 3 .860

1832.53 1832.53 1832.53

...

B E, 365 42 " TIlII GBUT N IIBUJ..t. II' Oa,oll'.-A. R. = Ii h. 27 m. 21i 8. Dee. 6° 30'. This Itupendoos object is situated in the middle of the 8CIlbbard of Orion's swonI. Diac:overed by Huygens, 1666. It bas been Bn object of the greatest interest, to all astronomers, in conaequence of its

=-

brilliancy and extraordinary magnitude. Sir William HertlChel 'repeatedly elamined it with ecrutiny with his fOrty filet refraclor, but detected nothing like resolvability. Moat IICC1lI'Bte drawings were made by his .on, without any IlUBpicion that it was composed of a mass of stara. A. Sir John HertlChel remarked, the greater the power employed the mo"" mysteriooa did the oI!ject appear. Dr. J. Lamant, of Municb, baa examined this nebula with great attention, and many yealll since affirmed that with the twelve in..h refractor of the Munich Obaenatory, he caught glimpses of multitlldes of point-like atMB, crowding and producing the brighter parts of the nebula; yet to this announcement little heed _ _ to bave been given. On moUnting the giant reftector of Lord ~, it wtI8 a matter of deep interest to learn the appearance of this nebula under the acrutiny of this magnificent inltrumenL More than one altronomer made the jounaey to the cutle of Lord ~, to inspect this wonderful object. For a long time it reaiated the full power of the greatest of aU optical instruments, until at length Lord ~ makes the following an-

_cement:

.

.. C_1e P""""own, MarcA 19. 1846-

~

.. In accordance with my promiee of communicating to you the reauIt our examination of Orion, I think I caa lIBfeiy.y there caa be bIlt

02

78

GEOGRAPHY OF THE

H":AV~NS.

little, if any doubt, as to the ~lvability of the nebula. Since YOIl left there was not a single night, when, in abiJence of the moon, the air

'l1li,

_ free enough to admit the use of more than half the magnifying power the speculum bears; atill,. we could plainly - . that. all alJout the trapeaium ill a IlIII88 of still'll; the real of tile nebula abounding· in atan. and exhibiting the characteristics of reaoIvability ItroDgly marked.

. "RoiAL"

This announcement baa been made the buill of an argument, by Dr. Nichol, to overthrow the nebular. theory of the formation of the univelll8 ; • theory which had derived much of its popUlaritY from the· powerful argument in its behalf made by the IIIlIDe gentleman, a abort tinl\l before. in his "Architecture of the Heevens." If Lord Rosse is quite lure of the resolution of the nebula, it but confirms the previous declaration of Dr. Lamont, and the nebular theory loses but little of its former strength by the removal of a prop already much shaken by the Munich A.uonomer. Resolved or unresolved, this is certainly, under every aspect, one of the most sublime objects revealed by teleacopic agency-ao vast that the mind fails, utterly, to grasp its mighty outlines. .-\ 8 a starry system, it is so distant that the light which. leaves it, to journey to our eyes, spends no lea! than :10,000 years in sweeping over the stupendous interval. As a: nebula, it containll materials sufficient for the production of millions of IIWlS and systems. VIeW it as we may, its vastnesa, its magnificence; mDBt exalt our ideas of the omnipotence of the Great Architect of the Heavens. Under the full power of the Cincinnati refractor, the deep contrast hetween the brilliancy of the stars and nebulosity. and the jet black heavens on which they are aeen, is one of the most beautiful Bights in the heavens. W hetlw this bitukfIPM be the .eIfilct of mere contrast, or an intrinsic darkness, occasioned by the abeence of aU light, it ill difficult to determine. This is not a solitary instance of the phenomenon in question. I have obo lIIlrVed the same in lleVeral other instanca-but in no case have I remarked such intense blackness in the heavens, as about this nebula.

=

=-

.. OllloYJa.-A. R. 6 h. 30 m. 4.1.. Dee. 20 "1' 8". A multiple star just below the belt· of Orion, an excellent object for fellting the light of telescopes. There are· no less than tm stars counted as the components of thia one. A 4, a II, B 8, C 7, D 8i, E 9, F 8. magnitudes.

+

34 HERBCHBL, OBIOJlJ8.-A. R. = 6 h. 33 m. 21 I; Dec. = go Oil' 2". A planetary nebula on Orion's neck. Discovered by Herschel, and described by hill BOn as "a &maU 'pale, but distinct nebula, with a &int disc, rather oval, and perhaps a little ·mottled." .

78 MERalBR, ORIONIS.-A. R. = I) h. 38 m. 33.. Dec. = 7". ." Two stars in a wispy nebula, just above Orion's hip." 18 a remarkable ~ Discovered by Mellier in 1780.

~O'

+Thill 0°

79

CONSTELLATION OF ORION.

+

62 OBI,WIa.-A. R. = Ii h. 39 m. M.. ~ = 60 13' 8". A dose double IItar in Orion'. left ahoulder. A 6, B 6; riIepitude. The position baa never cbanged. Poe. 20()0 01 Dist. In.76 Epoch lsaUS &rii.w.

ERIDANU8.

To RIvER Po.-This constellation meanders over a large and very irregular space in the heavens. . It is not easy. nor scarcely desirable, to trace out all its windings among the stars. Its entire length is not less than 1300 ; which, for the sake of a m01'e eas}'reference, astronomers divide into two sections, the northern and the southern. That part of it which lies between Orion and the Whale, including the great bend about his paws, if! distinguitlhed by the Dame of the Northern stream; the remainder of it is called the 8uutJtern 6tream. The Northern stream commences riefl.r Rigel (M~p No. V). in the foot of Orion, and flows out westerly, in a serpentine course nearly 400, to the Whale (Map No. IV), where it suddenly makes a compfete circuit and returns back nearly the same distance towards its source, but bending gradually down towards the south, when it· again makes a simihir circuit to the S. W. and finally disappears below the horizon.

w;,.

of {6 Orionis (Map No. V) there are five or sill stars of the 3d and 4th magnitudes, arching up in a semicircular form, and marking the firll bend ·of the nurthem stream. About SO below these, or 190 W. of {J, ia a bright star of the 2d magnitude, in the ,ecund bend of the northern stream, marked". This star culminates thirteen minutes after the Pleiades, and one hour and a quarter before (6. Passing ')-. and a smaller star west of it, there are four stars nearly in a row, which bring us to the breast of Cetus. SO N. of ')-, is a amalllltar named KUd, which is thought by·BODle to be considerably nesrer the earth than SiriUl. . T hetmim, in the BOuthem stream, is a 8Iar of the 3d magnitude, about 17~ 8. W. of the equare in "epUll, and may be known by means of a smaller star. 1° above it. AcktJrrw.r is a brilliant 8Iar of the 1st magnitude, in the extremity of the aouthern stream; but having 680 of S. declinat1on, can never be _ in this latitude.

80

GEOGR.APHY OF THE HEAVENS.

The whole number of stars in this constellation is eighty-four; of which, one i8 of the lst magnitude; one of the 2d, ..and eleven are of the 3d. Many of these cannot be pointed out by verbal description; they must be traced from the map. TELESCOPIC OBJECTS.

m.

= +00

=

98. P, EaID.uu.-A. R. 3 h. 28 m. 36 e. Dee. 03' 7". A delicate deuble Btar, in the line joining It Celi and fd at on&third their distance. A Si, yeUow; B 9, pale blue.

Oriom.,

Diacovered by HeracheI. Poe. 211110 Ill' Dial. 11".812 Epoch 1824.02 Btrun. This o~ is betweeu the BuU'. cheat and the northern branch of the River.

-

107 HUllcBn I, EBID.lln.-A R; = 3 h. 33 m. 02.. Dec. = 190 04' 8". A white nebula between the two northern reachee of

the River.

'.

Diacovered by Henchel, and deecribed U bright in the center."

.. pale but distinct,

round and

32 EaID.lm.-A. R. == 8 b. 46 m. J6.. Dec. == - 30 21\' 9".. A double star between the cheat of Taurue and the River. A II, yellow ;

B 7._green. Diecovered by HeracheL Poe. 3490 45'

Diat. 6".76

39 EaID.lm,-A, R.

=

Epoch 18211.00 Struve.

4 l1. 06 m. 48.. Dec. -

100 39' 4".

A

double ltar in the north, foUowing bend of the River. A 6, II full yellow; .. B 11, .. deep blue,", , . . Diacovered by Herschel. Poe. 1520 Ill' Dial. 6".28 Epoch 1833.14 Stru_

26 H...eBS~ IV. RaID.un_A. R.

=

==

4 h. 06 m, 50.. Dec. 130 09' I" A planetary nebula under the N. F. bend of the River.' Discovered by Herschel, in J784. who IIW it slightly eUiptieal, and thought it might be a 'globular cluter at l1li immeDae distance.

-

CONSTELLATION OJ' AUIlIGA.

81

.DIRECTIONS FOR TRACING THE CONSTELLATIONS ON

MAP NO. VI. AUlUGA-THE W AGOJfER. Fcmorohly situated for ezamiMtion in DecemlJer. January, Febrw.ry and Marek. . AURIGA.

THE Charioteer, called also the Wagoner, is represented on the celestial map by the figure of a man in a reclining posture, resting one knee upon the horn of, Taurus, with a goat and her kids in hid right hand, and a bridle in his left. It is situated N. of Taurus and Orion, between Peneus on the W. and the Lynx on theE. Ita mean declination is 45° N.; so that when on the meridian, it is almost directly over head in New England. It is on the same meridian with Orion, and culminates at the same hour of the night. Both of these constellations are on the meridian at 9 o~clock on the 24th of January, and 1 hour and 40 minutes east of it on the 1st of January. The whole number of visible stars in Auriga is sixty-six, including one of the 1st and one of the 2d magnitude, which mark the shoulders. Capella, .. Aurigfe, is the principal starin this constellation, and is one of the most brilliant in the heavens. It takes ita name from Capella, the goat, which hangs upon the left shoulder. It is situated in the west shoulder of Auriga, 240 E. of Algol, and 28° N. E. of the Pleiades. It may be known by a little sh.arppointed triangle formed .by three stars, 3° or 4° this side of it, on the left. It is also 18° N. of ~ Tauri, which is common to the northern horn of Taurus, and the right foot of Auriga. Capella comes to the meridian on the 19th of January, just 21 minutes

82

GEOGRAPHY OF THE HEAVENS.

before ~, in the foot of Orion, which it very much resembles in brightness. Mmlralina, ~ Auriga, in the eat ahoulder, i8 a liar of the 2d magnitude, 7lO E. of Capella, aud culminate. the nellt minute after Betelgu-, " Orionia, 37,0 S. of it. in the right leg, i8 a liar the 4th magnitude, SO directly aouth of MenkaIina. It may be 1'8IDIIJked" .. a curioua coincicJence, that the two IlIIrII in the shouldem of Auriga are of the 8IUD8 magnitude, and just .. liar aput .. thoae in Oric;m. an~ opposite to ~ Again, the two ~ in the shoul- " dere of Aunga, With the two m the shouldem of Onon, miIrIt the elltremities of a long, narrow parallelogram, lying N. aud S., and whoee length i8 just five timea ilB breadth. AhIo, the two &tan! in A uriga, and the two in Orion, make two slender and aimilar trianglea, both meeting in a common point," half way between them, at ~ in the northern hom

e,

or

of Taurue. . Delta, a liar of the 4th magnitude in the Iiead of A uriga, is about 90 N. of the two in the shouldera, with which it makes a triangle, about half the bight of thoae just alluded to, with the vertex at Delta. The two IlIIrII in the should81'8 are therefore the baae of two .imilar triangles, one 8lItending about 90 N., to the head, the other ISO S., to the beel, on the top of the born:" both figures together resembling an elongated diamond. Della in the head, ~ in the right moulder, and e in the ann of Auriga, make a straight line with BeteJgutaI in Orion, I in the square of the Hare; and ~ in Noah'. Dove; all being very nearly on the IIWl8 meridiam, 40 W. of the solstitial colme. II See next the Goatherd with his kids; he ehiDee With seventy eIarII, deducting only (our,

Of which Capella never seta to

WI,

ican:e a liar with equal radiance beams Upon the earth: two other eIaI'8 are seen Due to the second order."-Eudnria. And

TELESCOPIC OBJECTS •

+

• AVRI ....-A. R. = 4 h. 4S m.24.. Dec. = 370 38' 6". A. double liar preceding the hip of Auriga. A 6. pale red; B 9,light blue. Discovered by Sir W. Henchel, who recon1s the following _

PCM.

= 362" 37' 361 66

Diet.

= 6"6 .1i0 .46

Epoch" 1779.86

18~8.76

Stri..ve.

Though the di8taneee recorded by Benchel differ from the later ones, there is no retUIOII to believe that the difterence i4 due to an actual dlange in the plaeee of these two 1lIIrII. Bencher. meana of makiJ!g " meaauree were lese perfect than thoae now in use; and his mee8un!a are 1_ to be relied on, from thi8 cause. II AVRI.a.-A little north, aud IiIllowing • Aurip. double star. A 6, B 10 magnitude. Diacovered by Stri..va, with the Polkova refradca-.

A delirate

83

CONIITELLATION OF AURIGA.

=

== +

A CUI.. DonLK s-ru.-A. R. 4 'h. &7 m. 11.. Dec. S'JO OS' 4". On the 1 _ garment of Aurip. A 7. B 8 magnitude, _ a looooe clullter. .' ~vered by Str;ive, whoae measure. Itood as followB: pqa. ~190 12' Diet. = 1".61 Epoch 1828.60

,

I" AUR1GB.-A.R. =I\b. 04 m. 69 .. Dec.=+ 82° 29'8". A triple alar in the right knee of A urip. A &. B 71. C 16 magnitude. A and B, have been long known, C was recently added by Pro£ 8trC-w. Be records theBe meuunIB. A B Pc& 2250 (8' Diet. 14".653, Epoch 1830.66 A C 342 37 • 12 .a77 18:10.1\6

+

A CLUI'nB.-A. R. ' 6 h. 17 m. 18 e. Dec. = 35 0 10' S". On the robe under the \eft thigh of Aurip. This object is about 3' in diameter. and is composed of atara of varioUl magnitudes, from the 10th to the 14th. It is ~ by a amalI double Itar. A 91. B 11 magnitude. Diet. 5".00 Diacovered by Henchel. 1787.

=+

=

A Rrca CLUSTER-A. R. 5 b. 18 m. 41.. Dec. 850 U' On the left thigh aC Auriga. Diacovered by Me.ier, 1764, and described by him as " a _ of ataI'II ofa Iquare form, without any nebulosity, extending to about 16' of one 9".

degree."

+

A RE80LVA1ILE N'EB1l'LI..-A. R, = 6 b. 20 m. '&1.. Dec. = 340 06' 9". On the 1 _ garment of Auriga. J>i8oovered by Henehel in 1793, who say. that it _me to have one or two atara in the middle, or an irregular nucleua.

=

,

=+

R. & b. 41 m. 46 •• Dec. 32° 30' 1". In front of Auriga's \eft Ihin. ' Diacovered by Meaaier, 1764, and ~'bed""a maaa of amaIlltarI in nebulous matter." A FllfE CLUITU.-A.

+

8 AUls.l.-A. R. = & h. 48 m. (8.. Dec. 370 11"1". A line double star in the \eft wrUt. A 4, lilac; B 10, pale yellow. Pos. 2890 0' Diet. 30".00 Epocil 1832.64

=

=+

41 AURI9B.-A. R. & b. &9 m. 21.. Dec. 480 «' 1", On the chin of Aurip. A 7. white; B 71. ~olet. Pos. 3630 07' Diet. 7".99 Epoch 1830,31 8triive. ,

Many other double and triple atara, nebula! and cluaten, may be found on the chana, and by aligDmai1t their placea in the beavena may be readily made out.

CONSTELLATION OF GEMINI.

85

CHAPTER II. DIRECTIO:'llS FOR TRACING THE CON!lTELLATlONS ON

MAP,NO. VII.

GEMINI-THE TWINS. CANCEJI.-THE CRAB. CANIS MINOR-THE LrrrLE DOG.

Fa:vorahly situated for e:xami7Ullion in JanlUlry, February, Marck and April. GEMINI.

THE TWlN8.-This constellation represents the twin brothers, Castor and Pollux. Gemini is the third sign, but fuurth constellal:itm in the order of the Zodiac, and is situated south of the Lynx, between Cancer on the east and Taurus on the west.. The orbit of the earth passes through the center of the constellation. As the earth moves round in her orbit from the first point of Aries to the same point again, the sun, in the meantime, will appear to move through the opposite signs, or those which are situated right over against the earth, on the other side of her orbit. Accordingly, if we could see the stars as the SUD appeared to move by them, we should see it passing over the constellation Gemini between the 21st of June and the 23d of July; but we seldom see more than a small part of any constellation through which the sun is then passing, because the feeble luster of the stars is obscured. by. the superior effulgence of the sun. When the

H

lUll

ill jUlt entering the outlinea of • coIiateI1ation OIl the

86

GEOGRAPHY OF TIJE HEAVENS.

east, its weate.n limits may be aeen in the morning twilight,.JtISt aoovtt the rising lun. So when the 11m h.. anived at the western limit of a constellation, the eastern part of it may be aeen lingering in the evening twilight, just behind the setting 11m. Under other circumetances, when the 11m is said to be in, or to enter, a particular conltellation, it is to be understood .that the conltellalion is not then visible, but that thOll8 opposite to it, are. for example: whatever conlltellation sets with the sun on any day, it is Plain. that the one opposite to it mllBt be then riling, and continue visible throughout the night. A180, whatever constellation rises and seta with the sun to-day, will, six months hence,' rise at 1Imsetting, and set at 11m-riling. For example: the IIIIn is in the center of Gemini about the 6th of July, and mual rise and set with it on that day; consequently, six months from that time, or about the 4th of January. it will rise in the eaat, jus!: when the sun is setting in the west. and will come to the meridian at midnight; being then exactly opposite to . the sun. Now.. the stars gain upon the 11m at the rate of two hours every month, it follows that the center of this conateIIatiOll will, on the 17th of February, come to the meridian three hours earlier, or at 9 o'clock in the evening. It would be a pleuant ellercise for l&udents to propose questions to each other, 80mewhat like the following:-What zodiacal constellation will rise and set with tllll sun to-day 1 What one will rise at lIm-setting 1 What conltellation is three hours high at sun-set, and where will it be at 9 o'clock? What constellation rises two hours before the SUD 1 How . ~any daYI or IDOIlthe IIIlnce. and what hour of the evening or morning, • in what. part of the sky shall we _ the conateIIation whOll8 center is nb.. where the IIIID is! &c., &c. 'tn IIOIving these and similar questions, it may be remembered that the suJi ii·in the vernal equinox about the 21st of March, from whence it adVance8 through one sign or constellation every succeOOing mOllth thereafter; and that each ccmstellatinn'is one' month in advance of the Bigft of that name: wherefore, reckon Pisces in March, Aries in April, Taurus in May, and Gemini in June, &e. ;. beginning with- each COIllIteIlation at tb,e 21.., or 21d of the month. .

Gemini contains eighty-five stal'f!, including two of the ~d, four of the 3d, and six of the 4th magnitudes:. It is readily recognised by means of the two principal stars, Castor and· Pollux, a. and JJ, of the 2d . magnitude, in the head of the Twins, about 41° apart. There being only 11 minutes difference in the transit of these two stars over the meridian, they may both be considered as culminating at 9 o'cJock about the 'l4th of February. .Castor, in the head of Castor, is a s~r of the 2d magnitude, 41° N. W.

CON8TELLA.TIC»". OF GEMINI.

87

of';pollux, and is the northernmost and the bright"'st of the two. Pollux is a stili' of the 2d magnitude, in the head of Pollux, and is -ij0 S. E, of Castor. This is one of the stars from which the moon's distance is calculated in the Nautical Almanac.. - - " Of the &.med Ledean pair, One moat illua1rioua .tar adorns their IigD, And of the second order shine twin lights."

The relative magnitude or brightness of these stars has undergone considerable changes at different periods; whence it has been conjectured by various astronomers that Pollux must vary from the 1st to the 3d magnitude. But Herschel, who observed these stars for a period of twenty-five year~, ascribes the variation to Castor, which he found to consist of two stars, very close together, the less revolving about the larger once in 342 years and two months. Bradly and Mutelyne tDund that the .Une joining the two IIIaJII which form Castor was, at aU timeB of the year, parallel to the line joining Cutor and Pollux; and that both of the former move around a common center between them, in orbits nearly circular, as two balls attached to a rod would do, if suspended by a string affixed to the center of pvity between

them. "'J'heae men," .ys Dr. Bowditch, .. were endowed with a 1Iharpn_ of Tision, and a power of penetrating into space, almost unexampled in the history of utronomy." Abou~;SOC S. W. of Ca&tor and Pollux, and in a Une nearly parallel with thilM,;' a row of stare 30 or 40 apart, chie1ly of the lid and 4th magnitudes;-which distinguish the feet of the twins. The brightest of theBe is Aihen4, 1'> in Pollux's upper foot; the next Bmall star S. of it, is in hie other foot: the two upper IIIaJII in the line next above ,., mark Castor's feet. This row of feet is nearly two-thirds of the distance from Pollux to Betelguese in Orion, and a line connecting them will ~ through A\hen&, the principal star in the feet. About two-thirds of the distance from the two in the head to those in the feet, and nearly para11el with them, there is another row of three IItarB about 60 apart, which IIlIIlk the

b_.

.

There IU"8, in this C01llIteDation, two other reawbble parallel rows, lying at right angles with the former; one, leading from the head to the foot of Castor, the brighteat star being in the middle, and in the knee; the

88

GEOGR.\PHY OF THE HEAVENS.

other, leading from the head to the foot of Pollux, the brightest star"caUed

Waaat, I, being in the body, and C, next below it, in the knee. Waaat is in the ecliptic, and very near the center of the constellation. The two sta.ra, fA and Tejat, ., in the northern foot, are also very near the ecliptic: 'rejat is a IIIIIBIi star of between the 4th and lith magnitude., 20 W. of fA, and deser¥ea to be notU;ed becau.e it marks the spot of the summer solstice, in the tropic of Cancer, just where the sun is, on the longest day of the year, and is moreover, the dividing limit between the torrid and the N. temperate zone. Propua, also in the ecliptic, 2~0 W. of 0, is a star of only the 5th magnitude, but rendered memorable as being the star which served for many years to determine the position of the planet Herschel, after its firat discovery. • . Thus as we pursue the study of the stars, we .hall find continually new and more wonderful developments to engage our feelings and reward our labor. We shall have the peculiar satisl8ction of reading the same volume that was spread out to the patriarchs and poets of other ages, of admiring what they admired, and of being led as they were led, to look upon these lofty mansions of being as having, above them all, a common Father with ourselves, " who ruleth in the armies of heaven, and bringeth forth their hOllta by number." TELESCOPIC

OBJECTS.

A RICH CLURTK. .-A. R. = II h. 69 m. 01 So Dec. = 240 21' 8". Near' Castor'. right foot. A very fine object; consiMing of a crowd 01 .tars from the 9th to the 16th magnitudeL Discovered by Messier, 1764.

=

+

=

=+

6 h. 45 m. 56 So Dec. = ISO 10' "". A C,.USTER.-A •. R. On the calf of the right leg of Pollux; consists of minute stars of the 12th and 16th magnitudes, arranged IIOIDeWhat in the shape 01 a lim, as described by fonner ohserven. Discovered by Sir W. Herschel, 1783. 1.

GZlI(INORlJlI(.-A. R. 7 h. OS m. '1i4 So Dec. 160 49' 5". star on the left thigh of PoUux. A 4i, white; B 12,

A fine double yellowish.

Discovered by StrUve, and thus measured. Poe, 300 65' Dist. 9".56 Epoch 1829.86

=

=+

I GElI(INORUJII'.-A. R. 7h. 10 m. 34 So Dec. 22 0 Iii' 3. A double star on the right hip of Pollux. A 8~, " pale white; " B 9, "purple.If . Discovered by Henchel, 1781. Poe. 1960 M' DiaL 7".15 Epoch 1829.72 Strc.ve•

+

240 46' I; .. GZlIIIl10RUX.~A. R. = 7 h. 34 m. 47.. Dec. = A double star on the left shoulder of Pollux. A 4, orange; B 10, pale blue. The minute companion of this star was pointed out as one of a

CONSTELLATION

or

89

GEMINL

f8w which Sir John HeracbeI thought deaerved ~ attention, to determine whether it might not be a BGtellite Minmg by reJleeUtlIigM• .,piacovered by Henchel, with his twenty feet re1Iector.

Poe. 231 0 9'

DilL 6".0

Epoch 1838.98 Smyth.

61 GJ:Jllr.oau••-A. R..= 7 h. 17 m. 31 .. Dec. = +20034! 3". A coarse double and close double alar, making a quadrup)e set in the loins of Pollux. A 7i. deep yellow; B 9, yellowish; C 8, blue; D 9, bluish. DC Poe. = 420 24' Diat. = 6".6 Epoch 1~36.86 Smyth.

+

... GJ:.Il!IoalJ•. -A. R. = 7 h. 24 m. 23.. Dec. = no 14'. A beautiful· double Itar in the head of Cu'tor, and ll8llleel Castor. A 3, B 3i. magnitude. This is one of the inteJeating 1Jinary The earIieet position on record is by Bradly anti Pound. Poe. 35f)D 68' Epoch 1719.84 This is deduced from the recorded position of the line joining the_ter of the components of Castor, with re1enmce to a third IItar of the I I th magnitude; distant abeut 72", In 1800, Sir W. Hemchel made the poe. = 2930 03', ainoe then we lind, amOllg others, these measures. Poe. 261 0 01' DilL 4". :'158 Epoch 1828.89 Str~ ve. 256 07 6 .280 \836.88 Encke, Galle. 252 49 4 .886 1841.11 M;;.dler. M ..dler has ~ the elements of the orbit of this star, and found fur a probable Period 232 years. There are, however, yet many difficulties in the way of reliable reaullB, and computers differ. More obaervati0n8 are n~ to complete the examinati01l8 of this iriteresting binary system.

tdGr..

+

!'I8 GII.r.oalJx;......A. R. = 6 h. 45 m. 37.. Dec. 130 22' 6". A double star 011 the left instep of Pollux. A 5j, B 8. magnitude. The large .tar yellow, the mnaII one purple. Discovered by Henchel in 1781. Poe. 1790 54' . Diat. 7".95 Epoch 1781.99 HeracbeI. 174 '53 5 .73 1829.24 Struve. 6 .42 1841.27 M;;.dler. 172 02 its periodiI: )I:i.dler thinka this ""stem may be binary. in which _ time cannot fall much below 3000 years.

4

CJ,USTKR.-A.

R.

=

7 h. 28 m. 57..

On me left sboulder of Pollux.

Dec. =

+ 210 66' 7"

Discovered by HerolChel in 1783,' and desciibed as .. a beautiful ciUlla oCmany large and com~ small stara, abeut IS' in diameter."

82

GEOGRAPHV 01<' THE HEA VEJ....s.

ANUER.

,

THE C:EL'!,'!, fifth constella.tiuH sign of It is situated between E. and Gemini contains "u,'''''~, stars, of which 4th Beta a star of the 4th magnitude, in the southwester.I claw, 10° N.E. of Procyon,G Canis Minoris, and may be known from the fact that it stands alone, or a.t least has no star of thn same magnitude near it. It is midway between Procyon and Acubens. AcubeJL~. of the 5th tbe southeast~;E'n 10° N. E. of Beta, a st.raight it and Procymt. otherwise! by its' standing two verg close by it in Tegmin~\ \e in the back, small star, of between the 5th and Sio in a northerly direction from Beta. It. is a treble star, and to be distinctly seen, requires very favorable circumstances. Two of them are so near together that it requires a telescopic power of 300 to separate them. About t\E;nEitErlly 10us cluEinE Cancer, naked eyn. with Dog, W. of each. wi8e be discovered by means of two conspicuous stars of the 4th magnitude lying one on either side of it, at the distance of about 2°, called the rwrthcrn and southern Aselli. By some of the Orientalists, this cluster was denominated Pr(Z$cpe, the Manger, a. contrivance which their fanty fitted up for the

CONSTELLATION

ciF

91

CANCER.

accommodation. of the .Aaelli or Asses; and it is so called by modern ftstronomers. The appearance of this nebula to the unassisted eye, is not unlike the nucleus of a comet, aud it was repeatedly mistaken for the comet of 1832, which, in the month of November, passed in its neighborhood. The southern Asellus, marked 6, is situated in the line of the ecliptic, and in conneotion with 6 and Gemini, 'I, mark.s the course of the earth's orbit tilr a space ot 36° from the solstitial colure. There are several other double and nebulous stars in this constellfttion, most of which are too small to be seen; and indeed, the whole constellation is less remarkable for the brilliancy of its stars than any other in the Zodiao. The sun arrives at the sign Cancer about the 21st of June, but does not reach the constellation until the 23d of July. The mea.n right aBcenllion of Cancer is 128°. It is consequently on the meridian the 3d of Maroh. A few degrees S. of Cancer, and about 170 E. of Procyon, are four ltam of the 4th magnitude, SO or 4° apart, which 'mark the head of

B~ beginning of the BIgn Cancer (not the constellation) is called the

Tropic of Canur, and when the BUD arrives at this point, It has reach"d its utmOllt limit of north declination, where it seems to remain stationary a few days, before it begin8 to decline again to the 8OUth. This etationary attitude of the BUn is called the BUmmer MJilltice; Iiom two Latin words signifying the sun', Btanding .tiiJ. The distance from the first point of Cancer to the equinoctial, whlch at present, is 230 27!', is csllPd the ob/iquit!( of the tt:liptie. It is a remarkable and well ascertained iu::t, that this 18 continu8lly growing less and less. ,The tropics are Rowly and steadily approaching the equinoctial, at the rate of about half a IeCOnd every year; 80 that the sun dOllil not now come 80 far north of the equator in summer, nor decline 10 far IIOUth in winter, iii! it m\l8t have tIoae at the creation, by nearly a degree.

TELESCOPIC OBJECTS.

+

11 Cnelll.-A. R. = 7 h. 69 m. 02 s. Dec. = 270 116' 4". A cloae double Itar between ~ head of Pollux and the preceding claw

.C-.

A 7. B 12,

D.

.92

GEOGRAPHY OF ITHE BEAVPS.

Diat. S".18

Epoch 1828.26 8trilve.

=

=+

{ Cuc.I.-A.. R. 8 b. OS m. 01 L Dec. 180 07' 6". A fiue triple star just below the following claw of Cancer. A 6, yellow i B 7, orange; C 7i, yellowish. Discovered by the elder Hemchel. A B Poe. 3028' Dist.= 1".00 Epoch 1781.901HelIICheL A C 181 44 8 .06 1781.90 S

:!:

~~ 1!~ ~~ ~. ~::::n Struve. A B I O I 6" 1 .060 1841.31 l AC 147 64 6 .008 1841.31SMidler. 'rhis is a very remarkable object. Captain Smyth deduced a period for .It. and B of sixty years, while C performs its revolution about the other two in 600 or 600 yeam Here is It ternary ayltem; three I\IJIII revolving about their common center of gravity, and clou¥_ each attended by a retinue of planets. How wonderful must be the heavens to the inhabitants of the planets attached to this triple 8~.tem. Imagine a yellow BUD rising, an orange one on the meridian, while a purple or blue, or red one, DlDy be in the act of sinking below the horizon I Again, the powerfial analysis with which man urges his way through the intricaciea of our simple solar aylltem, woulcl utterly fail to trace the career of a planet subjected to the contencling inftuenoea of three grand om. like the sun. May we not infer, from this fRet. the existence of raeea of a higher order of intellect in the planets of theae ternary aystemB!

== +

• 2 CUCKJ.-A. R. = 8 h. 17 m. 6 L Dec. 170 17' r . .It. cloae double star above the northern legs of Cancer. A 6, B 6j, magnitude. Its position is probably fixed. . POL 2120 01'. Diat. 4:'.563 Epoch 1829.46 Strilve.

=

=+

,1 Cuc.I.-A. R. 8 h. 17 m 08.. Dec. 160 03' 3". A double star on the crab's northern middle leg. A 7. B 7i. Discovered by H8TIIl'hel. 1782. Measured by him u follows : POL 670 tH' Epoch 17H:'1.07 Herschel. In 1822. Sir James South and Sir John Herschel found the position to 0 be 37 47', whence a rapid retrograde motion 11'88 inferred, but aU su. quent measures disprove this inference, and inclicate a clirect motion. Poe. 390 04' Dial. 6".723 Epoch 1841.35 M;idler.

=

=+

I C~"c"I.-A. R. 8 h. 35 m. 35 8. Dec. 1SO 44' 4".. A difficult double star under the crab's mouth. A 4j, B 15, magnitude.

,Cul'cJU.-A. R. = 8 b. 37 m. 00 •. Dec. = ISO 20' 4". A double star at the end of the crab'. aorthern claw. A 61, pale orIIIIp; B 8, clear blue.. This is the tint double star I ever _11'. In July 1841, I had the pleuure of examining it at the obaervatory of' Sir Jamea South, Kensington. The colora were diatinet and beautifully contrasted• . POL 307° 06' Diat. 80".46 Epoch 1828.04 Struve. No material mange baa occurred in fifty-fOur yean, the time since ill discovery by .HeJICheL

93

CONSTELLA TION OF CANCER.

=

=

67 ME811U, C.lIle.I.-A. R. 8 h. 42 m. 211.. Dec. + 12° 23' 6". A rich but _ttemd cluster, at the root of the southern claw of Cancer. It is readily I88Olved. and with a power of 167 He_hel counteJ two hundml IIlara of various magnitudell, from the 9th to the smallest magnitude. I have frecJuently examined this apIendid objP.t"t, and from ita appearance suppose It to be one of the near .. island wuvemes. ' Discovered by Me.ier, 1780• .. 2 CneRI.-A. R. =8h.« m. 28 a. Dec.=+31 0 10'9"• .\ doae double star over the crab'. northem claw. A 6i. B 7 magnitude. Diaoovered by Sir W. Herschel. 1782. PO&. 333° 18' DiaL = 1".61 Epoch 1829.71 &ruvt>. There is little evidence of any change of position, though the meaaunlll JeeOIded are far from coincidenL "

+

.. 4 C."e.I.-A. R. = 8 h. 61 m.36a. Dec. = a:ao 62' 4". -' cloae douhle star, following the crab's northern claw. A 6, white; B 9, blue. Discovered by South, 1825. PO&. 137°47' DiaL 4",60 Epoch 1831.16 StrUve.

CANIS MINOR.

TUE Ln-rLB Doa,- This small constellation is situated about 6° N. of the equinoctial, and midway between Canis Mf\jor and the Twins. It contains fourteen stars, of which two are very brilliant. The brightest star is cfllled Procyon, marked G. It is of the 1st magnitude, and is about 4° S. E. of the next brightest, GoTrwlm, marked 13, wbich is of the 3d magnitude. Tbese two stars resemble the two in the head of the Twins. Procyon, in the Little Dog, is 23° S. of Pollux in Gemini, and Gomelza is about the same distance S. of Castor. A great number of geometrical figures may be formed of the principal stars in the vicinity of the Little Dog. For example; Procyon is 23° S. of Pollux, and 26° E. of Betelgues"e, and forms wHh them a large right angled triangle. Again, Procyon is equidistant from Betelguese and Sirius, and forms with them an equilate~al triangle whose sides al'8

94

GEOGRAPHY OF THE REA.VE,N8.

f'ach about 260 • If a straight line, conne~ting Procyon and Sirius, be produced 23° farther, it will point out Phaet, in the Dove. . Procyon is often taken for the name of the Little Dog, or for the whole constellation, as Sirius is for the greater one; hence it is common to refer to t>ither of these constellations by the name of its pl'incipal star. Procyon comes to the meridian fifty-three minutes 'after SiriUI, on the 24th of February; although it rises, i,n this latitude, about half an hour ~ore it. For this reason, it was called Pl-ocyrm, from iwo Greek words which signify (Ante Canis) " before the do~." " Canicula, fourteen thy atam; but fiIr Above them all, illustriouB throUgh the skies, Beams Proeyun: justly by Greece thUB called The bright /fR'tlrUnmr of the greo.ter Dog."

From an irregularity in the annual proper motion of Procyon, Bessel concluded that it was disturbed by some invisible opaque body of vast size, snnk .in space, near Procyon. StrUve has recently cast a doubt on the reality of this irregularity, and thinks it is due to imperfeot observations.

05

CONSTELLATION OF M()~OCER08.

DIRECTIONS FOR TRACING THE CONBTF.I.l.. ATJON8 Ol'r

MAP NO. VIII. MONOCEROS-THE UNICOaN. CANIS MAJOR THE GREAT LEPUS-THE HARE.

DOG.

TRE PaINTING Puss.

Favurably situated for examination in January, February aM Marek. MONOCEROS.

THE UNICOBN.-This is a modern constellation, which was made out of tbe unformed "tars of the ancients that lay scattered ,\ver a large space of the heavens between the two Dogs. It extends a considerable distance on each "ide ofthf! equinoctial, and its center is on the same meridian with Procyon. . It contains thirty-one small stars, of which the seven principal ones are of only the 5th magnitude. Three of' these are situated in the hf'!ad, 3° or 4U agart, forming a straight line N. E. and S. W. about 9 E. of Betelguese, in Orion's shoulder, and about ~he same distance S. of Alhena, in the foot of the Twins. The remaining stars in this constellation are scattered over a large space, and being very small, are unworthy of particular notice; TEl.. ESCOPIC OBJECTS. 104 P. VI,Molfoc..arJ8.-A.R.=8h.I8m. 50 •. Dec.=+ 00 32' 6". A coaJ'IIe triple. 01' dose double star. A 7j. B and C, each 8j magnitude. As A and B are 66" apart, we ahalJ OII1y have to do with B and C. This is ODe of Struve'. "vincinisseme" IItarB. Be reporbI theE _ POI. 1680 48'

DiIt. 0".78

11 M..-ocllaarll.-A. R.

=

Epoch IN.I'

«I h. 21 m. "'.. Dec. =

-

6° 66' 1"•.

96

~EOGRAPHY OF THE HEAVENS.

A line triple star in the right fore leg of MonOOllJ'08. A 61, B 7, C 8, magnitude. Discovered by Sir W. Hencbel, and by him IBid to be one of the lIIOI& beautiful Bights in the heavens. A B Po.. 101 0 44' Dist. ::".41i3 Epoch 1831.23 Strilve. AB 103 41 2 .657 18"2021 Mi>dler. A C A C

310 00 311 23

7 .253 7 .205

1831.23 1842.21 1842.21

StrUve.

M::dler. BC 304 40 9 .452 M:
=

16 MOl'OCzalrrI8.-A. R.

= 6 h. 32 m. 10 B.

t H • A triple star between the

88111

B 9," pale grey;" C 15," blue.'" Discovered by Str.. ve. Poe. A B 2080 66' A C 12 90

=+

Dec.

of Monoceros.

Dist. 2".76 16 .58

= + 100 02'

A 6," greeniah; "

. Epoch 1831.37lStr" 183I.a75

Llve.

50 MS••IJIR, MOlJOOll11Irr'B.-A. R. = 6 h. 65 m. 11 B. Dec. =SO 06' 7". A luge cluster in the Milky Way, on the Unicorn'. right shoulder, composed of stars varying from the 8th to the 16th magnitwk> Discovered by Me.ier, 1771. .

CANIS MAJOR. TUE GIlJ!lAT DOG.-This interesting constellation is situated southward and eastward of Orion, and is universally known by the brilliancy of its princi pal star, Siriua, marked G, which is apparently the largest and brightest in the heavens. It glows in the winter hemisphere with a luster which is unequaled by any other star in the firmament. Its distance from the earth, though computed at twenty millions of millions of milet'l, has been considered less than that of any other star: a dit..tanoe, however, !!IO great that a cannon ball, which fii'3s at the rate of nineteen miles a minute, would be two millions of years in pas~ing over the mighty inter-

CONSTE1.LATION OF CANIS MAJOR.

97

val; while Bound, moving at the rate of thirteen miles a minute, would reach Sirius in little les8 than three millions of years. It Day be IIbown in the _ IDIUIDI!I', that a ray of light. which occupiM only eight minute. and tbirteen II8COIIda in coming to us from the IUD, which is at the rate of nearly two hundred thouaand mi1ee a second, would be three y_ and eighty-two day. in puaing through the VlIIJt apace that Iiea between Sirius and the eazth. COJIII8Quently, were it b/oUed from the heavellll, ita light would continua visible to us for B period of three y_ and eighty-two daye after it had. ce.-l to be. If the neare8t IItarII pve BUeb ~ l'8Iultl, what ahall we say m thme which ue lituated a thou.nd timea u liar beyund th., u theae uefrom us1

In the remote ages of the world, when every man was his own astronomer, the rising and setting of Sirius, or the Dog-star, as it is caned, was watched with deep and various solicitude. The ancient Thebans, who first cultivated astronomy hi Egypt, determined the length of the year by thE" numbe'r of its risings. The Egyptians watched its rising with mingled apprehensions of hope and fear j as it was ominous to them of agricultural prosperity or blighting drought. It foretold to them the rising of the Nile, which they called Siria, and admonished them when to sow. The Romans were accustomed yeaJ;ly, to sacrifice a dog to Sirius to render him propitious in his influence. upon their herds and fields. The eastern nations generally believed the rising .of Sirius would be productive of great heat on the earth. Thus V"ugil : - . - " Tum IImilei _ Sirius apII: Anlebant herbm, et ~ -sea IBIJI'B negabat. " - " Pan:bed _ the irua, and blighted _ the com. Nor '_1'8 the beuIa; for Sirius, from on high, With l-tilimtial heat infileIa the *y."

. Accordingly, to that season of the year when Sirius rose with the sun and seemed to blend its own influence with the heat of that luminary, the I

98

GEOGRAPHY OF THE HEAVENS.

ancients gave the name of Dog-Jays, (Dies Caniculares). At that remote period the Dog-days commenct'd on the 4th of August, or four days after the summer solstice, and lasted forty days, or until the 14th of September. At present the Dog-days begin on the 3d of July ~ and continue to the 11 th of August, being one day less than the ancients reckoned. Hence, it is plain that the Dog-days of tlte moderns have no 'reference whatever to the rising of Sirius, or any other star, because the time of their rising is perpetually accelerated by the precession of the equinoxes: they have reference then, olJly to the summer solstice, which never changes ita position in respect to the seasons. The time of Sirius' rising vane. with the latitude of the place, and in the same latitude, is sensibly changed after a coune of yeara, on account of the precesaion at the equinoUs. ThiS enables UB to determine with approximate accuracy, the datea of many events of antiquity, which CBJlnol be well determined by other records. We do not know, for instance, in what precise period of the world Heaiod flourished. Yet he tella us, in his Opera et Diu, lib. ii. v. 185, that Arcturus in bis time rose heJiacally. sixty days after the winter BOlatice, which then was in the 9th degree of Aquarius, or 890 beyond itit present position. Now 890 : 54i = 2794 years since the time of Heaiod, which corresponda very nearly with bistory. ' Wben a star rose at sun_tting, or set at sun-rising, it was called the .A.cltrrmieal rising or setting. When a planet or star appelll'lld, above the borizon just before the sun, in the morning, it was called the H~/iacaJ rising of the star; and when it sunk below the horizon immediatE'ly after the sun, in the evening, it was calJed the Heliacal setting. Aceording to Ptolemy, atara of the.fir" magnitude are seen rising and setting when the sun is 12° below the horizon; &tara of the 2d magnitude require the sun's depreMion to be 180 ; &tara of the 3d magnitude, 140, and 80 on, allowing one degree for each magnitude. The rising and setting of the stars described in this way, IIinee this mode of description often oocura in Heaiod, Virgil, Columella, Ovid, Pliny, &c., are called podia:Il rising and setting. They served to mark the times of religious ceremonies, the seasons aUoUed to the several departments of husbandry, and the ov_ flowing of the Nile. H

The student ~ay be perplexed to understand how the Dog-star, which he seldom sees till mid-winter, should be associated with the most fervid heat of mmme1'. This is explained by considerin(J' that'

9Y

CON8TELLATION OF CAN18 MAJOR.

this star, in summer, is over our heads in the dayAs " thick the floor of heaven is inlaid with patines of bright gold," by day, as by night; but on account of the superior splendor of the sun, we cannot see them. Sirius is easily recognised, being the brightest star in the heavens, and is pointed out by the direction of the Three Sta1'8 in the belt of Orion. Its distance from them is ahout 23°. It comes to the meridian at 9 o'clock on the 11th of February. Mi1'%lJm, marked /1, in the foot of the Dog, is a star of the 2d magnitude, 5}0 W. of Sirius. A little above, and 4° or 6° to the left, there are three stars (If the 3d and 4th magnitudes, forming a triangular tigul'e somewhat resembling a dog's head. The brightest or them, on the left, is called M1dipken, marked 'Y' It entirely disappeared in 1670, and was not seen again for more than twenty years. Since that time it has maintained a steady luster. Wesen, marked ~, is a star of the 3d magnitude, in the back, 11° S. S. E. of Sirius, with which, and Mirzam in the paw, it makes an elongated triangle. The two hinder feet are marked by Naos and Lambda, stars of the 3d and 4th magnitud~s, situated about 3° apart, and 12° directly S. of the fore foot. This constellation contains thirty-one visible stars, including one of the lst magnitude, four of the 2d, and two of the 3d; all of which are easily traced out by the aid of the map.

time, and in the lower hemisphere lit night.

TELESCOPIC OBJECTS.

== -

, 1 C.un. Muo.rl.-A. R. = 6 h. 29 m. lI3.. 'Dee, 180 32' 0". A double Itar in the Greater Dog's left knee, about 3':' aoutb- c weill of SiriUII. A 6~, B 8, magnitude. Die&. !r.M Epoeh 1842,82 Main. Poe. 2111 0 36' .. C ... ~I. M.....01"&, SI.,uI.-A. R. = 6 h. 3R m. 06.. llee, =1H Y 30' 1", A Itar of the fuat ~tude in the mouth of the Greater

100

GEOGRAPHY OF THE HEAVEN&

Dog, the IDOIl briWant of all the fixed IItar8. The teleecopic appearance of tbia oiject mUl& be _ to be IIJIllII!clated Long befOre it enters the field of the teleacope, ita eoming ill indicated by a gradually brighteDing dawn, which slowly increaEa in aplen.dor, until the IItar enters with ita full blue, tj)() powerfu1 to be home by the light. lIB entrance BDd diIappeuance .-bletbe riling mel Betting of the IUD. Siriua was long regarded aa the neamat of all the fixed '1IIuB, from ita e:rceeding brilliancy. I.ong and delicate IDeII81ln!II have been made to determine ilB paralla:r, but without aatDfiletory _Ita. Yet ibl proper motion ill great, and readily deduced fiom a few yean of ot.erntionll. On a comparison of the place of Sirius, aa laid down by the earliest Greek utronomers, with ita preaent position, and computing the ehangee due to the preaent rate of proper motion. ~ deducea the curiou filet that the annual proper motion ill not ",ni/_! 'l'hiI ill true of a few other Ii ,00 staJII. 1'0 account for thia .phenollK'llOll, H~ ClOJICI!ivee that Siriu is subJected to the influence of lOme vast body, which, from the liact of ilB being non-luminous, haa never been diacovered. How wonderful would it be, ifby a ripllICI'Utiny of the devistions of tbe proper motiOll8 of Sirius from uniformity, we should be led to a knowledge of the position in space of this dark disturbing body, of whCllle place and exiltence, indeed, the eight can reveal to us nothing. The latest and best measures for parallax are by Henderson and McLear, who found for the angle subtended by the radiu of the earth'. orbit, at a distance equal to Sirius. OH.t3. or about one quarter of one IIOOOnd of space. In eIIBe we adopt this aa the true paralla:r, the distance of 8iriu must be nearly eighty million. of millions of miles, aDd from ita splendor we are able to infer, with certainty, that ilB magnitude is very much greater than that of our IUD. Indi!OO, Dr. Walliston, auuming the diltance to be I;mt half the above, concludes fiom his photometrical measures, that Sirius, if seen as near .. the sun, would present a diameter four times greater than that of the BUD.

=

=-

". CUIB MnollIs.-A. R. 8 h. 48 m. 48 L Dec. A double IItar on the Dog's right ear. A iii, yellow; B Diacmered by Struve, who gives theBe ineaaurea. POL 3430 31' Diet.. 3".22 Epoch 1831.30

6H •

ISO 60'

91, grey.

14 HliIIlICR&L, VB Cu,s Mnollll.-A. R. = 6 h. 6' m. 10 .. A clueter of BtarI back of the Dog'. head, about 20' in diameter. The atara range from the 8th to the 11 th magnitude.

Dec. = - 130 29'

,H.

Discovered by HencheL 12 HSUCR ..., VB CUll MUO.IB.-A. R. = 7 h. 10 m. 35 L Dec. =-160 21' 4H • A clueter ofBtarl between the Dog and Unicorn; and comiata principally of BtarI of the 16th magnitude. Discovered by MilIa HencheL .

CONSTELLATION OF LEPUS.

101

LEPUS.

To HABE.-This constellation is l!Iituat~d directly south of Orion, and comel! to the meridian flt the .,ame time; namely, on the 24th of January. It hae a mean declination 18° S. and contains nineteen small stars, of which, one is of the 2d, one of the 3d, and six of the 4th magnitudes. It may be readily distinguished by means of four stars of the 3d magnitude, in the form of an irregulflr square, or trapezium. Zeta, of the 4th magnitude, is the first star, and is situated in the back, 5° S. of Saiph, in Orion. About the same distance below" are the four principal stars, in the leg!'! and feet. These fOl'm the square. They are marked A,j3, ,)" II. A and /3, otherwise called Arneb, form the N. W. end of the trapezium, and are about 3° apart. 'Y and II fOl'm the S. E. end, and are about 21-° apart. ,The upper right' hand one, which is Arneb. is the brightest of the four, and is near the center of the constellation. Four or five degrees S. of Rigel are four very minute stars, in the ears of the Hal·e. TELESCOPIC OBJECTS. , LEPORls.-:\. R. = 5 h. 04 m. 50.. Dee. = - 120 03' 9". double star in the left ear of the Hare. A 4i, B U, magnitude. Poe. :1,,9° 31' DiaL 12".34 Epoch 178~.69 Herschel 3:17 39 12 .81 1832.25 Struve.

A

,. LXPORI ••-.o\. R. = Ii h. 5 m. 51.. Dee. = lao 08' 0". A douhle star at the rool of the ear. A 5. B 9, magnitude. POI. .358" 68' Dis&. 3".053 Epoch 1832.23 Struve.

12

102

GEOGRAPHY OF THE HEAVENS.

Dl&ECTlONS FOR TRACING THE CON8TELLATJONS ON

MAP NO. IX.

LBo M.uoR-TuB GREAT Lim•. SUTAN8-0TUE SUTANT.

Favorohly rituoted for exmni7lD.ticm in Marek, AprU, and

May. LEO •

. THB LloN.-This is one of the most brilliant constellations in the winter hemisphere, and contains an unusual number of very bright stars. It is situated next E. of Cancer, and directly S. of Leo Minor and the Great Bear. The Hindoo AaIzonomer, Varaha says. " Certainly the IIklthern aoI,lice W1III once in the middle of .A8ieAa (Let,); the nonhern in the lint degree of DIu.miII&tIJ" (.tquariU8). Since that time, the IOl.etitial, u well .. the equinoctial pointa, have gone backwards on the ecliptic 7f,o. 1'bia divided by 5Oi", gi_ 6378 YeBlll; whicll carry us back to the year of the world 464 •. Sir W. JODeI, laY. that Varaba lived when the IDIaticea were in the lint ~ of Cancer and Capricorn; or about 400 yeBlll befOre the ChriIIian era.

Leo is the fi.fth lign, and the ai:dll cQDsteIlation of the Zodiac. The mean right ascension of this extensive group is 150°, or 10 hours. Its center is therefore on the meridian the 6th of April. Its western outline, however,comes to the meridian on the 18th of March, while its eastern limit does not reach it before the 3d of May. This constellation contains ninety-five visible stars, of which one is of the 1st magnitude, one of the :.!d, six of the 3d, and fifteen of the 4th. The principal star in this constellation is of the 1st magnitude, situated in the breast of the animal, marked A, and named RegulU8, from the illustrious Roman consul of that name.

CON8TELLA TION OF LEO.

. 103

It is situated almost exactly in the ecliptic, and may be readily distinguished on account of its superior brilliancy. It is the largest and lowest of a group of five or six bright stars which' form a figure somewhat resembling a sickle, in the neck and shoulder of the Lion. There is a little star of the 5th magnitude about f1' S. of it, and Olle of the 3d magnitude 5° N. of it, which will serve to point it out. . Regulus is t.he brightest star ill the constellation. Great use is made of Regulus by nautical men, for determining their longitude at sea. Its lolitude, or .distance from the ecliptic, is less than 1°; but its· dedi1lOJ.Um., or distance from the equi1llJCtiol is nearly 13° N.; 80 that its meridian altitude will be just equal to that of the sun on the 19th of August. Its right ascension is very nearly 1500. It therefore cul~inates about 9 o'clock on the 6th of April. Wheu Regulus iI 011 die meridian, Cutor and Pollux aze _ about 400 N. W. of it, and the two atara in the Little Dog, are about the II8DIIl diItance in a 8. w. diJectien; with which, and the two fOrmer, it makeII alarp ~ triangle whole ~ertex iI 11& Beguhu.

The next considerable star, is 5° N. of Regulus, marked'!, situated in the collar; it is of between the 3d and 4th magnitudes, and, with Regulus, constitutes the handle of the sickle. Those three or four stars of the 3d magnitude, N. and W. of,!, arching round with the neck of the animal, describe the blade . .Al Gieba, marked 'Y, is a bright star of the 3d magnitude, situated in the shoulder, 4° in aN. E. direction from,!, and may be easily distinguished by its being the brightest and middle one of the three stars lying in a semicircular form, curving Lowards the west; and it is the first in the blade of • the sickle. MJwjera, marked" is a star of the 4th magnitude~ li.tuated in the neck,4° N. of.Al Gieba, and may be

104 .

GEOGRAPHY OF THE HEAVENS.

known by a very minute star just below it. This is the second star in the blade of the siokle. • Ro,s oJ Asad, marked /4, situated before the ear, is a star of the 3d magnitude, 6° W. of Adhafera, and is the third in the blade of the Bickle. The next star, I, of the same magnitude, situated in the head, is 2io s. W. of Ras al Asad, and a little within the curve of the sickle. About midway between these, and a little to the E., is a very small star, hardly visible to the naked eye. . 1AmJJda, situated in the mouth, is a star of the 4th magnitude, 3&-0 S. W. of I, and the last in the sickle's point. Kappa, situated in th~ nose, is another star of the same magnitude, and about as far from,. as ,. I and. are about ai° apart, and form the longest side of a triangle, whose vertex is i.n •. Zosma, marked 3, situated above the back of the Lion, is a star of the 3d magnitude,18° N. E. of Regulus, and midway between it and Coma Berenices, a fine cluster of small stars, 18° N. E. of Zozma. Tketa, situated in the tail, is another star of' the 3d magnitude, 6° directly S. of Zozma, and so nearly on the same meridian that it culminates but one minute' after it. This star makes a right angled triangle with Zozma on the N., Denebola on the E., the right angle beini at). Nearly in a straight line with Zozma, and ), and south of them, are three or four smaller stars, 4° or 6° apart, which mark one of the legs . .1Jene/Jda, marked /J, is a bright star of the 2d magnitude, in the brush of the tail, 10° S. E. of Zozma, and may be distinguished by its great brilliancy. It is 6° W. of the equinoctial colure, and comes to the meridian one hour and forty-one minutes after Hegulus, on the 3d of May; when its meridian altitude • is the same as the sun's at 12 o'clock the next day. When Denebola is on the meridian, ReguJus is _ 250 W. of it, and DUd, in die 1q1W8 of U. M.jor. beaD a90 N. of iL Ii will

m-.

105

CON8TELLA TION 01' LEO.

tbeee two, _large right aJIIIed biaagle; the right angle bfing al Denebola. It ill 80 nearly on the _ meridian witll »had that it eulmiDatee only tOur minutes befure it.

Denebola is 351° W. of Arctur1l8, and about the same distance N. W. of Spica Virginis, and forms, with them, a large equilateral tria.ngle OD the S. E. It also forms with Arcturus and Cor Caroli a similar figure, nearly as large on the N. E. These two triangles, being joined at their base, constitute a perfect geometrical figure of the form of a Rhombus: called by some, the DIAMOND or VIllGO. A line drawn from Denebola tbrougb RegulWl, and continued 70 or SO fiuther in the _ direction, will peint out and .. of the 4th and 6th magnitudes, IIitua&ed in the fore cia.., and about so aput.

e

TELESCOPIC OBJECTS.

=+

=

L.o~J..-A. R. 9 b. 19 m. &a •• Dec. 90 W rY'. A WJrf close double star on the Lion'. left fore fooL ThiI hu long beea •

. •

IDOIIt difficult test

«#d.

Diacovered by Heracbel, in 1782, who found the poa. = 1100 MI, and eItimated tile distaw:e al one quarter the diameter of tile larger star; ~ magnitude ill 6i, tile IIID8lJer 7i. POI. 15a<> 56' Di&. 0".970 Epoch 1825.21 8tril_ 178 18 0 .800 1835.33 Struve. 194 00 0 .BOO 1841.35 ~1er. In 1842 it WIllI ~ . . _1IingIe atar, by Mad1er. The elementa of the orbit haWl been computed by Kiidler, who finda _ period of 82j yean. By hia computatiOll8 the a&ar8-were distant 1".45, tIleir maxinm, in 1800. After _ lapae of fifty-two yeara they will reach their Ieut diatance 0".2, which will -.reeIy be meuurable in tile IDOI&

powerful inatnunel)ta.

+

57 HJlRlcan I, LlIOlUI.-A. 1l. = 9 h. 23 m. 07.. Dec. = 120 12' I". A double white nebula in the lower jaw of Leo. '!'here is _ double nUIlI with the nebuloeiliee commingling.

=

=

,. LlIOlfll.-,\. R. 10 b. II m. 08.. Dec. +'100 39' 0". A be8utiful double atar near the Lion'. mane. A 2, bright orange; B 4, greenish yellow. _ Thia is doubtleaa _ binary ayatern, whoae period may reach _ tlwulmld yearll ! I have repeatedly examined this splendid 0bject, witll _ po_ of 600; the Cincinnati refractor ehOWl the cliab of both the IItaI'I round and clear.

DUcovered by Herachel, 1781. POI. 103" 22'

nut.

2".60

Epoch 1831.51

StrUve.

106

GEOGRAPHY OF THE HEAVENS.

=

=+

67 P. X. LaoNI8.,....A. R. 10 h. 17 m. 09 •. Dec. 90 86 2". A neat double star on the Lion's right shouldet. A S. B 9i, magnitude.

The measures indicate lhity in the componenlll.

Di.acovered by Herachel.

.Pos. 630 28'

Dist. 4".110

65 54

3 .20

Epoch 178l1.l3 Berachel. 1832.66 Sur.ve.

=

49 LEO!us.-:-A. R. 10 h. 26 m. 38 a. Dec. close double star under the right shoulder of Leo. pale blue. Discovered by SUC;ve.

POI. 161" 09' 158 01

Dial. 2".37 2 .50

+A 906, white; 28' 5". A B 9, .

Epoch 1830.76 Struve. 1838.37 Smyth.

95 MESSIER, LEONII.-A. R. = 10 h. 35 m. 31 a. Dec. = 12<' 31' 09". ·A white nebula on the ribs of Leo. Discovered by Mechain, 1771. One degree east, and following this nebula, is another, lese bright, also ru.covered by Mecbain. 18 BaRBeRU I, L>:ONJs-A. R. = 10 h. 39 m. 49 I. Dec. = 130 28' 0". A pair of bright c1a88 neblllre, with a third faint one in company, on the belly of Leo. This region of the heavens is filled with nebulous clouds, a part of the great stream whit'h cncircles the entire heavens. Discovered by Herschel in 1783.

=

54 LaONJa.-A. R. 10 h. 46 m. 56 s. Dec. double star over Leo'. back. A 4:6, B 7. Discovered by Sir W. Herschel, 1781.

POlL 1020 48'

Dist. 6".18

=+ 250 36' 0",

A

Epoch 1830.35 Sur.ve.

+

229 P. X, LBONIS.-A. R. = 10 h. 56 m. 44 s. Dec. = 40 30'. A close double star preceding the Lion's hind legs. A 8, B 8, magnitude.

Discovered by StrUve, and by him measured .. fullOWB: PO&. 2760 48' DiaL 1".076 Epoch 1829.13

=

=

13 BERBCRBL I, LBOlnB.-A. R. 10 h. 57 m. 37 a. Dec. ()O 49' 6". A bright nebula preceding the Lion'. hind ~ Discovered by Herachel, and one of a V88t number of aimilar objecta in this region. N ear this object Sir William examined more than 150 square degrees of diffused nebulosity, ~ extent 80 vast .. to defy the powers of arithmetic to compute its dimensions. If we abandon the theory of the existence of chaotic nebulous matter, and regard all these multitudinous stains of light as consisting of myriads of IIUD8, the ex tent of these "island universes" here located, is almost infinitely greater than all that the human eye can grasp on the brightest night. Herschel expresses himself thus. " The high degree of rarefaction of nebulous matter, .hould not be COD* Iidered an obstscle to the theory of its finally being condensed into a body of the density of the sun; for supposing tfie nebula distant 320 billions of miles, and i~ diameter equal to 10', then must its magnitude uceed that of the BUD more than two trillions (If times ! "

107

CONSTELLATION OF LEO.

What then must be the extent of a group of objects cmeriDg 160 equare degrees, and so remote that their milliOllll of Rggn>gated IlUDi pr0duce but a barely perceptible lltain of light on the deep blue ground of the heavena!

t

239 P. X, LBOIU8.-A. R. = 10 h. 68 m. 17.. Dec. = 7° 69' 09". A double star c1011e to the Lion'. hind legs. A 8, B II ,magnitude. It is probably fixed in poaition. POlIo 1640 46' Diat. = 8".03 Epoch 1833.28 Strilye.

+

. 9. P. XI, LBOl'I'JI.- .... R. = II h. 06 m. 17.. Dec. = 21 0 00' OS". A neat double star on Leo'. loina. A 7j, B 7j, magnitude. DiscoveIed by Stru ve. POlIo 287 0 48' Diat. 1".062 Epoch 1829.70 StrUve.

=+

=

66 MBISIBR, LzmIl8.-A, R. 11 h. 11 m. 48.. Dec. IlIO 52' 04". A large elongated nebula with a bright nucleus, preceded by . another of a similar shape. DiscoveIed by Michain, 1780, and regi8teIed No. 66 and 65 Meuier. A third nebula follows on the AIDe parallel, 174 seconds of time.

+

, LBOl'I'Is.-A. R. = II h. 15 m. 35.. Dec. = 11 0 24' 08". A binary star on the Lion'. flank, 70 south-Wl'.st of Denebola. A 4, pa1e yellow; B 7j, light blue. Discovered by Str:'ve POB. 9?D 00' Dial. 2".30 Epoch 1827.28 86 00 2 .60 1842.38 Smyth.

Other nebuhe and double stars will be found on the star mapa.

SEXTANS.

THE SEXTm, called also URANIA'S SEXTANT, is a modern constellation that Hevelius made out of the unformed stars of the ancients, which lay scattered between the Lion, on the N., and Hydra, on the S. It contains forty-one very small stars, including only one as large as the 4th magnitude. This is situated very near the equinoctial, 130 S. of Regulus, and comes to the meridian about the same time on the 6th of April. The other stars in this constellation are too small to engage attention. A few of the largest of them may be tra.ced out frr~ the map. .

108

GEOGRAPHY

or

THK HEAVENS.

TELESCOPIC OBJECTS.

=

=

161 P. IX, SII:U.llfTIa.-A. R. 9 h. 36 m. 09 .. Dec. 30 II' ()4.... A double .au OIl the old Lion'. leg, bat included in the DIIW COIIICe11ation, the 8extBnt. A 8," yellowim white;" B 13," blue." POll. 1460 00' DiBl 4".00 Epoch 18U.26 Smyth. 142 20 3 .317 1830.24 Struve. -

163 H..IICBU I, SUT.lKTII..-A. R. = 9 h. 57 m. 16.. Dec.= 60 66' 09". An elonpted bright nebula, OIl the limb of the 8extmt. Liacovered by HemcbeI, 1787. .

" H••IICBU I, SIIXTU'TII.-A. R. = 10 h. 06 m.1I8 .. Dec. = 0 III' 01". A brightrolllld nebula on the &.me of the 8extBnt,'" lowed by another at the diMance of twenty.mne II8IlOIId. of time.

+4

Diacovered by HemcbeI, 1783; who\ ho_er, overlooked the fOllowing one, which _ 8IlJ.quently diaccmIred by hilaon.

+

35 SIIXT.llfTIl.-A. R. = 10 h. 35 m. 02 .. Dec. = 11°35' or. A double .au on the north extreme of the limb. A 7, B 8. i'0I. 240" 47" Dis&. 6".76 Epoch 18211.20 StrUve.

DIREm'lONS FOR TRACING THB CON8TBt..LATION8 ON

MA.P NO. X. HYDRA-THE WATD. SDPBIIT. POCULA-TBE CuP'. FELIS-THE CAT. To COMPASS. FatJOrtibly situated for examiMlion in MarcA, ad May. ,

~

HYDRA AND THE CUP. HYDIlA, THE W ATEIl SEJlPENT, is an extensive constellation, winding from E. to W. in a serpentine direction, over a space of more than one hundred degrees in length. It lies south of Cancer, Leo, and Virgo, and reaches almost from Canis Minor to Libra. It contains sixty stars, including one of

CONSTELLATION 01' HYDRA.

log

the 2d magniillde, three or the 8cJ, and tweive of the 4th. . .A1pkard, or Cor Hyd1'a, marked II, in the heart, i•. a lone star of the 2d magnitude, 23° S. S. W.·of Regulus, and comes ~ the meridian at the same time with a., in the point of the sickle, about twentY minutes before 9 o'clock on the lit of April. There is no other considerable· star oeiLr it, for whieh it can be mistaken. An iinaginary line drawft from 7 Leonis through Regulus, will point out Cor Hydrm, at the distance of 23°. . The head of llydra may be distinguished by means of four stars of the 4th magnitude, 2io and 4° apart, and forming a rhomboidal figure. The three upper stars in this cluster form a small Al'ch, and may be known by two very small stars just below the middle one, making with it. a very small triangle. The three western stars in the head, also make a beautiful little triangle. The euten star in this group, marked " is about 6° directly S. of Acubens, and culminates at the same time. When Alphard.is on the meridian, .A1kc8, marked II, of the 4th magnitude, situated in the bottom of the Cup, may be seen 24° S.E. of it, and is di~ tinguished by its forming an equilateral triangle with IJ and 7, stars of the same magnitude/6° S. and E. of it. Alkes is comm~)O both to Hydra and the Cup. IJ, on the S., is in Hydra, and 7, o~ the N. E., is near the middle of the Cup. .A line drawn from Zozma, through:. Leonis, and continued 3Blo directly S. will reach IJ j it is therefore on the same culminate at the same. time on meridian, and the 23d of April. The Cup itself, called also the Crr.iter, ml).y be e.asily distinguished by means of six stars of the 4th magnitude, forming a beautiful crescent, or semicircle, opening to the W. The center of this group is about 15° below the equinoctial, and directly S.

will

.

K

110

G&OGRAPHY OF THE HEAVEN&.

of ~e hioder feet of Leo. The c~sceot form or tJie stars in the Cup is so lItriking and well defined, when the moon is absent, that no other descriptioll is necessary to point them out. Its center comes to the meridian about two hours after Alphard,-on the same evening; and consequently, it colminates at 9 O'clock,· on., month after· Alphard does. The remainder of the stars in this constellation may be e8sily traced by aid of the' map. When the head of Hydra is OD the ·meridian, its other extremity is many degrees below the horizon, 80 that its whole length cannot be traced out in the heavens until its center, or the Cup, is on the meridian. ~ Near the equator roUe The aputling H dra, proudly eminen&

To drink the ~l~. refulgent _ ; Nearly a rourth7~ encirling eune Which girdI the ecliptic, his 'VlIIIt foIda inYOlve ; Yet ten the Dumber ofbia IIIanI di1fu8ed O'er the long track of~ enormoua spires: Chief beams bia heart, II1ll1l of the eecond ranlE, But emuloua to gain the fiJIIL"-Eudoria.

TELESCOPIC OBJECTS.

+

108 P. vm, Hnll&-A. R..= 8 h. 17 m. to.. Dec•. = 70 10' 06". A double IItar between the t-d of Hydra and Cancer. A e, .. pale yellow;" B 7i, .. roee ~.' Diaoovered by HeneheL . Po.. 260 46' Diat.10".38 Epoeh ~831.95 . Struve. 17 Hn._A. R. 8 h. 47 m. 39.. Dec. =-70 21' 08'". A ebe double IItar between the Uail:om'. tail and Hydra'. heart. A aDd B 7 magnitude • . Diacovered by Hencbel. POL' 358° 60' Dist. '''.33 Epoch 183l.1i9 StrUve.

==

=

27 HUBcau IV, HYD....-A. R. = 10 h. 17 m. 01 L Dec. 17° 50' 08". A planetary nebula in the middle of Hydra'. body. Diacovered by Henchel, 1786. c C.ATJ:.II.-A.·R, = 10 h. 62 m. 00 L Dec. = - 1~ 28'.09'". ' A .tar with two diataut companiona On the base of the Cup. 'n-_ remarkable for their color. A ., orange; B 8, blood red; C 9, pale blue. DifIimmce between A and B 42".1 .. .. AandC .. .9 -

III

CONSTE1.LA.TION OF HYDRA.

89 P. XI, CIl.lTIIBI8.-A. R. == 11 b. 11 m. 88.. Dec. == - Q60 01' 1M". A...n double IItar between tba Cup aad tba Lion'. hiDd lee&. A 8i. Bit, JllBgDitude. DiacoveIed by Str..ve. POL 3140 06' Dist. Epoch 1880.118 8Vilve:

r.66

== -

,. CUTIIBI8.-A. R. = 11 h. 18 m. M.. Dec. 160 48' 08". A close double IItar in She center of the goblet. A 4, B 14, JDBgDitude.

DiacoveIed by HIIl8CheL POL IOS0 06' DiM. 3".00

Epoch 1838.116

Smyth.

17 CIl.lTIIBIB.-A.R.==lt h.II4m.III .. Dee.=-IIS028'OO". A doUble IItar in tba boundary of the Cup. A 61, B 7; magnitude.

Diacovenld by HencheI, 1783. POL lI070 08'

Dist. 10".01

•

Jpoch 1833.111 Smyth.

CONSTELLATION 01' VIRGO.

113

CHAPTER III. DIILECTlONtI FOil TlU.CING TUB OON8'l'BLLA.TIONB ON

MAP ~O. XI. V~Tn

VmsD'.

COIlVt1&-TBB Caow.

Fa1JOro/Jl!l situilted for examination in April, May

and June.

.

VIRGO.

Tn VmGIN.-This is the sixth sign, and seventh constellation in the ecliptic. It is situated next east of Leo, and about midway between. Coma Berenices on the N. and Corvus aD the S. It occupies a eonsiderable space in the heavens, and contains, according to Flamsted, one hundred and ten stars, including one of the 1st, six of the 3d, and ten of the 4th magnitudes. Its mean declination is {;o N., and its mean right ascension is 195° .. Ita center is therefore on the meridian about the 23d of May. TbuUD enters tblllign Virp, OIl the 13d or Aug., but doell' not enter the corutelJation before the 16th or September. When the lUll • in thia Iign, the earth ia in Pi.ecee; and vice V8IIII, ,

Spica J7irginil, marked G, in the ear of corn which the Virgin holdsin her left hand, is the most brilliant star in this constellation, and situated nearly 15° E. N. E. of Algorab, marked G, iii the Crow, about 35~ S. E. of Denebola, and nearly as far S. S. W. of Arcturus-three very brilliant stars of the 18t magnitude, that form a large equilateral triangle, pointE2

114

GEOGRAPHY 01' THE' HEAVENS.

iog to the S. Arcturus and Denebola, marked /J, are also the base of a similar triangle on the north, terminating in COl" Caroli, which, joined to the former,' constitutes the Di.aTrum.d of Virgo. The length of this figure, fro(ll Cor :Caroli on the north, to Spica Virginis on the south, is 50°. It. breadth, or shorter diameter, extending from Arcturus on the east, to Denebola on the west, is 351°: Spica may otherwise be known by its IOlitary splendor, there being no visible'star near it, except one of the 5th magnitude, situated a~ut 1° below it, on the left. The' position oftbis star.in the heavens, has been determined with great exactness for the benefit of navigators. It is oDe of the stars. from which the moon's distance is taken for determining the longitude at sea. , Its. situation' is highly favorable for this purpose, as it lies within the moon's path,and little more than 20 below the earth's orbit. Its right ascension being 199°, it will come to oUr meridian at 9 o'clock about the 28th of May, in tha.t point of the heavens where the sun is at noon about the 20th of October. v~ DWkecl .. ia a alar of the 3d magnitude, in the right ana, northern wing of Virgo, and ia situated nearly in a 1Itraiaht. tine with, and midway between Coma Berenices, and SPica Virginia. It ill 1910 8. W. of Arcturus, and about the 8IIIIIe diBtance S. E. of Coma Berenice&, and forma with thMe two alu!!e triangle, pointing to the IIOUth. It beaIII a\so 180 S. S, E. of Denebola, and comes to the meridian aboat lwenly_ three minutes before Spica Virginia. , Zeta, ill a star of the 3d magnitude, 1110 N. of Spica, and wrcy near the equinoctial. Gamma, aituated near the left Bide, ia a\so a alar of the '3d magnitude, and very near the equinoctial, It ia 130 due __ of ~, with whi..h and Spica it forma a handsome triangle. Eta, ia a star of the 3d magnitude, in the II01dbem wing, 60 W .. of ), and but 210 E. of the III

autumnal equinox. Bela, caDed also Zomij-., is a s&ar of the 3d magnitude, in the shoulder of the wing, 710 W. of a, with which and )-, it forma a line near the earth's orbit, and para1Iel to it. ~ a, ) and Spica, form the lower and longer side of a large apberical triangle, whose vertex ia in ~. The other IItanI in this figure may be eaaily traced by means o~ the map. About 130 E. of Spica, there are two stam of the 4th lII8IpIitude, 30 apart, which murk die lOot of Virp., on- two ItanJ are on Deady the _ meridian with

CONSTELLA.TION

or

115

VIRGO.

keturua, aDd eulmiDate ~ at the_"- The l - . one marked Lambda, is on the tIOUth, aDd bat SO W. « the principal !dar in Libl1l. Several other ItaJII of the 3d magnitude lie -uered about in tbiI_ IIeIJa&ioo, and may be traced out by the map.. .. Her 10YeIy tre.. glow with . " , light; Sian CJI'IWIBlt the bracelet on her band ; Her -.. in ample fold, gtitten with ItaJII : Beneath her mowy feet they shine; her eye. Lighten, all gloriou, with the hea-ty ray.. Butfint the !dar which _ the golden.-"

zodiac«

.llIr.ron.-The &.moua DeI!dera, u we have alrMdy notieed, with the eign Leo; but another zodiac, disecmnd among the ruins at Estne, in Egypt, commencea with Virgo; and from tbia circuJD. IIIarule, IIOIDf) have argued, that the regular preceIIion of the equinox. eIIIabliIIbed a date to this at Ieut 2000 yeam older than that at Dendera. The cJiIIcoTeriee. of Champollioa, however, render it probable that til IIIJdent relic of utrology at EIID4I WIUI erected during the reign of the Emperor Claudiu, and ~tly did not p.-le the _ at DeDdera I'X!I!!T!!eJ!C'

more than fourteen yeam. Of this, however, we may be certain: the autumnal equinox DOW COl" reaponda with the fimt degree of Vargo; and, COII8Bq1lllntly, if we find. IOIfiac in which the 8WIIIIIel IIOIatice wu placed where the autumDal equinox now ia, that zodiac carriea us back 90" on the ecliptic; til divided by the annual precellion of 501", must Ih: the date at about 6460 ,-.rs ago. This computation, according to the chronology of the Sacred writings, carriea us back to the· earliest agtl8 of the human specill8 on earth, and pnmlII, at least, that utronomy _ among the fimt atudiea of

mankind. The ID08t rational way of accounting for this zodiac, ..y. Jamieson, is to ucribe it to the family of Noah; or perhapa to the .patriarch himsel( who conatructed it for the benefit of those who mould live after the deluge, and who preerved it u a IDollUlll,ellt to perpetuate d.e -.:tua111tate of the heavena immediately mblequent to the enatioo.

TELESCOPIC OBJECTS.

+

A N KaULA.-\. R. = 12 h. 06 m. 01.. Dec. = 1110 47' OS~. This nebula is situated between Vug6'• •htwing· and Leo'. tail. Discovered by Measier, 1781, and.deacribed by him 88" a nebula without a star, with an extremely ~t light.

.

.

NuULJ. ...:....A..R.= 12 h. 07m. 87 •. Dec. 140 en' OS". On the upper part or Virgo'81eft 'Iring. Described in the Bedford Catalogue u "a very curious object. resembling a weaver'a Ibott\e,.and lying 8CfOIII the parallel. The upper branch is the faintest, and exhibitB a palpable nucleua. " . Discovered by Henchel, 1783. .

+

A

LOl"G PUII-WRTTB

A Ln•• N ••vu.-A. R. . . II b. 18 m. ~ ••

Dec. =

+ 06

0.

118

GEOGRAPHY OF THE HEA.VENS.

Il' 06". Tbie II8baIa ill IiIuated w-w- the Vilgin's IhouIden. ICbel reports " to have \wi) DflUdei about 90" apart. DiBcmeredby M-ur, 1799. . .

Her-

m:

17 Vraanns.!"'A. R. = 12 h. 14 24.. Dee. = 060 ·11' OS". A double BtIIr between the ih.oaldera of Virgo. !\ 6, B 9, lDIIgIlitude. POB. 3360 46' Di.t. 19".32 Epodl 1829.26 8&ri:.ve. The ClIIIIIpCIMIdIJ appear to be stationary.

=+

=

A Rou'-D NnuL.L.-A. R. 12 h. 14 m. 52 a. Dee. 180 . U' 06". It 8ppeu1I oII the upper put of the Vilgin'. left wing. Diaoovered by Mechain, 1781. It ill one rtf a multitude rtf nebulous _ forming a wonderfal moe, and pBIIIIing round the heaveJIII in a direction nearly perpendicular to the Milky Way. The diacovery of this great stratum, is the result of the unwearied zeal and ~ of Sir William BeracheI.

==

m.

A. BRran NaauL.L.-A. R. 12 h. 2\ 36 .. 09". 'I'bia nebula ill situated on Virgo'. left shoulder. DiIIcoYered by Orioni, 1771.

Dee.

+ 08Q III' .

A Lolra ELI.rPrIuJ, NU1.Tl.£.-A; R. = 12 h. 23 m. 54 Dee. = + 1110 18' 011"9 Itappearl on the·outer aide of Virgo'. left wing. In. _ three detI- equare a large number of nebullll are found, whoe I.

relative poaitiona are exhibited in the diagram marked nebulm in Virgo. . ,. VrRar'-ls.-A. R. = 12 h. a3 m. 33.. Dee. = - 000 34' or. A "'-kable binary BtIIr, OIl the Virgin's right side. A 4, B 4, magnitude. In COIIII8q11I!DCe rtfaome very early obaervatiOllIl, by Bradly. Pound, u..ini, and Mayer. it was thought that thil star presented an admirable opportunity of testing the inftuenee of gravilation among theae remote o\:dectI. As early as 1718, the poeitions of the components seem to have been approlimateiy obtained. M _ were again made in 1720, 17l1li, and by Sir W. Benched in 1780. Theae. combined wRh modern obervatiOll8, fumiabed the data for the. computation cir the elements of the orbits, deacribed by thee two auna about their common center of gra~ty. From the earlieat period of observation, the distance between the two ltan oomposing " Virginia, had been on the decrease, while the angular velocity ".. rapiclly increuing; following, in this lIl8peCt, the analogy of the planets and comets, whOl!e angular velocity rapidly increases as their diatance tiom the IUn decreaEa. toir John Berachel made the lint eftOrt at a detenuDiation of the elements of the orbit, and tbund a period of 613.28 yeara by. the fint computed elements, and of .6:l8.90 yean by the aecond set of elements. Theae results were greatly in elTOJ'. owing to the fact, as Sir John Herachel .y8, to the use of Bradly's ObeerviJ.tiOll8 of 1718. In tbe _time M. M;;.dler, Dorpat, had !'howll that the periodic time could not weD exceed 157 yeara,.a result finally reached by Berachel bimaelt: . After much laborious ea1cu1ation, M. Mildler reached the conrlusion tba& the peribe1ion 01' peaeutar ...... occuned 1836.31, and that the

of

CON8TELLATION ~ VIR~

117

periodic time was 145.409 y-. With hil1aat IIIIl of eImnenta, he h. computt>d an ephellK'ris. of this system, from which ..... copy uIoUow.:. Poe. 3500 53' 06" DiaL OS".417 Epoch 1847 367 43 04 02 .1\66 .1848 355 56 06' 02 .689 1849 3M 13 03. Oil .816 1860 362 39 011 00 .939 18111 361 13 06 0:1 .057 18611 349 53 06 03 .170 1863. During a part of the year 1836, the star was ~ perfect\y round, even. in the most powerful instruments. Objectll which had been 80 widely eepuated, when filIIt discovered, were now 80 placed as that the one edipud 1M otker. Towatds the close of 1836, the hidden star began to emerge, and this double object was seen tlmtgaied.· At the beginning or 1837, the best telescopes again 88W the tuf() ,tar. aeparate and distinct. From that time, to the ~nt, the distance has been on the ~. while the anlllliar velocity bas bePn regularly diminiabipg. My.own obaervations show the ephemeris computed by Kidler, to be pretty Be.curate, but even yet considerable discordance exists .between observation and computation, showing that more accurate data are yet wanted to

complete this moat delicate and difficult investigation. A filw measures are here given. Poe. = 3190 07' . DiaL 07".49 Epoch 1720.31 Casaini.

. 1781.89 HerBCbal L. 02 .86 1822.00 Str.. ve. 01 .68 1830.69 Bessel. 01 .05 1833.37 Striive. QO .68 1837.4\ StrGve. II 01 .7:J 1841.44 M~dler. 06 01 .90 1843.33 Smyth. 28 03.09' 1847.60 Mitchel. By • comparison of the I88t obaemd.iOllll with the ephemeris, it win be IIleD that the angular velocity is greater than predicted, .. is also the in310 285. 262 246 077 020 ·011 367

04

04 10 32 65

crease of distance between the components.

e VIBSUUI.,-A. R. =

... _

13 h. 01 m. 40 a. Dec. =- 040 41' 00"• tripl8 star em the lower part of the Virgin'. aoutham wing. A

fi. B 9, C \ 0, rDagJJi,tude. POL A B· 3440 02' A C 295 00

.

Dist. 07".02

65 .00

Epoch 1837.071. S--' 1831.15 5 ~3-'

+

A CLOAlI BnullY Sru.-A. R. = 13 b. 26 m. 01 a. Dec. = 000 30' 04". This star is situated on V"ugo'll0"!Br gannent. A 8, }) II, DIIIgIIitude. • . .

I>ia1overed by StrUve, 1825.

• Epoch 1826.37 JStrnve. 1834.38 Struve. \841.37 Madler. The period of J8VIIbJt;ioa. is, probably, not liar fram·18O y-. POL \00 00' 24 08 36· 02

DiaL 01'\600 01 .690 01 .747 .

81 VI_1lI18.-A.R.= 13Ja. 29m. 13 .. Dec. =-070 03' OS".

118

GEOGRAPHY OF THE HEAVENS.

A cIoIe cioabIe liar OIl the right aide of the 10wer pnnent of the VUgiD. 8uIpedal of .!ow zetmgradalien. POlL 'I" 07' DiM. 0i".82 Epoch IMl.39 M.,)dler. M VIUIlfIl.-A. R. ~ 13 h. 35 m Oi.. Dee. = + 040 21' 00". A cIoIe double It. OIl the lip of VirgO'lleft wing. A 6, B 9, magnitude. POlL 2330 M' J31 05

DiaL 03".6 03 •.a

Epoch 1839.37 Smyth. 1847.06 Mitchel.

\

,

R. = I' h. 19 m. 68.. Dec. = - 01° 30' 04". A delicate double liar in the corDer of Virgo'. akirt. A 6, yellow; B •

VIBIJIlIIL-A.

13, blue.

Diacmered by Btrihe, 1829. POI. 1080 32' DiaL 03".73 Epoch 1829. n StrUve. Other double 8taIB and' nebuhe will be tound on the chart.

+

A DoUBU NBB'aU.-A. R. ...:.. 12 h. 3~ m. 33 8. Dec. = 120 26' 0 I". This nebul. is situated in the center of Virgo'8 left wing, with two or three lIIDBIler ones in the immediate vincinity. In this object we find 80me support to the celebrated nebular theory, which supposes the sun and 8taIB to have been formed from the conciellBlltion of nebulous fluid .. The object befure us auggestB the chaotic state of a binary star, andpOaai'bly these'two abadowy objects are perlOrming, even now, a revolution round each other. Abandoning this theory, and having recourse to the iclea that these dim stains are mighty univenea of shining stars, here we have two such 80 loeated as poIIIIibly to be mutually operating upon 8IICh otI!er. Should actual physical connection· ellist, and one of these mighty aystems be actually sweeping round the other, what a mpendoul period mWlt mark the cycle of these "island universes." By such periods W8 might even l'IlCkon the hours of eternity itself! "

CORVUS.

TIfB Caow.-This small constellation is situated on the eastern part of Hydra, HiO E. of the Cup, and is on the same meridian with Coma Berenices, but as far S. of the equinoctial as Com~ Berenices is N.. of it. It therefore culminates at the same time, on the 12th of May. -It contains nine visible stars, including three ,of the 3d magnitude, a~d two of the 4th. This constellation is readily distinguished by means of three stars of the ad magnitude, and one of the 4th, forming a trapezium or irregular square,

119

CONSTEI,LATION Qi' CORVUS.

ihe two ~pper ones being about 3i o apart, and the two lower ones ~o apart. . . The brightest of the two upper stars, on the left, is called .Algoroh, marked G, and is situated in the E. wing of the Crow; it has nearly the same declination S. that the Dog-star has, and is on the meridian about the 13th of May. It is 21tO E. of Alkes in the. Cup, 1410 S. W. of Spica Virginis, a brilliant star of the 1st magnitude, to be described in the next chapter:. . Beta, on the back of Hydra and in the foot of the Crow is a star of the 3d magnitude, nearly 70 S. of Algorab. It is the brightest of the two lower stars, and on the len. The right hand lower one is a star of the 4th magnitude, situated in the neck, marked Epailfm, about 6° W. of /J, and may be known by a star of the same magnitude situated 2° below it, in the eye, and called . .AI Ohiha. • is' 21io S. of the vernal equinox, and if a meridian should be drawn from the pole through Megrez, and produced to • Com, it would mark the equinoctial colure. . Gamma in the W. wing, is a star of the 3d mag-· nitude, 3tOW. of Algorab, and is the upper. right hand one in the square. It is but 10 E. of tbe equinoctial colure. . lOoE. of ~. is a star of the 3d magnitude, in the tail of Hydra, marked "I; these two: with Algorab, form nearly a right angled triangle, the right angle being at~. TELESCOPIC OBJECTS •

•

I CORVI.-A. R. = 12 h. 21 m. 96 .. Dec.=-16°M'C)4". A VIe double star on the Raven's right Wing. A 3, B 8i !DIIgDitude. Discovered by Herschel, 1782. Pos. 2100 54' . Dist. 23H .6 Epoch 1831.3(. Smyth.

120

GEOGRAPHY OJ' THE HEAVENB.

DlRBCTlON8 FOR TRACING THE CONSTELLATIONS" ON

MAP NO. XII. URSA LOR-THE GWT BUR.

FavoroIJly litvated fQr ei:amiMtion in M"" J'IlM.

July, .Augut and 8eptemlJer. tJRBA

MAJOR.

THE GUAT BUR.-This great constellation is situated between Ursa Minor on the north,aud Leo Minor on the south. It is ODe of the most noted and conspicuous in the northern hemisphere. It has been an object of universal obsen'ation in all ages of the world. The priests of Belus, and the Magi of Persia; the shepherds of Chaldea, and the Phamician navigators, seem to have been equally struck with its peculiar outlin~s. And it is somewhat remarkable that a remote nation of American aborigines, the Iroquois,. and the earliest .Arabs of Asia., should have given to the very same constellation the name of " Great Bear," when there had probably never been any communication between them; and when the name itself is so pm:fectly arbitrary,. there being no resemblance whatever to a bear, or to any other animal. " " It is readily distinguished" from a11 others by means of a remarkable cluster of seven bright stars, forming what is familiarly termed the Dipper, or Ladle. In "some parts of England it is called '" Charles'. Wain," or wagon, from its fancied resemblance to a wagon drawn by three horses in a line. Others call it the Plow. The cluster, however, is more frequently put for the whole cODstella• tion, and called, simply, the Great Bear. But we see no reason to reject the very appropriate appel-

CONSTELLATION

or

121

URSA MA.JOR.

lation of the .ahepherds, for the resemblance is certainly.in favor of. the Dipper: the four sta1'8 in the square forming the bowl, and the other three, the handle. When the Dipper is on the meridian, above the pole, the bottQm lies towards UB, with the handle 00 the right. . Benet:no.sch, marked 'I, is a bright star of the 2d magnitude, and is the first ·in the handle. The' secol).d, or middle star in the handle, is Mizar, marked " 7° qistant from Benetnasch. It may be known by means of a very minute star almost touching it, called .Aicor, which appeal'8 to be double when· seen through a telescope, and of a silver white. The third star in the handle is called.ALidA, marked., and is' about 410 W. of Mizar. AJioth is very nearly. opposite Shedir in Cassiopeia, and at an equal distance from the pole. Benetnasch, Mizar, and Alioth, constitute tht handle, while the next four in the square form the bowl of the Dipper. Five and a half degrees W. of Alioth is, the first star in the top of the Dipper, at the junction of the "handle, called Megre%, and marked a; it is the smallest an.d middle ~me of the eluster, and is UBed in various observations .both on sea and land, for important purposes. At the distance of.4lo s. W. of Megrez, is Phad,marked 1, the first star in that part of the bottom, whiQh is next the handle. The &tan! in this clllster are 80 ....eD known. and may be

80

easily de-

acribed without Jefimmce to their Jelative bearings, that they would rather eonfuae than II.I8iIIt the atudent, were they given with ever 80 much Beeuracy. The aeveral bearings for this cluster were taken when ~egrilS _ on the meridian, and wiD not apply at any other time, though their Jellpective distancea will remain the aame.

At the distance of 8° W. of Phad, is. the westernmost st.ar in the bottom of the Djpper, called Merak,: marked (3. The bright star 5° N. of it, towards the. pole is called DuIihe, and marked Go; but these two, L

122

GEOGRAPHY

OF

THE HEAVENS.

"

Merak and Dubhe, are, by common consent, called the Pointers,because ihey always point towards the . pole; for, hit the line which joins them be continued in the same direction 281° farther, it will just reach the north pole. The names, positions, and relative distances of the stars in this cluster, should be. well remembered, as they will be frequ~ritly adverted to .. The distance of Dubhe, or the Pointer nearest to .the north pole, is 281°. The distance between the two upper stars in the Dipper is 10°; between the two lower ones 8°: the distance from the brim to the bottom Bext the handle, is 41°; between Megrez and Alioth is 5f0 ; between· Alioth and Mizar 41 0 , and between Mi7;ar and Benetnasch, 70 • The I'l".uon why it iI! important to have these distancea clearl~~Je.:! in the mind is, that these star&, being always in 'View, and more .. than any other, the student will never fail to have a standard measure before him, which the eye canl.euily make use of in determining the distances between other atara.

The position of Megrez i~ Ursa Major, and of Caph in Cassiopeia, is somewhat remarkable. They are both in the equinoctial colure, almost exactly opposite each other, and equally' distant from the pole. Caph is in the. colure, which passes through .the vernal equinox, and Megrez is in that which epasses through the autumnal equinox .. The latter passes the meridian at 9 O'clock, on the 10th of May, and the former just six months afterwards, at the same hour, on the lOth of November. Psi, in the left leg of tTrsa Major, is a star of the 3d· m.agnitude, in a straight line with Megrez and Phad, distant from the later 121-°.. A little out of the same line, 3° farther, is another star of the 5th ~agnitude, marked . Omega, which may be distinguished from +,.from its forming a straight line . . .with the two Pointers. The right fore paw, and kinder one, are dis-

CONSTELLATION 01' URSA MAJOR.

123

tinguished by two stars of the 4th magnitude, between 10 and 20 apart. The. two stars of the left hind paw are of the 3d magnitude. These three duplicate stars are'nearly in a right line, 200 S. of, and. in a· direction nearly parallel with, Phad and Dubhe, and are the only stars in this constellation that ever Bet in this latitude. There are few other stars of equal brightness with those just described, but amidst the more splendid and interesting group with which they al'e clustered, they seldom engage our observation. The whole number of visible stars in this constellation is eighty-seven; of which six are of the 2d, three of the 3d, and a.bOut twice as many 01" the 4th magnitude. TELESCOPIC

286 H. I, U...· Muo.II.-A. R.

OBJECTS.

=

09 h. 49 m. 30.. Dec.

J.

+

.69'" 30'. A round nebula, thus deacribed in the Bedford Catalogue. "A bright claaa round.aebula at the baclr. of UlII8 Major'a left ear.· It ia lucid white, and Iightaup Ii the center. There are two linea, of three ataJB eacli, acroM the field, of which the ooe preceding the nebula is of the 7th magnitude, and that fOllowing of the 10th; between ~_ the sky: is intensely blaclr., and show. the nebula at if floating in awful and illimitable apace at an inconceivable diatance. Dr.' Derham, whose judgment led him to COIIIIider nebuba at vaat areaa of Iiglit," infiillibly beyond the fixed atara," thought that some of them might be openings in the opacity surrounding the visible ayatam, which chaama show us the light of the empyrea1 sphere beyond it. ,"Discovered by Sir w. Herschel in November 1801, and he say. that 'on the nOrth following aide there is a filint ray intarrupting the roundness.' " I have recently examined this ol!ject with care, but it had sunk too low to be well seen. It appeared filinter than any of those whose descriptiona fullow, and smaller. It occupiee an insignificant portion of the field of view, and in caae we receive it .. a distinct globular cluster, an "ialand universe," ita distance mWlt be enormous.

+

47 M. U aa. MUORI8.-.'I.. R. = 11 h.OIi m. 24 •• Dec. = 650 52' 09". Is thus described in the Bedford Catalogtl1l. "A large planetary nebula or globular collection of nebulous matter, on the Great Bear's flank, with several stars in the field, one of which is pretty. close. It lies 'about 20 8Outh-e8st of ~erak. jWlt south of the line joining Mehlk and Phad. Thia! very singular otUect is circular and ,uDiform, and after

124

GEOGRAPHY OF THE HEAVENS.

a 100g inIpection Ioob like a eondenaed mll8ll of attenuated light, II8eIII ingIy of the size of Jupiter. .8ir W. Herachel relllll1'ka: • From the obI8lYations of the twenty ilet telescope, it appears that the profunditj of this ol!ject is beyond the guaging power of tha,t instrument; and as it must be lIUfIiciently diaIaot to be ambiguoua it cannot be I.eM than tha& of the 980th older '--or 980 times more remote than Sirius." , Discovered by MIlIIIIier in 1781. 43 H. V, UB8. Muo.II.-A. R. = 12 h. 11 m.,04, = + 48° II'. This object was examined by myself on the e1>ening of the 2d July. '1847, when the following memoranda were made: , I.

~.

Magnifying poWer 260. . The nebula is elongated north and BOUth. IA:lCa the field of view. A faint star was _ near each extremity. The nebulosity very faint on the right. gtadually fiIding away at each extremity. The nucleua resembles a small star elongated 10 as to _ the Icmger axis of the nebula at angle of about 300. ' , Power 500. The nebula undergoea but little c:hanp. The nucleua I.eM perfectly defined than with the lower power. . 'fhia object may be found by drawing a line from. through " UIIB 0 Majoria, and extending it about 71 beyond the last named star. A 1tl¥mgh 1Brge, it is faint, and requires a large aperture to give it much intetest. In cUe it be a universe of fixed stars, its distance must be beyonil.the Btret.ch of imagination, and the clUstering of worlds at its center must be fiIr pater than .in any other part of its vast extent. It may be an immense annulua, or ring, _ obliquely; and, poaaibly, reaembIea. _what our own sidereal &tratum in figure.

Btretching nearly

195 'R I, UBI. MuoBls.-A. R. = 11 h. 58 m. 51 Dec. == + 57' 03". Deacribed in the Bedford catalOgue as a bright clll8ll nebuhi. My own notes are in the foUowing language: A small, elonI.

4~

gated nebula, running nearly north and BOUth. The' length is four or five timas the breadth. The nucleus is quite sharp. The entire length doea not appear to exceed 30" or 40". Ii is p~ by a eoarae double star. Examined with a power of 260, and an aperture of 12 inches. Discovered by Sir William 1JendleJ, 1778. Its shape is not unlike the preceding nebula, but its brightnl!lll is much greater. It requirea • good instrument to bring it l\Iirly to view. .

t

194 H. I, UBI. MUOBIS.-:-A. R.= 11 h. 17m. 211. Dec. = 44027' 09". This object waS examined by myself in July. 1847. t is a faint nebula, elongated from .north to IOUth. There is a teI~c star on the.right, equal in brighau. to the nuc1eua of the nebula. It is followed by three telescopic stars, forming a flat i.oaceIes triangle, whose yertalt points to the nebula. Its length is about 50". A ray from Reg. ulus to" Unq, Majoris, reachea the nebula at about two4hirds the distance , hetwilen the atara.

+

46 H. V, UB•• MUOBIB.-R. A. = 11 h. O~ m. 02 L Dec. = 116° 81' 08": I ~ ~ nebula elongated in the direction of the paralleL

c;oN8TELLATION

OF URSA MAJOR.

125

new.

With. poWer "¥D, the nebnlolity exteDda half 8CJ'CB the field of The nucleus ill certainly douIJle. The lIDaIler' point of light ill below, and to the right, at a diatance of about 10". No mention ill made of the double nucle\18 by either Henchel, « by any astronomer whoae deecrip-

.

~~~~~

=

=+

=

=+

".2 UBSlB Muo.I •• A. R. 8 h. 56 m. 13.. Dec. 67° 46' 07".. A double star, in the ~. forehead, A 5j. B 9i. TIie color of the principal Btu ill white, while ita companion is blue. • POll. 2830 00' Dist. 7 H .95 Epoch l'18lU2 Heracbel. 263 33 4 .59 1831.14 Struve. This would indicate OI:bi&ual motion; but, owing to the defecta in H. achel'8 early obaerYations, it requireB CODfirmation.

g

U RUI lIIUO.IB.-A. R. It h. 09 m. 38 L Dec. 320 25" 08. A binary BtIIr. in the Bear'8 \eft hind paw, A 4; B 5j. magnitude. Sir John Herachel finds fOr this system a period of revolution equal to 59 years. M. Savary givea 58* Ye&ra fOT ita period. In CUll these remlts are reliable, a knowlroge of the diabince of this ayetem would give to us the relative magnitude of the 8tarB, and their IDIIIIII, compared with our sun. • POll. 1430 4'1' Dial '3".50 Epoeh 1780.33 Herschel. 229 30 1 .82 1827.26 Struve. 143 20 2.30, 1843.16 Smyth. HeI'\l is ellhibited a complete revolution of the angle of position through S6()0. from the epoch of the first observation to that of the last. , U.SlB Muo.IS-A. R. = 11 h. 09 m. .9 L Dec. = A double star, on the Bear'. left hind foot,. A 4, B 12. POll. 1470 O~ '1".8 Epoch 1834:31

+ 380 58'.

D¥-

(' U.BlB MuoRI8Mu .....-A.R.=13.h.17m.28 ••

Dec.=+

550 4.¥ OS", A beeutiful double star, in the middle of the tail of the Bear, A 3, B 5, magnitude. ' Pas. 1450 20' Dial 14".24 Epocli 1819.70 Struve. 147 24

14 .40

1839.a2 Smyth.

It is uncertain whether any physical connection exists between the ~. components, though an identity of proper motion would lead us to think them united. In exhibiting this double alar to thOle. not familiar with the heavellll, on taking the eye from the telescope, and looking at the star with the unaided vision, many penions exclaim that they Bee the 1ID811 star with the naked eye. This is, however, a mistake. 1'he faint star really seen is not the one shown by the teIeacope. but a mUM more distant minute star, called AIt:or. Indeed, with the gieat refractor of the Cincinnati Obeervatozy, Alcor, which to the eye appears I!'O vezy cloae to Mizar, does not even fiill within that field of view of the teleacope, 'whiclI , ill occupied by Mizar in ita center. ' . From tbe fact that Alcor and Mizar have an ldentity of proper motion, it haa been argued that they may constitute a binary system-two IIUIl8 revolving around their COIIIIIlOIl center of gravity. 8houJd this be true,

128

~

GEOGRAPHY OF THE HEAVENS.

be

UIIlII*l .. pat .. that uIipIcI to IICuB of the magnitude, they caDDOt complete their _oIu&ioo in a period _ than 190,000 of our yearl! ! ' , In the Memoira of the Obaervatory of the CoUegio Romano, 11141, iome aingUlar noticee of Mizar are 1118de. which I venture to translate. I give the aubB&ance of the notices .. foUowa : " On the 18th April, 11141, M. Madler comuiunicated to M. Arago the UguIar filet that, at 9 o'clock and 8 minu.... on that evening, he had

thclr distance

laDle

_ Mizar witlwut (J tompanion. About 10 o'clock, the BlDaU star Ieappeal'\!Cl 'in aU ite brilliancy. He thinb be had ob8erved the .aUJilt phenClmenon, with an ininior inatrnment, in 18M, and inters tha~ the ' 8Inall star is variable, with a long period. The Italian utronOlll6lll report the detection of four minute ~tII in the, _ all of which appear to be vanable.

field with Mizar, lOme _

DIRECTIONS FOR TRACING THE CONSTELLATIONS ON

MAP NO. XIII. BoOTES-THIl BEAR ,'DRIVER. CORONA BOREALIS--THE NORTHERN CROWN. QUADJlAN&-THE QUAJ)RANT.

CANES VENATICl-THE GUY HOUNDS. COMA 'BUJ!lNlCES--BERENICES' HAIJl.

FaviJrahl!l siJ:uoJ.ed for examinatitm in '

and J u l y . ,

May,

JU'M

BOOTES: THE BEAR DuvllJl is represented by the figure of a huntsman in a I:unning postilre, grasping a club in his right hand, and holding up in his left the leash of his two grey hounds, Asterion and Chara, with which he seems to be pursuing the Great Bear round the pole of the heavens. He is thence called Aretophylax, or the Ie Bear Driver." This constellation is situated between Corona Borealis, on the east, and Cor Caroli, or the Greyhounds, on the west. It contains fifty-four stars

CONSTELLATION OF BOOTES.

127

including one of the 1st magnitude, seven of·the 3d, and ten of the' 4th. Its mean declination is 200 N., and mean right ascension is 2120 ; .its center is therefore on the meridian 9th of June. Bootes may be easily distinguished by the position and splendor of its principal star, ArcturUs, which shines with a reddish luster, verymuoh resembling that of the phmet Mars. . Arcturus, marked G, is a star of the 1st magnitude, situated near the left knee, 260 S. E. of .Cor Caroli and Coma Berenices, with which it forms an elongated triangle, whose vertex is at Arct1l1'1is.

the

Five or aU: ctep,e. 8. W. of .4.rdurwI IU'8 three eIaJ1I of the 3d and 4tll magnitudea, lying in a curved line, about 20 apart, and a little below the left knee of Bootee; and about 70 E. of. An;tulllll are tbtee or four other &tar8 of tiimilar magnitude, aituated in the other leg, making a larger curve N. and S. . Mirac, DIIll'ked .. in the girdle, is a star of the 3d 1DIIIPlitude, loo N. N. E. of Arct.UI'UI, and about 11 0 W. of Alpbacca, or. in the Northern Crown. ~nUl, marked ,., in the west shoulder, is a Ilar of the ad magnitude, nearly tOO E. of Cor Caroli, and about the IIIIDI8 distance N. of Arct.Ulllll, and forms, with thee two, a rilht angled triangle, the right. angle being at SeginU&' . . .' ...wudvr0p8, marked /A, situated in the top of the club, is a Ilar of the 4th magnitude, about 10jO in an easterly direction from ,., whicli lies in tbeleft Ihoulder: and abouUjO S. of Alkaturope is anOther alar of the 4th magnitude, in the club near the east shoulder, marked Delta I is about 90 distant from MirIc, ~ 7jO from Alphacca, and forms,.with theBe· two, a regular triangle. . Neltkar, marked A is a.tar of the 3d magnitude, tituated in the bead, and is about 60 N. E. of Seginu.. and 60 W. of Albturope; itCOlmI with I and 8eginUt, nearly a right angled triangle. the right angle being at N!Ikkar. TheE are the principal stan in this COII8teIIation, except the tbtee IIIar8 .r the 4th magnitude aituated in the right band. Th_ ..... may Ije known, by two of them being clc.e together, 'and about 60 beylRld Bene~h, the. first star in ~ handle of the Dipper. About 60 E. of Benetnasch is another .tar of the 4th IDttgJIitude, mated in the I'JD, which fonne, with Benetnuch and the three in the band, an equilaleral IriaDgIe. .

Arcturus is mentioned by name in that beautiful paSsage in Job, already referred to, whel'e the

128

GEOGRAPHY OF THE HEAVENS.

Almighty Q.Dawers "out of ihe whirlwind," and saya:. " ~ thou the sky'. benevol~ restrain, And callE the Pleiades to shine in vain! Or, when Orion sparkles from his sphere, Thaw thP cold eeasona and unbind the year! Bid Mazzaroth his station know, And teaCh the bright bduf'IIB where to glow ! ..

. Young', Paraphrtw.

.

.

'fELESCOPIC OBJECTS.

+

, BoiiTIB.-A. R. = 14 h. Hj m. 30 s. Dee. = 520 06' 04". A delicate triple star in the right hand of Bootes. A 4i, B 4i, C 8, . magnitude. . . Discovered by Strr. ye.

A B POI. 149" 00' AO 3309

Dist. 00".3 38.06

Epoch 1836.28 1836.~

2. S....~

5 .....\'9.

= 370 14' 04" R. = 14 h. 15 m. 81 s. Dec. = + Between the left foot of Bootes and Virgo, on a line be-

A WRITE Rou •• Nnuu...-14 h. 11 m. 44 s. Det-. Discovered by Herschel, un 1st May, 1785. A N
DOUBT.E SrAB.-A.

. tween Spica, ~ B~tis.. A 6, B white, B 71, bllH.'; Discovered by PI8ZZ1. POI. 1860 03' Dist. 06".26

Epoch 1825.40 StrUve.

+

=

BoOTIS.-A.·R. 14 h. 33 m. 12 s. Dec. = 170 06' 05". On the left leg. A 3i. B 6, magnitude• . POI. 990 03' Dist. 06".00 Epoch 1836.51 Smyth. 96 57 08 .~8 1847.60 Mitchel. 'Ir

+

t BOOTIB.-A. R. = 14 h. 33 m. 31 s.. Dec. = 140 25' 01 .... A cloee double star on the left leg of Bootes. A 3i, B 41. Discovered by Herschel, 1798. POI. 1290 17' Dist. 05".190 Epoch 1830.47 StrilYe. 128 24 06 .924 1847.62 Mitchel. . This reault, after an interval of aeventeen years, determines, it would _m, the fixity of the' components, though from early obaervatioDl m0tion had been suspected.

=+

t.BO.~J8.-A. R. = 14 h.a8 m. 00 .. Dec. 270 45'Oln. A fine·double staron the left hip of Bo··tes. A 3, pale orange; B 7,_ green. This is cartainly one of the most beaut'.ful. among the double

stars.

•

DiscoYered by·HerscheI. POI. 320 0 41' Dist.02".581 02 .917 323 38 3iO 50 02 .568

.

Epoct. lIi31.41

Struve.

.

M;;.dler.

1841.41

1846.66 Mitchel;

. CONSTELLATION

OF

129

BOOTES.

+

£ BOI'Tla.-A. R. = 14 h. 44 m. 00.. Dec, = 19" 48' OIH. A binary star OIl the left knee of BoIi_ A Si, oiange; B 6i, purple. The orbit WBB computed by Sir John Henchel in t8as, but with lillie auccess. Mii.dler thinks the periodic time eannot l>e nearly 80 short .. that obtained by Henchel. It will probably exeeecl.400 yeara. Discovered by Henehel, 17SG. . Poca. 3340 10' Diat. 07".22 Epoch 1829.46 Btr;·,ve• . 3M 41 07 .09 ' 184l.48 M;;dler. 317 06 .482 1!l:l7.63 Mitchel.

«

A SKnt. NlIB11U.-A•.R. = 14 h. 63 m. 63.. Dee.. ... 32' 07". Between the right band of BoO... and Draco. . Diseov~ by Henehel, 1788. .

+ 640

+

89 BoOTl8.-A. R. = 14 h. 44 m. IS·.. Dee.. ... 490 U' 08". On the rjght wrist Of Bootes. A 6., B 6i, magnitude.' ..' Poca. 440 12' Diat. 03".71 Epoch tH30.02 StrUve. 37 00 04 ·.00 . 1847.80 MitcheL TheM _ show • retrograde motioD, BB do all the previouB 0IlHtI

+

44 BoiiTIB.-A. R. = I( h. 68 m. 81.. Dee. = 480 II,' OS". A eloee double star in the apacelOllowing the right arm of Bo<;tea. A 5, B 8, ~tude. ThiI star baa oocuion~ no little difficulty, owing to the abrupt changes which have' occurred in the relative positions of the eomponenta. . Mii.dler thinks Herschel's first obaervation is wrong by 180 degrees; an error euily committed, Clm8idering the neal equality of the two stars. On this hypothelis the periodie time may not difl8r much &om sixty or seventy years. A "" _ are added. Poca. 600 06' Dist. 02".00 Epoch 1781.62 BeracheL 228 00 4)1 .60 1819.48 StriiYCI. 233 39 02 .66 18~9.80 Struve. 237 02 04 .068 1841.47 Miidler. 238 20 03 .788 1847.62 Mitchel. fA 2 BoOTI8.-A. R. = 16 h. 18 m. 28.. Dei:. = ~ 37° M' or. A binary star on the tip of the stafF of"B0(;te8. A 8, B 8i, magnitude. The eomponenta are preforming their revolution in • retrograde order, and in a period of 300 or 400 years. 1'hese IIlCl88ure8 will show the rate of motion. . .. Poa. 3570 14' Dist. Epoch 1782.68 HeneheL 327 00 Ol".~ 1826.77 StrUve. . 3Ui 04 01 .080 1836.65 StrUve. 808·43 06 .886 1841.46 M;odler•.

13p

GEOGRAPHY

or

THE HEAVENS.

DRAC·O.·

THE DllAGON.-This constellation, which compasses a large circuit in the polar regions .by its ample folds and contortions, contains many stars which may be easily traced. . From the head or the monster, which· is under the foot of Hercules, there is a complete coll tending eastwar$lly, abou t 17° N. of Lyra; thence he winds down northerly about 14° to'the second coil, where he reaches almost to the girdle of Cepheus, thEm he loops down somewhat in the shape of the letter U, ....nd makea a third coil about ISO below the first. From the third coil he holds a westerly course for '. about 13°, then goes directly dc.>wn, passing between the head of the Lesser ~nd the tail of the Greater Bear. This constellatio~ contains eighty stars, including' four ofthe 2d magnitude, seven of the 3d, and twelve of the 4th. . ... The bragm next. winds like a mighty stream ; Within ita ample folds are eighty stara, Four oCtile second order. Faihe Wjives His ample spires, involving either Bear."

.

The head of the Dragon is readily distinguished by means of four stars, sq, 4°, and SO apart, so situ. ated as to form an irregular square; the two upper ones being the brightest, and both·ofthe 2d magnitude. The right hand upper one, called Etanin, has been rendered very noted in modern astronomy from its connection with the discovery of a new law in physical science, called the .Aberration of Light. The letter name of this star is Gamma, or Gamma Draconis,' and by this appellation it is most frequently called. The other bright star, about 4° from it on the left, is Ro.stahen, marked ~. • See Map xvn for part of Draco.

CONSTELLATION OF DRACO.

131

About 4° W. of 13, a small star may, with close attention, be discerned in the nose of. the Dragon, which, with the irregular square before mentioned, makes a figure somewhat resembling an Italic V, with the point towards the west, and the open part towards the east. The small star in the nose, is . called Er Rakis, marked ",. The two liliiii1 star. 1i0 or 1)0. S. fA Rutaben ani in the left foot of Berc:uIea. .

.

Rastaben is on t.he meridian nearly at the same moment with Rae Alhague. Etanin, 40° N. of it, is on the meridian about the 4th of August, at the same time with the three western stars in the face of Taurus Poniatowski, or the V. It 'is situated less than 2° west of the solstitial colure, and exactly in the zeDith of London. Its flWOJ'able position has led English astronomers to watch its appearance, for long periods, with the most exact • and unwearied scrutiny.

is

In the year 172.'1, Mr. Molyneux and Dr. Bradley fitald up a very accurate and eoatly inIItrument, in Older to discover whether the fixed I&ara had any aensible parallax, while the earth moved from one extremity of its orbit to the other i or which is the same, to determine whether. the nearest fixed IIIBrII ani Bituated at BUch an immense distaJice from the earth, tbat any star which is _n this night directly north of us, will, lix months bence, when we ahall have gone I 90 milliona of miles to th45 ealitward of the place we are now in, be then seen exactly north of UB 1IIill, without changing its position 80 mudl as the tbiclm- of a spider'. web. . . . .. These observationa were subsequently repeated, with but little intermission, for twenty yt!anl, by the most acute obaerveia in Europe, and with telescopes varying from twelve to thirty-aix feet in length. In the meantime, Dr. Bradley bad the honor of announcing to the world the very nice discovery, thet the motion of light, combined with the progrl!88iflf motion oflhe tarlA in ill orbit, _ Ihe ~}J bodiu to be Bte!I in /I diJIerml poBition foam whllt Ihev would be, iJ the eye were lit rut. Thus _ NtabIished the principle of the Aberraiion of light. 'I'hia principle, or law, now that it is ascertained, _ma not only very plain, but ..,Il evidenl For if light be progressive, the position of the teIeacope, in Older to receive the ray, mUBl be diftimmt from what it would have been, if light had ~ inatantaDeowI, or if the earth stood IIIill.

132

GEOGRAPHY OF THE .HEAVENS.

Hence the place to which the teleIcope is directed, will be dift8rent from .he true place of the object.' .. . The quantity of ~ aberration is determined by a simple proposition. The earth deIcribea 69' ~' ·of her orbit in a day = 3Ma", and a ray of light'C0IDe8 from the II\IJI to U8 in 8' IS" = 493" : DOW twenty-fOur boum or 86400" : 493'.' :: 1I64~' : 2~'; whicb is the clwige in the 8&ar'8 place, arising from the CR)IBIl above mentioned. Of' the fiIUf IICarI fOrming the irregular square in the bead, the lower and right band one i. ~o N, of Etanin. It is caI\ed Gnsmillm. and ia of the 4th .magnitude. A fiIw degrejlllE. of the squar\!, may be seen," with a liUIe. care, eigbt &tara of the 6th magnitude, 8nd OIIe of the 4th, which.liea SO E. of Grumium. This group is in the firat coil of the

Dragon. '. . The 8BCOIld coil is about 13° below the first, and may be IflCC!gJIiaed by means of fuur &tara of tbe 3d an!1 4th magnitudea, 10 situa~ as to form a amall square, about half the size of that in the bead. The brigbtest of them ia on the left, and is marked Delta. A line drawn from, Raataben through Grumium, and produced about 140 , will point it out. A line iliawn from Lyra through Zi Draconis, and pr0duced 100 fiuther. will point out Zeta, a star of the :~d magnitudt>, ~tuated in the third' ~ ~ may otherwise be known, by its being nearly in a line with: and. midway, between, Etanin and· Kochab. FlOD\? the remaining ..... in this constellation are easily traced. . EttJ, Theta, and .Mich, come next; all atsra of the 3d magnitude, and at the distance, severally, of 60, 40 and 60 from~. At ABich, the third star from ~,the tail of the Dragon makee a BUdden crook. Thuban, Ko.ppa. ~. follow De~t, and complete the tail.

TlruJJan, marked II, ill a bright- star of'the 3d magnitude,11° from Asich, in a line with, "nd about midway between, Mizar and the southernmost guard in the Little Bear. By nautical men this star is called the Dragon's Tail, and is considered of much importance at sea. It is otherwise celebrated as being formerly the 7Wrth polar star. About 2,300 years before the C\lristian era, Thuban was ten times nearer the true pole of the heavens than Cynosura now is. . KaJI'I}(J is a lltar of the 3d magnitude, 100 from Alpba, between Megnoz and the pole. Mizar and Megrez, in the tail of the Great Bear, form, with 'I'buban and ", in the tail of the Dragon, a large quadrilatera16gme, whoae 1000gwt aide ia frorp Megrea to ... Giar&.r, the last .au in the tail, ia between the 3d and 4th magnitudee, and flO from ... The twp .poin\e1'8 will a1ao point out Gianear, lying at the distaDce of little _ than SO fiorD them, and in the direction fIl the .pole.

133

CONSTELLATION OF DRACO.

TELESCOPIC' OBJECTS.' A. OnT. N8BllLA_A. R. = 16 b. 02 m..03 .. Dec. 13'. Under the body ofDraeo. Diacovered bY Herachel, 1789. 1t iB filint at the edgee.

A

+ c;ao .

=

.

+

NUULA.-A. R. =.16 h. 36 m. 6:J .. Dec. 690 62'. In the eenter of Dtaco', body. . DiIIootend by Henchel, 1788. Thill oI;eet brightens at the center, pteElting • nucIna Dot vmy.JI8I" SKUL RoUJrD

iBctIy defined. It is fOllowed in the __ field by • much larger e1ongated nebula, which aeeme to have eacapeel all preceding oIMerve1'8, It was discovered,4th July, It147, by Mre. Mitehe1, while ~ in a eritical examination of the above object. It is taint, but 1l811ain, and bu . . oval. or elIiptical1igun.

==

". DucoIlJI.-A. R. 17 b. 02 m. 02 s" Dec.:"- MO 41' 02". A bifttJry 1Itar, flIJ the tip of Draco'. tongue. A 4, B 4i. magnit\lde. DiacoveJed by Heracbel, 1781. Since which period • mrograde JDOo uonbae been in progreea, as is fully lUlltained by the reported _urea, -.iz.. POL 2320 22' .Disl 4".31i Epocb 1781.7S H8lIJClleL 206 06 8 .23 . 1831.22 Str:.ve. 190 67 ".90 1847.70 MitcheL fine

=

+

..,. 1 Ducorrll.-A. R. 17 b. 44 m. 47.. Dec. 7'J;O 13'. A double ltar, in the middle of Draco'. back. A 6i, B 6. Both wbit& This distance is about 81"; the poIIition 160. No change ~1ll8 to have taken place.

See.Map; No

xvn.

=+ 6QO 69'

A DoUBLS inA_A. R. = 17b. 26 m. 07&. Dec. OS". Between the right tbot of Hercules aDd Draco', eye.

magnitUde; POL 2660 !l8' 266 20

.

DiIlS".17 8 .03

A 8, B 8j. .

Epoch 188US Stri.ve. 1847.70 Mitchel •

Between the fih& twist «Draco and biB bead. Discovered by HI!ftICheI, in 1786. .

•

. 'Dec. 68038. >

A PunTny Nn17u.-A. R.= 17b. &em. 39 •.

This singular object is described in the Bedford Catalogue, without any mention of a rellilllkably bright but ImBU nucleui which occupies its eenter. Thill point· wail detected by myaelf, July, 1847. When the . eye and att.entiou is attentiTeiyfixedon the eentral point, the Debu\a fadu frum tAt view, and the moment the attention is withdrawn from the nucleue, and • CII8UIIl glance is directed to the nebula, the &tar fadee and the nebula brightens, up in a most beautiful IDIUlIIeJ'. Thill curioua phenomenoo was IIOticed by many JI8lIIOlIII ill my: company. No 0D8 . can doubt the connection between this nebuloue _ and the IOlIIId central point of light. It is unlike • 1Itar, as it is round and clear, with • minute diIIk and no IIIIliatioDII. I have diIeovered but 0D8 other Clbjec& . lib it. Here ill the COIlIl8CtiDg IiDk between pIaDIIIa1y D8bulaI BD4

M

134

GEOGRAPHY OF THE HEAVENS.

, nebulous stars;, at leaoot, such would be the opinion of those who still adhere to the nebuloUB tMr"'Y' ' , 'fhis remarkable ol!led, 88 will be seen from the position,is in the pole

of 1M ecliptic.

'

• DUIlOIUS.--A.

R. = 18 h. 48 m. 50 a. Dee. =

+ 590 II' 07".

A double star. on Draco'. neck. A 5, B 9. magnitude. M..d1er thinks the components phyaicall! connected. with il period of about 1600 y _ POB. '900 00' Dist. 28".37 Epoch 1781.68 HencheL 346 83 80 .26 1832.60 Stril_ 344· 51 32 .10 1841.48 l'tlii.dler•

==

• DB,A.ctnrIILI-A. R. 19 II. 48 m. 41.. Dec; 690 51' 06". III the bend of Draco'. back. ' A 6i. B 9~. magnitude. Discovered by Hersche~ whose first measures are probably wrong in 8QD18 way. 88 they would indicate il great motion. between 1781 and 18M, "'I¥ch is not llUBtained by the later observations. POB. 3550 40' Dist. 2".69a Epoch 1841.66 M;idler•

. COMA BERENICES.

BERENICE'S HAm.-This is a beautiful cluster of, small stars, situated about 50 E. of the equinoctial colur', and midway between CorCaroli on the northeast, and Denebola on the southwest. If a straight line be drawn from Benetnasch through Cor Caroli, and produced to Denebola, it will pass thro.ugh it. The principal stars are of between the 4th and ,5th m~itudes. According to Flamsted, there, are thir~en of the 4th magnitude, and, according to others, there are seven; but the student will find, agreeably to his map, that there are but three stars in this group entitled to that rank .. Although it is not easy to mist.ake this group for any other in the sanie region of the skies, yet the stars which compose it are all 'so small as to be rarely distinguished in the full presence of the moon. ,The cpnfused luster of this assemblage of smal~ stars, some\vhat resembles that of the MilkyWay. It contains, besides the stars already alluded to, a number of nebulm. ' .'

CONSTELLATION OF COMA BERENICES.

135'

i,

The whole number of stars in' this constellation 43; its mean right ascension is H~5°. It, conse-quently, is on the meridian the 13th of May. _ _ _ _--I'. Now behold The gliUering maze of Bere1ua', Hajr I Farly the &talII; bUt such .. seem to kill rbe jlowiTlg e,_ with a lambeJU Ire: Four to the teleacope alone are seen...

TELESCOPIC OBJECTS.

=

s6

=+

Cox.. BUNJCEB.-A. R. 12 h. 45 m!'25 II• . Dec. 22 0 (17', A triple . , between the 'rr- and Virgo'. northern wing. A ll, B indistinct, C 10, Such are the magnitudes aaaigned by Captain Smyth. I measured the components on the ~7th July, 1847, and found the individual measures accord well with each other.· P08. A:O 4()0 04' DilL 1".316 Epoch .. above. A to C 125 31 In 1830, Strl. ve gives the IIl8IIIIIIle8 of A to C .. illlowa : Poe. A to C 1240 43' Diat. 28".61 Epoch 1830.13, Captain Smyth IDIIkea the diIance between A and B, in 1834, 1",00, In 1843, 1",6.

=

=

64 MESIJER, COlIIB BERIHCElI.-A. R. = 12 h. 48 m. 52.. Dec. A large elliptical nebula, between Bernice'. hair and Virgo'. left ann. Discovered by Me&Bier, 1780, Sir J ohri Herachel considers this nebula resolvable, though not resolved. He _y.: "I am mllCb mistaken if the nucleus be not a double star, in the genellll direction of the nucleus; 320 mQch increaseS this SUJlo picion; 340 shows well a vacuity below the nucleus."

+ 220 33' 02".

BUlflC"&S.-A. R. = 13 h. 05 m. 03.. Dec. globular cluster, between the Coma and Virgo'. left and. A brilliant IDaIIII of minute stara, varying from the, 11 th 10 the 16th magnitudes. Discovered by Mesaier, 1774. Resolved by Herschel, who finda.it gready com~ at the center. This is one of the many magnificent

=t 63

MUIII"&R, COX.. 190 01' 03". A

" island univetBils."

.

Sir John Herschel, with his 20 feet reflector, saw this object with curved radiations of IItarB, IIOJIl8What resembling the claws of a crab.

+

-&2 Cox.. BUlflC"&S.-A. R. = 13 h. 02.m. 12.. Dec. = 180 22' 06". A very cloee double star, between the Lady's hair and Virgo'. left hand. A 4!, B 5, magnitude. Both abi.ra are said to be pale-yeJlow. It is No. 1728 of 8triive'. great catalogue, and is among bill "vicinil!8imle," or very c1~ stara. The meaaurea run thUB: . .

138

GEOGRAPHY OF THE HEAVENS.

Pc-. 090 30' DiIt. . Epoch 1827.88 Stril.... 11 06 OH.649 1829.40 -' lingle 1833.87 128 11 _ _bat eIoapted 1834.48 191 11 1336.39 After this, the - . m e l lUll made with IiUIe ~, up to 1841. when Madler, or Dorpat, 1Ii- theM : POll. 1830 1/1' Diat. 0".3~7 Epoch 1841.46. H_ is, dou~ a binary II)'8tem, but one of great difficulty. The IIaIII being nearly equat in magnitude, it is diffieult to diatinguish the angle or position from the IIUIIII, increued by 1800.

• ASTERION ET CHA..RA; VEL CA~ES VENATICI. THB GUYHOUNDS. This modem constellation, embracing two in one, was made by Hevelius out of the unformed stars of the ancients, which were scattered between Bootes on the east, and Urea Major on the west, and between the handle of the Dipper on the north, and Coma Berenices on. the. south.' . . These Hounds are .represented on the celestial sphe.re as being in pursuit of the Great Bear, which Bootes is hunting round the pole of heaven, 'While he holds in his hand the leash by which they are fasten~ together. The northern one is called .A.tterion, and the southern one Ohara, The stai's in this group are considerably scattered, and are principally of the 5th and 6th magnitudes jOt' the twenty-five stars which it contains, there is but one sufficiently large to engage our at-" tention. Cor Daroli, marked Go, or Charles'8 Heart, so named by Sir Charles Scarborough, in memory \ of King Charles the First, is' a star of the 3d mag- . nitude, in the.neck of Chara; the .southern Hound.

When on the meridian, Cor Caro1i ia ·17IO directly south· or Alioth, the third IItar in the hanclIe or the Dipper, and is 80 nearly on the same meridian. that it culminatee only OIIe minute and a half after it. Thill \ 0CCIIlII on the ~th of May. A line drawn from COl' Caro\i. through Alioth, will lead, to the north polar 1Itar. This IItar may also be reacliIy ~~guished by its being in a

CONSTELLATION OF THE HOUND!!.

137

IItraiPt line with, and midway between, Beuetnaaeb, tb/! filllt star in the handle of the Dipper, ani Coma BenmiClel!: alld, also, by the fact that,

when Cor Caroli is 011 the meridian, DeneI!oIa bears illO S. W., and ArctuI"Wl 260 S. E. of it, forming, with these two Btara, a very large triangle, whose vertex is at the north. It is aI80 at the nm1hem es.tremily of tlte large Diamond, already deacribed. . . The re~g Btal8 in this conatellation Bre too BJDa1l, and too. much -uered, to excite' our interest.

TELESOOPIC OBJEOTS.

+

2 O.llWJ[VBlJATICORUJ[.-A. R. = i2 h. 08 m. 06.. Dee.":'" 41 0 33'•. A double liar, neB? Obara'. month. A 6, yellow;' B 9, blue. Discovered byHencheJ, 1782. 1'0& 2590 38' Diet. 11".42 Epoch 1832.16 Str'.ve. Ita fixity seeD18 to be determined by a comparison of aU the recorded ot-rvatiOll8. . .

., LAROE NEBUL.l.~A. R. = 12 h. 4:1 m. 22 So llec.·41 0 59'07". Immediately preceding the Cl'OWIl, or Oharl..·s Heart. Discovered by Mich!lin, in 1781. Described in the Bedford Cl!taIogue as .. a fine pale white o1!ject, with evident aymptoJDB of being a compressed cluster of small stan!." .' 61 M. O.llfUlII Vn.lTIcQRux"":"A. R. = 13 h. 23 m. 06 s. Dec. 480 01' A pair oflucid nebula. near the ear of Asterion. Discovered by MMIi.er, 1712. Figured by Sir John HelllChel, 1830. ReeoIved by Lord ~ into onemagniticent cluster. in the abape of an iJDDlt'use whirlpool, in 1847. . . I have repeatedly examined this most wonderful object with the 12 inch reliactor of theOincinnati Obeervatory. 'rhe lIllY nebula is'seen with a bright nucleuB, lIImOIJDIled by a·ring of hazy light, which is divided, in a part of ita circumference, into two branches, which forcibly remind me of the Milky-Way and ita division. 1'he smaller .nebula is round, and ita light is seen nearly, if not quite, commingling with that of the ring aurrounding the principal object. This o1!ject strongly resembled our own great BteIIar syatem, 80 long as it was viewed at the distance to whiril· ordinary telescopes could carry the beholder. But, under the gaze of Lord RoI!se'8 stupendous reftector, the most bewildering o1!ject buTBts upon the sight. A mighty center, where, in spiral curves, radiate masses of light, 80 vast as to overwhelm the imagination.. 'rhe resolution of this most renlarkable nebula ia one. of the areat achievementa of Lord Roa!e'8 telescope. .

=

+

or.

3 MusnR, O.l.uJ[ VBlf.lTlCOIlUX.-A. R. = 13 h. 34 m. 46 .. Dee. = 29P 10' 06". A magnificent cluster, said to contain not Iesa than a thousand sIarB, between the IIOIIthern Hound and the knee of Bootes. Discovered by MeBBier, 1764; and described as" a nebula without a liar, brilliant and round." Resolved by Henchel, 1784, with his 20

+

.2

.

138

GEQGRAPHY OF THE HEAVENS,'

ilet zefIedor, wbo calla it .. a beautiful e11Dter of IItanI, II' or tI in diameter." , I haw repat.edJy examined this fine object. The _ of Man k greedy compaded toptber at the renter, and spreM out in brilliant nMliationa in aJi direetion.. The IargeIt radiations extend downward, .. . . with m inverting eye-pieee.

COR 0 NAB 0 Kif A L 18.

TRE NoaTHEu CaoWN.-This beautiful constellation may be easily known by means of its six principal stars, which are so placed &8 to form a circular . figure, very much resetpbling a wreath or crown. It is situated -directly north of the Serpent's head, between Bootes, on the west, and Hercules, on the east. Tbia ~ _!mown to the Heb_ by the name of hhtarotA J and by this Dame the IItaIII in <;:orona BOII!IIIM are ~Iled, in the East, to

.

this~

Alpkacca, marked Go, of the 2d magnitude, is the brightest and ,middle star in the diadem, and about 11 ° E. of Mirac, in BoOtes. It is very readily dis'; tinguished from the others, both on acMunt of its position and superior brilliallcy. Alph8.cca, Arcturus and Segiuus, form nearly an isoscelestriangJe, the vertex of which is at Arcturus. . This constellation contains twenty-one stars, of which only six or eight are conspicuous; and most of these are not larger than the third magnitude. Its mean declination is 30° north, and its mean right ascension 235°. Its' center ie, therefore, on the meridian about the last of June, and the -first of July. . ...~nd, near to HeIi«, eftbJgent ray. Beam, .biatIne, from thy rb.rry crown: • 7Wen'JI and one. her 1ItaIII; but eight alone COD8pICUOII8; one doubtful, or to claim The II!COnd emler, or accept the third."

CON8TEo..A TION OF LEO JlIN01l.

18V

DIRF.cTIONS FOR TRACING THE CONSTELLATION' ON

'MAP NO. XIV.

LBO MnmR-TUE Ln-ru LION. LYNx-TUE LYNX.

PavorolJly situated·for ezomination in'Mareh, April and 1f!ay..

.

\ .

LEO MINOR.

THE LrrrLE UON.- This constellation was formed by Heveliu!!, out of the Stella informelt, or unforpted stars of the ancients, which lay scattered between the zodiacal constellation Leo, on the south, and Ursa MaJor, on the north; Its mean right ascension is the sam~ with that of Regulus, and it comes to the meridian at the same time, on the 6th of April: The modem co1llJtellationa, or thOle which have been added to oar celestial mapa, Since the adoption of the Greek D~tion, in 1603, are referred to by the (etteN of the English alphabet, instead of the Greek. This ill the eaae in ~ to Leo Minor, and an other co1IIItel\ationa whOle origin ill subsequent to that period. .

Leo .Minor contains- fifty-three stars, including only two' of the 4th magnitude. The pri~cipal star is situated in the body of the animal, l:JOnorth of Gam~a Leonis, in a'straight line with Phad, and may be known by a group of smaller stars, a little' above it, on the northwest. It forms an equilatem triangle with Gamma and Delta Leonia, the yertex being in Leo· M"mor. This star is marked with the letter.1, in modern catalogues, and, being the principal repreaentative of the conete1Jation, ill itaelf sometimes called the Little Lion: SO E. of this atBr (the Little Lion), are two stars of the 4th magnitude, in the Wt paw ofltra Major; and about loo N. W. of it, are two other lIIUB"of the 3d magnitude, in the first hind paw.. . .. The 8maIler linn now 8IIeCeedl; a cohort

Of fifty &tara attends his IItep8 ; ,

And Uweei to aipl ~ UniIIDJe."

140

GEOGRAPHY OF THE HEAn:N8.

TELESCOPIC OBJECTS.

=

100 HZ.'CRlCL I, Laona MI"ORJR .......A. R.. II 11. '2 m. « ". Dec. = 340 00' 06". A bright oval nebula, between Lynx aud Cancer.

+

.

DiBcovered by Hei-achel, 1781; and registered _ a wsry beautiful nohula, 8' long and 3' broad. '. Other llllbula will be found OIl the chart.

THE

L~NX.

THB constellation of the Lynx, like that of the Camelopard, exhibits no very interesting features, by which it can be distinguished. It contains only a moderate number of inferio.r (Jtars, scattered over a large space, north of Gemini and between Auriga and Ursa MBrjor. The whole number is fi)rty-four, including only three tbat are so large as tbe 4th ·magnitude. Tbe largest of these, in the nose, is in the solstitial colure, 14°nortb of Menkalina, in tbe eaSt shoulder of Auriga. The othe·r two principal stars are in the brush of tbe tail, 310 southwest of another star, of the same brightness, in the mouth of the Lesser Lion, with which it makes a small triangle. Its center is on the meridian at 9 o'clock, on the 23d,or, at half-past 7, on the 1st, of February . .

TELESCOPIC OBJECTS •.

+

. ,LTlfcll.-A. R. = 8 11. 07 m. ·IH B. Dee. = 590 26' 08". A close double star, in the nose of the Lynx. A 6, B 71. J>iaccmnld StriiYe. POL 880 68 DiBt. 0".816 Epoch 1830. ~ 8trii Ye.

!7

+

·174 P. VI, LTlfcrl.-A. R. = 611. 30 m. 'h. Dec. 690 36' 06". A double 1Itar, under the eye of the Lynx. A 7., white, B 10. lIlue. . DiaccmIred by Btrilq. ' Poe. 1330 28' DiaL '''.197 Epoch 1830.68. The compmion 8ppeara to be ftriabIe, 1'8DIing from 8i to the 12tb magnitude. l' LTlfcIB.-A. R. 611.38 m. 67.. Dec. = 690 37' 06" A "

141

CON8TELLATION OF THE LYNX.

double liar, uDder the eye of the I.ynx. A Ii. "goIdeu ye1Imr," B I, MpwpIe." _ . . DiacoveIed bv Strn ve. • }>OII. 500 61' Diat.' 0" 897 Epochl830.88

+

I, L-nlcls.--A. R. = 09 h.14 m. 311.. Dec. A bright nebula, on the be pa_ of Leo MiJ!or, bot iDduded within the IimiI8 of the Lynx. Discovered by Hel'llCheI, in 1786, who dellcribes it u nIUDd, pale white, and sparlding in the center, with an IIdditionalliint nebulOBity BUrrOUDd137.

HKIIIICRKL

3.0;0 II' 09".

iDg the DU~- Some 3'

~

diameter.

I.~'

mRECnONS FORTRACJNG THE cONSTELLATION ON

MAP

N'O. XV.

LmllA-TJiE ScALES.

Favoralily situated for emmination. in May, Ju:u 41Id JvJy. . -\

-

LIB RA.

,

THE BALANCE.-Thi~ is the seventh sign, and eighth constellation, from the vernal equinox, and is situated in the Zodiac, next east of Virgo. The sun enters this sign,.at the autumnal equinox, on the ~3d of September; but does not reach the c.Tm8tellotwn before the .27th of October. Virgo was the goddess of justice, and Libra, the scales, which she- is usually represented as holding in her left hand, are the appropriate emblems of her office. When the sun enters the sign Libra, the days and nights are equal aU over the _world, and seem to observe a kind of equilibrium, like a balance . . When, however, it .is said that the vernal and autumnal equinoxes are in Aries and Libra, and the tropics in Cancer and Capricorn, it must be remem,. bered that the sign8, Aries and Libra, Cancer and

142

GEOGRAPHY OF THE HEAVENS.

Capricom,and not the constellations of these na·nes, are meant~ for the equinoxes are now in ~he c;onsiellatioDs Pisces and .Virgo, and the tropics in Gemini and Sagittarius; each constellatian ho.vjng gone forward tme sign in the ecliptic. About twenty-two centuries ago, the C01UJtellation Libra coincided with the sign Libra; but, having advanced 300 , or more, in the ecliptic, it is now in the sign Scorpio, and the constellation Scorpio is in the sign Sagittarius, and so on. . While Aries is now advanced a whole sign above the equinoctial point, into north declinati9n, Libra. has descended as far below it, into sQuth declination. Libra contains fifty-one star~, including two of . the 2d magnitude, and several of the 4th. Its mean declination is 80 south, and. its mean right ascension 2260 • Its center is, therefore, on the meridian about the 22d of June. It may be known by means of its four principal stars, forming a quadrilateral figure, lying northeast and southwest, and having its upper and lower corners nearly in a line running north and south. The two stars which form the northeast side of the square are situated about 7° apart, and disti·nguish the· northern scale. The two stars which form the 1!I0uthwest side 'of the square are situated about 6 0 apart, and distinguish the southern scale. Zubeneschamali, marked ~,in the· northern scale, about 21 0 E. of Spica, and 80 E. of Lambda Virginia, ill a &tar of the 2d inagnitude, and ill situated very near the ecliptic, about 42io E. of t)le autumnal equinox. The distance from this.tar clown to Theta. Centauri, is about 2).J0, with which, and Spica Virginia, it forms a large triangle, on the right. ZltberWgemabi, markl'd ri, is a)w, of the 2d magnitude, 9~o below Zubeneachamali, tqwanJ& the southwest, and it comes to the meridian about twenty.six minutes after it, on the:t&l of June. Zubenelgemahi is the north~mmost of the four bright stars in this figure, and is exactly opposite the lower one, which is I lOS. of it The star marked 1'. i. a star of the 3d magnitude, in the northern acaIe. 70 S. E. of Zl1oont!lgemabi, and nearly opposite to ZUlJellt·... cbamali, at the distance of I lOon the east. 'fheae two make lbe diagonal of the equare east and weaL

143

CONSTELLA.TION OF LIBRA..

rota is a &tar of the 4th magnitude. and COJIIItituleli the IllUthemlllOllt Ct Der of the square. It is about 6" S. E. of Zubeneschamali, md 11 0 S of Zubenelgemabi, with which it tOrDIB the ~ diagonal, north and 80 Ith.

Zubmelgvbi is a .tar of the 2d magnitGde, aituaied below the rputhem acale, at the distance of 6°, from lola, and marks the IOUthero limit of the Zodiac. It is situated in a right line with, and nearly midway between, Spca Virginia and Beta Scorpii; -and comes to the meridian nearly at the _ IIIOIIIIIIlt with Nekkar, in the head ofBo;;tea. '!'he remaining &Iar& in the eoostelIatiCID are too stnaIl to engage attention.

'

The aeholar, in tracing out this eooateJlation in the heaVeDB, will perceive that Lambda and Mu, which lie in the filet of Virgo, on the weat, fonn, with Zubenesebama1i and Zubenelgemabi, almoat B8 bandaome and perfiect a figure as the otber two.stars in die Balance do. on the east. 0 BJ ECTS.

T EJ,E SCOPIC

=

=-

STu.....:A. R. 14 h. 14 III; 11 Ii. Dec. ()70 01' 07".-160, east by north, from Bpica Vuginia The ItalII are equa1, and of the 8th magnitude POll. 1660 0t!' DiaL 5".02 Epoch IS36.44 SIIIyth. 'A

DovBLE

=

A CLOSE DOUBLE BUB.-A. R. 14h. 11\ m. 06.. Dec. 100 56' o:r.-cioee to thebeel of the Virgin. A 7!, yellow, B 9~, greeniab. Dieeovered by Str:.ve. 1827. '

Dist. .".41

POll. 3260 87'

Epoch 1828.83.

A CJ.OIIi:LY COMPACTED CL'UIITEB.-A. R. = 111 h. 10 m. 26 .. Dec. = 020 41' 03". ' Over the Balance. , Discovetedby Mesaiet, 1764, who regiaterB it _,a round nebula, in which, he is confident, not a star exista; '8Ild yet, in May, 1791, Bir William Herachel, by the aid of his 40 filet re8eetor, counted in this object no ' - than 200 8&anI, , This is one of the great c\uslel1l comparatively near our IIidereal Btra:bnn, and somewhat resembling that in flercules, hereafter described and figured. The drawing WB8 made under a power of 280, and 12 inches-' aptll1Ure; the ot;ect WB8 thUII described.' ,

+

f

OB III LIBIUII.-A. R. = 15 h. 68 m. 35 .. Dec. = - 1oo 55 06. A lIIOIIt elegant triple 1ItaT, between the upper BCaIe of Libra and the right leg of Ophiuchua. A. 4!. B II, magnitude. Poe. A B 1870 56' DiaL 1" .50 Epoch 1782.361HeracheL A C 88 37 6 .38 1780.39 5 '

! ~ 3~ ! ~ ~: :

::

~ .~~~

1825.4&} StrUve.

~ ~'

~.481Madler.

0 .97 1846.48 1. Mitchel. 7 .16 S. The disks are per(ed, with a power of 600 timea. • A B 24 52 A C 74 42

1« A

GEOGRAPHY 01" TIlE HEAVENS.

LJ.... eo........

Dec. = -100 te' or. D~

tween the

CI.V8'na..-A. R.

=

15 h. 08, IlL G6 ..

by HeI1dIeI, 1786. It hIM • 110ft of IlCJIIIII!I.\ti link ' -

c:ouaen- of IIaJa aDIl the ditltet nebula.

--•

DIRECTIONS FOR TJlACINGTHE CONSTELLATION ON

)fA P, NO. XVI. ScolU'Io-THE

ScOIlPIOl'f. ,

Favorohlg aituated fur "ezamina#on in June, July, and August. 8CORPIO.

THE Sea.PION.-This is the eighth sign, and nint.h constellation, in the order of the Zodiac; It 'presents one of. the moat interesting groups of Btars, for the, pupil to trace out, the:t is ~o be found in the s~uthern hemisphere. , It is sltuated southward a.nd eastward of Libra, and is on the meridian the 10th pC July. ' .. The IUD enters this Iign on the 23d of October, but d~ not reach the ctmBteJlotion befOTe the 20th of November. When astronomy _ fint cultivated in the East, the two eolstices and the two equino"ea took place when the IUD WII8 in 'Aquarius and Leo, 1'aurua ,and Scorpio,

'respeCtively.

, Scorpio containe,aceording to Flamsted, fortyfour stars; including one of the 1st magnitude, one of the 2~, and eleven of the 3d. It is readily distinguished from all others, by the peculiar ,luster and the position of its prin~ipal stars. Antares, marked a., is the principal star, and ia situated in the heart 01\ the Scorpion, about 19° E. of Zuhenelgubi, the southernmost star in the Balance. Anwes is the most brilliant star in that region of

CONSTELLATION OF SCORPIO.

145

the skies, and may be otherwise distinguished by its remarkably red appearance. Its declination is about 26° S. It comes· to the meridian about three hours after Spica Virginis, or fifty minutes after Corona Borealis, on the lOth of July. It is one of the stars from which the moon's distance is reckoned, for computing the longitude at sea. There are iJur great tltatll in the _ - . FtJ'IIIIJIMuI, AJdelIarrm, &gulw, and ArItInI. which fOrmerly anawen!d to th. IOl8titial and equinoctial pointa, and which were much noticed by the uIronomen of &he Eat.

About S!0 N. W. of Antares, is a star of the 2d magnitude, in the head of the Scorpion, called GrajJiaa, marked~. It is but 1° N. of the earth's orbit. It may be recognized by means of a small star, situated about 1° N. E. of it, and also by its forming a slight curve with two other stars of the 3d ,magnitude, situated below it, each about 3° apart. The broad part of the constellation near Graffias is powdered with numerous small st"rs, converging down to a point at Antares, and rellp.mbling in figure a boy's kite. . As you proceed from Antares, there are ten conspicuous stars, chiefly of the 3d magnitude, which mark the tail of the kite, extending down, first in . a south-southeasterly direction, about 17°, thence easterly, about 8° further, when they turn, and advance about 8° towards the north, forming a curve, like a shepberd's crook, or the bottom part of the· letter S. This crooked line of stars, forming the tail of the ScorpioIl, is very conspicuous, and may be easily traced. The first star below Antarea, which is the last in the back, is of only the 4th magnitude. It is about 20 S. E. of Antarea, and is marked '1". Epailor., of the 3d magnitude, is the aecond star from Antarea, and the fiDt in the tail. It is aituated about 70 below the star '1", but inclihing • IiUIe to the eat. . Afi.f, of the 3d magnitude, ia the 3d star from AnI.ue8. It is aituated

N

'

146

GEOGRAPHY OF THE HEAVENS.

4j0 beloW Epilon. It may o&henriI8 be known by _ _ of •

-n

IItar clOle by it, on the left.

Zeta, of about the BaDle magnitude, and situated about 88 fill below Mu, ill the fuurth atar tiom Antarea. Here the fine tumB lUIIdImly to the tIIIIt. Eta, also of the 3d magnitude, is W, fifth IItar &om Anw., IDIl abom 310 eaat of Zeta. 71Ida, of the lJIIIIle magnitude, ill the sixth star &om Anw., and .bout .10 E. of Eta. Here the line tumB epin, cumug to the nOltb, and terminates in a couple of stars. Iota, ill the eeventh star tiom Antarell, 310 above The&a, cuniDg a Ii~ lie to the left. It ill a star of the 3d magnitude, and may be known by JDeaIIII of a 8IIIIIIl1itar aIJDOIIt touching it, on the east. Kappa, a star of equal brightness, is leu than 20 above Iota, uad a IiUIe to the right. . Le8utk, of the 3d magnitude, ill the brightest of the two Iaat in the tail, and ill situated about 30 above Kappa, still further to the right. It may readily be known by meaua of a 8IIIIIIler star close by it, on the welt.

This is a very beautiful group of stars, and easily traced out in the heavens. It furnishes striking evidence of the facility with which most of the constellations may be so accurately delineated as to preclude every thing like uncert~nty in the knowledge of their relative situation . .. The hean, with IUBter of amaziog Mree, Refulgent vibrates; faint the other)llllt8. . And iIHlefinedby stars of meaner note."

TEL E 800 PIG 0 B J E 01' 8. AlJT£RBI, OR " ScORPII.-A. R. = 16 h. 19 m. 36 .. · Dee. = 260 C)4,' 03". . Diacovered to be double, at the Cincinnati Obeervatory, July, IM5. A I, orange, B 12, blue. The oontrut of color ill diatinetly marked. The small star follows the principal one. on the aame parallel. Distance 2".6. 'rhe principal star W88 pronounced to be double, by the Wuhington obeerven, in August, 1846, but &hill error baa been BUbsequendy corrected. This furms the IIIOIIt nmwkabIe tlouble IItar now on the ca.... loguee,-there being no star of the 1st magnitude known, having 80 minute a companion, at 10 mort a distance. It was lint divided with a power of 260, and aperture of 12 inchea. The best power for measures is 500, with an aperture reduced·to 9 inehea. My measures indicate a alight increue in the diatance betwesl the MQ components. This, however, requires confirmation.

=

=-

, ScoRPn.=A. R. 16 h. 02 m . •, . . Dee. 190 02' Olr. Reptered 88. double 1Itar. DiIcovered to be triple, at the Cincinmdi

.

CONSTELLATION 0)' SCORPIO.

147

O'-natory, UI46. A and B Dearly equal, and of the 8th JIIIIiIitude; C 7, magnitude. Diatance from A to B = 1".2 From A B to C W'.oo -:1POL A+BtoC=338029'

+

--2-

FromAtoB= 37 67 This liar __ tint _n double by Hencbel, in 1779; but itII great w.JUthem declination brought it too near the horizon, in the latitude of his oilBervatory, to _ the close mal'll. The same may be aaid of Antares. I have JeCeIltly received inteUigenl'B, that measures of Antarea have been lDoIde in England, 1847• .. &oa.II..-A. R. = 18 h. 11 m. 28.. Dee. = - 150 12' or. A delicate double liar, 2
/d Beoa.n.-A. R. = 15 h. 66 m. 08.. Dee. = - 190 21' 07". A ECODd rate Greenwich liar. Diaeo...-ed to be double by Herechel, 1779. A 2, B 5;, magnitude. Madler thinks thiI a binary aylltem of long period. The measures are .. fOllow : POL 250 09' DiaL 14".37 Epoch 1779.72 Henehel. 26 30

13 .66

1823.28 Her. & South.

My own measures are: POL 260 is' DiIIt. 13".68 Epoch 1846.60. Agreeing nearly with Henehel and South. The Bedford Catalogue givee: POI. 240 09' Dist. 13".01 Epoch 1836.39. From theee IDBII8UleII, there ie very litt1e evidence of any change, either in diBtaDee or, angle of poaiti\lll.

dB BalL£UlfT CLVITU.-A. R. = 18 h. 07 m. 28 .. 36' 04". Dieeovered by MeIIier, in 1780. who describee it .. Je8BmblinlJ the nucleus of a comet. It ie 40 E. of I S...orpii. and midway between " and /d. It is remarkable .. being located on the weetern edge of an immenae openinIJ. or vacant 8pOt, in the heavens, of 4 0 in breadth, in which the mOlt powerful telescopes reveal no stara ! The center of this cluster is very brilliant. and the 8urrouncling points of light profuaely acattered Herachel regards it as one of the richest and most condensed massee of iItaJ'II yet dilloovered in the heavens. Examined and figured, 2d AUgust, 1847.

A L.a.a&.

Dee. -

~

CLV8TEB.-A. R. = 18 h. 013 m. 61 .. 2&0 07' 05". It precedee Antares 1io on the same parallel Discovered by Messier. .Reeolved by Herachel; who I5timaIeB iw profundity of the 344th order. AS_ALL COMPR.RRJ:D

Dee. =

-

148

GEOGRAPHY OF THE HEAVENS.

Tbia eoodeIIlIed groapis aIao on the western edge of the opening above referred to, and baa given rise to the following remarks by A rago. referring to the idea ex...-J by Henchel. that, wherever chasms in the heaYeII8 are found, near by, exteDBive clWlterll and ,nebula will be discovered. " Let UIJ," _18 M. A rago, "connect these fuets with fhe observe.tion which baa shown that the stars are greatly coudel1!led toward the center fA the spherlcdl cllJlllerll, and. with that which bas afforded the proof that these stars sensibly obey a certain power of conden8llti.on (or clustering power). and we shall feel disposed to admit, with Hel'IIChel, that nebube are formed sometimes. by the m-nt operation of a great number of apa, at the expense of the acattered. stars which originally occupied the IUrrounWng regions; and the existence of empty or ratxtged spaoos-to JUIl the picturelque expresBioo of the great astronomer, will no longer present any thing which will coofound the imagination."

A L.uun: RUOLY'A.BU NBBtJL~-A. R. = 16 h. 51 m. 04.. Dec. _290 50' OS". Discovered by Messier. Resolved by Henchel; who estimatea its dilllance to be of the 73~th order. It resembles a comet, and baa been reported as such, at least once, in a very public manner. . All the reponed cl\lllterl in this constellation are readily detected by any ordinary telescope. Their resolution does not require a high pt'wer. But to show them in all their ~ and brilliancy, a powerful instrumentis~.

--DIRECTIONS FOR TRACING THE CONS'I'ELLATIONS ON

MAP NO. XVII. URSA MINOR-THE LEsSER BEAR. CEPHEUS• . CAMELOPARDUS- THE CAMELOPARD.

Favorohl!l situated for examination in Marck, April, mul Mfl!J. URSA MINOR.

'

THE LITTLE BEAR.- This constellation, though not remarkable in its appearance, and containing but few conspicuous stars, is, nevertheless, justly distinguished from all others, for the peculiar advantages which its position in the heavens is well known to afford to nautical astronomy, and especially to navigation and surveying.

CONBTELLA TION OF

uaSA.

MINOa.

14"

The stars in this group being situated near the celestial pole, appear to revolve about it, very slowly, and in circles so small as never to descend below the horizon. In all ages of the world, this constellation has been mOI'e universally observed, and more carefully noticed than any other, on account of the importance which mankind early attached to the position of its prillcipal star. This star, which is so near the true pole of the heavens, has from time immemorial, been denominated the NORTH POLA& SUB. By the Greeks it is called Cy7llJ3'ltre,' by the Romans, Oynoaura, and by othe", nations, .AJ7'1J.C'COiJak. ' . It is of the 3d magnitude, or between the 2d and 3d, and situated a little more than a degree and a half from the true pole of the heavens, on that side of it which is towards Cassiopeia, and opposite to Ursa Major. Its position is pointed out by the direction of the two Pointers, Merak and Dubhe, which lie in the square of Ursa Major. A line joining ~ Cassiopeia, which lies at the distance of 32° on one side, and Megrez, which lies at the same distance on the other side, will pass through the polar star. . So general is the poplliar notion, that the North Polar Rtar is the true pole of the world, that even surveyors and navigators, who have acquia'ed considerable dexterity in the use of the compass and the quadrant, are not aware that it ever had any deviatil;)O, and consequently never make allowance for any. All calculations derived from the observed position of this star, which are founded upon the idea that its bearing is always due north of any place, are necessarily erroneous, since it is in this position only twice in twenty-four hours; once when above, and once when below the pole. According to the Nautical Almanac, the mean disx2

150

OF THE HEA \' li':l'4§L

tance of fl'1tsm the true pole for the is 10 29' 28", and ascension is 1 h. 5 m. and 10.66 s. Consequently. when the right ascension of the meridian of allY place is 1 h. 5 m. and 10.66 s. the star will be exactly on the meridian at that time and place, but JO ~9' 28" olmJe the true pole. Six hours after, when the right ascension of the meridian is 7 h. 5 ffi. and 10.66 s. be at its great§§Lt or 10 29" west of the tr04.' allel to to the hori§§fsEl the right the meridian if 10.66 s. will be again OS2 but at d 1° 29' 28" pole. In like manner, when the right ascension of the meridian is 19 h. 5 m. and 10.66 s. the star will be at its greatest eastern elongation, or 1° 29' 28" east of the true pole; and when it has finished its revolution, and the right ascension of the meridian is 25 h. 0.668'. or, whitt thing, 1 £0.66 s. the stElr on the 1° 20' 28" ahnvv N. H. Th53 of the meridian or is the di~tanL55 {if A riCO! from the and place of 5'fht ascension of the "'' §§ RIme, J>; found, hy n.kling to the given time the SUll'S right ascension at the IllUDe time, ami deducting 24 houl'lI, when the sum exceeds 24 hours.

From the fOl'egoing facts we learn, that from the time the star is on the mel·jdian, above the pole, it dedates farther and fiu·ther from the true meridian, every hour, as it moves to the west, for the space of si x hOURRl R §§L55"i "es at its great§§53Y west, f§§?iI?proaches the below Rhzfmng the next siRl then agvin n5tnridian; being half thn {if the meridiali':, time eaft

CONSTELLATIO:'i OF URSA MINOR.

151

Hence, it is evident that the surveyor who regula.es his compass by the North Polar Stat·, must take his observation when the star is on the meridian, either above or below the pole, or make allowance for its altered position in every other situation. For the same reason must the navigator, who applies his quadrant to this star for the purpose of determining the latitude he is in, make a similar allowance, a.ooording as its altitude is greater or less than the true pole of the heavens; fur we have seen that it is alternately half the time oJxme and half the time below the pole. The method of finding the latitude of a place from the altitude of the polar star, as it is quite simple, is very often resorted to. Indeed, in northern latitudes, the situation of this star is more favorable for this purpose than that of any other of the heavenly bodies, because a single observation, taken at any hour of the night, with a good instrument, will give the true latitude, without any calculation or correction, except that of its polar aberration. If the polar liar always occupied that point in the heavens which ill directly opposite to the north pole of the earth, it would be easy to underIbmd how Iatitudecould be determined from it in the northern hemisphere ; fOr in this cue. to a penon on the equator, the polm of the world would be aeen in the horizon. Consequently, the Star would appear just viaibIe in the northern horizon, without any elevation. Should the person now travel one degree towards the north. be would see one degree below the liar, and be would think it had risen one degree. • And since we, always see the whole of the upper bemiapbere at Ode Wlw, wben there is nothing in the horizon to obstruct, our vision, it f0llows that if we should travel 100 north of the equator, we should see ~ 100 below the pole, which would then appear to bave rn.en 100; and should we stop at the 4211 degree of north latitude, we should, in like manner, bave our norizon just 420 below the pole, or the pole would appear to bave an elevation of 420. Whence we derive this general truth:

7Y&e ekvatjqn of tM [)Ok of 1M equatur, ill aiwaY8 equal to tM latitude

of 1M plat:e of obBeriIatimi.

A ny instrument, then, which will give us the altitude of the north pole, will give us also the latitude of the place. The method of illuatrating this phenomenon, as given in most treatisee OIl the globe, and as adopted by teacben generally, is to tell the scholar

'152

GEOGRAPHY OF THE HEAVEN8.

that the north pole ria. higher ~ higher, IS he travels fiutber and farther towards it. In other words, whatever number of degrees he advances tuward8 the north pole, 80 many degrees will it rise above his horizon. '1'hiII is not only an oImOUB errtIr in principle. but it misleads the apprehension of the pupil It is not that the pole ill eJemted, but that our Iwrizem deprwJed as we advance towards the north. 'fbe . lIIIIle objection lies againat the artificial globe; for it ought to be 80 filled that the Iwriztm might be rBiIed or depreM8d, and the pole remain in ita

u

own invariable JIOIIUioD.

Ursa Minor contains twenty-four stars, including three of the 3d magnitude and four of the 4th. The seven principal stars ,are so situated as to form a figure very much resembling that in the Grea.t Bear, only that the Dipper is reversed, and about one half as large as the one in that constellation. The first star in the handle, called Cyrwsura, or AlruccohoJt., is the polar star, around which the rest constantly revolve. The two last in the bowl of the Dipper, corresponding to the Pointers in the Great Bear, are of the 3d magnitude, and situated about 15° from the pole. The brightest of them , is called Kochab, which signifies an axle or hinge, probahly in reference to its moving' so near the axis of the earth. Kochoh may be easily known hy its being the brightest and middle one of three conspicuous stars forming a row, one of which is about 2°, and the other 3°, from Kochab. The two brightest of these are situated in the breast and shoulder of the animal, about 3° apart, and are called the Guard8 or Pointers of Ursa Minor. They are on the meridian about the 20th of June, but may be seen at all hours of the night, when the sky is clear. Of the four stars which form the bowl of the Dipper, one is so small as hardly to be seen. They lie in a direction towards Gamma in Cepheus; but as they are continually changing their position in the heavens, they ma.y be much better traced out t'J:om the map, than from description.

CONSTELLATION OF URSA MINOR.

158

Kochab is ahout 250 distantfl'om Benetnasch, and about 240 from Dubhe, and hence forms with them a very; nearly equilateral triangle. - - - " The t - r Bear Leads from \be pole the lucid band; the stan Which tiJrm this oonatellation, fiUntly 1Ibine, Twice twelve in number; only one beame fOrIh Conspieuoua in high splendor, named by Greece The c~; by ua the POUR BTu."

The following stars have small telescopic companions: G or the pole star. IS or Kochab, the right hand upper star in the bowl of the little dipper. C The left. hand upper star in the bowl. The companion discovered 1841, by Prof. Challis, with the Northumberland equatorial, at Cambridge, England. I The star near the root of the tail. Companion 12th magnitude, pale blue. a The star next but one to Polaris, in the tail. The principal star is of a greenish ti~e, while the companion .is grey. There are a few faint nebuIm in this conl!ltellation. CEPHEUS.

CEPHEUS is represented on the map as a king, in his royal robe, with a scepter in his left. hand, and a crown of stars upon his head. He stands in a commanding posture, with his left. foot over the pole, and his scepter extended towardl!l Cassiopeia. as if for favor and defense of the queen. - - - " Cepheua illumes The Deigbboring _vena; IItiIl fiUtbfuI to hiI queen, With tbirty-4ive taint luminariee madr.'d."

. This constellation is about 250 N. W. of Cas.. siopeia, near the 2d coil of Draco, and is on the meridian at 8 o'clock the 3d of November; but it will linger near it for many days. Like Cassiopeia, it may be seen at all hours of the night, when the sky is clear, for to us it never sets.

154

GEOGRAPHY OF THE HEAVENS.

n-

By re&mmee to the IHl the map, wbicll all meet in the pole, it will be evident that a liar, near the pole, moves over a much lull &paUl in ODe hour, than ODe at the equinoctial; aDd generally, the nearer the pole, the narrower the Ip8CB, and the BIoweJ' the motion. The atam that are 10 near the pole, may be be&ter described by their polar distatu:e, than by their decliDatioo. By polar diatance, ia meantthe distatu:e from the pole; aDd ill what the decliD!.ti1Hl wanta of 900.

In this constellation there are 35 stars visible to the naked eye; of these, there glitters on the shoulder, a star of the 3d magnitude, called Alderallrin, marked '" which with two others of the same brightness,8° and 12° degrees apart, form a slightly curved line towards the N. E. Tfle last, whose letter name is Kappa, is in the right knee, 19° N. of Caph, _ Cassiopeia. The middle one in the line, is Alphirk, marked 1', in the girdle. This star is ooethird of the distance from Alderamin to the pole, and nearly in the same right line. It cannot be too well undemtood that the bearinga, 'or directions of one .tar from another, BB given in thia treatil!B, are strictly app1icable only wbeo the ~ one ill on, or near the meridian. The bearings given, in many ca-,'are the leut approximations to what appeaIB to be theif relative poeition; and in IOIIIe, if relied upon, will lead to elTOl'll. For example :-It is aaid, in the preceding paragraph, that Kappa, in Cepheils, bears 19o N. of Caph in Cllllliopeia. This is true, when Cilph is OIl the meridian, but at thia very moment, while the author is writing thia line, Kappa appear_ to be 1go due wW of Caph; and six months hellCl/t will appear to be the same ~. etIIt of it. The reuon is obvious; the circle which Cepheus appears to describe aboul the pole, is within that of CassIopeia, and consequently when IHl the eut of the pole, will be within, or betW«1l Clllllliopeis and the tdthat is, weat of CBBIIiopeia. And for the _ reason, when Cephef•• is on the west side of the pole, it is between that and Clllllliopeia, or et.IBt of it J.et i~ also be remembered, that in BpeBking of the pole, which . . shaD have frequent occasion to do, in the COUIIIe of thia work, the NorlA Polar StilI', or an imaginary point very near it. is a1_ys meant; and not BB some will vaguely apprehend, a point in the horizon, direl:tJy N. of us. The true pole of the heavens, is alway. elevated just BB many degrees above our horizon, BB we are ntrrlA of the Equator. If we live in 420 N. latitude, the N. pole will be 420 above our horizon. (See Nurlh Polar Star.)

There are also two smaller stars about 9° E. of

CONSTELLATION OF CEPHEUS.

155

Alderamin and Alphirk, with which they form a square; Alderamin being the upper, and Alphirk the lower one on the W. 8° apart. In the center of this square there is a bright dot, or semivisible star. The heoJ. of Cepheus, is in the Milky-Way, and may be known by three stars of the 4th magnitude' in the crown, which form a small acute triangle, about 9 0 to the right of Aldel·amin. The mean polar distance of the constellation is 25°, while that of Alderamin is 28° 10'. The right ascension of the former is 3380 ; consequently, it is 22° E. of the equinoctial colore. 'l'ELESCOPIC OBJECTS.

=

1.

=+

C"••I.-A. R. 20 h. m. 08.. Dec. 170 13' 06". A line double liar QJl the right knee, about baJt:.way frwD ~ Cepbei to • Ura Minoris. A .1, while, B 8t, blue. The colol'8 well defined. Paa.. 1260 1" DiaL 07".08 Epoc:h 182Q.l8 StrUve. 123 08 01 .60 1838.88 Smyth. There is little evidence of any change in the position of the componeD'" &

=

=+

~ C..nl.-A. R. 21 h.26 m. 31.. Dec. 690 51' 07". A fine double liar, on the left aide of the girdle. A 3, b 8, magnitude. POL 251 0 00' Diat. 13".01 Epoc:h 1843.16 Smyth.

CAMELOPARDUS.

THE CAMELOPABD.-This constellation was made by Hevelius out 9f the unformed stars which lay scattered between Perseus, Auriga, the head of Ursa Major, and the Pole Star. It is situated directly N. of Auriga and the head of the Lynx, and occupies nearly all the space between these and the pole. It contains nearly 58 small stars; the five largest of which are only of the 4th magnitude. The princi!lal star lies in the thigh, and is about 200 from Capella, in a northerly direction. It marks the northern boundary of the temperate zone; being less than one degree S. of the Arctic circle. There are two other stars of the 4th magnitude near the

156

GIWGRAPHY OF THE HEAVENS.

right knee, l~ N. E. of the first mentioned. They may be known' by their standing 1° apal·t and alone. The other stars in this constellation are too s!Dall, and too much scattered to invite observation. TELESCOPIC OBJE CTS. A BRIGHT Pr..ur.·UBT Nnm.....-A. R. = 03 h. 63 m. li9 .. Dec. 6()o 23' 06". On the ftank of the Camelopard. See map, No. VL Di8covtnd by HemcbeI, 1787.

+

1 C.uIKLOI'4BDl.-A. R. = 04 h. 19 m. 23'. Dec. = 5:10 8:1 03". !t. double I&ar between the hind boo&. A 7~, .. wbite," B 8i, • blue." See map, No. VL POL 3070 06' Dist. 10".13 Epoch 1830.57 Struye.

t C41ULOPUDl.-A. R. = 04 h. t7 m. 18 I. Dec. 6:10 09' CKr. A elOlle double Itar, near the preceding one, and between the hind boor... A 5~, yellow, B 71, pale blue. See map, No. VI. Discovered by StrUve, and thus meuured by him : POlL ;111 0 40' Dill&. 1".686 Epoch 1829.79.

=

=+

A DoUBo STu.-A. R. 04h. 56 m. 191. Dec. 790 01' OS". Over the lower put of the badt of the Camelopard. A 51, B 9, magnitude. P08. a160 23' Dill&. 37".01 Epoch 1836.10 South. 349 01 83 SO 1836.29 Smyth.

CONSTELLATION OF SAGI'tTARlUS

1m.

CHAPTER IV. DIRECTIONS FOR' TRACING THE CONSTELLATION,S ON

, MAP NO. XVIII.' SAGlTl'ARIV'S-THE ARCHER.

SoQroIlf

SoBIESKI-Tn 5mBLD OF SoBIESKI,

Fo:vorahlJ situat.e4 fur ezami7UJtiot& in' J'IIly, August, mul Septemher. , ,

,

SAGITTAR'IUS.

TBE ABCBER.-This is the ninth sign and the tenth constellation of the Zodiac. It is situated next east of Scorpio, with' a mean declination of • 35° S. or 12° below the ecliptic. ' The sun enters this sign on the 22d of November, but does not reach the C01I.8tellatio1l. before the 7th of December. It occupies a considerable spa~e in the southern hemisphere, and contains a number of subordinate, ~hough very conspicuous stars. The whole number of its visible stars is sixty-nine, including five of the 3d magnitude, and ten of the 4th. It may be readily distinguished by means of five stars of the ad and 4th magnitudes, forming a figure , resembling a little, short, Iltraight-handled Dipper, turned nearly bottom upwards, with the h~ndle to the west, familiarly called the -MiJk-Dipper, beCaUl!8 it is partly in the Milky-Way. 'Ilhis little figure is so conspicuous that it cannot easilY be mistaken., It is situated about Sao E. of Antares, and comes to the meridian a few minutes ' after Lyra, on the 17th of August. Of the four

o

168

GEOGJU,PHY OF THE HEAVENS.

!!tars formin;g the bowl of· the Dipper, the tWOllpper oneil are only 30 apart, and the lower ones 5°. The two lDI8Iler ltars'(orming the handle, and extending weetwanJly about 4io, and the .eutemmoat 0118 in the bowl oC·the,Dip~. are all of the 4th magnitude. 'the liar in the mid o( the handle, is marked A, and is placed in the bow of Sagittariu.. just within the Milky Way. Lambda ma,Y otherwise be Imown by ita being neaily in a line with two otheJ: stars about 4io apart, extending towards the 8. E. It is also equidiatimt from • and I, witli which it ~ ahandsome triangle, with the vertex in A. 'About 6° above I., and a little to the welt. are two

&tars close together. in the end of the bow. the .brightest of which is .of the 4th magnitude, and marked p.. 'J'bill ltar aerves to point out tIM. winter 1OIatice, being about 2° North of the tropic of Capricorn, aDd Ie. than 0118 degree east of the aolltitial eqlure. If a 1inebe drawn from .. through .. and prQduced about 8° IBrther to the west. it will point out I, and produced about 3" from I, it will point out)-; &tars of the 3d magnitude, in the arrow, The latter is in the point of the arrow, and may be known by means oC a small slar just above'it. on the right. This &tar is 80 nearly on the IIIIJII8 meridian with Etanin, in the head of Draco, that it culmin~tes olily two minulM

afterit. . , A few. other conapicuoul liars in this constellation. forunng a variety • oC geometrical fipre-. may be easily traced (rom the map.

,TELESCOPIC OBJECTS. A CLU8'R"-A. R. = 17 h. 56 m. 01.. Dec.:;: - 22° '30' 6". Near the upper part oC the bow of the Archer. It, is a coarse cluster oC _II ltara, (orming a cil'\'ular figure. It ill 2,° S. E. of p. Sagittarii. Discovered by Messier. 1784. p.

848ITT.l.llll.-A.

R.= 18 h. 04 !Do

Ill.

Dec. - 21 0 06' 7".

A quadruple ltar on the north end o( the Archer's bow. Registered aa triple by the elder Herschel. Diacover!ld to be qllllllruple by hie BOIl. A. 3i; B. 18; C. 9,; D. 10, magnitude. POI. A. B A C A D

= 260 = 3lli =

0

114

0 0 I)

'

Dist. 1O"0~ 40. 0 Estimation.. .. 46. 0

A GLOBl1L.1.11 CLUBTER.-A. R. = 18 h. 14 m. 41.. Dec. _240 66' II". Discovered by MeMier, 1764. Resolved by t!it w; HeracbeI. It it not very bright. but censtitU\lee a good -test (or IJI8C8 'penetrating power. It is between the Head and· Bow of the Archer. and it midway bt!tween fA Ophiuchi and' /A Lyrm.

==

A Load CLl1ftSa.-A. R. 18 h. fim. 14.. Dec. - 190 10' 2". Between the Archer's head and the .meld of Sobeiski. "The gathering portion of the group l1118umes an arched form, and is thickly Itrewn in the upper part of the field, where a pretty knot of minulll

159

CONSTELLATION'OF SAGITTARIUS.

alimmereJ'll OCCIJpis the _tel, with III1ICb atar d\l8t anRIDIl." It N. K. of fA 8agittarii.

,

ia 60

•

==

A 6'LOB17U. CL1IITU.-A. R. IS h. 28 m. 25 .. Dec. _ 240 01' 4". In the speca between :the head -.nd bow ot: Sagiuariua, midway between fA and r ISagittariL Drawn by LeGentil in August, 1774. Daeribed by Me.ier, 1764, u a "nebula without.a alar." 'Reaolved~ Sir W. Hencbel, and estimated u of the 344th order of dislance&.

==

M S.l.8JTrUII_A. 1t. 19 II. 81 m. 83.. Dec. -180 211' 'I'. A delicate triple.tar in the IIJIIlC8 betWeen the heacla of Capricom and the Archer. A 5i; It 8; C 18; mapitude. Discovered by Sir John HI!IalbeI POlo A B 420 8 Diat. i8/ /J l E tim ted 1837 6B A C 280 0 20.1)..5 I a "

== ==

==

A P.l.U BL1IB PL.a.l...T.l.Bi NBB1IL.t..-A. R. 19 h. 34 m, 58 .. J)ee. = - 140 31' 6". Between the beads of Capricorn and BagiUariu.. Diaeovered by Sir W.Henchel, 1787. I examined this object 7th July. IM7. It is a little eIonaated. very sharply illuminated, and well defined. .Them are 18urallllJlllll stan in the ield of vie.. The bluish lint of the pJanl,lary nebula is well marked, and anoLher pointof analogy with the planets. Hel'llCbel and Neptune are marked by their blue tint, and indeed I am confident that Neptune wu .eD at

oft'en.

the Cincinnati ObIervatory .. year before ita discovery.

It wu thought

to be a planelary nebula. and was 100 from tile 4e1d of view by accident

before ita position wu taken. But the region of Ipace wa. w e l l _ benld, and the m~t I IBW the planet it looked Iiuniliar.

==

A GLOB1IL.t.. CL1Im••.-A., R. 19 h. 56 m. 38 8. Dec. = _ 220 22' 0". Between the left arm of Sagittarius and the head of Capo ricorn, 7io S. Weat of fA Capricorni. Discovered by Mechain. 1780. Reeolved by HBI'IIIlheI. and located by him in the 734th order of dito\aDo c.. It is a Wnt clullar, and ooly I'8IOlved with powerful inlllrumenta.

SCUTUM SOBIESKI. SoBIESKI'S SmELD.-A small conJltelIation north of the Bow and Arrow of Ragittariu8, only remarkable for its telescopic objects.

TELESCOPIO

A

LU8B NBBJ7LA_A.

R.

OBJECTS.

== IS h. 11 m. 23..

Dec.

== -

160

15' 8". Just below t:!obieaki's Shield, discovered by MlHIIIier, 1764, and registered a8 a train of light without stara. Sir VI. Heracbel deecnbea the objec:t a8 follow8: .. A wonderful extensive nebuloaity of the milky kind. Th,re are _raIl1larB visible, but ~ can have DO connecIion

t 60

. GEOGRAPHY OF THE REAYENS.

trith tile nebulOllity, and are doutKJe. belonging to our own syatem and are _ttered before it." Hill lOll .YI: .. The eb,ief peculiarities which I have observed bl it are, the reaolvable knot in the foUowing portion of the right brauch, which i.e in a considerable degree isolated from the lurrounding nebula, atrongly suggeating the idea of an ab!lorptiOll of the nebulous matter; and aecondly, the much smaller and feebler knot at the north precedinlt end of the ..me brauch, where the· nebula mum a ludden bend at an acute angle." I have examined this object with great attenti()o, and do not find Its appearance sa figured in the Bedford Catalogue. We are not informed by the author, whether Ilia drawing is original or copied. The horae Ihoe, or Greek Omega n ahape given to it by Capt. Smyth, diMppears under the 1i inch retiactor.

=

=

A GRE&T CloUST&R.-A. R. 18 h. 09 m. 49 I. Dec. 180 i7'. Discovered by Messier. 1764, a rich and :x,autiful object in a dense portion of the Milky Way, northeaat 70 from ,.. Sagittari!. Thill object, although surrounded by a vast multitude .of stan, seems to· be separate and distinct from them, and forming a univene of itelf. There ill • large star near the center, and two predominant ones in the north preceding edge of the cluater. Thill eluater lIMes with more as&oniahment, as all its stan are distinct and comparatively large. It ill "ell shown by a te\e8COpe of moderate power: A FUrB FIUoD OP BT.lu.-A. R. = III h.OIl /Do 49.. Dec. - 180 27' 05". Below tbe 1!d\ hue of the Shield of Sobieaki, ~ a rich porIioD of the Milky Way. Discovered by Messier, 1764; and described by him sa". _ cl _ _ great nebulosity, of which the light ill divided intoseveralparta." The object is readily resolved with powerful illl&mmenlll. . A TnKscoPIc Dovan BT.l• .-A. R.'= 18 h. 07 m. 87 m. Dec. 190 55' 05". A 8t; B 10; magnitude. DiIICovtired by Sir John Henchel, and described a. being placed in • Wilt nllbula, of an elliptical form, and 60" in diameter. It may be fouDd 1to northeut of,.. Sagittarii.

.== -

Tbill COII8Iellation waa formed by HeveliuB, and Ilea bet"een Antinou.. a.nd the Serpent's taiL Having no very bright stars, it is difficult to trace. A line drawn from;t in the knee of Antinoila, to ~ in the left bee of Ophiochoe, p.- througb several amalllllara in the Shield.

CONSTELLATION 01' HERCULES.

161

DIRECTIONS FOR TRACING THE CONSTELLATION ON

MAP

.NO. XIX.

HERCULES •.

Favorably situat8d for eZa1ni7UJtion. in May, June mu.l . July. . '

HERCULES is represented on tbe map, invested with the skin of the Nemman Lioh, holding a massy club in his right hand, and the three-headed dog Cerberus in his left. . .. He occupies a large space in the northern hemisphere, with one foot resting on the head of Draco, on the north, and his head nearly touching that of Ophiuchus, on the south. This constellation extends from 12° to 50° north declination, and its mean right ascension is 255°; consequently its center is on the meridian about the 21st of July. It is bounded by Draco on the north, Lyra on the east, Ophiuchus or the Serpent-Bearer on the south, and the Serpent and the Crown on the west. It containlll one hundred and thirteen stars, including one of the 2d, or of between the 2d and 3d magnitudes, nine of the 3d magnitude, and nineteen of the 4th. . The principal star is Bo3 Algethi, marked a., is situated in the head, about 25° southeast of Corona Borealis. It may be readily known by means of another bright star of equal magnitude, 5° east, or southeaSt of it, called Ras Alhague. Ras Alhague marks the head of Ophiuchus, and Rae Algethi that of Hercules. These two'. stars are always ~een together, like the bright pairs in Aries, Gemini, the Little Dog, &e. Tqey come to our meridian about the 28th of July, near where 02

162

GEOGRAPHY OF 'l'ItE HEAVENS.

the sun does, the last of April, or the middle or August. About midway betw_Ru AJgethi on the southeast. and the Northern on the northwiet, may,be _n ~ atld i, two 8tare of the 3d magnitude, situated in the weat shoulder, about 30 aparL The norUlernmOllt of thee two are called Rutiliew. Tbo.e four standn the shape of a diaJDOnd, 80 (Jr 100 southwest of &be two in. the moulder of BeJ'OUlea, are .. situllted in the head of the Crow~

.8erpenL

'

.

•~ bout 120 E. N •. E. of RntilicUB, and HijO directly north of Baa AIgetbi, are two atan of the 4th 'magnitude, in the east shoulder. They may be known by two very minute Btare a little above them on the left. The two ..wa in NCb ehoul~ of Hercules•. with Hatr Algathi in the head, form a regular triangle. , . The left, 0'1 east arm of Hercules, ,,·hich· fI'IIIIpB the triple-beadrd mOntrter C~rberuB. may be traced by mean8 of Ihree or four Btare of the 4th magnitude, situated in a row 30 and 40 B'pBrt, extending from the lIhoulder, in a northeaaterly direction. That smaIl cluster, situated in • triangular form, about 140 northeast of Ras Algethi, and 1SO e8IIto IOUtbeaBt, of the left shOUlder, diatinguiRh the head of Cerberus. Eighteen or 2()0 northeast of the Urown. are four are of the 3d and 4th magnitudes. marlled ...., ~, I, formi", an irrelfUlar "quare, of whirJa. thl' two southern ones are about 40 a part. anti in a line 60 or 70 south of the two northern ones, which are nt·arly 70 aparL Pi, in the northeast oorner, may be known by means of one or two other BlDall stare. close by it, on the easL Etfl. in lhe IIOrthweat comer, may be known by its being in a row with two IIIDBIler Il\arI, eXlenclin, ~ward8. the northwest, and about 40 apart, The stars of the 4th mar mtude, JU8t south of the Dragon', head,pomt out the left foot and aucle of Hercules. , ' Several other stars, of the 3d and 4th magnitudes. may be traced ou& in thill constellation, .by reference to the map.,

TELESCOPIO OBJEOTS. AND BJN AItT STA1t8.-R". ALBBTIII or • BBRCULJ&, A. R. 17 h.07 m, 21 s. .Dec, = 140 34' 05". A beautiful double star on the bead of Hereules. DiaL = 4".6. Pas. 1180 08'. 'file compo.. nenta are of the magnitudee 3! ,and 6!. the largest liar orange, the 8maller one greenieh. There ill no reason to ~lieve that these etars ..... physically united. although the opinion _ml to have prevailed among utronomere that BUcb a union would be found to exist among all the colored double 8IarII. ,Pas. 1170 36' ' DiaL 4n.92 Ep, 1847.62 MitcheL

=

DoVBLJ:

+

=+

,. HBItcULI..-A. R•.= 16 h. 14 m.1i8 s. Dec. 190 32' 00". A ~ne double liar on the left arm. DiaL 38".7. POlL 2420 03'. A al white, B 10 lilac. No change in distance or position bas been detected. except what may be imputed to erron of observatiou.

.

CONSTELLATION OF HERCULES. ,

163

+

I HBRCULIL-A; R. = 16 h. 35 m.lIS.. '.Dec. = 310 53' ()7". A cl08e Uirw.ry star, over the left hip. A &l magnitude,:O 8 magnitude. Di8COvered by Sir W. Henchel, Juty, 1782. ' 'rhe compsnion was subtlequently milllOlld by the dil!Coverer,' aa be bfolieved, in consequence of its heing hid by the larger star. He makes th.. fo\lowing remark, the interest of which is greatly enhanCed by 8Ubaequent discoveries: II My obaervationl of thi, atar furnish us with a phenomenon which is new in RStronomy; it is tilt occultat~ of om .tar by another. This epoch, whatever be the cause of it, will Le equally remarkable, whether owing to 80lar paraDax, proper molio", or motion in an orbit. whose plaQe is nearly coincident with the vi_I ray. The star WlI8 seen single, up to 1828, when a few meaeures were made by Struve. It again became single in 18,28, and 80 continued up to 1832, .nce which time ita double s.haracter ha, been followed. In 1842 the distance had increaaed to l' .177, according to Mildler, who computed the elemenle of the orbit of this ,wiftly revolving binary eyatem. III periodic time is about 31 years. On the evening of the 15th of Sept., 1847, the following meaeuree were made with the Cincinnati Refractor. Poe. 1090 12' Diet. 1".078

=+

890 13' 08", • HUCl1LII.-A.,. R. = 16 b. 87 m. tIS L Dec: an exceedingly double star, on the left thigh. Discovered by ~Uilve, 1827, and rank.ed among bis cl~ objects. It became BingJe, and finv if any reliable meaeuree have 8ince been Obtained. It 'haa been many times attentively examined b,y mYil8lf, anel 8tlpPCilllly 011 the evening of the 27th Jllly, 1847, when a power of 1200 WdS employed. My aasietant and myself agreet! tliat the star was slightly elongaled nllBrly alOng the Jl:Brallel, but it was very uncertain. '

cw.e

+

, I HnccLI8.--A. R. =17 h. 08 m. 288. Dec. 250 01' 09". A presumed binary star, on the right ahoulder. A 4. 11 8i mllgnitude, on the foUowing evidence: ' Poe. = 162' 28' Die. 33",75 Ep. 1779.61 Herschel. .. 173 42 .. 26 .11 •• 1829.,7 SUuve. .. 175 01 .. 24 .05' •• 1839.62 Smyth,. Otber double stan wiD he round by an ex~mil1ation of the stllr map. Among them .. on the left elbow, , on the tight thigh, ~ on the right _ , and p. in the bend of tbe left arm, are the brightest.

Dee.=+ e.

GBUTCLl1ITU_A.R.=15 h. 35 m. 58s. 36?4IS' 08". Ijo from • Hereulia, and on the line joining _ with , rl'bia object was diaeovered by Halley' in 1714, 'and W88 deaenbe.t a.I a'.. liuJe patch of light." , It was rei!xamined by Meaaier in 1764, but its true character waR still 1IIUevea1ed. M_ier was uncertain whetke! IIn.v nor was within the nebula. Under the power of Sir William Herschel', great rdlector. tm. object, 80 faintly _n by Meaaier. bunt into ten thou8Bnd sturs. It • certainly one of the IDOIIt magnificent objects in the heavens, • nd iK ~y ever _ for the first time without ucla_tiona of a","nish- ' - The drawing will be found to agree with the following deseri~ ,

164

GEOGRAPHY OF THE m:A\,El'i~

tion, written while the object ... y.nder the eye, on the evenin, ot 13th July. 1847, in the Cincinnati Observatory. ' .. A brilliant cluater. nearlY glo,bular. A spur of bright .tars runs oft' to the Iel\, terminating in a sharp poinL Then lollows in going round the center, ftoaa north to east, a dark apace; at 900 Irom'the first spur or ray. another i. seen I_perfectly formed. and more broken at the extremity, containing a Jl8ir of double stars near the end. The next 900 pretty well filled with stars out to the circumference, pBs.ing throllB'h the extremities of the radiation. of stars. Then another imperfectly formed spui of sian, containin~ B pair of double stars midway betweeu. the cenier and the extremity Of the spur. The lIl&ce next following rather vacant, especially near the double ater ; then followa B bent radiation of bright stara curving to the right, and causing the upper part of .the cluster to assume a Haltened f i g u r e . " · This is doublleaa one of the many matnificent "island unive....... recently revealed by the great instrumenta of modem times. In 1718 it constituted one of Bi:1: known nebula. In 1766. the number had inc..ea.oo to 103, and is now ,above 3,000 ! The, elu.toring of SUIlS at the center of this grand astral system, is greater than is rairly attributable to thl/' optical eft"ect in piercing by the visaal ray through a globular duatar of equally distribull!d .tan. There aeema to lit· a condensing power, which b.. exeRed itaal( to draw th" centrll suns into d~ preximity.

+

A GLOBUL.tB CLu8Taa.-A. R. 17 ~ 12 ~ 14.. Dec. = f3" 18'. OliO nQrtheast of • Herculia. ' ' Discoveflld by Meaeier in 1781,~nd seen by him .. a nebula without liars.

,

With fine instrumenta it proves to be B brilliant objt-ct, some 7' or 8' in diameter. surrounded "ith many straggling stars. A group of brighter stan forma an inverted figure six around and sbove tbe nucleus of the chister. It is of the 88me charactar as the preceding object, but is I_ ntensive, II.IId probably much more remote. 80tb thr.88 clusterR may be resolved with a 4 incb gla... and a power of 100 to 200 times. They tOrm Ii~ objecta for examination. '

Nuuu,-,-A. R. = 16 h. 411m. 23 L Dec. 40 east by north from 'I' Herculia. . Discovered in May. 1787., It is a large, round, pale blue nebula, and has been mistaken for a comet. Tbe aize of these objecllO, in ,case we regard them as remote .. tbe fixed stars, muet be vast beyond comprebension. If an I'bject baYing • diameter of 95 million. of'miles. can only be seen as a mere point oC IIgbt. wbat must be tbe actual dimenaions of these planetary nebule, presenting as tbey do, in many instances, measurable liiamelen of from 03" to 20". Such atQpendouB globes favor the idea that these are vasl collections of nebulous maUer, slowly coooellaing under the power of the attraction of gravitation. Such objecta 118 the one now under examination, may present an appearance like that,presented by our own 8un, wben, aOOurding to the nehuloUII ~, ita expanded dimeDHiou A

FINB PUNBTAU

= 1- 47049'.

165

CONSTELLATION OF JlERCULES.

tmbraced the graod citcumfeteuee r4 the Orbit of Neptnnl'.· T I!xaminecl the object on the lit of Au. . . under 'fery ••.,rable cimulllltallceOlj 'J'be disk-lilte character which usually iI INn on plBllelary nebu.. ill not well defined on this object. Indeed \here illIII much n.. OOloul baze lllnounding the nucle.., that it. appea_ iI "ery like a dillt.Dt clll8ter. The haze fades away ~ . . . . from tile nucleus, and iI finally

Iost.

.

.

,

'rbere are three 7th magnitude alan in the Beld of view. iI aome 7" or S" in diameter.

.

Tbe Dr-bula

PUJl'.-r••Y NU17U.-A.R. == 18 bo87 m. '" .. Dec. + 24 05'. Tbil object iI bright and wen deftJllld. I nami"ed il clOtIely on the lit of AUlLult. 1847. It. diIk iI aboilt 8" in. dilrneler.

=

A

SMALL 0

aud a little eloopled in one directigp. Discovered by Stril va. .

,., DIRECTlON8 FOR

~CJNO

MAP

THE CONSTELLATIONS ON

NO. XX.

CYGJf1Jft--.oTUE SWAJI. LYllA-TUE HARP.

LACERTA-THE LIZAllD.

Favorohl'!J situated for e:rtU1Iinatitm in' .Augu, Sep.

tember and 0ctdJer. --

CYGNUS.

THE Sw~-This remarkable constellation is situated in the Milky Way, directly east of Lyra,. and nearly on the same meridian with the Dolphin. It is represented on outspread wings, flying down the Milky Way, towards the southwest.' , The principal' stars which mark the wings, the body and the bill ·of Cygnus, are so arranged, as to form a large and regular Cross; the uprig~t piece. lying along the Milky Way from northeast to southwest, while the cross piece, representing the wings, crosses the other at right angles, from southeast to northwest.

166

GEOGBAPBY OJ' THE BU,VENS.

:AriJed, 'or DetuJIJ Cygni, marked a., in the body of the Swan, i8 a atar of the' 2d magnitude, 240 e8.llt-northe8.llt of Lyra, and 300 directly north of the Dolphin. It is the most brilliant star in the constellation, and ill situated at the upper end of the CrollS, and comes to the m:eridian at 9 o'clock, ,on the 16th of September. . . Sad'r., marked ,.. is a liar Gf the 3d DI8gIlitude, 60 southwest Gf Deneb, IIitualed Bactly in the ell*, Gr where the upright piece iDterIECt8 the _ piece, atJd ie about 200 eat of Lyra. Iklto., the priDcipai alar in the west wing, Gr arm Gf the croaa, is aituated northwest Gf s.d'r, at the distance of liule mGre than 8°, and is of the 4th magnitude. Beyood I foward. the es:Iremity Gf the wing are twG IIII&ller Item about 60 aJlll1. and incIinibg a IiUle obliquely 10 the nGrth; the Jut Gf which T8ICheI nearly to the finIt coil of Draco. Th_ atarI mark the well wing; the . . wiDg may be tnIced by _ _ of IIIar8 very IIimilarlylituated, . GimGk, marked .. ia a alar of the 4th magnitude, in the aut wing, jlHt II far aut of Sad'r in the _ter of the era.,.. I ia W8Bl of it. Thia row of three equal ItarI, I', ,.. and .. form the bar of the CfOIII, and 8ft! equidilllant &om each Gther, being about so apart. Beyond • Gn the aut, at the distance Gf 60 Gr 70 there are tWG Gther atarI; one of the 3d, the other "of the 4th magnitude; the Ia.iI. GCwhich maru the es:tremity Gf the eUtern wiD,. The alam in the neck are aU too amaH to be noticed, There is Gne, ho'lrever, in the beak Gf the Swan, at the fbot of the _ , called Albireo, marked /d, which ia of the 3d magnitude, and can be _n very plainly. It ia about UP IOUth_t Gf Sed'r, and about the .me distance 1Ontbeut of Lyra, with which it mak81 nearly a right w In the IIII8ll apace between s.d'r and Albireo. .y. Dr, Herschel, CO the alam in the Milky Way _ to be clu8tering into tWG separate divisiGns; each divilion eontainin, more than one Aundnd G1Id N:tyfiDe tlwwand Ilan," , AlbireG beam northerly frGm Altair about 200 , Immediately IOUth and lOutheut of Albireo, may be _n the ·FGX aDd Goose..: and about midway between Albireo and Altair, there 'RlBY betraced a line of four Gr five minuta ala,., called the A _ _ ; the held Gf which ie on the IOUthW8It, and Can be dielinguiehed by III88DI Gf tWG atarI ..tuated cloee together. . Acconling tG the Britieh eatalogue, thia eonetellatiGn cantaine eighty~ ODeltar8, incIndinr ODe Gf the lilt and 2d magnituda, m Gf the ScI, and 12 Gf the 4th.

anIle.

TELEscopic OBJECT8.

+

/d C1'91'1 -A.' R. = 19 h. 24 JD, 16.. Dec. 270 37' OT', A large and brilliant colored dGuble I!lar Gn the bIll Gf the Mwan. 13io IOUtheut G! Veaa, or .. Lyl'8l. A 3, B 7, magnitude. The principal

167

CONSTELLATION OF CYGNUS.

alar is orange, while the companion is a, blue, ~ting a lue CODtJ:aot in color. Bradley meaeured, the componenta in' 1766, Iince which 110 aenaible ch~nge baa occurred. , Poa. 570 34! Die. 34".20 Epoch 1765.00 The bl!at JIOIIition iii 64,0 40", u about a merm between thoae 'If' Herschel, PlBZZi, Strii.Ye, South, Dawe., and Smyth, none 01' whom differ Iiom the others in their reaulta by a whole d . - , This atllr ft'rJD8 one of a group of five in the ahape of a cross, and point out the body of the Swan. They may readily be found OD the map; ~ i. at the extremity of &be longer pert of the principal piece in the ,CfOlS.

, Cy..,.-A. R. = 19 h. 89 m. 68.

Dec.

+ «0 «' 06".

A

delicate double 8taJ in the middle of the left wing of the SWan, preceding • Cygni by ISO, and OIl the IBme parallel. A 3j, pale Jellov.;. B 9,

--green.

~

by Herschel, who made th.- meuutell. POR. 71 0 39' Diet. 2".60 Epoch 1783.82. ' This alar hu occuioned no little difficulty, in consequence of the disappearanee of the lIIDail companion during the years from 1802 up to 1823. SinCe that tilJlf! it hal been regularly followed. Herschel's dilolanee seems to have been in error, u the followin, JDellsurea ,.iII.Mw:

PO&. 400 39' " 1I6 42

Di.. 1".91 .. I .67 "'I .80

Epoch 1826.65 '8iru~e, ..

1831.73

..

.. 31 63 .. 1836.62" _ Mii.dler thinks the !ltars may perform a ""olution about their common ~ter

of gravity in about 675 yean of our time,

;t OyowI.-A. R. = 19 h. 40 u,. 2h. Dec. +'330 21' 07". A fine double atar on the Swan', lIeck. 7jO distant from ~ ill a nllrth·nortbr eaII\ direction. A 1\ mag., B. 9, pale blue. . ' Diecove~ by Herechel. in 1781. Since good meuurea have been obtained, no reliable rhange indl&lance IIr positiOn hu been ~ved. . Poa. 720 88' 06" Di.. 26n .821 Epoch Ukl.49 ,M!Wler.'

..,. GTlfw,.-A. R. = 19 h. 61 m. SO .. Dee. +620 4)\'•. A double etar, between the tip of the Swan 'I ~ing wing snd the tail. A 6j, bright white, B 8. lilac. ' Poa. 1840 82' Dis. 3".06' Epoch 1837.68 Smyth. No change hu bMJ perceived iIi this beautifulaet of IIlaI'II. A Cys.,.-A. R. = 20 b. 41 m. 11.. Dee. double etar, on the Swan'. \ower or right wing. iii. A 6, B 6 mag.

POL 1300 00'

Dis. CY',07

+ 36Q M' 03", act.., 1)0 IOUtIHu& ~ ,.

Oyg.

Epoch 1848.71 Strii'fe.

+

61 Gun-A. R. = 20 h. 69 m. 43 L Dec. 370 68'. A binary etar. on the inner tip of the Swan'. Jirbt wing. A 61, B ,6 _anitude, both yellow. Thill sylllem c1uatera round it more 01 intereat thall any other in the heaYllll.. Ita binary charac&er, ~ 8WUU- of iii

168

GEOGRAPHY OF THE HEA.v~S.

'proper motion, the determination of ita annual parallax and dislanee, the eomputation of ita'-. and ita influence on Madler's woooerf\lJ.theory of the Central Sun, aD combine to make it an object of great imparIaDca. Piuzi _ tile firat to announce the rapid and equable proper motion of the componeuU of this system, am~unting to 5".02, in A. Rand 3".02 in declidation. ~Witb auch a propt'r motion, and the approximate dillaiJce' firat obtained by MM. Arago ami Mathieu, it is easily ~ monstrated that these two IUIIB are sweeping tblough.apace with lOch an , amazing ....Iocity that it exceedl the lWiftness of Mercury 60,000 tim_ E'I'BD thie lIIIounding ramlt "'.. luhlequently found to faU far below the truth. After inountingthegrestHelio~of the Konmgaburgh ObBerfttory, M. B-1 determiDed to examine thiB double ater, with .. view to the exact determillBaon of i\8 annual parallax. After a long aeries of elaborate and delicate obaerYationa, his efforts were'c~ with BUcce.. and in 1838 he writes to Sir John F. W. Herschel, as tOllows: .. , selected among the aIara which IUrround 6l OyIPli. two between the 9th and lOth'magnitudes, of which one (a) is Rearly,perpendil'Ular to the Iioe joinbig the two atan, and the other nearly in the direction of this Iinf,. I have measured the distance. of these aIara from the point which bisecta the aame distahce between the two stara of 61 Cygni. I haye COIIIIDonly repeated the obaerYatiop ~ttef& timee every night." , From th., obaenatioM, it was discovered that the central point between the corqponenta of 6l did not remain at the same disience from tIIe.ra of reforence, but was more than 0",6 ful1ber from the alar (0) in aummerthan in winter. After ptoper reduc:tion, the parallax -"'.. found to !If! 0",3l36, with refen>nee to which we recol'll Bease1'a rellllU'u, in Ibe IOtlowing language: "As the_n error of the aanual parallax 'Of 61 Cygni is !IDly ± 0".0202, and COJl88qull\ltly not one-fif\r.enth of ita computed value, 8Dd as these compariaona abow that the progre&. of the influence of the palallu, which the observations indicates, followl the theory a8 nearly as can be expected, conaidering ita lmallne.I, we can, no .longer doubt &IIatthis parallax U lIMlaiblt\- Aasumiag it 0" 3136, we find tbe distance of the ltar 61 CylJlli tiom the lun 657,'00 times the milan diatanee of tbe earth from the lun. Light employs 10,3 yean to traverse the dista~. Aa the annual prcIpIIr of III Cygni amounta to 6",123 of a great circle, the relati'fe 1J!O&i0ll of this., and the 8un muat be Considerably IDOI8 than sixteen aemi.oJametera of the eal1b', orbit, and the Itar mUBt baye a conatant of abemtinn of more than 52", When we "hall have IUcceeded in !leterminin, the elementa of Cbe motion of both the stara fonning tlia double ltar round their common center of gravity, welhall be a)lle In detHmin8the lum of their..... ,have attenti'fely considered _ ~ng obeer..tinneof the 1'('lative poaitiOll8, but I couaider them u yet W"t'J inadequate to aft'ord the elementa of the mbi&. I oonaider~ onlyaufticient to abow that the annual angular motion ia BOm_here about two-thirdl of one degree; and thai the distance at die beginning of this century had a minimum of about l5". We ara _bled, hence, to conclude that the time of a re'folution is more tban NO yean, and that the semi-major axis of the orbit is 88M under an

_<111

CONSTELLA.TION 01' CYGNUS.

]69

angle of more than 16" of apace. If, howrrer, we proeeed from " numbe.... which are merely limite, w. find tIHo um of the _ of both stars ' - tban balf lb. Run'. _ " TheIle extraordinary detaila bad alftllllly rendored thiB ltar of extftmJe intere8l, wben M. MiOdler publiehed to the worid biB great theory of the Central Sun. and releN to tbe rapid annual proper motion of 61 CYgDi, .. ODe of tIHo l'BMIIta deducible from biB theory; and further employ. ilB parallax and diltanee in ..limating the diBtence to Alcyone, in the Pleiadell, the ltar &xed upon Ill! the preeent center of our Adral 8YUm. Poe. 96003' Dill. 16",3 Epoch 1839.69. Smyth. .. 101 02 .. 17.3 .. 174-7.60 Milchel. Other double and mul\iple ItarB will be bind upon the cbarla.

A CuaJOV8 NnvL.t..-A. R. = 19 h. 40 01.86.. Dee. 07' 06". It ill thlll delcribed in the Bedtord estalogue:

+ 500

.. A very singular oh,ject. In my teleacope it iB email, aDd somewhat _mbles a ater out of (OC\lll; but both tbe Henchel. agree, 011 viewing it throngh their powerful inetrumenla, that it appears to conatitute a connecting liok ""tween the planetary oebuIe and tbenebuloaa atan. It w .. diHcovered Sep...mber. 1793." I bave repeated Iy examined thil remarkable object with a 12 ioch apEll'tore. Ita diameter ill about 6" or 8", and when the gaze is attentively fixed upon the center, tbe nebulOlll matter gradually f~ ./rY¥m till .;gilt, and a eImr, bright, round 6Iar in lbe tenter. 'l'bis Mar mow. no radiation, Buch U udally a-)llDy aters viewed with tbe fuU opening, but baa a clean litlle disk, lOch I I the teIMcope shows on other stars with a reduced aperture, under the moat fiavonble ci reumltances. By throwing oft' the eye from the center, and looking carereIy 0..,.. the field of view, the nebula mums in all itl beauty, and the central ater il no looger _no Tbi. is, doubtieM, opticaJ. yet it is no& _Iyexplicable. Tbat the faint nebul~ Ihould be beuer _n tJUt of till tuM of vision, is easily undel'>ltood, buttbia should be true, also, Of the central atar, and wben the nehula hrillbten8 up onder the eye, the &tar mould increaee in brilliaDcy in the like propprtion. In esse W8 abandon the nebular bypothesis, this object, and one or two other. of like cbaracter, ber.ome utterly inexplicabl... If we ..y that each particle of nebuloue light is a BUn or otar, and that tbe mas of hazy ligbt, .., uniform in ita brigbtn_, is but the cludering of million. of sun. in a aat aDnulus. how etupelldon. mUJlt be the eize of that lucid point which occupied the center of this wonderful object, and is ao distinctly _aled by the telescope t The old idea of a migbty predomiDftnt central globe would, on lucb an hypothesis, ~ to be well fuunded, for il would require miIliOlll of nebulouB pointa to constitute a blaze of light equal to this central ater. Tbis object is found 011 the tip of the preceding wing of ,be Swan, and 610 nol'll\ of I Cygni.

u __

+

A J.opaa SX.""L CLvnBR_A. R. =!IO h. 18 m. 17.. Dec. 370 69' 09". Discovered by Maier, 17M. Near the roo& of the Swan'. neck [counted bat twenty ItaIII in the

IeId 01 VIew, July, 184.7. and th_ _ much_&*red.

170

GEOGRAPHY OF THE HEAVENS.

FrnD.-A. R. = II h. 26 m. 29 .. + 470 W 08". It. between the Swan'. tail and thf! I.izanl. Many other cluatera and nehul. will be found on the chan, from

A Dec.

hALL CLU.,... . 011 RU'K

which their JIIa- in the beav_ may be ~i1y found.

LYRA.

THE HARP.-This constellation is distinguished by one of the most brilliant stars in the nortbern hemisphere. It. is situated directly south of 'the first coil of Draco, between the Swan, on the east. and Hercules, on the west; and, when on the meridian, is almost directly overhead. . It contains twenty-one stars, including one of the 1st magnitude, two of. the 3d, and as many of the 4th . .. There Lyra, for the brightn-. of her Ilam, Mont than their number, eminent; thriee seven She counta, and _ of thaae iIIuminataa The heaveD far round, bluing imperial, In the jitYt order...

This star, of " the first order, blazing with imperial" luster, is called Vega, marked Ci, and sometimes Wega; but more frequently it is called Lyra, after the name of the constellation. There is no possibility of mistaking this star for any otber. It is situated 14!° S. E. of 'Y Draconis. It may be certainly known by means of two small, yet conspicuous stars, of the 5th and 6th magnitude, situated about 2° apart,.on the east of it, and making with it a beautiful little triangle, with the angular point at Lyra. 'rhe northemmoA of 111_ two _1I1lara • marked .. and the soath""lOne, {. About SO S. E. of " and in a line with Lyra, • it atar of the 4th magnitude, marked I. in the middle of the Harp; and 40 or 50 8. of I. are Iwo.1lara 01 the.3d magnitpc)e, about 2° apart, in the pr\aDd of the Harp, formiDs uother triangle, wbo.le YBrWx. in I. T~ Ilar

171

· CON8TELLATION 01' L YIlA.

on the east is marked ,.; that on the west. ~ If a line be drawn from ,. Draconia through Lyra, and produced 6° farther, it will reach~. 'rhis is a variable atar, changing from the 3d to nearly the 5th magnitude in the space of a week. It is supposed to have spols on ita 8urface and to tum on ils axis, like our flun. Gamma COIMS to the meridian 21 minut..s after Lyra. and predae!y at the same moment with .. in the tail of the Eagle, 17io S. of it.

The declination of Lyra is about 38io N.; consequently, when on the meridian, it is but 20 S. of the zenith of Hartford. It culminates at 9 o'clock, about the 13t~ of August. It is as favorably situ. ated to an observatory at Washington, as Rastaheu is to those in the vicinity of London. Its surpassing brightness has attracted the attention of' astronomers in all ages. Manlius, who wrote in the age of Augustus, thus alludes to \ it: .. OIn, placed in front above the rest, diBpla,.

A vigoroualialH, and darta aurpriaing ray ..' .htronomicon, B. i, po 15.

TELESCOPIC OBJECTS.

=

=+

VMA, OB '" LYB.l.-A. R. 18 h. 31 m. 30 s. Dec. 38u 38' 01", the moat brilliant star in the northern hemisphere, attended by a companion of the t 1th magnitude, distant 43". Poa. 140° Epoch 1843 There is no reaaon to believe that the relation between these two sian is other than optical. The proper motion of Vefia .oooallioDB a change in the diatance and angle of poIIition of the Imall companion. Many efforte have been made to obtain the annual parallax of this star. 1n 1836, M. Struve concluded the value of the parallax to be 0".12;', with a probable error of 0".055. This result lielda a distance of one lmd a half millions of times the aemidiameter a the earth's orbit. The apo peatanC8 of '" I.yne in large telescopes is Imly magnificent. Before the IIblr enters the field of view, its cominB is announced by a dawn of light like that of the early morning, which groWl brighter and brighter, until the alar, like the Bun, enters the field, with a brilliancy which the eye can ~y bear. By artificial occultation, at the Oincinnati Obeervatory, no 1_ than rizteen minute stan have bean.counted within the limits of this dawn surroundinB Vega. By the revolution of the pole of the equator around the pole of the ecliptic, in about 10,000,_ this brilliant object will becolDfl the puk

.tar.

172

GEOGIlAPHY

or

THE HEAVENS.

1'hf! ItUpendOUI distauee or Vega, as roughly ascertained by Struft, pve .;,., to hia ingeniou8 theory u to the probable relative positions of the sta,. of ditf"rent magnitudetl. He considered the mra of tbe fiM magnitude dialaot about two millions of times the radius of the.earth'l orbit, thoee of the 6th magnitude lIizteen millions, thOll8 or the 12th .i4:ty millioll8 of times the _ unit. '

+

. ~ Ln••-A. Ii. = ISO 44' u9". Dec. 3S" 10'. OS", a COSI1l8, qlladruple star. or the three componenl8. A ia of the 3d, B of the 8th, U of the 8ith, and D of the 9th IDllgllitude. '('hiB alar ia ranked amoog the vari"blll onea, and' baa a period of 6 days, 10 hou .... 86 minute!!, changing from the 3d to the Otb magnitude. I

un 6 LUB.-A. R.

=

18 h. 89 m.

ot..

Dec. =

+ 39

0

30'

03", a double etar. One of the mOBt remarkable objects In the heavf'JJII, .\ of the Oth. B of the 61th magnitude. 'I'be following DleUUreB abow a retrograde motion.

1I,,,ul. A B P08, 330 66' Die. 3".44 Epoch 1779.83 116 06 . 3 .03 1831.44 110 25 t .46 1847.60 6 1.1'Il.B. 0 D P08, 1730 t8' Dio. 3".110 Epoch 1779.83 . 155 10 II .67 1831.44 149· 10 II .66 1847.60

HerscheL tltrilv..

Mitcbel. HersdleL . Str4ve. Mitchel.

There ia Itroog evid"oC8 that .ch of these aeI8 ia bifUJl'Y. A revot.. Ing about B In about:WOO years, while C and D complete their revolution in about half that periCld. From the equality of proper motions In tbe four alara, it is iofetftd that a phyaical union may exist among the two peira, In which r.aae tbe one pair will perform a revolution. about the .other In about ODt! millioo ofy.ral . 1'hia ltar ia 1i O north.1t of I,YnB. and may be readily divided Into two stars with the smallest optical power. 'I'be quadruple character ie made out with a power of 150 or!WO. s..veral minute pointa of light are seen tJetween the pain.

{ L"alB.-A. R. =18 h. 39 m. 15.. Dec. A Oth. B 6ith maguitude. P08, 114 90 06' Die. 43".08

double 1ItRr.

1/ L"a••-A. R. 18 h. 4S m. 48R. Dt,c. quadruple star, jult south of ~, euily divided.

r 1,,,alB.-A. R. 19 h. 08 m.r 18.. Det-.

+ 370 26' 00", a coane

+ 311" 38' 0", a

OOBIW

== + ISO 52' 66", a fine

double .tar; compoaenta of the magnitudes 6 Bnd 9. Pos. 840 08' niB. =lI8".3

A FIn CLVITBR or S.uJ. Sr.l._A. R. = 19 h. 10 IDo 19 ..

Dec. =

+ 290 M' Oil".

.

CONSTELLA.TION OF LYRA..

173

Diecovered by Meaaier, 1778, but ~ by him a. a fiaint nebul.. Rrsolyed by 8ir William Henchel in 17M. and located in the 844th onI"r of distances. 'rhere i. a great clu8wrillg about the center, and a ricb profusion of stan in the field of view. It may be found on a line joining fA Lyllll with fA Cygni, aboul 6io from the fint star. This object is one of the many inagnificent aRral AyBteDll, wbich are BCBUered 10 profuoely through the boundleaa region8 of apace. Ita light requires more than a thouaand yean to reaeh our BYstem. .

+

Tn AlIlIVL..... NBB1IL.t.-A. R. = 18 h.47 m. 37 8. Dec. ""'" 820 50', midway between fA and,. on the crOl8-piece of the Lyre. This wonderful object _ firll noted by Darquier, in 1779, 8B • dim

Ptaon~':tion

B~I,

by Sir WOllam it proved to be in the form of a perforated ring or annulua. . With powe""ul inatrumenta tile dark interior ia ~ fiDed with faint gauzy ligbt. 'rhe figure is not exacdy circular, the diameten· being iB about the ralio of 4 and 6. Many penontl bave declared their conviclion thet they BlW the minule lItan which it ia believed compoae tbia lingular objtod. I have never be<-n able to Blliefy myaelf that it hili been 1Birly retIOlved. l.ord great &eleaeope h.. changed ita figure B1igbtly. by liDding 8l1li&11 fUarnenta of light, extending within and without the ring, in the direction of the larger axia. Benchel estimates the profundity of tbia object to be of the 950th order. Sueb an amazing distance absolutely overwbelms th. imaginalion. A thoulllllld w- the diatanee of the DealMt fixed 8&an ; Ita magnitude mull be immel188, .. ita diameter ia lOme 6" or 6", even wb _ _ at 8Ueb aD immeuurable distance. It I'l'quirea a 4 or 6 ineb refractor to yield ita figUre distinctly •.0 the eye. It ia viaib\e in amaIIer inatnunenw, but would be miataken for a .tar, by aDY other tban a practiced eye.

H._'.

p2

174 '.

GEOGM.PHY OF TH·g HEAVENS.

DlRJo~CTIONS

FOR TRACiNG THE CONSTELLATIONS ON

MAP NO. XXI.

THE

AQUILA ET ANTJNOUSDELPiIlNUS--THE DOLPHIN.

.EAGLE .\NO .

.ANnNous.

TAuRus PONIATOWSKI-PONIATOWSKI'S BULL. ANsn ET ULPECULA-THE AND GOOSE.

V

Fox 'FtiwrolJly Bituoted for· examination in August, Sepi6nher, and October.

.

. AQUILA ET ANTIN()U8. THE EAGLE AND ANTIl!fous.-This double constellation is situated directly lIouth of the Fox and Goose, and between TaurUs Poniatowski on the west, and the Dolphin on the east. It contains seventy-one stars, including one-of the Ist magnitude, nine of the 3d, and seven of the 4th. It may be readily distinguished by the position and superior brilliancy of its principal star . .Altmr, marked G, the principa! star in the Eagle, is of the 1st, or between the 1st and 2d magnitudes. It is situated about 14° southwest of Dolphin. It may be known by its being the largest and middle one of the three bright stars which are arranged in a line bearing northwest and southeast. The stars on each side of Altair are of the 3dmagnitude, and distant from it about 2°. This row of stars very much resembles that in the guards of the Lesser Bear. Altair is one .of the stars from which the moon's distance is taken for computing longitude at sea. Ite mean declination is nearly 8io n(\rth, and when on the meridian, it occupies nearly the same place in the heavens that the sun does ~t noon on the 12th day of April. It .culminates about 6 minutel

CONSTELLATION OF AQUILA ET ANTINOtTS.·

beforeO·o'c1ock, on the last day of August.

175

It rises

acron.!lcall!l about the beginning of June. Ovid alludes to the Mng of thill conll&elJat10n; or, more properly, 10 that of the principalatar, Altair:- - " Now view the skies, . And you'D behold Jove's hook'd-bill bini ariae." ~"F(J8ti.

- - " Among thy .plendid group Ow. dubious whether of the IKCONJI .,A,NIt, Or to the rrRST entitled; bot whOll8 cleim Seems to deserve the PIUT." Eudnai4.

The nortbemlllOlt sta,r in the line, next above Altair, is called Taraud, marked,.. In the wing of the Eagle, there is anotber row composed of three stare, situated 4,0 or fiO apart, ex lending down towanls the IOOthwest, the middle one in this Ii..,e is the smallest, bein~ only of the 4th magnitude, marked ,..; the·next i. of the 4th magnitude, marked Delta, alld Rtuated SO lIOuthwest of Altair. As you proceed from ·1. there is snother line of three a1are, of the 4th magnitude, betwaen 50 and 11 0 apart, extending fIOutherly, but curving a little to th" west, which mark the youill Antinor... The northern wing of the Eagle is not distinguished by any conspicuous sta~. Zeta of the ad magnitude, and Epai/tm, of .the 4th magnitude, are DeBr the to,1 of the lea wing. From I to 8, in the wri.t of Antinon.. may be traced a long line of etano, chi~fty of the 3d magnitude, wbOll8 letter names are 8, .,,.., ?, and t. The direction of tbia line is from southeast to northwest, and its Ipn~h is ahout t50. Eta iK remarkable for its cl&angeahle appearaftce. Its greateat bright_ contillUCI! but 40 hours; it thpn gradually diminish... (or 66 hours, w h"n it.. lu."·r remains Ptalionary for 30 hours. It then waxes brighter and brill';htpr. unlil it arrear. al{8in u a slar of the 3d magnitude. From thf'&6 phenomf'nll, it is inferred that it not only ha••pota on its ...nace, like our sun, but tbat it al.., turno on ita axis. Similar phenomena are observed in Algol, S. in the Hare, I, in Cepht!u&, and G, in tbe Whale, and many others. - - " Aquila· the next, Divid... the ether with her ardent wing; Beneath the S_, nor far from PegatJII8, POliTIC E,A,9L ....

TEI.ESCOPIC OBJECT8. A Fnrll CLUBTER.-A. R.=18 h. 42 m. 82. Dec. 60 27' 02". It preeedes the left foot of Antinou&, and is on the Shield of Sobieski.

DPcovered by Kirch in 1681, and described u" a small obacure spot with a atar shining through." It was resolved by Dr. Durham in 1733. This was' one of the iii:

176

GEOGIlAPHY OF THE HEAVENS.

clutelW or nebula delcribed by Halley in t 7 t 6. wbo ~entured to J)l'PCtir.t tbat more would be' found. This object is figured in tht' BetlforJ Catalogue, but is very different &om tbat pr_nted in thi. volume. A TIlIPLB s-r.. B.-A. R. = 18 b. 54 m. 81.. Dec. - 0 0 55' 09". Known to PiltZZi sa double, subdivided by Struve. A 9,H 9, C

16, magnitude. Poe. A B 1480 0' Dis. 25".61 E b 1888 59 SSmytb. ' B C 115 0 2 .0 5 poc ' ? ' Estimations. B C 76 0 1 .676 IS47.60 MitcheL The object,may be found between the Eagle'. wing and the left buel of Antinoue. STAR.-A, R. =19 h. 28 /II. 01 .. Dec. = - 100 46' right knee of Antinous. A 9, B 10, C 12, magnitude&. 83So 04' Dis.8".02 EpochtlS85.58 Smyth. 168 05 S .00 .. .. AB 819 04 2 .54 IS47.60 Mitchel. 169 17 Some suspicion exists witb reference to the Pouible binary cbarac:tv of the set. A TRIPLB ClSn • On the Poe. A B A C

+

A DoUBLB BUB.-A. R. - 18 h. 57 m. 59.. Dec. 6° IS' OR", on the edge of the Eagle'. wing. A 7~, B 9 magnitude. Poa. 11140 38' Dis. ~O".t88 Epoch IS81.70 ~truve. " 152 28 " 9 .492 . . ' 1847.65 Mitchel. A SI.... LL ....1'1'» I.ooeB CLUlITIIB.-A. R. 19 h. 08 /II. 86 s. Dec.1° 11' 09", between the lower wing of the Eagle and the thigh of AatinoWl, consisting of fifteen or twenty ala.... with indication. of .tar-duat. Examined 16th July, 1847.

+

A STBLL.t.R NBBUU.-A. R. = 19 h. 2:1 m. 55.. Dec. SO M' 01", on the Eagle's b.ck, 50 east of AllIlir, or" Aquilal. Discovered by Sir W. HI.'J'1IChel, and estimated at the 900th Older al diBtancea. Examined on the 16th July. IS47. The ohject is very amall, brightening at a vertex, and running oft' iD the shape of a fan. Several elars in the field; a bright one above, aod one below the nehula.· Sir John Hel'1lChel aaya, "It i.like a nebula well resolved, and is a curious objecL" A Dulc .... TB DouBLt ST.t.R.-A. R. = t9 h. 85 m. 02 .. Dec. = 80 00' 05", on the Eagle's back, 2° eut of Altair, and a little muth of the parallel. A 7~, B 9! magnitude. Poe. 2620 82' Dis. 82".12 Epoch IS25.52 Strnve.

==

+

11' AII.I1IL•• -A. R. 19 h. 41/11. 10 .. Dec. = 1I0 26''''''. A cJoaa double 1Ilar, u.r theno~ wing of Aquila. A 6. B 7 mac. Poa. 1220 00' Dis. 1".50 Epoch 1831.70 Smyth. " ISS 09 " 1 .10 "1847.66 MiIcheL

CONSTELLATION OF AQUILA ET ANTINOUS.

177

+

=

• A41uIUl.-A. R. 19 h. 42 m. ~8 8. Dec. = 80 26' 0;'''. A first magnitude 1IIar; with a 10th u....gnitude c
«'

+

23 A~ulL&.-A. R. = 19 IL 10m. 24 .. Dec. = 0° 48' 00". A "'oee dooble alar, onder the Eagle's lIOuthem wing• .Di8covered by Herachel, who appears to have made a mistake in enwring hill _ _ HI. IJOBitioll is 1620, disUnce 3".1>0, epoch 178l.68. ; . The BedfOrd. Catalogue marks the position more than 1800 dif. "rent, and' tbinb Herachel wrote BOUt" for nortn, in recording his m-naUooll. This IIIar _ earefuUy Jlleuured on the 4th of Auglllt, 1847, and gave theae resulta: Dis. 3".67. POL 120 09' Bedford .CaI. Pos.= 120 06' Di.I. 8".1 Epoch 1838.68.

+

A DouBLa SUlI_A. R = 19 h. 37 m. 21.. Dec. 100 28' 06", on the Eagle's head. A 8, B 10 magnitude. POL 2780 18' Dis. 8".00 Epoch 1783.60 Herachel .• 276 27 8 .99 1826.66 Bouth. 4 .00 1836.76 Smyth. 278 SO 4 .33 1847.72 Mitchel. 278 38 The distance between the componenta to be on the ipcreue, wbile the angle of position remain" nearly if not quite the same.

_UIII

DELPHINUS.

To DOLPBIlf.-This beautiful little cluster of stars is situated 13° or 140 northeast of the Eagle. It consists of eighteen stars, including two of the 3d magnitude, and' three of the 4th, but none larger. It is easily distinguished from all others, by means of four principal stars i'n the head, which are so arranged as to form the figure of a diamond, pointing northeast and southwest. To many, this cluster is known by the narrie of Job's Ct!ffin; but from whom, or from what fancy, it first ob.tained this appellatiol;', is not known. ·

liS

GEOGRAPHY OF TEE HEAVENS.

There is 8. star of the 4th magnitude, situated in the body of the Dolphin, about 3° southwest of the Diamond, and marked Epsilun. The other four al'e marked .Alpha, Beta, Gamma, and Delta. Between these are several smaller stars, too small to be seell in presence of the moon. . The mean declination of the Dolphin is about 15° north. It comes to the meridian the same moment with Deneb Cygni, and about 50 minutes after Altair, on the 16th of September. " Thee I behold. majeetic CygtaUII. On the marge dancing of the heavenly - . Arion'. friend; eighteen thy appearOne teleecopic."

.1'11

TELEscoptC

OBJE.CT8.

=

A PLAN.TART NUULA.-A. R. 20 h. 15 m. 15.. ·Dec; 190 36' 06". Betweom the Dolphin's pectorul fin and the arroW's head. Discovered by Sir William Hel'llCbel, 1782This is a large though faint planetary nebula, the surface being eYenly itluminated. Sir John Hel'llChel suggests that the minute stars in doee proximity to the nebula, may be Bate/litu, He remarks "that the enormous magnitude of their bodies, and consequent probable mass (if they be not bollow sheila); may give them a gl'llvitating energy. which. however large "e may conceive them to be, may yet be capable of retaining in orbits three or four times their own diameter. and in period. of ,reat length, small bodies of stellarchal'llcter." Should this suggeartion ever be verified, we might be led to attribute BOrne of the anomalous motions (a. yet unaccounted for), among some of the fixed atarB, to the diaturbin, inlluenee of an invisible body of this cbBl'llcter. In cue any such faint body were situated near Siriue, for example, the hrilliancy of thia star wonld entirely hide the nebula. Ar1ificial oocuItation may detect IIOme of theN unknown objects.

+

A S.ALL CLU8ftR.-A. R. = 2() h. 26 m. 21.. Dec. 060 53', near the Dolphin'. tail. . Discovered by Sir W. Herschel, 1785. . It is a mB811 of small ..... with _ral larger in the field •

.1'11

+

• ~ D.LPRll1'l_A. R, 20 h. 30 m. 03 .. Dec. 140 02' 06". A delicate triple .r, in the Dolphin's body. A 4, B 12, magnitude. The minute star B, was added to the previously discovered pair by Sir John Hel'llChel. It bad escaped his father and Striive. . POL A B 1050 00' DiM. 16".0 Epoch 1734.79 A C lHl 08 30 .0 ..

CONSTELLATION OF DELPHINU&

179

+

,.. DKUHI.I_A. R. 20 h. 39 m. Ui.. Dec. 1110 38' ot". A beHuUful double .... on the Dolphin" held. A 4, y"Uow; 8 7, light green. No change hu been deleeted. Pee. 173003' 00" Dill. 12".0 Epoch. 1830•

. VULPECUL'A E'r ANSER.

THE Fox.AND THE GOOSE.-This is a modem constellation, introduced by Hevelius, into a space between the Arrow and the Swan. "I wished," remarked Hevelius," to place a Fox with a Goose in this space of sky well fitted to it,. bec~use such an animal is very cunning, voracious, and fierce. Aquila and V ultur are of the same nature, rapacious and greedy." In 1672, while examining this new constellation, Hevelius discovered a star in the head of the Fox, which he had never before seen. This star remained visible for the space of about two years, after· which period it disappeared, and, has never since been recognized. This new constellation has been pretty fairly 8.llopted by astl'onomera, and may now. be said to be pretty firmly fixed in the heavens. Its author counted .27 stal"8 within its limits. The number has been successively increased by later astronomers, until finally, Bode has fixed the places of 126 . stars in thil!t small space. The intrusions or additions of Hevelius to the old constellations have been better received by astronomers than those of any other modern innovator, probably because his constellations were placed where they seemed to be actually required for convenience of reference. TELESCOPIC OBJEOTS. A DUIC.t.TK novBn Sr.t.• .-A. R. = 29 h. 00 m. 10 .. 200 38' 07". Close to the AllOW, under the Fox'. &boulder. Ii 10, nagnitude. DiIcovered by Sir Jamea South in 1828. POlIo 3400 06 Di& 11",6 Epoch 1839.70

+

n.-

AI

180

GEOGllAPHY OF THE HEAVENS.

AS.ULDoIl'at.. ttr.. -A.R. SOh. IIi m. 47 ..

Dec.=+ go

M' 02". On the FOl['. loins. A 8, B 14, indigu blue. About a minute of time p.-Jing tbja object. and 20' _th of it,. a minute e10118 dooble ...., di8emered by &rUve. and • No. 2872 of hill great catalOgue. DOlCR-a.LL N"Il'L.t..-A. R. 19 h. 62 m. 39 .. 'Dec. Ito 17' 01". Diacovered bJ MeMier, I')'". . This Ie _ of the large and magnilicent nebule, located in ODe of the rieheat Jl8rU of 'the heaven.. A. fint _n, it re.mbled two balla joined together like a dumb-bell, or double headed abot. and hence ita name. A. more powerful inatrumenta bave' been directed to ita uaminalion. ita form baa become more wonderful and myaterioua. The drawinlf rep_ta this object .. _n with the Cincinnati Refractor, July, 1847, at wbieb time it w.. deacribtocl wbile under the eye, u follow.: , .. The abape of the nebula Ie an oval or ellipse, wbOllll larger uIaI occupies fOUT-fifths of the field of view, with a power of 260. 'J'he fi~ure imperfect to the left of tbe lower vertex. The right hand ball of ligbt rather the largea&, the round figure being brokenbJ two blunt poinl8. 1'he upper . .r ia _n a liule oulllide the outline. The leA hand rn. . of ligbt takea the aame form u that on the right, only th. light does not exteDd u.p or down quite a. far. At each extremity a alar ulocated. The verIIcea of the great or general outline comparatively faint. Several atara are visible on the nebula. One diatinctly seen in the center of the right hand mall! of light, one in the center of the principal a:ri.. fainter than the fim mentioned; one still more faint bJ ~ below, and to midway between the. two. Anotbet Ie _ the right of the one fint mentioned. There are beaidea many alan in the ..me field of view." ' Lord a.-'a great teleacope b.. produced no great c,hange in the figure, whil~ it baa revealed more light in the comp-.l parte of the nebula. Nichol deecribea it .s having" no longer diatincm_ of c0mpletion of form. but a atrange ma811 internally moat irregular. clustermg apparently around two principal nucl~i, or knolll of slM ..... and preIII!IIling, where it merges into the dark, the utin08& indefiniten_ of ontline," and yet tha figure baa an oUlline quile .. well defined .. tboae usu811y pretlfln~ in drawings of this objecL JObi. objecl is doubll_ the union of tW.l mighly c\U8tel'll IIf myriad. of auna, and al the double stan' are _ttered profusely through space, we occuionally find what may be july trrmed double nebula and durlbk r.iUllters. 'rhe distance of this object muat be abaolutely overwhelming, and ita dimensions beyond the POWerR of e.omputalion. It may be picked up on a line joining ~ Cygni and the Dolphin, and alK)Ut 70 BOulheaat of the first named star. The angle of JXMilion of the line joining the cenrera of the nebulous _ , ia3lo 08'... _ured by Capt, Smyth. '

8ERPENTARIUS, nL OPHIUCUS.

~ONS

181

FOR TRACING THE CONSTELLATION ON

MAP

NO. XXII.

SBIlPENTAlUUS, VEL .oPHIUCBUB-TuE SUPENT-BEAIlEB.

F(Jf)(Jrably 8ituated for exomi7llltitm in ill/ne, Jv1y, and August.· 8ERPE~TA

RIU8, VEL OPHIUCUH.

THE SUPENT-BEA:RE:a is also called 1Esculapius, or the god of medicine. He is represented as a man having both hands clenched in the folds of a prodigious serpent, which is writhing in his grasp. The constellation occupies a consid~rable space in the mid heavens, directly sou th of Hercules, and west of Taurus PoniatowskL Its center is very nearly oyer the eqUft.tor, opposite to Orion, and comes to the meridian the 26th of July. It contains seventy-four stars, including one of the 2d magnitude, five of the 3d, and ten of the 4th. The principal star in Serpent.arius is called Baa Alhague, marked G. It is of the 2d magnitude, and situated in the head, about 50 east-southeast of Ras Algethi, marked G, in the head of Hercules. Rae Alhague is nearly 130 north of the equinoctial, while RJw, in the southern foot, is about 250 south of the equinoctial. These two stars serve to point out the extent of the constellation from north to south. Rae Alhague comes to the meridian on the 28th of July, about 21 minutes after Ras Algethi.

About JOO IOUthweat of Baa Alhague are two smaU IIW'8, one of the 8d, &be other of the -ith magnitude, aearoely more than • degrer. apart. They diatinguh the left or weat moulder. The northern ODe is marked Iota, and the other Kappa. EI_ or 'weI.., degreM IOUth-Ioutheut or au Albague, are two other ..III of the 3d magnitude, in the east moulder, and about 20 apart. The upper one ill called Che/eb, or fd, and the low. one Gamma.

Q

182

GEOGRAPHY 01' TIlE HEAVENS.

n- .tala ia the he.d and Ihoalden of 8erpentariu. with the vertex ia

form a CriaDJIe,

Rae AIhIgue, and pointin, towa.rd. the IlOI1beut.

About 40 east of -/t is a remarkable cluster of four or five stars, in the form of the letter V, with the open part to the north. It very much resembles the Hyades. This beautiful little group marks the face of TAURUS PONIATOWSKI. The solstitial colure passes through the equinoctial about 20 east of the lower star in the vertex of the V. The letter name of this star is k. There is something remarkable in its central position. It is situated almost exactly in the mid heavens, being ne8l'1y equidistant from the poles, and midway between the vernal and autumnal equinoxes. It is, however, about one and a third degrees nearer the north than the south pole, and about two degrees nearer the autumnal than the vernal equinox, being about two degrees west of the solstitial colure• . DirectlYlOuth of U1e V, at the diIWIoe of about 12<', ue two VfIlJ apart, situated in the right band, where it grupe the _pent. About" balfway between. and nearly in • line with the two in the hand and the ,wo in the ehouIder, iI another star of the 3d magnitude, marked Zeta, &ituat.ed in the Serpent,. oppoaitB the right elbow. It may be !mown by meana of a minute .tar jll8t under it. Manic, marked A, in the left arm, iI • atar of the 4th magnitude, about U)O IOUthWest of I and ... About 70 farther in the _ _ cJireo. tWn, ue two ItBra of the 3d magnitude, &ituated near the band, aDd • little more than a degree apart. The npper one of the two, which • about 160 north of Grafliaa in Scorpio, iI eaIled Yed, marked I, the other iI marked f. T~ two ItarI mark the other point in the folda the monater where it iI,ruped by 8erpentariua. The left arm of SerpentariUl may be euily traced by mean. of the two atara in the .houlder, the one (A) near the elbow, and the other two in the hand; all Iyin, nearly in a line nortb-northeut, and IOUthIOUthWeat. In the _ manner may the right arm be traced, by 8&aIa .ery &imilarly &ituated; thet is to. "y, firat by the two in the . . • houlder, jUlt weat of the V, thence 80 in a lOutherly direction inc1inillg a little to the eat, by " (known by a little star right under it), and then by thl! two small ones in the right hand, situated about 60 below (About 120 from Antarea, in an eaalel'ly direction, are two ItBra in the right foot, about 20 apart. The largeat and lower of the two, is on the left hand. It is of between the 3d and 4th mqnitudea, and marked ,. • There ue leYeral other ItBrI in thiI conateIlation, of the 3d and "il aaguitudea They may be traced out &om the mapIo

lilian IIIIrB, about 20

or

SDPENTAllIU8, VEL OPHlUCHVS.

183

T ELE SCOPIC OBJECTS. , OPBnJCKI.-A. R. = 18 h. 18 m. 00.. Dec. = - sao 04' OS". A fine double ur, on the Serpent Bearer's foot. A 6, B 7i msgnitude. Pos. SO 01' Ina. 8".08 Epoch 1832.88 Discovered by Sir W. Henebel, 1780. 'rhere ie but little ewidence of ally phyllical connection between the componenta.

_au_

+

OPBI1JCBI, a binary ur.-A. R. = 18 b. 2J m. 61.. Dec. SO 04". A 4. B 8, mBlflitude. The following are recon1ed: Pos. 760 30' Di.. 0".50 Epoch 1788.18 Henchel. 881 48 .0 .84 1826.61 Struve, 866 05 I .00 1889.87 Smyth. I 47 8" 1 .~9 1841.69 . Mildler. 3 42 1 .42 1847.85 Mitchel. Frc»m th_ obaervationa, it ie evident that the un are revolving about their common center ofgravity, in a period ofabaut 120 years.

_

A

'I'

A

= 17 h. M m. 2J.. Dec. = -- SO 10' 04". do. biDaJy liar, OD the right IwId of Opbiuchu, the clo.at of

OPBI1JCaJ.-A. R.

WIrf

Benchel', double lIBra. Diacoyered, April, 1788. A 6, B 8, a.gnitude. A third liar, dia1eD& 88", in the lame field of viaw. The foIlo"ing _ u _ will ohibit the progreEq changee : Po-. 8810 36' elongMed Epoch 1783.n Henchel. 11/9 M 0".438 1836.82 Struve. 116 38 0 .771 1841.67 Mil.dler. Itt H 0 .779 1846.61 Mitchel. Mii.dler I'IIID8I"U. with re"rence to thia .,1Item, u 10110".: of The ~ riodic time mU8t be aSout 110 years. The inclination and eccentriCIty appear to be considerable. 'rile diatance . . a miwmum in 1816, or a 8hurt time befOre. It bu regularly inc:reued _ since. It ie hoped , that oo.natioDi further auutb than Derpat may foUow thia binary aye-

rn..

t.em with atteotion."

Combining all the obaervationa, a aborter period _me to be indicated.

perhaps not exceeding 90 years. The yearly chanp in the angle of po.itioa, from 1817 to 1848, amonnll ,to 4 0 33'.

=

=

70, or P OP.I1JCBI.-A. R. 17h.67m.11s. Dec. + 10 31' 08" A swiftly revolving binary system. . A 4i, B 7, magnitude. Thia liar has engaged tbe attention of many distinguiebed IUItronOo The rapidity of ita motion excited the notice of ita diacoverer, aud caused the following rl'COrd : .. Tbe alteration of the Ingle of p0sition that h.. taken place in the angle of position of thie double III.ar ie I't!III8I'kable. October 7. 1779, the stare were exactly in the 1IIIIIIII parallel, the preceding star being largest. • &ptember H. 178 I, it wu \10 14', P f; and, May 29, 18M, it wu 480 01', n p; which gives a change of 181 0 69', in 24 yean and 264 day.... The orbit hu been computed by several utronomera; bat with tbe greatest care, recently, by M. Midler, who bu reached the otraordiDary couclulion, that th_ I'll-

DI8No

184

GEOGRAPRl' OJ' 'liRE REAVUH.

yolYillI iliai'll 81'8 moYblg uDder the diBhubinr inlll1enCII of _ body, aa ,et undiaconred. Miidler'a elements 81'8 the "'lowing:

Perlaatre r--ae, Periodic time,

tbinJ

'r =

1812.73 92.869 yean. The angle between the maj. UiB and line of nod.., ~ = 142'l 05' 08" Eccentricity, e= 0.4438 Mean annual a . of motion, m = 23U84Angle of posilion, on. = 126 47 02 Inclination of the plane, of the orbit, I = 64 61 04P

=

The following meuuree will8how the che,ngea which han occurred' Die. 3".59 Epoch 1779.77 HeJ'BChel. 3 .79 1821.74 Struve. 5 .53 1830.57 Dawes.

POll. 90000' 157 36 137 20 178 54 175 26 120 45

6 .44 6 .38 5 .53

1837.62 Be_L 1841.53 M;;dler. 1847.55 Mitchel. The diacrepanCII between computation and ot-rvation, IUlCribed bJ Mlidler to the inIluenoa of IOID8 unknown disturbing bod" have '-a recently aUributed to aberTalion, prodnced b'l the motion of the BtarII in their orbita. This matter ill yet in a BtBte 0 uncertainty•. There are many double BtarII in this conatellation, which will be readilJ fonnd on the charta, diatinguiahed, .. OBual, by their round f",..m,-n other stal'll being angnlar, or ltar-ehaped. Under fayorBble circum&taDcell, all iliai'll appear round, and disk-like, in large and perfect inatrumenta.

RrcK GLOBVL4R ClovITEB.-A. R. = 16h. 38m. 66.. Dec. 10 40' 08". This object J haYe repeatedly examined. It nearly filta the field of yjew. with a power of 21i0. its diameter being from 7 10 8 minutes of apace. There .are three bright Itar8 in the cluater, with A

=-

.-oy amaller but prominent onea scattered in the field. M-a diaroyered it, in 1764, but ..w no BtBn. Henchellocates it at the distance 186. It may be found nearly on the1ine joining. and /l, and fItO diatant from the fil'lll star. It is rep_ted in the Bedford Catalogue .. rn-eaUy contkrwd at the center. I find thia remark ICal'CBly applica'b\e to its appearance, .. _ with the 12 inch refractor. The resolution is complete.

A

CLUBTJlR OF 001.....11.0

Dec. = - 3° 61' OS".

SUBB.-A. R.

=

16'b, 48 m. 45 ..

Discoyered b, MMBier, 1764, and by him deICribed .. a beautiful round nebula. It is euily resolved, and, under • full aperture of 12 inches, is • noble object. 'rhere 81'8 three pretty m.. tinct etar-like radiations, running out from the center, and fuur or 8 . . little patches of aeparate atBra in the ..me 8eld of view. It foIlOWll • Ophiuchi, on the aame parallel nearly, and about SO diatanL Sir W He_hel makes its profundity of the 243d order. ' ,

,

=

A L ....er GLOBVLAR CLVII'I'JIJI.-A. R. 17 h. 29 m. 18 L Dec. = - 3° 00' 09". Sa William H8I'IIChel delCribea thia object .. foOowa:

185

SERPENTARIUS, VEL OPWUCUS.

• ExtnJmely bright, round, euUy resolvable. With a power of 600, I am _ the 1IIa\'ll, The heavena are pretty rich in IIIarI of a certain _. but they are Jarpi' than thoae in the eluat.er, and euily to be diatinguiahed from them. This cluat.er ill considerably behind the _tteJed eta.... u lIOme of them are projected on iL From the ot.ervaUons of the 20 feet' eeleaeope, which had the power of dillceming objects 76,08 ~ u tar u the eye, the profundity of thiII clUlltl'.r must be of the 900th order." This cluster msy be found 6jO IOUth by weat from ,. Ophiuchi, nearly midway from ~ Scorpii and the &ail of Aquila. It ill a JiBe object, la.rge and weD deJined. A L ......

.uD

E ....JLy

RuoLv.n CLl1IT...-A.

R. = 17 h. 47 m.

32 So Dec. = - ISO 68' 02". betWeeD the left leg of OphiUchUl ud the bow of 8qittari... .

Dia:o'I'ered by M_er, 1764. It ill OIl a line north",.t from po 8r.o giUarii, and dillcaDt about 60.

+

A OLD.. Donu 8T.....-A. R. 16 h. M m. 18.. Dec. = 80 41' OS". On the right shoulder. A 7, B 8. Poe. 1850 40' Dill. 1".34 Epoch 1880.97 StrO.Ye. 187 00 1 .60 1882.41 8my~ 148 67 0 .826 184.7.'10 MitcheL T'- Iut meuuJel would indb&e binary charader, and I am coa fident that they wen weU made. 36 OPBJ11CBI.-A. R. = 17 h. 06 m. 29 .. Dec. = - 26° 11' 06" A double, or rather, multiple, star, betweeD the, left foot and. the 8cor pioll's,&aiL A 4i. B 6j, magnitude. Poe. 2130 20 Die. 5".82 Epoch 1848.61 Airy. 216 49 4 .27 1847.61 MitcheL

+

73 OI'BI11ClBJ.-A. R. = 18 h. 01 m. 87.. Dec. = SO 68' OS" 8etweeD the left ahouIderof Opbiachua and the Serpent'l taiL A 8, B

7;. magnitude.

DiIIcovered by HencheL Poe. 2670 II' Die. 0".90 Epoch 1788.82 HencheL 267 87 1 .98 1822,46 Her. & South. 269. « 1 .M 1831.011 8trO.ve. 265 00 1 .4U 1842.00 Smyth.. 163 00 1 .2'14 1841.66 MitcheL Here ill cerlainly a binary 1IYstem. The early -.res of 8i1 W. Herschel, u well u those by Henche\ and South, are dillcordant with the later measures. From 1881 to ]847, a period oU6 years, therehu '-n a chaage of 80 • The JDOtioI1 ill retrograde. A Donu 8T.....-.'. R. = 17h.17 m. 21 .. Dec. =+ 16041" 04". Between the heads of OphiuchUI and Herewee. A 7, B 13. DiIcoYend by Striive. POI. 61 0 M' Die. 4".078 Epoch 1880.28 8trO.ve. 62 SS 8.6M 1847.60 MitcheL The. oblervalioua imply bity ill thiII ...

186

GEOGRAPHY OF THE HEAVENS.

88 P. XIV, OPBI17CBl.--A. R. = 16 h. 20 m. 10·.. Dec. = - 70 46' 09". A delicate· double star. near the right thigh of Opbiuch\lllo A 7i, B 12. Reck.oned a difficult object, from the small size of B. Poa. 3020 44' Dis. 4" .687 Epoch 1831.48 Stri've. 3Op. 00 6 .000 1833.47 Smyth. ~ 14 Ii .292 1847.70 L. M. There is strong evidence of fixity in theBe> meaaurea, and there is little reaaon to believe that th_ elar8 are otherwise than oplically related.

l

--DIRECl'IONS FOR TRACING THE CONSTELLATIONS ON

MAP

NO. XXIII. I

PTwAsus-Tu FLYING HORSE. }'.QUULUS-THB HO:aSE'S HEAD.

tor

Favorohly situaJ.ed exo:mi:n4tiun in September, DcIdler, NuvemlJer.cmd 1JecemJJeT. . PEGASUS. THE FLYING HORSE.~This constellation is repre'sented in an inverted posture, with wings. It occupies a large space in the heavens, between the Swan, the Dolphin and the Eagle, on the west; and the Northern Fish and Andromeda, on the east. Its mean right ascension is 340°, or, it is situated 20° W. of the prime meridian. It extends from the equinoctial N. 35°. Its mean length, E. and W., is about 40°, aod it is six weeb in passing our meridian, viz. from the 1st of October to the lOth of November. We see but a part of Pegasus, the rest of the animal being, as the poets imagined, hid in the clouds. It is readily distinguished .from all other constellations by means of four remarkable stars, a.bout 15° apart, forming the figure of a.square,called the 8qwre of Pega8U8. The two western stars in this square come to the meridian about the tad of

'1

I!

CONSTELLATION OJ' P~ASU..

187

October, and are about 13° apart. The northern one, which is the brightest of three triangular stara in the martingale, is of the second magnitude, and is called &heat, marked jJ. Its declination is 26!.° N. Markoh, ·marked ., also of the second magnitude, .situat~ in the head of the wing, is 13° S. of Scheat, and passes the meridian 11 minutes after it. The two stars which form the eastern side of the square, come to the meridian about 'an hour after those in the western. The northern one has already been described as .Alpkerat%, ora, inthe head of Andromeda; but 'it also belongs to this constellation, and is 14° E. of Scheat. 14° S. of Alpheratz, is .Algmib, a Persei (see Map No. I), the last star in the wing, situated 6io E. of Markab .

cap",

.A~, in Peguut, .tlpMratZ, in ,A~eda, and in Ca.. on lbe pri_ ~ and point out .its direclion

IIiopeta. are situated

through the pole. For thiS reaaon, they are aometimes called the tJuu They fonn an arc at that greatcirele in the heavena from which iIuI didanees of all lbe heavenly bodies are _ured. It is an arc at the equinocti.al colure, which ~ lbrough the vernal equinox, and wbich the BUn _ about the Slat at March. It is, in astronomy, what the meridian of Greenwich is iu geography. H the 811n, or a planet, or a Btar, be said to have 80 many degrees of right 1UCtlfl8iou, it mean. that the auu or p1anIIt ha. -wm so many degrees from this prime meridian. . Emf, marked .. 80metimea called Enir, is a atar of the third magni. tude, m the nose of Pegasus, about tOO w. S. W. of Markab, and half way between it and the Dolphiu. About one-third of the distance from Markab toward. Enit; but a little to the S. there is a Btar of the 3d magDitude, in the neck, whose letter name is Zeta. The loose cluster c1iJeCtly S. of • line joining Ellif and Zeta, forlll8 the bfIIUI of Pegasul.

~.

In this constellation, there are eight~-nine stars visible to the naked eye, of which three are of the second magnitude, and three of the third. TELESCOPIC OBJECTS.

= ° or

A DouaLa STn.-A. R. = sfh. 14 m. 41.. Dec. 19 04", between the head at Pegasus and the bind 1... of the FOL A 4, conaidered variable; B 9, magnitude. . POI. 3100 08' Dis. 36".4 Epoch 1333.96

188

GBOGlL\PHY,ov THli: IIli:AVUS.

Altbo. DO 18D11,'b1e cbanp hu yet been cIiIcoYend in tbi8,llet•• common proper motion would iodicate IIIIDe phyeical wUon. A L.6.BIJ_ .6.11'11 B.'LLU.T CL17I1'n_ _ A. R. == 21 h. 22 m. IS .. 110 27' 04". betwl!BD tbe months of Pegaaua and Equulua. DiacoYefed by Meraldi, 17~, and deacribed him u" a nebuloua IIlar, quite brigbt, and compoaed of l18Veral 8t!l....' It wu fully reaolved by Sir William Herschel, 1783, and placed by him in the wtd order of dilllaDC& Thia object • greatly condensed III the center, and hu maDy radiatiODa. There • • great- cond_uon at the center, and even a brilliant nueleua, around which the IIlan are _ttered in rich' profusion for. diIIlance of about 2' in diameter. Beyond the chialer • I_rich in Itara. '!'be BpaC8 p.-ling the clu" .'nearly ftCaDt. The 'following apace • tolerably well filled with Btara. '

Dec. ==

+

!7

til.

==

':+

A SXUL DooBL_ BTu_A. R. U h. 06 m 87 .. Dec. 160 24' OS",belwl!BD the head and lap of Peguua. A 7i, B IO!. The fint yellow, the BeClODd grem. , Discovered by 8tril..,e. POI. 8160 24' Dis. 7".68 Epoch 1828.96 Strii.,e. 381 29 8 .os 1847.66 MiLcheI; This • certainly • binary system.

==

+

37 P ..ut_A. R. 22 h. 21 lD. 68.. Dec. == OSO 37' or, • binary Ita!' on the maDe and near the head of Peguus. A 6, B 7iDiacoYered by Strii.,e. Poe. H2° 86' Die. 1".86 Epoch 1881.\2 Struve. 118 M \ .10 1889.66 gmyth. 121 46 0 .98 lSU.70 Mitchel. Here is IItrDDg II'rideDce of, binary cham:ter,u the angular velocity hu been on the increase, and the distance • certainly diminishing. .

.

== +

66 H. I.t P ..U l . -.... R. == 22 h. 66 m. 58.. Dt.c. 11 0 27' 09", an elongated nebula in tbe Horae's mane. DiB!:o.,ered by Herschel in 1784. This is an exceedingly faint and difficult object. I examined i t _ fuOy in September, 1847, and although it wu readily found, it required very c\0II8 guiIlg to makll any thing out of it. It atretcbes between two IIara. the upper one of which is not touched by the nebulous ma&ter. A minute t81eaeopic star just precedes the upper extremity of the nebulou. matter, which ~ to have been overlooked by preceding ot.... era. There is iomethiDg of a glow at the center after long gazing, and under a side glance. '!'his object ill though~ to be a S.t ring _ obliquely. It is 0118 of the most difficult oJliects in the heav8Jl8, and requires a powerful irlIlruo ment for I\8tiafactory examination. ,

180

. EQUULU8, VEL EQUI BECTIO.

EQUULUS, VEL EQUI SECTIO. THE

Lrrn.B

HORSB, OR TRB HORSE'S HEAD.-This

Asterism, or small cluster of stars, is situated about 7° west of Enif, in the head of Pegasus, and about halfway between it and the Dolphin. It is on the meridian at 8 o'clock on the 11th of Oetober. It contains ten stars, of which the two principal are only of t1!.e 4th magnitude. These may be readily distinguished by means of the long irregular square which they form. The two in the nose, are much nearer together ·than the two in the eyes; the former being 1° apart, and the latter 2io. Those in the nose are uppermost, being 4° north of those in the eyes. This figure also is in an intJeTted position. These four stars are situated 10° or 12° southeast of the diamond in· .the Dolphin's head. Both of these clustel'8 are noticeable on account of ibeir figure father than their brilliancy. TELESCOPIC OBJE eTS. 376 P. XX, E4I.VVLIIl.-A. R. = 20 h. 47 m. 40..

Dec. =

+

030 fifi' 06", a close double star between the Hone', head and the boW cl Antinons. A 6, B 8, magDitude. Diacovered by StrCt.ve.

POI. 289° 10' Dis. 1".8 Epoch 1829.48 Striive. 287 45 1 .874 1847.6fi Mitchel. Th_ mea~urel may pouibly indicate a .1ow retrograde motion, a ebanp of 20 about in 18 years. 1'hia would give an annua ~ 10 the .ystem of more t.han 4000 years.

=

=

• E~utJLlIJ.-A. R. 20 h. 111 m. 011.. Dee. 09" 4\' 01", a delicate triple star, preceding the Hone'. forehead. A 5~. B 7~. Diacovered to be double by Herachel; eubdivided by Struve. POlo A B 29()O 00' Di.. 0".50 Epoch 1838.88 Smyth. 288 A e 84 79 78 76

06 21 21 01 25

0 .1174 9 .87 12 .37

1847.60 Mitchel. 1780.fi~

Herachel.

1823.511 Her. & 8oatb. 11 .20 1838.88 Smyth. 1\ .08 1847.60 Mitchel. TheRe meaeurea determine the binary cbal8cter of A and e, which ia llkewiae rendered more eerlaiD by the eg.uality of tbeir proper motioD.

190

GEloGRAPHY OF THE HEAVENS.

H_ Wfl an preaented with a magnificent IIJetem. Thl'ftl nos NYO'" ill, about their common center of pvity. aDd sweeping. toptber with their lI'aiM of planet. and comets, throDgb the regioOll of BpIlC80

+

A EQ,Ul1UI.-A. R. = 20 II. M m. 19.. Dec. = 060 33' 03H • A fine double star precedinJ the Hone's nll8ll. A 6. B 6•• magnitude. Discovered by 8tru ve. . .

Dis. 2".6 Epocb 1833.72 ~myth. I .9 1847.60 Mitcllel. 'rhele ~atiOD8 are not 801llc:ien& to determine the binary chaJ'IdIL Poe. 2250 311' 2~7 "2

1_DIRECTIONS

FOa

TRACING TilE CONSTELLATIONS ON

MAP NO.XXIV. AQUABJUS"""':TuE

W ATEa-BEABEB.

CAPBICOIlNUS-Tn GOAT.

FavoroiJly situated for examination in 8qJtem/Jer, NtnJeTllher and DecerriJer.

~r,

AQUARIUS. THE WATEa-BEAREJl.-~his constellation is represented by the figure of a man, pouring out water from an um. It is situated in the Zodiac; immediately south of the equinoctial, and bounded by the Little Horse, Pegasus, and the Western Fish on the nortli, the Whale· on the east, the southern Fish on the south, and the Goat on the west. It is now the 12th in order, or last of the Zodiacal cODstellations; and is the name of the 11 th sign in the ecliptic. Its mean declination is 14° souih, and its mean right ascension 335°, or 22 hours, 20 min.; it being 1 hour and 40 min. west of the equinoctial colure; its center is, therefore, on the meridian the 15th of October. It contains one hundred and eight stars; of which the four largest are all of the 3d magnitude.

un

CONSTELLATION OF AQUARIUS.

.. Hia head, hill shoulden, and hi, lucid breMt, Glisten with 1IlIl1'8 ; and where his urn inclines, Ri"era of ligbt brighten tbe wat'ry track."

The northeastern limit of Aquarius may be readily distinguished by means of three I!Itars of the 4th, and one of the 5th magnitdde, in the hand and handle of the urn, so placed as to form the letter Y, very plainly to be seen, 150 southeast of Emf, or , Equulei, or 180 S. S. W. of Markab, in Pegasus; making with the two latter nearly a right angle. About 4jO west of thia figure is El Jkli1t, marked .. a liar of the 3d magnitude, in the aut ahol,1lder, and the principal ODe in this con&tellaaOD. loo BOUthWest of 4, ia anotber' etar of the same magnitude, &ituated in the weat moulder, called Sad u.$lud, marked ~ .dncAa, marked 8, of the 6th magnitude, is in the right aide, SO BOUth of.. 90 eeat of 8, is another alar of the 4th magnitude, whose letter Dame is Lomhda.. &Ileal, marked I, of the 3d magnitude, lying below the Imea, II sitnated 810 BOOth of A; and 14 BOUth of I. the brilJiant liar Fomalhaut, of the lat magnimde, terminatea the caacade in the mouth of the &utbem Fish. This star ia common to both theae eoMtaeIIalion., and is one of those from wbich the lunar dietance is computed fur.laining the longimde at _. It culminates at 9 o'clock on tbe 22d of October. Fomalhaut. Deneb KaItoa, and Alpha in the head of Phamb:, malle a large triangle, whose vertex is iD Deneb Kaitoa. Those 0la1'8 of the 4th magnitude, aimated 0&0 BOUth of ~ and Dearly thl' eallle dietance from 8 , are in the tail of Capricorn. 'fhey are about 20 apart. 'l'he weatern one is called Dtmb AIgtdi. The !'Nt of the IIal'8 in the caacade are quite lUI.n; they may be traced from the letter Y, in the urn, in a aoutheaaterly direction toward. the tail of Ceme, from which the _de iUddenly bend. oft' near I, in an oppoaite courae, and finally disappears in the mouth of the Southern Fish,3()O BOUth of Y.

''''0

TELE8COPIC OBJECT8.

=-

4 Atluun.-A. R. = ~ h. 41 m. 67.. Dec. 8° 13' or. A cIoae binary star, betweea Aquariua and EquuJeua. A 8, yellow; B 8, purple. Diaco"ered by Sir W. Hencbel. The fullowing measures are the 0II1y 0lI8l which I ba"e l*D abII to find. Epoch 178t.88 HtlI'IIChei. Poa. 8610 30' Dia. 00".80 . 18:aU9 BtriI._ 00 .81 26 07 ,. 88

00.8

184l.61

Mildler.

192

GEOGBAPHY OF THE HEAVENS.

=-

A PU1U'U.Y NIIB~.....-A. It = laO h, 66 m, 27 s, Dpc. 11 0 69' 00", In the middle of the Scarf of Aquarius. It may be found nearly on the parallel of" Caprieomi, and 120 east of it. Diacovered by Sir William Herachel in 1782, Ita diameter amount. 10 no ' - than 20", The surface evenly tinted aDd of a delicate pale blue. It. diIk iscomparatively _11 de6noo, and tbe tint ~blea.thet of Uranu and Neptune. Ita distance most be equal 10 that of the fixed stan, u it hu no annual parallax. Its diameter•• &/Ierefore. cannot be Ie. than three thouaaJJd milliona of mile&. I have hquently uamined this wonderful and on tbe 91b of i4eptember. 1847. found it. diameter 10 be about 9" or 10". 'fhe uppt:r part is wanting in roulldu-. giviDg it the appearance of an obtuse crescent.

+1,

=

=

12 Aq,u ....lI_A. R. 20 h, 65 m. 87 s. Dec. -1)60 27' or. A cia. double alar in the apace bet-. the 8earf of Aquarius, and &be head of Equuleua. A Iii. white; B Bi. light blue. Diacovered by Strihe. POlo 1890 86' Dis. 02".66 Epoch 1831.31 8trUve. 191 00 02 .80 1831.82 Smyth. 191 80 08 .28 1847.63 Mitchel. There is aome&hing extraordinary about tbis star. The ~ oIItained by ...y _rea is nearly fi>ur limo.. u great .. tbat in the boob ; and the alar B inatead of being of the 8j magnitude, is certainl~ .. low 88 the 16th. I aatiefied myself of this by turning the in&trumell& on ~ Aquarii, wha. companion is of the 16th magnitude. The liar may be variable, but the i n _ of distance is unaccountable. ~

=

=-

Aq,UARIJ-A. R. II h. t8 m. 07. Dec. 060 16' 00". the right shoulder at Aquarius. A 8. yeU&w; Bill, hlue. Discovered by Henchel, who gave the POlo 8260 48' Dis. unoartaiu. Epoch 1781 3VO tIO 02".00 18d3 Smyth. This lut i8 'a mere eatlmation.

OD

=

=-

19 Aq,u ....n.-A. R. 21 h. 63 m.41 L Dec. 170 (9' 09". A beautifUl double alar on the .tail of Capricorn. A 6, B 8. magnitude. • POlo 2480 84' Dis. 04".60 Epoch 1i128.19 Strlive. 242 08 04 .468 1847.70 Mitchel. These _rea cJecide the character of the alar. The componenta mlllt be optically united.

=

Gr.oBUL .... CL17......_A. It 11 b. 16 m. 10.. Dec. 010 St' 0\", on thenecltof Aquarius. DUcovered by Mp.raldi in 1746, mere thaD a hundred yean ago, amOll, the 81'11 known nebula. , It _ fully re.olved by Sir William Henchel, with his 40 iIe& n8ector, When the entire ma.. W88 found 10 00IIlIist of myriada of ...... ranpl in a colllJll'l*ed form, and c1a.ly clustering about the -*aI. .He IIIItimated ita profuodilJ .. of. the 243d order. This object

A Fnn

=-

ana

CONSTELLATION OF AQUARIUS.

193

_ n:amined with a POWIII' of 250, aDd a 12 inch aperture, on the _Ding of the 9th of September, 1846, and dncribed aa follow.. 'rbl dueter (,Dtera the field in great beauty. II is distinctly JeIIOived, though the atara compGlling it are very miDute, with gl'4!8t condenaalion at and lII'OUod the center. The diameter of the brighteat Portion is about 2' by wtimation. A coane doable star foIIowe above the eluater. Several bright alare iu the field. There are DO radiationa of atara. the _ being neady globular. with an outline IOmewhat broken. '1 AQ.lI.t.an_A. R. = 22 h. 06 !D. 27 L Dec. =- 21 0 Iii' 00". A double alar betw_ the Water-t-lIIJ' and the SouthllJ'n Fish. A 6.

B 8i, magnitude.

])iacovered by Heraclael, but regiBlered by him without meaaureL Poe. 1200 4~ Dis. 05".17 Epoch 1828.78 Herschel & South. 120 22 04 .326 1847.70 Mitchel & L. An interval of 24 yeara between th_ meaaun!ll, indica\ell the fixity of the componenla of m- atara.

=

=-

~ AQ.u .... II.-A. R. It Ii. 20 m. 36 e. Dec. 000 110' U2". A binary Blar OD the left wriat of AquariUL A 4, B 'i, magnitucIaB. Discovered by Herachel in 1779, and found to be binary u early ..

1804.

Poe. 3.'j60 14'

DiL 03".626 Epoch 1S30.98 BesseL 352 4.1 03 .389 1836.06 i:!lriive. 352 10 04 .123 1841.48 Midler. 34A M M .:10 1842.59 Smyth. 346 42 03 .948 1847.70 Mitchel. The lut meaaurea but one _m to be in error both in diBlance and position. Midler thinks the period of thia system may be about 780 year&. My own measurea were confirmed by thoae of my ...ialan&, the _dings agreeing admirably with each otblll'. CLOD Doun. Sr.....-A. R. = It h. 34 m. 40.. Dt'eo == 90 OS' 08". near the atream iaauing from the _ and near the A 7. B 8i, magnitude. DillCOvered by HeracheL Poe. 311" 12' Dis. 03".00 Epoch 178t.74 HeracheL ;H 7 22 U121.92 StrUve. 313 08 02 .7 1838.67 Smyth. 314 36 01 .82 1847.70 Mitchel. The diBlance in this II8t _ to be diminillbing. and a revolution in an orbit whoaa plane is oearIy coincident with the visual ray appean probable.

-

A

,,_'a mouth.

'T AlI.lI.t.lIn.-A. R.= 22 h. 89 m. 13.. Dec. =- 140 68' 09 H , Above the left knee of Aquarius. A 6, B 9i. magnitnde. Dillcovered by Herachel in 1782.

A TalPLK Sr.....-A. R. = 22 h. 89 m. 3& L Dec. = -60 03' 05". In the mouth of the vue. A 7i. B 8. V 8. mapitude.

R

194

GEOGRAPHY 01' THE HEAVENS.

04 AlI.u....n_A. R. =",8 II. 10 m.41 .. ' Dec.=_140 19' 07. In the space between the IItream and the left knee of Aquari\l& A 6, B 8i. owpitude. DiacO't'ered by PiaI1Ii. 107 AlI.unn.-A. R. = lI8 II. 87 m. 41.. Dec. = - 190 84' 01". Near the eenter of the IItream flowiug &om the IUD. A 6, white; B 7i, blue. Diacovered by Henehel in 1780.

OAPRIOORNU8.

THB GOAT.-Thii is the tenth sign, and eleventh in the order of the Zodiac, and iB situated south of the Dolphin, and next east of Sagittarius. Its mean declination is 20° Bouth, and its mean right ascension, 810°. It il therefore on the meridian about the 18th of September. It is to be observed that the first point of the sign Capricorn, not the constellation, marks the southern tropic, or winter solstice. The sun, therefore, arrives at this point of its orbit the 21st of December, but does not reach the C01I8tellal.irm of Capricorn . until the 16th of January. The lunhaving now attained itsutmost declination south, after remaining a few days apparently stationary, begins once more to retrace its progress northwardly, affording to the wintry latitudes of the north, a grateful presage of returning spring. At the period ef the winter fJolstice, the sun is vertical to the tropic of Capricorn, and the southern hemisphere enjoys the same light and heat which the northern hemisphere enjoys on the 21st of June, when the fJlID is vertical to the tropic of Cancer. It is at this period, mid day at the south pole, and midnight at the north pole.. The whole number of stars in this constellation is fifty one; none of which are very conspicuous. The three largest are only of the 3d magnitude. There is an equal number of the 4th. '

~onstellation,

CONSTELLA.TION OF CA.PJUCORNUS.

195

The head of Caprioom may be recognized by means of two stars of the 3d magnitude, situated a little more than 20 apart, called Giedi, marked G, .and Dobih, marked ~. Tbey are 280 from the Dolphin, in a southerly direction. Giedi i8 the most northern star of the two, and is double. If a line be drawn from Lyra through Altair, and produced about 230 farther,it will point out the head of Capricorn. These two stars come to the meridian the 9th of September, a few minutes after Sad'r, in Cygnus. .. A few other stars, of inferior note, may be traced out by reference to the mapa. The sign of the Goat was called by the ancient orientalists the "Southern Gate of the Sun," u Cancer was denominated the" Northern gate." The ten stars in the sign Capricorn, known to the ancients ~y the Ilame of the" Tower of Gad," are probably flOW in the constellation Aquarius. TEI.ESOOPIO OBJEO'rs •

R. 20 b.09 m. lO.. Dec. = - 13° OS' 01". f,. dQuble star 01 apecla,intereaL A 3, B 16.lJIIIjJnitude. This minute ,r.oint of light was regarded by Bir John Henchel " poasibly a IJQteJJite, and ,hining by a rejlecletl light. On a cursory review of this region of the heavlUlll, in september, 1846, I turned the illlltrumeDt on 01- Oaprieomi in the preaenoe of nearly a fun moon, and inlltantly deteeled the IIIIIIU companion. I had forgotten that this was one at the IItar8 to which Henrehel had directed attention, and euppot
, CURJCORl'I'I.-A. R. = 20 h. 19 m. 44. .. Dee. = - 18" 2ct 01". A double BlBr with a distant companion. A 6, B 9, 0 7!, mag. Pos. A B 1760 42' Die. 3".8 Epoch 1830.73 Smyth.

176 66 3 .094 1847.70 Mitchel. This object is follJlCl on the rigb, ear of Capricorn.

196

GEOGRAPHY OF THE HEAVENS.

.

02 CAPRlcoa.I.-A. It = 20 b. 20 m. (3 s. Dec. = -, 190 06' «>''' •. A double liar between the right I!IU and the eye of the auum.L A 6. B 7. magnitude. POI. 239 0 09' Dis. 21".8 Epoch 18M.59 Smyth. 'rhe conneDou ia merely optical... _me to be ehown by the recorded D1eaa~res.

«

A GLoBuua OLulTn_A. R. = SO b. m. 39.. Dec. = 130 07' 06". Between Aquarius and tbe neck of Oapricorn. due eallt of " Oapricomi. Diacovered by Meaier in 1780. Resolved by Henchel. and prononnced to be in the 2(3d order IIf distance.. and dellCribed by him .. followa. "It ia a clueter of aIarII 01 a round figure, but the very faint sian on the outside of globular c\uetenl are generally a little dispereed. 80 . . to deviate from a perfectly circular fOrm. • • •• 'rhere are many Blan in the ..me field of view. but tbey are of seveJal magnitndee, tolally diftinnt from tbe exceesively BlDall ones whicb com",*, the cluster•. It is not )I08'ible to form aD idea of the number of Blan which fOrm such a cluater, but we are not. to.estimate them by hundreda." .

A Fun: OLUSTBB_A. It = 21 h. 31 m. 16.. Dec. = - I3D 62' 0(". Under the caudal fin of the animal. Diacovered b,. Messier in 1764, who ..w it circular, and without

' .

-y~.

Resolved by Sir William Henchel in 1783. Examined by myself in September. 1847, and described .. follows. An inegular cluster. It brightens at the center, and throw. out three distinct radiations of stars. All are directed downwards, or towards the north. An 8th magnitude ltar precedes the c1U1fer by about 5 minutes of arc. Several slanl lIN in the field.

--In closing our review of the constellations, we present the following table, exhibiting, for each month in the year, the rising, culminating, arrd setting of the visible constellations. JANUARY. Ruing. Hercules, Corona Boreali8, Boates, Virgo, Crater, Py;ds Nautica, Argo Navi8.

Culmil'Udillg.

Draco, Polaris, Camelopardus, Lynx, Gemini, Monoceros, Canis Major.

I

Belting.

Cygnus, the neck, ·Pegasus, the hoofs, ! Pisces, the ribbon, •Cetus, the body. I Eridanus, · Columba Noachi.

I

19'7'

TABLI'. OF CONSTELLATIONS.

..;

FEBRUARY. Riring.

CulmimJI'

:l• .

&ItiJw;

a:

Lyra, Cygnus. the Pisees. 1M Ji4, Hereules,........,Aould•• Cepheus. the "'-. Aries• • f0r6 • • Serpens. Ute head, Polaris, Cetus._the Mall, Virgo. t1te.fed. . Ursa Major .[0r6 kg"i Eridaaue, Corvus. Lynx, the tail, Lepus. Ute f0r6legs. Canis Maj.,hind. lIydra,1he lenDer fda. Cancer, IM~. Hydra, 1M , . . Argo NavHI. MARCH. (Jygnusr-fo1l'g wing Lacerta. the back. Andromeda,UteOOdy. Lyra. Cepheus. the aNA, Triangulum. MusCA. Hereules. the 1Iead, Polaris, Ophiuehus,. lIead. Ursa Major, hiftd legs. Taurus. Orion. Serpens• • f1tiddle. Leo. the flank, Libra, Crater. Canis Ma,j•• the TretItl. Hydra, • tail. Hydra, 1M body. APRIL. Lacerta, Andromeda. the body. Andromeda. Ute foel. Vulpeeula, Cusiopeia, • waiBt. Medusa'. Head, Sagitta, Polaris, Ta.urus. the Aorm. Aquila, t1ie tail, Ursa Major, 1M tail, Ori&n,the lIead, Ophiuehus, ". __, Canis Venatiei, • Monoeeros, j'OT'6 legs, Scorpio, ". __, Vergo, the tIJdiBt, Pyxis N autiea. Centaurus, . , lwrId. COlYUS, the tail. Antlia Pneumatiea. MAY. Andromeda, tAe.fed, Perseus, the head, Aur1r. tile legs. Peguus,. f0r6 kg., Cusiopeia, the lea. GemIni, the legs. Equulus, the IIOIII!I, Polaris, Caneer. Delphinus,. botIg. Draco, the tail, Hydra, tile "-'I., Crater. • Antinous, Bootes, 1M boily, Scorpio, the tail, Libra, COI'VUII. Centaurus, the hall. Centaurull, lite 1IetMl. Lupus, the 1aeacL JUNE. Medusa'S Head, Auriga, • kiM. Gemini. the 1aeGd. Triangulum, Camelopardus. Cancer,. boily. Pisces. IJ&e N. fish. Polaris, Leo, tile f0r6 • • Sex. Uranile. Pegasus• • 1Ding. Draco. 1M botJv. Aquarius, .1&ouldBr" Hereules. the 1Jack, COI'VIIII. Hydra, tile tail. Capricornull•• lIead. Opbiuehus. LUpus. the 6eM. Sagit~ius.'" boily. SeorpiQ. tile 1tIil.

198

GEOGRApHG OF THG

HGAPp;NP~

U Y RUi"'4!. Auriga, Vir; wavt, l'erseus, Musca, A;jeB~ tM head, Pisces, the tail, ,Gqup£:"ius, ike lrg8, Sagittarius, the hipt.

C"lminaJi '~p. Lynx. the Mad,

Setting

Lynx, the hind k!J3. C"mek,p;,r
AUGUST. Lynx, the body, . Ursa Maj., the head, itemiei,it,;eto;'.za,'m Pdarie, Auriga, the lmeu, Cepheus, the sceptre, t~e' hexed, Cggnn;, tl£zf lx71y, Cetus, mnuth, Vulpecula,

Leo Minor, Cpma geruice;, Bootes, the feet, Lil£ra, Serpentaries,-,• •

iii~~~~!~r::is, ,g~~~~~~:~s,

Sagitta:riws,thewailrl.

SEPTEMkE

Leo Minor, the head, Ursa Major, the bodv, Canes Venatici, itl£nx, !.he 1£im£ legii, Draco, the tail, 'BoZZteo, the krwi;:;, Gemini, the bodies, Polaris, S,rrpens, t.~ he.'!.1" itrion, the ;/ur.ilder" CepheuB,liilad q'body Ophiuchus, the 'IIXJirI, Eridanus, Cetus, the In!l8, Cculptotie.

Peg8l!ils, ~'re Cr~rsst, Aquarius, Pi;chz Auutrali,.

SentUTn Suqie;Gi, Sagittarius, PAcis9,u;tualie.

T B R Leo Minor,the body, Ursa Major,the tail, BoateB, t1I'ii1u:r.11~z Czs1lce" t7n' OOr-PG, Aeaeo, the fail, Corona Borealis, Canis Minor,-laead, P"lari£l, ,Hercll!£ls, ,'£lWl11zT.en, n'£Zf,n,ee,rr'niii. tfilt 1UiCk, Cassiopeia, the head, Ophiuchus, the het.ul, Orion, the Andr,rmerlii, bn'£ast Tnuree Poniat'£fwsnT, !!epus, the,. Pisces, the ribbon, Capricorn us, the head n'ferUi££ii( Cnem,£,ga. CBtu§, the '£,'£il, Pi,ci, itus'£rali§. Canes Venatici,

~'too,

f;;
o E B R Draco. the last ('.oil. Heroules, the kls, Ursa fbiin'Jt, tke head, Ceebems, et R~muB, Polaris, Sagittf£, Perseus, S}iO'Ultitr8, Aquila, the body, Aries, fhe ~,Jdy Eluulu§, Cetus, the mouth, Aquarius, Fornnt Chnmioa. AhP. Geull£tori§,

TABLE OF CONSTELLATIONS.

RUing. BoOte8, Coma Bernieea, Leo, Sextan8 Uranial, Hydra, Argo Navi8. Canis Major.

199

DECEMBER. Cu?minating. 8dting. Draco, "" midille, Lyra, Ur8a Minor, haunch, Cygnus, t1Je hb.ul, Polari8,' Vulpecula, t1Je legl, CamelopardUB, body, Peg&BU8, t1Je hb.ul, Taurus, t1Je hb.ul. ,Pisce8, t1Je W.fisk, Eridanu8. Cetus, t1Je tail, Fornu Chemica.

N. B. The risings are taken alOlig the horizon, from the north, round by the east, to the south; the culminations from the north horizpn, over the pole and zenith, and thence down to the south horizon; the settings are reckoned from the north, by the west, roqnd to the south. Polaris, though not always precisely on the meridian, is included in every month as a guide.

THE FIXED STARS.

201

CHAPTER V. 'rUE FIXED STARS-THEIR DISTANCE AND MOTIONS-TIIB ,MILKY WAY - CLUSTERS - NEBU1..&

TRus far in our examination of the constellations, the stars have only bp.en considered in their relations of apparent magnitude or brilliancy and position. Their absolute magnitudes, distances. motions, and positions, have Dot been regarded, except as notices have been taken of a few among the telescopic object". We propoee to conaider. now, the discoveries which have recently been made in sidereal astronomy; and we commence with the puralla« of the fixed stars. ' DUllrITloN.-The parallaz of an, heavenly body is the apparent change in its position, occasIOned by any real change In the position of the Spp.ctstor. Thus, if a person on the earth's surface should, while looking al the mOOI\ just rising. be suddenly transported down to the earth's center, as he descended the moon would appear to ascend, and this seeming change in the moon's place is a parallal:tic change. The rapid apparent whirling of the rorest trees, occasioned by flying swinty past them in a coach or car, ia a similar effect from a like cauee. More accurately, the moon's parallax is the angle formed at the moon's center by two lines, the one drawn tangent to the earth's surface, the other drawn to the earth's center. In case a spectator could be transported to the moon's center, at the instant she is risin/r above the horizon of any place, and could S88 the earth's radIUS drawn to this place, the two visual rays drawn to the extremities of this radius would form an angle a' the eye of the observer, which would be the moon's Iwrizootal para1la:J:. These two visual rays and the earth's radius form a triangle, in which one side {the esrth's radius) is known, the angles are readily measured. and hence it becomes pOllsible to learn the value ofthe remaining sides, either of which measures the moon's distsnce from the flarth. When, therefore. the parallax of any heavenly body is once determined. it is an easy matter to compute its distance. If one could be transported to a fixfld stsr. when rising, and view from this position the earth's radius. the angle formed by the visual rays drawn to the two extremities of this radius, would be the . star's parallax. In consequence of the vast distance of the fixed stars, this angle, thus formed, is too minute to be sppreciable ; DO instruments devised by humlln skill or science, can be OOD-

202

GEOGRAPHY 0:" THE HEAVENS.

struoted 80 a8 to mea8ure SO minute a quantity. We are, therefore, obliged to re80rt to some other method to determine the parallax of 'he 8tar.. In case the earth were at rest in the universe, there would be no possibility of eyer meaeuring the distance of the fixed stars; but its aDnual sweep around the SUD in an orbit wbose radius is sbout ninety.five millions of miles, transports the as'ronomlOr through space, around an orbit wbose longeet diameter i, neasly two hundred millions of miles. If, now, the obl8"er send up a visual ray to a fixed star, wbeD at one extremit1 of thl! 10Dgeat diameter of the earth's orbit, and at the end of SIX months, when he IIhall haye reacbed tbe othlll extremity of the same diameter, be send np a second yisual ray to the same star. these two rays will stand upon a bli8e Wb088 length ia nep.rly two hundred. million. of miles, and the aDJ.le formed by them. at the fixed 8tar. will be its paralIare. )'0 render this plainer. suppose a globe bright as the sun, and of a diameter equal to that of the earth's Olbit, filled this grand cif. cumferellC8 ; the apparent diameter of such a globe, 88 seen from the ,tar in queation, would be its parallax. At first yiew it would seem almost irupouible to remOYe a .pectator so far, that a globe of two hundred millions of milea in diameter should IIhrilik to aloint almo.t impercep~ble, Qr that by di.tanC(l he diameter shoul become scarcely perceptible with the moet powerful iDitrumente; yet this is literally trlle. To measure this appareJlldiameter, or to .blain Ibe ...,le Of Ihe yuual rays draw. from ill ext.remiti88 to a fixed lltar, has for more thaal hundred years, called into requisitioQ Ibe highest tlkill, pniua, and patience, eyer put forth by maD. The problem ia no Ie... thu the determination of the distances of the fixed litera. Three proo C8IIIIeIl have ~n employed hi..lbe investigation. of thi' probl8lDt each of which. ancl its reaullll, we Hall succinotly preaem. 1. BIlADLU'S MITBOD.-SUPpoae a telescope bolted firmly &0 a solid rock, hewn in the fOlID of a yertical abaft. 'I'his rool! is absolutely immovable, and the teleacope ia 80 .ituaied tha' ita axia ia exactly vertical. and ia pedeelly immovable. In the focus of the eye piece of the teleacope. let two spider's webe of the finelt telttnre cro.. each other at right angles, and by tbeir intersection fortn a point of almoat mathematical minutellH8, precisely in the axis of the telescope. With·lhi. inatrumeDl &be utronomer ia prepared to commence hia research of the parallax of a fixed atar. Placing hia eye to the inatrumen" he watobea until a cenaia hed star entera the field of the telescope. It actually threads like a bead of Ugh" the apider's line drawn I parallel &0. the direction of the atar'. ap(MU8Dt diurnal motion; ia moyes DB, and the precise instant when It reachea the intel'tleetion of the spider'a linea i. noted and recorded, and thua the tint ob~atlon is terminated. Now Ihe telescope, ita rocky but.

THE FIXED STARS.

203

and the obaerver, are earned by the earth round the sun, and in ease any change in the apparent place of the star is occasioned by the revolution of the earth in its orbit, as the star is watched night aner night, throollhoot the ,ear, it will be found slowly to leave the spider's hne which It at first threaded, and ll1'8Ciually to move eIther towards the north or south, while it tails to cross the center at the exact instsnt of time first recorded. A little thought will render clear this heautiful and silllple method of aacen,aininf the parallax, or apparent change of place, of the fixed stsrs. Such was mainly the method employed by Bradley, the great !Inglish astronomer. lts accuracy was wonderful, hili it failed to detect any ·parallax. Buried in depths almost iDliDite. the stars .escaped from thil Ii...t 80rutinizing p'roceaa. 2. HERSCHEL'S METHOD:-lu the outset Ot'Herschel'sexplorations among the double stars, he believed them to be only opti~any related; that is, their proximity was occasioned by the fact that the visual ray drswn by the obse"er to one ltar, passed almost exactly through the other. In case then, two lltars could be found nr:j near to each other, ot whose components the one was about double the other, it wal fair to conclude that the smaller was twice as remote as the larger, and if properly chosen, the annual revolution of· the earth in its orbil could hardly fail to cause some change in the relative pOBitions of these stars. 'Suppose that on tbe first ot January the email star is seen exactly on the right of the large one; at tbe end of three montbs it ia seen.a little to the south and jUlt undE'r the large one; at the .,)oae of six month a it is to l.he left; at tbe ~nd of nine montb.a it is just above and a little north of the large star; and when the year closes it COID8II to resume ita primitive position. In case Such changes are repeated from 1ear to year, and in the Bame order, and in maD' double atan, It is impossible to resist the COIIolu8ion. that it IS • parallactic change. Such was the method prsctised by Herecbel, but . . onforesee~ discovery destrOJed tbe hope of detecting the parallax in this way. 1t was found that these double stars, in many instances at least, were not merely related by accidental position, but were actually united by the great law. of univerl8l gravitation; one star or Bun revolving ahollt the' other, or rather the two aonl revolving ahout their common center of gravity. The actnal motionl! became,:in tbis way, so involyed in these only apparent or parallactic motions, that to distinguish them became impossible. These methods then failed to reveal the distances of the stars, although they were not without result!!' of the most important character, and without a knowledge of which, the problem of the paral1ax could never have been r8aolve4. Bradley ifiscovered the flfllGtiOfi and aberration of the fixed stars, while Herschel reached U1e grand fact of the bifllJf7l character of the double ltars.

~04

GEOGRAPHY O}' THE HEAVENS.

3. BESSIIL'S MIITHoD.-At\er mouDting a large teleacope callII heliometer, reculiarly adapted Cor the micrometrical measure oC large as wei as minute d18iancea among the double stare, BeBRel· Blliected 61 Cygni as the object on which he determined to concentrate hiB entire attention. This double siar was eligibly situated in the heavens, and could be observed nearly eTery month in the year. It had near it several minute Btars which could be uaed as {,oints oC reCerence, and finally the rapidity oC its proper motion Indicated its probable nearneBS to our sun and .ystem. Bessel selected two minute stars as points oC reference, the one in a line nearly perpendicular to the middle point of the line joining the components of 61 Cygm, the other in the db'ection of this line. With the heliometer he me8lured the distance of the middle point oC the line Joining the components oC 61 eygoi, Crom each of the points of reference, 16 times each night, and finally detected a change in these distances which eeemed to depend on the orbitual revolution of the earth. Some three years of observation confirmed the accuracy of the first results, and gave the parallax of this double star equal to 0".3480, or only , about three-tenths of one second of arc, 80 that if a globe of 100,000,000 of miles in diameter, could be seen from this fixed ltar, its diameter would not appear greater than about the sixthou8andth part of the sun's a~parent diameter. The parallax once obtained, the distance is readily deduced, and is found to be 657,700 times greater than the earth's distance from the sun, or Sl) remote that the light of the star oo1y reaches us after a journey of more than ten year" although it fties at the rate oftwel ve millions of miles in every minute. . The distance of the double star being known, observation gives us about 540 years for tbe period in which the components revolve around their common center of gravity in an orbit whose diameter is about ninety times the diameter of the earth's orbit, while the amount of matter in these two stars i. a little le88 than half that contained in our sun. Since BelHI determined the parallax of 61 Cygoi, other 88tronomers have pursued the investigation with IUccesS. The following have been deduced by the RUHian astronomer M. Peters, and announced in a recent work by M. Struve, oC Pulkova. 00".349. Absolute parallax of 61 Cygni ,. " .. LytIB 00 .103. " "Polaris 00 .067. " " Groombridp No. 1830 00 .226. " " .. Aurige or Copella 00 .016. " " , Ursa,. Major 00 .133. " •• • B06Us, Arcturis 00 .127. ed

+ + + + + + +

205

THE FIXED ST A.U.

Fr~ the table it is readily seen tbat 61 Cygni islbe nearest .of all the fixed stars whose distanoes have been discovered. M. StriiYe, b'y a beautiful trsin of reasoning, ·deduotll the relative distances of the. stars of the various magnitudes, from the let to the 6th magnitude inclusive, and finds them to constitute a geometrical progression whose common ratio is 1 di vided by thp square root i. Calling lbe distance oC the 6th magnitude stara 10.000 he finds

or

Mapitude.

Dill. determlDed.

ComJlu..d.

1.0000 0.6998 0.5001 0.3609 0.2413 0.1424

10000. O.itm. 0.5000: 4 0.3536. 3 0.2500. 2 0.1768. 1 It will be seen lbat the numbers in the two columns scarcely ditrer, except in the case oC stars of the 1st magnitude, and here too few eXist to furnish M. Struve with the requisite data Cor his computations. So that this most cnrious law of distances would seem to be founded in nature. Every even terlD is half the preceding even one, and the same of every odd term. If it were now possible to determine the absolute mean distance oC the stars of anyone mBNnitude, the ~l diatances of all other magnitudes would readJly be derived from this remarkable law. 'fbi. haa been approximately accomplished by the Russian astronomers. Frolp the actual parallax of about thirty stars of the 2d magnitude, the value of the mean parsllax of all the stars of that magnitude haa been derived, and we are now able to present lbefollowing table: J Distance (radiu of ~ STime lbr li"'110 l App. mag. !'arallax. l Earlla'I orbit ... 1). S 1"olDt'I JIl ),t-:. n. S 1 00".166 1,216.000 19.6 2 00 .098 2,111.000 33.3 3 00 .065 3,151.000 49.7 4,375.000 4 00 .047 69.0 5 00 .034 6,121.000 96.6 6 00 .024 8,746.000 137.9 7 00 .014 14,230.000 22U . 24,490.000 8 00 .008 386.3 9 00 .006 686.5 37,2oo~000 Henchel's lao 00092 224,500.000 364l·0 _allelt ltar. S· • 6 5

It is not pretended that these i'eBults are absolute. These Yaluea are only approximate, but the errors are comparatively amall; and ahow. to us clearly, lba Yaatneaa of lbe UDiva.... of God.

S

206

GEOGR.APHY OF THE HEAVDS.

Having learned in this way the distances of the fixed atars, the inquiry arises. how are these objects distributed throughout apace' Are they scattered inditrerently in all directions, and at distances nearly equal from each other. or is their diatribution governed by any attainable law? The bright circle of light called the Milley W:1Jf' which sweeps round the entire circuit of the .heavens, aud whl~h to t,he naked eye ap~rs only fain~y luminous, when exaJDlDed With the telescope, III found to consist of millions of stars, crowded and condellB8d together with the moat extraordinary richnees ~d profusion. Herschel conceived the idea of measuriDg the dep~s to which the stars extended in the Milkf Way, and by reselling out beyond hs extreme limite. aacertainlDg the figure which would be formed by cutting this vat bed of stars by a plane drawn perpendicularly to ita surface. lt is manifeet, that if the stare are all at equal distances, and finit.e in number, that wherever the stratum extends deepest into space, there will we be enabled to count the greatest lIumber of stars iD' the field of a given telescope. And indeed, the number counted in any two direetiona, by the same teleacope, will give the relative depth to which the stara extend at these two points. Soch wa Herschel's plan of lOUfIIling the Milky Way, and of learning its figure. With the full f.ower of his twenty feet reftecting telescope, he thought it pOSSible to pierce through even the deepeBt portionll of the Milky Way, and to send the visua\. ray far beyond. Tbis idea. so long maintained by the followers of Herschel, hal recently been attacked by Prof. Strftve of Pulkovs. who maintaiDs that it was abandont'id by Herschel himself in his. later papers. Sir John Herschel does not accord with the views of Str6ve, but maintains the original opinions of his father. From the investigations of the two Herschels, the vast strstum of stars, called the Milky Way, appears to be arranged under the fiJ!tre of a ftat ring, whose thickness is small when compared wuh ita diameter. The central' parts of the ring are not so thickly strewn with stars as the outer portioDs or circumference. - The rim is divided iDto two branchea, or streams of stars. which diverge from each other for a certain dilitaDce~ but finally re-unite aDd ftow on together. The two Herschels have made a sufticient number of observationB to determine the figure cut from this bed of stars by a plane perpendicular to its surface, and cutting acroaa the porti.on where the two streams are most distant from each other. There are portions of the Milky Way iDcluded in this IIBtltion, in which it is said,' the stars extend 80 deep in space that the seriea in a right line, from the sun out to the e1treme limit, cannot number leBs than jltJe hundred. Btars. each as remote from thl10ther as 61 Cygni is from our sun. lu case we admit thill statement, there are stars belonging to ow

THE MILKY WAY.

5107

Milky Way 80 widely eepuated, that their light will require mon thlUl ten thouslind yeare to pa.. from one kI the other, or to sweep across abe longest diameter of abis mighty nniveree of stars. If Struve's idea of Lbe absolute u":!'atJunnabk challlcter of the Milky Way be adopted, it only incre&88s the sw.eep or IBlilfe of SUDS and systems, grouping tbem inkl subordmate clu'stermgs, and uniting them inkl one unbounded, immeasurablt', innuDl",r. able, whole. In whatever way,. under whatever IIspeet, we eont.!mplate Lbis vast constellation of constellations; this magnificent cluster of clusters; the number, distance, magnitude, aud brilliancy, of its components, cannot fail to fill the mind with wonder and uklnishmenL Admhtillg that the telescopic vision sweeps beyond die limits of the Milky Way, it may be asked, what does the eye eoooun""r in these remote regions? Many objects lying in these far distaDt portions of apace, have already been noticed among the tale&Copic objects of Lbe dUrerent constellations. Tbese are tbe cluaUr. MIIl·MbuJI& By a careful examination of these wonderful objects, Herschel finally reached the conclWlion, that all tbe elualere, and many of the aebuhe, were immense aggf')gatiolll of stars, forming"separ8te univerees, as extensive and rich as tbe Milky Way iteelf. He even ventured to attempt the measure of the relative depths of these remote objects. His method is simple, and be readily comprehended. The naked eye can discern stsn 0 the sixtb magnitude, or thoae twelve times as remote al Sirius, the largest and brightest star in the heavens. In case the pupil of the eye could be expimded kI twice its present dimensiona, it could then penetrate twice as deep inkl space as it now can, or would see Sirius if it were removed backward twenty-four times deeper into space. Now, although the pupil of the eye cannot literally be expanded kI twice or thrice iilt preeent size, the telescope comes in kI accomplish precisely ti,e same effects; and admitting that an object glasa permits all the lillht which falls on it kI pasa through, itsrowerkl p'enetrate space Will be in the ratio of its surface to that 0 the pupal of the human e:re. By covering a large object gla.. with circular coverings, pierced with aperturea of one inch, two inches, &0., diameter in tbe center, we may give kI it, at pleasure, different space penetrating powers. Fixing the relation 'of these to the eye, we are prepared kI examine any object, and determine, approximately, its distance. Suppose a nebula is seen faintly VISible, with three inches of aperture kI the object gla... We expand the aperture to four ineh_it appears brighter, but no stars are seen. We increase the aperture kI five inches, the nebula grows still brighter at the center, but as yet no point-like stan are vieible ; a farther increase kI six inches, however, shows the objt'Ct kI

mal

lOS

GEOGRAPHY 09 THE HEA.VENS.

eo...t of millioDl of minote .... Jnt IeDdered visible to the eye. Now thelengah of the nIDal ray of the teleecope. compared with that of the unaided "'.. is readily de&ennined; and knowing this, we learn, approXImately. the distance of' thil cluster of stare. In thil way Sir W. Herachel de&ennined the profundity of all the principal clua&erl. Some of the Debul., coald not, by an, lpace penetrating power of his. great teleecopes, be reeolved Into etara. Their shapee were irlegular. aDd their outlines ill defined. Some were easily visible to the naked ey.. and yet DO telescopic power could resolve them into stars. Others were found to contain occasional stars, with oentera of more or 1... condensed light; finally, stars were found lurrounded by a nebulous baze of vut flxtent, wbose center waa occupied by the star. Examining aod comparing aU the.. pbenomena, Herachel finally reaohed the conclusion, that while v'" nombera' of appareot nebol., were real closters of stars, yet there were some In which the material composing tbem was a kind of luminous mist, like that forming the tails of comete. He conjectured that this chaotic matter might po..ibly furnish the material out of which, by condenaation, stars inight be forming. The nebuioul seare, as well .. the planetary nebula, ..emed to accord very perfectly with thie hypothesis. Dooble and triple nahul., were found, from which the double and triple stars might eventually spring. and thul grew up, imperceptibly, the outlines of a magnificent theory, a eoft of sublime cosmogony of the oniverse. Thf1118 speculation., enlarged by La Place, .. we shaH see hereafter, were made to lender an accoont of the sun and planets, and the pecnliar arrangement of the solar s1.stem. The nebolar theory, as it is termed, had for a long whIle its ardent supponers, aDd if not absolutely adopted by distinguished astronomers, at least, it was received by them with no inconsiderable favor. The resolution of the nebola in Opon, by Lord Roa... and by Prof. Bond, of Cambridge, has in some degree shaken the faith of some in thil lemarkable hypo"'esis, while it i,s justly remarked, that Herachel only adopted it after the relolution of hundreds of nebolll8. , In case we abandon the idea of chaotic matter existing in Ipace, and adopt the notion that the· filmy, almost spiritual, objects, which barely stain with light the blue of the heavenl, are immen.. congeries of stars, it only expands our knowlMp of the illimitable elltent oflhe universe of God. Some of theaa objects are so remote, that a hundred thousand years moat roll away. before the light which they emit could traverae the di.. tance by whieh we are separated from tham. Many of thEl clusters of stara appear under globular forma, and from the manifest condensadon about thAir cenwrs, 8eem to indicate the aistence of 80me active energetic power,like gravita-

THE MlLIY WAY.

lioo. which ill eurting ita inftaence on tile individual ltare 01 theee grand ayatema. The ex&enlion of the law of univereal gravitation to the region of the fixed ltare. waa long believed, before it could be pOli,ively demonltrated. By the diseovt!l7 of the binary or revolving lunl, thil conjecture became a pOBuive fact. In a large number ofinatancea, the orbita deecribed by theae bodies around their common cen&ere of gravity, have been computed according to the law of ~vitation. and in every instance the predictionl have been venfied. That stara do attract each other ia now poaitively demODIlratecl. and the law of attractioD ia the jnverae ratio of the aquare of the dietance, or that of gravitation. If two or three atara, grouped together, are sabject to thil law, it is reaeonable to conclude that larger collectionl, such al the Pleiades, or Coma Berenieea, may be under the controlling power of the ame foroe. And if thil be trae, why not extend ita operation to the mighty clas&er of clal&era, the Milky Way itaelf. 'fhi. haa beeD done recently by M. Mldler, of Dorpat, Russia, and he thinks he haa determined, approximately, the center of the atratum of atare. or th~ uIrGll1J.tem, compoling the Milky Way. By comparing the ab8Ola&e placel of the fixed stare, at intervala of one or two hundred/eare, it ja found that a large numbf'r of \hem are in motion, an with an appreciable velocity. 1'his il not merely apparent, but in many lnstanC1!8 mast be absolute change of place in space. Some stare are moving very swiftly, and exhibit their progresaive changes in a few months; while othere, again, mo.,e with IUch extreme alowness, that nen bundreda of y81r8 are neceuary to render their change appreciable. It seems quite as rea80nable to suppoae that thelle complex and jn.,ol,ed motiona of the distant ltare, Bhould be go.,emed by Bome Bimple and beautiful law, al that the planeta, whoBe apparent motioDI were far more eomplicatf'd, should be reduced to order aud simplicity. This great task of unre,eling the complicated phenomena of the proper motion of the fixed etare, haa been attempted by the RUBsian aatronomer. It had long been conjectured that the analogy exiating in the eolar aYltem would bold among the sys&ema ohtare. And that .. the Iun wal valtly larger than hil re,olving planeta, and sa each p,nma,.,. planet wal much luperior to his re,ol'ing moonll, eo there miJht exist in lpace 80me Ufltral nm, whOle T88t proportions would far exceed all the stan lubject to ita nontrolling inftuence. 'rhis analogy wal broken by the diecovery of the binary ltare. Here we find many inltances in which the componenta are exactly equal in magnitude; othera, afain iD which the one il llightly auperior to the other; in Ihort, al pOIIIble relatioDI of magnitude. Thil deea not interfere with the IItability and perfection of the sya~ml. The componenta mol,e 'about their common center of graTity aa though it were filled

_gAt,

.

'

2JO

GF.OGRAPHY OF THE. HEAVENS.

with a mall 0(. 101icl matter. Mldler rejec&8 &be idea, thea, of the es.istence of any VBSt. central globe, alld srgUes thllt in case it. existed, it would be impo88ible to preveotit8discovt
MILKY WAY.

The p01#WzYf

1 "11,

eq.ualed by The mlcromete'. now In use, 1Lngle inch into eighty thousand equal parts! Ilnd should two close fixed stars commence to separate from each other by so small a quantity that eyen three millions of years would be required for a complete reyolution in the heaven" these delicate instruments would detect the motion in a single year. With such instruments, it is not wonderful that human geniul dares the most difficu} t researches.

ttl

GEOGRAPHY OJ' THE HEAVENS.

CHAPTER VI. GENERAL PHENOMENA. 01' THE SOLAR SYSTEM. 'rHUS far our attention has been directed to the phenomena of the sidereal heln·ens. Tbe names, positions, and relative mag· nitudes of the stars; their ch,anges of light, proper motion, and physical association into systems of greater or less'complexity, have heen considered and explained. The mind has penetrater the marked efFecta of ita changes of pOlition in regard to the Earth; and the Moon, so conspicuous among the bodies which J[ive light by night, and from ber soft. and lilYery brightnels. 80 pleasing to behold; remarksble not 'only for ohanges of position, but for the varied phasel! or appearances which she presents, as she waxes from her crescent form through all her difFerent stages of increase to a full orb, and wanes back again to her former distinguished figure. The partial or total obscuration of these two bodiPII, whil'h sometimf!s occurs,--darkness taking place even at mid-day. and the face of night, before lighted up by the moon'. beaml, being suddenly Ihaded by their ahaence,-haye always beell among

THE SOL'R SYSTEM.

213

the mOlt atriking astronomical phenolDena; and so powerful in their in8ueRC8 upon the beholdeR, al to fill them with perplexity and fear. If we observe these two boeliel, we Ihall find, that, besides their appaRnt diurnal motion acrOl1 the heavenl, they exhibit other phenomena, which mUlt be the elfec' of motion. 'rhe Illn. during one part of the year. will bll >llIen to tile livery day fnrther and further toward the north, to continue longer and longer above the horizon, to be more and more elevated at midday, until he arrives at a certain limit; and thpn, during 'he other part, the order il entirely reveRed. The moon sometirnel is not a88n at all; and then. when she first becornps visihle, appears in the west, not far from the setting lun, with a slenllpr crescent form. Every night she appears at a grtIlIwr distance from the setting sun, increasing in lize. until at leugth she il found in the eaat, just aa the lun is linking below the horizon in the wes1, The IOn, if his motions be attentively observed, will be fnllnd to have another motion, opposite to his apparent diurnal motion from east to wes1, Thil may be perceived distinctly, if we notice, OD any clear evening, any bright star, which i8 fir8t vi8ible after Bunset, near the place where he lIunk below the horizon. The following evening, the atar will not be visible on account of the approach of the sun, and all the stara on thE' east of it will be sUCC888ively eclip8ed by hi8 raY8, until he shall have made a complete apparent revolution in the heaven8. Theseare the most obvions phenomena exhibited by these two bodie8. There are, a180, aituated within the limits of the zodiac. CE'I'win other bodies, which, at first view, and on a superficial examination, are scarcely distingui8hable from the fixed 8tars. But observed more attentively, they will be seen to 8hine with a milder and lteadier light; and be8ides being carried round with the 8tars, in the apparent revolution of the great celestial concave, they will 888m to cbange their place8 in the concave itself. Sometimel they are 8tationary; 8ometime8 ther apppar to be moving from we8t to eaat, and sometime8 to be gomg back again from ea8t to we8t; being seen at 8un8et 80metimes in the ealt, and 80metimes in the we8t, and always apparently changing their p08ition with rej[ard to the earth, each other, and the other heavenly bodies. From their wandering. as it were, in thi8 mal/ner, through the heaven8, they were called by the Greeks ".~ "."'''', planets. which 8ignifies wanderer•• There al80 sometimes appear in the heaven8 bodie8 of a very extraordinary aspect, which continue yi8ible for a con8iderable period, and tbeedi8appear from our view; and nothing more i8 seen of them, it may be for years, when the, again present themselves, and take their place among the bodIes of the cell'stial sphere. They are distinguished from the planets by a dull and cloudy

214

GEOGRAPHY OF THE HEA'ENS.

appearance. and by a train of light. As they approach the 8un. however, their faint and nebulous light becomes more and more brilliant, and their train increases in length, until, they arrive at their Dearest point of approximation. when they sbine with their greateilt brilliancy. As tbey recede from the sun. they gradually lose their sp,lendor. reaume their faint 'and nebulous appearance. and tbeir train diminishes. until tbey entirely disappear. Thf'y line no well defined figure; they seem to mo,e in e,ery possible diret'uon, and are found in every part of the heavens. From their train, they were called by the Greeks .......-r ..,. comets, which signifies haYing long hair. Tbe caules of these Yarions phenomena must have. early constituted a very natural subject of inquiry. Accordingly. we shall find. if we examine the history of the. science. that in very early times there were many specUlations upon this subject, and . that different theories were adopted to account for these celestial appearances. 'I'he Egyptians, Chaldeans, Indians, and Chine.e, early ~. many astronomical facts, many ohll8"atiollll of important phenomena, and many rules and methods of utronomical calculation; and it h.. been imagined, that they had the ruillll of a great system of utronomical science. which. in the earliest ages of the world, had been carried to a great degree of perfection, and that. while the principles and explanatiollll of the phenomena were 100, the isolated, unconnected raet., rules of calculation, and phenomena theDllllllyell, remained. Thus, the Chin-. who, it is generally agreed, JKIIIII888 the 01d1!8t authentic obserYatiOlls OIl record. hIIve recorded in their annals a conjunction of aye planets at the same time, which happened 2461 years before Christ, or 100 years before the flood. By mathematical calculation, it i. aacertained that thi8 conjunction really occurred at that time; The first obIIervation of a BOlar eclipse, of which the world h.. any knowledge, w.. made by the Chineee, 2128 years before Christ, or 220 years after the deluge. It.-ne, al80. thRt the Chinese understood the method of calculating eclipaea; lOr, it is said that the emperor wu 80 irritated against the great officers of state for neglecting to predict the eclipse, that he cauEd them to be put to death.- The utronomical epoch of the Chinese, according to Bailly, commenced with Fom, their. first emperor, who flourished 2952 yeara before' the Christian era, or about 350 years before the deluge. If it be ..ked how the knowledge of this antf'diluvian utronomy was preee"ed and transmitted. it is 88id that the columns on which it was regisrered haye sumyed the deluge, and that th~ of Egypt are only copies, which haye becom" originals, now that the othlll'll have been fo.... gutten. The Indians, al80, prof_ tn haye many ce1eBtial OOoefYBtiona of a Yery early date. The (}haldeans baY8 been justly celebratl'd in all agee for their astronomicalobt!erYatiool. . When Alexander took Baby• It i, wen known that the Chine .... hRVe, from lime immemorial. cnnoi""rett their 80lar eclipses and conjunctionI' oflbe planets al' prognostics of importanee 10 the empire, and thallhev haYe been predicted .. a mailer oC stale policy.

THE IIOLAR IIY8TEM.

215

Ion. hi.. p~ptor, Calliothellflll, foulld a aeries of UhaJ.letln obserVation.. made in that city, and extending back, with litlle interruptioll. through a period of 1903 yeaN ~illg that evpnt. This would carry us back to at leut 2234. years before the birth of Uhriat, or to about the time of the dispenioa of mankind by the confusion of tongues. Though it be conceded that, upon this whole period in the history of the sci"nCt', the ohscurity of very remote antiquity must nece.arily rest, still it will remain evideut that the phenomena of the beavenly hodiea had t-n oboerved with great attention, and had been a SUbject of no ordinary interest. But, however numerous or important were the observation. of oriental antiquity, they were never reduced to the shape and sy ouuetry of a regular .,lI&8m. The Greeks, in all probability, derived many notions in regard to this acience, and many facti and obaervatioll8, from Egypt, the great filUlitIlin of ancient learning and wisdom. alld many were the apeculatioll8 alid hypothaM of their philulI"pbers. In the fabulous period of Grtlcian history, Atlu, Hercules, Linus and Orpbeu.. are mentioned a8 persons di"tinguiahed for their k Ilowledge of astronomy, and for the improvementl which tbey made in Ih" science. Bilt, in regard to tbia period, little is known with certainty, and it must be tonBidered, III it is termed,

t

fabulow. . The firet of the Grep,k philosophers who taught astronomy, W88 Thales. of Miletus. He flourished abont 640 years before the Christian ere. Then followed Anaximander, Anaximenes, Anaxagoras, Pythagoras, Plato. Some of the doctrines maintained by these philosophers were-that the earth was round; that it had two motions, a diurnal motion on its axis. and an annllal motion around the SUn; that the sun was a globe of fire; that the 1D00n received her ,light from the sun; that she W88 habitable, contained mountains, spas, &c.; that her eclipses were caused by the earth's shadow; that the planets were not deeigned merely to adorn our heaven.. ; that they were worlds of themselves; and that the fixed stars w!lre centers of distant systems. Some of them, however, maintained that the earth W88 flat; and others, that, though round, it was at rest in the eenter of the universe. When that distinguished school of philo8tJphy was established at Alexandria, in Egypt, by the munificence of the sovereigns to whom that portion of Alexander's empire had ·fallen. astronomy received a new impulse. It was now, in the second century after Christ, that the first complete system or treatise of astronomy, of which we have any knowledge, was formP.CI. All before bad been unconnected and incomplete. Ptolemy, with the opinions of all antiquity, and of all the philosophprs who had preceded him, spread oat before him, composed a work. in thirteen books, called the M.,.&A. Eun"t", or Great SystP-m. Rejecting the doctrine of Pythagoras. who tlIulfht that the sun wa. the center of the uni verse, and that the earth had a diurnal tDO

216

GEOGRAPHY OF THE HEAVENS.

tion on h. axis and aD annual motion around the 8un, as contrary to the evidence of the sen888, Ptolemy endenored to account for the celestial phenomena, by supposing the earth to be the center of the universe, and all the heuenly bodies to revolve around h. He seems to have entertained an idea, in retrBrd to the "upposition that the earth revolved on ita axis, SImilar to one which somt" entertain even at the present day. "If," says he, .. there were any motion of the earth, common to it and all other heavenly bodies, it would certainly precede them all, by the exceBs of ita maBS being so great; and animalB, and a certain portioo of heavy bodies, would be left behind, riding upon the air, aod the earth itself would very Boon be completely carried out of the heavens." . In explaining the ceJestiaI phenomena, however, upon his hypathesit, he met with a difficulty in the apparently atBtionary attitude and ~ grade motions which he 1811' the planets 80meUIJIIlII bave. To explain this, however, he auwc-l the pbmeta to revolve in amaII c:iroles, which he called epicycles, which were, at the I8me time, carried around the earth in larger cin:Iea, which be called ditTerenlB, or carrying circles. In following out biB theory. and applying it to the explanation of different phenomena, it became n-.ry to add new epicycles, and to have reo COUJ'18 to other expedients, until the ayatem became unwieldy, cumbroue, and complicated. This theory, although, astronomical obeenatioua c0ntinued to be made, and 80me diatinguisbed as&rooomerB, appeared from time to time, W88 the prevailing theory until the middle of -the fifteenth century. It W88 not, however, alway' received with implicit confidence; Dor were its difficulties alwa¥.! entirety unappreciated. ' Aiphon8O X, king ofCutile, who ftourished in the thirteenth century, when contemplating the doctrine of the epicycles, exclaimed... were the nni_ thus conlltructed, if the Deity bad called me to biB counsels at the creation of the world, I could have given him good advice." He did Dot, however, mean any impiety or irreverenoe, except what W88 directed _ apinst the ayatem of Ptolemy. About thll middle of the fifteenth century, Copernicus, a native of Thorn, in PruBsia, conceiving a passionate attachment to ,the 8tudy of astronomy, quitted the profession of medicine, and devoted himself, with the mOBt intanse ardor, to the study of this science. .. His mind," it is said, .. had long been imbued with the idea that simplicity and harmony should characteriZe ilIe arrangementa or the planetary system. In the'complication and dillorder which, he Baw, rei~ed in the hypothesis of Ptolemy, he perceiVed insuperable ebJ8Ctions to ita being considf'red as a representation of nature...· ,. In the opinions of the Egyptian sages, in those of Pythagoras. Philolans, Arilltarchus and Nicetas, he recognised hi" own earliest conviction that the lIarth was not the center of the universe. Hia attenr.i.on was much occnpied with ~e speculation of Mar-

THE SOLAR SYSTEM.

217

unaa Capella, who placed tbe sun between Mal'8 and tbe moon,

ad made'Mercury and Venus revoln atoulIlI him as a center; and with &he systl!1Il of Appollonius Perpul, who made !ill the planets revolve around'tm. sun, ""bile the sun and moon were C81Tied around the eanh. in the center,of the universe.' , ", The examination. however, of these bypothese" gradually exJM'lled thfl difficulties with which the subjflClt was beset. and, afler th6 labor of more tban thiny yeal'8, be was permitted to see the true system of the univtorse. The sun he considered as immo.able, In ,the center of the systelil, while thll earth revolved around him, between the orbits of Venus and Mars, and p,roduced, by i,ts rotation about its axis all the diurnal p~l'nomena of the eeleati\11 sph~re. The' otber planflts lie considered 'lis revolving about the sun, in orbits extflrior to that of the earth. Thus the stations and retrogradations of the planeta were tbe necessary consequence of their own motions. 'Combined with that of the earth about the sun. He said that... by long observation, hfl discovered, that, if the motions of the planets be compared with that of tbe eartb, and be estimated according to the times in' wbicb they perform 'their revolutions. not only their several appearances would follow from this hypothesis. but that it would so connj!Ct &he order of the pldnets. ,their orbits. magnitudea, and distances. and even the apparent motion of the fixed , 8t.a,ra, that it would be impossible to remove one of these bodies out of its 'place without disordering the rest, and even the whole of the universe also." , , Soon after the death of CopE'rnicus; arose Tyeho Brahe, born at Knudstorp, in Norway. in 1546. Such was the distinctioll which be had attained as an astronomer, that. when dissatisfi"d with his residence in Denmark, he had resolved to remove. the king of Denmark, learning his intentions. detained him in tbe ·kingdom. by presenting bim with the ",anonry of Rothschild, with an income of 2000 crowns per annulD. He added to this sum a pension of 1000 crowns. gave bim the island of HUl'n, and established for him an observatory. at an eJ:pense of about 200.000 crowns. HfOre Tycho continued. for twenty-one years, to enrich astronomy with his obsflrvations. His obBervations upon the OIoon Well' important. and IIpon the planflts. numerous and pl'tlCise. and have formed the data of the preBflllt generalizations in alltronomy. He. however. rejl'ctfld the system of Copernicus; considering the earth as immovable, in the center of the system; while the lun. with all the planets and comets revolving around him. 'performed hiR revolution around the earth; and. in the course of twenty-four houl'll, the stars also revolved about the central body. This theory was not as Rimple as that of COpfll'nicus, and involved the absurdity of making the sun, planets, &c., revolve around a body comparatively insignificant.

T

218

GEOGRAPHY OF THB HEAVENS.

Near the cloae, of .the 16th century. atoee two, lOin, who wrought most importapt ch~gea in the science, Kepler B.Dd Galileo; the former a German. the latter an Italian. , Previoua to Kepler, all investigations proceeded,upon the aupposition that the p\an8ts lD!Jved in circular orbits, which had been a apurce of much error. This aupposiuoD Kepler showed to be false. He discovered that their orbits w~ emplles. 'Phe orbits uf their secondariea, or IDOO~, he also found to be the same curve. He n.ext determined the dimensiona of the Qrbits of the planets. and found' to what their velocities ip their motions through their orbits, and the times of thflir revoluuons, were proportioned; all truths ofthe greatest importance to the science. While Kepler was, making these discQveries of facta, very essential for tbe explsnation of many phenomena, Galileo was discovering wopders in the heavena never before ~n by the eye oflDan. Having improved the telescope, and applied it to the heavens, he obse"ed mquntains and valleys upon the.surface of our moon; satellites or secondaries were di~covered revolving abuut Jupiteq and Venus, as Copernicus had predieted, wal seen exhibiting all the different phaaea of the moon,:waxing and waninl{ as s~e does, through various forms. Many minQte stars, not viSible to the naked eye, were,descried in the Milky Way; and the largest fixed stars, instead of being magnified, appeared to be Rmall brilliant points, an incon.trovertible argument in favor of their immense distance from U8. All his diacoveriea \ served to confirm the Copernican theory, and to show the absurdity of the hyp.othesis of Ptolemy. , . . Although the general arrangement and motions oft}le planetary bodies, together with the figure of their orbits, had been thul determined, the foree or power which, carries them around in their orbits, was as yet unknown. The diacovery of this wal reserved for the illustrious Newton.- By reflecung on the nature of gravity-that power which causes bodies to descend towards the eenter of the earth-ainee it· poes not sensibly diminish at the greatest diatance from the center of the earth to' which we can attain, being as powerful on the loftieat mountaina liS it is in the deepest cave.rns-he wss led to imagine that it might extend to the moon, and that it might be the power whiCh kept her in her orbit, and caused her to revolve around the eerth. HI! was next led to luppole that perhaps the same powel carried the primary planets around the sun. By a series of calcfdationa, he was enabled at length to establish .the fsct, that the aame force which determines the fall of ab apple to the earth, carries the moona in their orbits around the Illp. • The diecovery or Newton . . . ill 80JIle l118uure antloipaled by Copemic1ll, ,""pJer and Hooke, .

219

THE SOLA.R SYSTEM

To recapitulate brietly: the system (not hypothesis, for mucb of it bas been esta~lished by mathematical demonstration), by wbich we are now enabled to explain with a beautiful simpficity the different phenomena of the sun, planets, moons, and comets, is, that the sun is tbe central body in' tbe system; that the planeta and CGmets mGve rGund him in elliptical orbits, whose planes are more Gr. le88 inclined to eaoh other, with velocities bearing to each other,. a certain ascertained relatiGn, and in times related to their distances; that the mOGns, Qr secondaries, revolve in like manner, abGut their primaries, and at the Sllmli time accompany them in their mGtion arGund the sun: all meanwhile revolving on axes of their own; and that these revolutioDll in their orhits, are produced by the mysteriGus power of attraction. The particular mGde in which this system ill applied to the explanation of the different phenomena, will be exhibited as we proceed to consider, one by one, the several bodies abo.. mentioned. 'rhese bodies, thus arranged and thus revGlving, cGnstitute what is termed tbe sGlar system. The planets have been divid"d into tWG classes, primaries and secondaries. The latter are also termed mGGns, and sGmetimes satellites. The secGndaries ara those which resGlve abGut the primaries. Thera have been discGvered sixteen primaries; namely. Mercury, Venus, the Earth, Mare, Vesta, Juno, Ceres, Pallas, Astraa, Hebe, Iris, Flora, Melia. Jupiter, Saturn, Urauns, Neptune. Mercury ill the planet nearest to tbe sun, then fGllow .the others in the order in which thl'y are named. The nine small planets between Mars and Jupitl'r ara telescopic, and have been termed lIsteroids. There have been discovered nineteen secondaries, Gr mGGns. Of these, the Earth has one, Jupiter fGur, Saturn seven, Uranus six, and Neptune one. None Gf these, except our moon, are visible without telescopic aid. We proceed to examine the objects constituting the solar system, in detail. . • The orbits or path. of the planet• •" ........ ocover.d by tracing Ibe course of th~ pllUlel by me.... of !be lind a.arl

•

220

GEOGRAPHY OF THE HEA¥ENS.

CHAPTER VII. THE SUN.

THE sun is a vast globa, in the center of the solar system, dispensin, ligh~ and heat to al1 the planets, and governing all their mollons. ' It is the !freat parent of vegetable life, giving warmth to the seasons, and color to the landscape. hs rays are the cause of various vicissitudes on the surface of the earth and in the atmosphere. By' their agency, al1 winds aTe produced, and the waters of the sea are made to circulate in vapor thro.ugh the air, and irrigate the land, producing springs and rivers. The sun is by far the largest of the heavenly bodies whoss dimensions havs been ascertained. Its diameter is somt'thinl[ mort' than 883,000 miles. Consflquently,it contaills a volume of matter equal to /QfM'teen hundred tlwwand globes of thfl size of the earth. Of a body so vast in its dimensions, the' human mind, with all ita eiJ'orta, can form no adequate conception. The whole distance between the earth and the moon would not suffice to embrsce one-third of its diameter. Were the lIun a hollow sphere, perforated with a thousand openings to admit the twinkhng of .thfl luminous atmosphere around it--and were a globe as large as the earth placed at its center, with a satellite as large as our 1II00n, and at the .ame distance from it as she is from tbe eartb, there would be present to the eye of a spectstor on the interior globe, a universe as splendid as that which ROW .appears to the uninstructed ey-. universe as large and extenaive as the whole creation was conceived to be, in the infancy of astronomy. The next ,thing which fills tbe mind w.,ith wonder, is lh, dillame at wnich so great a body must be placed, to occupy, apparently, so small a place in the firmament. Tbe sun's mean distance from the earth is twelve thousand times tba earth's diameter, or a little more than ninety.five millions of miles. We may derive some faint conception of such a ilistance, by considering that the swiftest steamboats, whicb ply our waters at the rate of two hundred miles a day, would not traverse it in. thirteen /t"ndred year.; and, that a cannon ball, flying· night and day, at the rate of sixteen miles a minute, would not reach it in

tie_yean.

.

THE SUN.

221

The Sun, when viewed through a' telescope, presents the appearance of an enormous globe of fire, frequenLly in a state of :violent ~itation or ebullition; dark spots of irregular form, rarely viSible to the naked eye, sometimes pall over his disk, from eallt to west, in the period of nearly fourteen day•• These spots are usually surrounded by a penumbre, and that, by a margin of light, more brilliant than that of the sun. A spot when tirst seen on the eastern edge of the sun" appearll likl! a line wbich progressively extends in breadth, till it reaches the middle, when it begins to contrset, and ultimately ~isappeare, at the western edge. In some rare instsncea, the same spots re-appear on the east side. and are permanent for two or tbree. revolutions. But, as a general thing, the spots on the sun are neither permuient nor uniform. Sometimes several small onea unite into a large one; and. again, a large one separates into numerous amaH oneil. Some continue several days, wel'ks, and eTen montha, together; while others, appear and disappear, ,in the course' of a few houre. Those spots that are formed gradually, are; for the most part, as gradually dillolved; wbilat tbose that are sudd..nly formed, generally vanish as quickly. It is tbe general opinion. that spots on the sun were first discovered by Galileo, In the bel{inning of the year 1611 ; though Scheiner, Harriot, and FabriCiUS. observed them about the 8ame time. During a period of eighteen years from this time, the sun was never found entirely clear of spots, excepting a few days in December, 1624; at other times, they Wjlre frequently seen, . twenty or thirty at a time, and in 1625, upwards of tifty were seen at once. From 1650 to 1670, scarcely any spots were to be seen; and, from 1676 to 1684, the orb of the Bun presentAd a~ 'unspotted disk. Since the beginning of the ei~hteenth century scarcely a year has passed, in which spots have not been visible, and frequently in great numbars. In 1799, Dr. Herschel observed .one nearly 30,000 miles in breadth. A single III!COnd of angular IJI888Ure, on the aun's disk, 88 seen from the earth, corresponds to 462 miles; and a circle of this diameter (containing therefore nearly 220,000 square miles) is the least space which can be distinctly discerned on the IUD 88 a fliai61e tlrell, even by the mOlt poWerful gluaes. Spots have been obaerved,however, whOlle m-r diameter has been more than 44,000 D1i1al; aDd, if IIOJD8 records are to be trusted of even ltill greater extent , Dr. in a letter to the author, says, "I have for maDy years axamined the solar spots with considera~e ~ and have several times seen spots which were not less than the one-twenty-fifth part of the ~', diameter, which would make them about 22,192 miles in diameter, yet they were visible neither to the naked eye, nor through an opera gl88ll, magnifying about three times. And, therefore, if any spots have been visible to the naked eye-which we must believ.e. unI_ we refuse

rnA,

T

222

GEOGRAPHY OF THE HEAVENS.

respectable testimony-they could not have been much 1_ than 50,000 miles in diamel\ll'."

.

The afparent motion of these sPlit!! over the son's surface, i8 continua ly varying in ill direction. Sometimes they seem to move acros, it in 'traigAt lines. at others in CUnH! lines. These phpnomena may be familiatly iIIu8trated in the following manner.

.

.

Irf~~_ ~~ ___

__ _

!

Wi

$' PIg. I.

Fig. 1.

:

-

!.

.•_.... 1 __.__

M.

.'

i

LeI E E repreeenl Ihe ecliplic j N S, il. north aDd 100lb pOlea,' M the poiDI wbere Ihe .POI enlen, and m Ibe poinl wbere illeave. Ibe lun'l dilt. AI the end of November,. and lhe beginning of December, Ibe lII!0t will appear 10 IIlOve downwardl, acroa the 1110'. di.k, from left to right, deocribillll the .traight line. M .... · Fig 1 j IIOOn allur thi. period, tbeoe line. begin gradu.Jly to be inftected toward. tbe north, till ahout Ihe end of February, or the beginning of March, wben they delCribe the CUNe Iinp. refr.eenlrd in Fig. II. After Ibe b~ginlling of March, the curvature deere........ til the latter end of May, 0, Ihe beginning of June, wben they again de.cribe .I,Bigbt line. lending op"""ntl. as in Fig. 3. By and hy the"" Itraigbt line. begin to be infteeled ""'""" ",ar"'. liII aboul the heginning of September, wben they lake ,be lorm of a curve, baving ill convel[ aide toward. Ibe lOull1 pole of the lon, BI in Fig... Fig. a

Fig. 4.

~"$:

It

i

I

~

-_. .. _.u .' :.,..

MI· .II

I

:

•

•••• 7...i .....··· . I

..

As these phenomena are repeated eyery year, in the same order, and belong to all the spots that have been perceived upon the sun's disk, it is concluded, with good reason, that these spots adhere to the sorfa('.8 of the 80n, and revolve with it, upon an axis, inclined a little to the plane of the ecliptic. The apparent revolution of a 8pot, from any particular p~nt of the 80n's disk, to the aame point again, is accomplished lD 27 days, 7 hours, 26 minutes, aDd 24 second8; bllt during that time, the apot has, in fact, gone through one revolotion, torther with aD arc. equal to that described by the sun, in his orbit, in the 8ame time, which reduces the time of the sun's actual rotation on hi' axie, to 25 days, 9 hours, and 36 minutes.

THE SUN.

223

, Th!! part of the lon'8 di8k not occopied by lpot&, il far from bei ng uniformly brigbt. Itl ground ia finely mouled' with an appearance of minute. dark dota, or p""",' Beracbel remarka t.l\at theae pores, when attentively wawhed, are found to be in a constant atate of chaolle. This ia certainly an error, if the change spoken of ia one visible under the eye; for I have watched theae minute pores with the greatest serotiny, but nner found while UDder the eye, the alightelt change. The elder BeJ'tIChel CODceiveO that the ann'a body waa dark or opake, and that it waa 8urrounded by' a luminou8 ocean or atmosphere of vaat extent. Beneath thil and above the aun'l surface he thought there might exiat a atratum of clouds, and with thia constitution he proceeds to account for the phenomena of the epoU. Tbe black core of the spot he rel(8rds 81 the solid opake body of the lun, _n through an opening in the lumio008 • atmosphere and ift .the SoatinJ. cloud I below. it, wbile the parual 'shade or penumbra he attnbntes to the hght reSected from the cloudy atratum. ' , I have watched the lolar spoll for three years with great a&o tention, and find it quite imposlible to reconcile the phenomena with any theory which IUpPOseS extreme mohility in th!! particlee composinlf the exterior surface. The outline of tbe penumbra is aeen sharp, keenly defined and cutting directly acrolls tb. small mottlinga or pores, aa though the exterior were a crust, hard and solid. melted out from under by some internal agent. Again. the outline of the dark core of the spot eate jnto the penumbra sharp and sudden. sometimes in long black filam!!nta of irregular shape, but always without any s'uch gradual shading off' as might be anticipated in case great mobility existed among the partieles of matter composing the exterior coating of the lun. The German astronomer Schwabe, of Dessau, haa discovered the remarkable fact, that there is a periodical return of the solar spota. In 1828 a very large number of spota were observed. Then for five years the number decrl'a8ed regularly. until in 1833 the apota counted reached a minimum; an increase now commenctld, and continued yearly up to 1838, when a maximum Dumh!!r was reacbed. Then a decline commenced, and continued to 1843, when but few 8pota were 8een. Since tbatlear the Dumber visible has been gradually on the increase; an during tbis year. 1848, I have never seen the 8un wilhou,t 8pota. anel many groups bave been very large. In exaniining the sun. I have occasionally seen that eurious phenomenon. called by the Germans" Lichtftacken .. lumi_jlalu•• They are brilliant points of swiftly moving light seen nellr the lun. and apparently as bright or even brighter tban the sun its!!lf. Some auppose them to be motea Soating in the upper regioDs 01

224

GEOGRAPHY OF THE HEAVENS.

the air; while othera resist this hypothe~is, without propounding any more satisfactory one. . ' ' We append, the foltowing table, exhibiting the elements of the sun as determined for the lst of January, 1801. Mean longitude, t8()o 39' 10". t Longitude of p8figee, , . 279 30 06.0 Greatest equation of center, 16517.3 lbular diminution of center, 17 .s Inclination of axis (82~O), , 7 3000.0 Motiol! in a mean solar day, 69 08 .3 Motion of perigee in 366 daya, 1 01 .9 Apparent semidiameter, , 16 00 .0 , 8,8 Mean horizmital parallax, Rotation on its axis in sidereal' days, .25d.•01154 Time of pBIIIing one degree of mean 'longitude, lMh.20m.58&.14 .01681131 Eccentricity of orbit (radius unity)" '1.384,471 Volume earth .. unity, . ' ,;, 364,938 M888earth .. unity, Mean diatanee (96,000,000 miles), earth', rad. unity, 23,91M 0.2548 ~nsiZ~::.,::o of_ to yolume, True . (883,000 miles), in diametenofeartb, 11l.454 Arcompanying the sun, there is an extraordinary luminous appearance, Called the zodiflClJl light, which is seen at certain seasons ,of the year after su'nset, or before sunrise, like the fainl tsil of a comet, extending upward from the sun, in the plane of the ecliptic. Dr. Herschel I~onceived this phenomenon to be a nebulous atmosphere, yet uncondensed, and surr<~unding the sun, whose lenticular shape aroile from its rotary motion. There is great difficulty in explaining this phenomenon, on the theol)' of gravitation alone, for gravity will not permit material partlc/ea to remain' at so ~reat a distance from the sun as the extreme particles constitutmg the zodiacal light. May not the same power which operates (as we shan hereafter see) to produce the tails or comets, on their near approacb to the sun, be active in supporting, by repulsion, the particles of the zodiacal tight in their great elevation above the IIUO'S lunacel We shall again refer to this subject, whl'o we corol! to treat of tbe comets. • The direct light of the Bun is greatly diminished by the atmosphere hy which it is surrounded. This is manifest from the fact that the edJ{8 or disk is far less luminous than the central portion, which is directly the reverse of what ought to be exbiblted in case no cause operates to absorb thp. light. The Iig-ht of the Run has been estimated to be more than 300.000 timl's greater than that of the moon. 'fhe most inllloRII artificial light yet discovered, when seeh against the sun, loob like a black IIpot on its surface,

· MEIlCUBY.

MERCURY. McacuRY ia the neareat planet to tbe aun that haa )'Ilt been dillcovered; and, with theexceptioD of the ..teroide, IS the' small. 68t. Its diameter is only 3140 miles. Ita bulk, therefore, i, about 17 timee less than that ,of the earth. It would require lOore than twenty millions of auoh globea to compose a body ftJ Ilal to the ~un. , It revolves .on ita uia, from west to esst, in 24 houre, 5- mioutes; and 98 IIeCOnd8; which make8 ita day about 10 minutea longer than oura. It performa ita revolution about the sun in a f.·w minutes Ie" than 88 day.. and at a mean distance of nearly thirty-seven millioDl of milea. The length of Mercury'a year, tberefore, is equal to about three of our montha. The rntatiou of • planet on it aD CODBIitutea its day; its revolutioA about the BUn COII8titutea itB year. Mercury ia not only the moat den88 of all the planeta, but J&o mves frolll the a\ln 88ven time8 aa much light and heat as the earth. The truth of thi8 88timate, of course, depend8 upou the npposilion that the intenaity of aolar light and beat, at the planets, varies inversely .. the &quarea of their distances from the suu. . Thialaw of analogy, did it exiat with rigorous identity at all the planets, would be DO argument against their being inhabited: because we are bound to preaume tliat the Allwise Creator haa .ttempered every dwelling-place in his empire to the physical 8ODstitutiou of the beings which he haa placed in it. From a variety of facta which have been obaerved in relation to the production of caIoriI:, it dOIlII not appear probable that the degree of Mat OIl the surfiJoe of the di1Iilrent p1aneta depends on their respective m.. tancea from the BUD. It is more probable that it depends cbietly on the diatn1>utiou of the IUlMtantt of calorie on the IIIIl'fiIce8, and throughout the atmospheres of these bodiea, in different quantities, aceording to the different lituationa which they occupy in the BOlar system; and that these different quantities of caloric are put into action. by the ioflue~~ of the IOIar rays, sO as to produce that degree of Ie118ibk heat l8qWBIte to the wants, anil to the greateat benefit of each of the planet&. On this hypotheeis, which is corroborated by a great variety of facta and experiments, there may be no more sensible heat expenenced on the planet Mercury than on the BUrface of Herschel, which ,is fifty times furthtir removed from the BUD. Owing to the dazzling brightness of Mercury, the 8wiftness ~ ita motion, and ita nearness to the 8un, astronomera have made bot comparatively few discoveries respecting: it.' When viewed through a telescope of considerable magolfying power,

226

GEOGRAPHY OF TilE HEAVUH.

it

exhibits, at dUrerent periods, all the various phases of the moon; except that it never appeare quite full, because its tInlightened hemisphere is never turned directly toward the earth, only when it is beAmd the sun, or eo near to it as to be hidden by the splendor of its beams. Its enlightened hemisphere being thus always turned toward the sun, and the opposite one being always dark, prove that it il an opake body, limilar to the earth, shining only in the light whieh it reCeives from the sun. 'rhe rotatiop of Mercury on its axls was determined, from the daily position of its horns, by M. Schroeter, who not onl1 discovered spots upon its surface, bui leveral mountains In its southern hemisphere, onll ofwhieh was lot miles high-nearly three times as high as Chimborazo, in South America. It is worthy of obeervaUon. that the highest mountains which hue been discovered in Mercury, Vanus, the moon, and, perhepe, we may add, the earth, are all situated in their _them hemispheres. During a few days in March and April, Au~ust and September, Mercury may.be seen fot several minutes, In the morning or evening twilight, 'when its greatellt elon~tions happen in those months; In all other parts of its orbit, .It is too near the sun to be seen by the nakeel eye. The greatest diStance that it. ever derarts from the son, on either side, varieB from ISO 12' to 28° 48 ,

alternately.

The revolution of Mercury about the Bun, like that of all the planets, is performed from weBt to eaBt, in an orbit whil'h is nearly circular. Its apparent motion, aB Been froUl the earth, is. alternately. froiD west to eaBt, and from east to west. nearly in atraight lines; sometimes, directly across the face of the sun, but at all other times either a little above or a little below iL Being commonly immersed in the-Bun'B rayB in the evening, and thus continuing invisible until it emerges from them in the morning, it Bppeared to the ancients like two distinct stsrs. A long series of obse"ations was requisite hefore they recognized the identity of the star which was seen to recede from the sun in the morning with that which aprroacht'd it in the evening. But as the one was never seenunti the other dissppeared, both were at last found to be the lame planet, which thus oscillated on ear.h side of the sun. Mercury's oscillation from west to east, or from east to west, is really accomplished in just half the time of its revolution. which is about 44 days; but as the earth. in the meantime. follow8 the 8un in the same dirpction. the apparent elongations will be proionltPd to between 55 and 65 days. The passage of Mercury over the sun's disk is denominated a transit. This would happen in every revolution. it'the orbit lay in the same plane with the orbit of the earth. But it dOt!s Dot;

227

MERCURY.

it cute the earth'. orbit in two opposite pointa, u t~e eellpdc doee the equa&or, but at.an angle three times 1888. These pointB of intersection are called tbe raodu of the orbit. Meteury's aacending nodI! ia in the 16th degreelloC Tauru.; ita dll8Cending node in the 16th degree of Scorpio. As the earth passee theae nodes in Novem6er and May, the tranaitB of Mercury must happen, for many agel &0 come, in Gne of these montha.

.

The fuIlowiug ill a Iiat of all the tranaita of Meroury, &om the time the firBt was obaerved, by a-ndi, November 6,1631, to the end of the preEDt Cl8Il~.

1631 Nov. 6. 1644 Nov. II. 1651 Nov. 21661 May 3. 1664 Nov. 4. 1674 May 6. 1677 Nov. 7. 1690 Nov. 9. 1697 No.. I.

,1707 May 1710 Nov. 1123 Nov. 1736 Nov. 1740 Nov. 1743 Nov. 1753 May 17M Nov. 1769 Nov.

6. 6. 9. 10. 2. 4. S. 6 9.

1776 Nov. 1782 Nov. 1786 May 1789 Nov. 1799 May 1802 Nov. 1815 Nov. 1822 Nov. 1832 May

212. 3. 6. 7. 8. 11. 4. 5.

1835 Nov. 7. 1845 May 8. 1848 Nov. 9. 1861 Nov. B. 1868 Nov. 4. 1878 May 6. 1881 Nov: 7. 1891 M;ay 9. 1894 Nov. 10.

By eomparing the mean motion of any of the pIaneIa With t h e _ motion of the earth, we may, in like manner, determine the perioda in which theBe bodies will return to tbe same pointa of their orbit, and the IBme positions With respect to the slln. The knowledge of these periods will enable us to detennine the hour when the planeta rille, let, and pus the meridian, and. in general, all the pbenomena dependent. upon the reolative position of the earth, the planet, and the sun; for at the end of one of these periodlo they commence again, and all racur in the _ or'der.· We have only to find a number of sidereal y~ in which the planet oompIete. exactly, or very nearly, a certain number of revolutious; that is, to find snell a number of planetary revo1utiona ... wben &aken together. aball be elladly equal to one, or any number of revolutious of the earth. In the CIIII8 of Mercury, this ratio will be .. 87.969 ill to 866.166. Whence we find, that7 periodical revolutions of the earth are equal to 19 of Mercury : 13 periodical revolutiona of the earth are equal to 54 of Mercury : 33 ~odical revoiutious of the earth are equal to 137 of Mercury : 46 periodical revolutions of the earth are eq" to 191 of Mercury. node, may happen at interva18 TherefOre. tranaiIII of Mercury, at the _ of 7. 13,33.46, &0., years. Transita of Venus, .. well .. eclipsea of the IIUII and moon, are calculated upon the _ principle. l'be 8iIkreuI revolution of a planet reapecta ita lIhIoIfM motion, and 18 _ured by the time the p1anet takes to revolve &om aDy fixed liar to the _ liar again. The ~ revolutiOR of a planet n!8p8Cla ita reIatit!e motion, and illDN8Ured by the time that a planet occupi. in coming hack to the _ position, 'With respect to the earth and the sun. The Iidereal revolution 'Jl Mercury 18 87 ,d. 23 h. I Ii m. 44 s. Ita

228

~EOGRAPHY OF THE REA VRN8.

~PUXlietJl reYoIution ia Ceund by dividing the wholecircumfimmce of 8600 by it. reIalitJe motion in teapect to the earth. Thus, the meaD daily moIioD of Mercury ia 14' ~.656; that of the earth ia 3548".318; and their diIlimmA it 11184".237, being Mercury'. relari"., motion, or what it gam. on the earth every day•. Now, by aimple proportion, 11184";237 ia to 1 clay .. 3600 iI to· 115 d. 21 h. 3 Ill. 25 ... the period ,« a eynodiealreYoluti~ ofMereury. I

The MIlO/ute motion of Mercury in itll orbit, is 109,757 milM an hour; that of the earth, is 68,288 miles: the difference. 41,469 miles~ is the mean reitJtiflfl motion of Mereury. witb respect to the earth. The transit of Mercury acroll!l the disk of the sun, which occurred on the 8th of May, 1846. was observed st the Cincinnati observatory. By the new tables of Levemer. ita place was predicted. so that the various contacts with the sun took place to within sixteen seconda df the computed time. The planet was seen very diatinctly as a round black spot on the bright aurface of the Bun. The density of the planet, and its absolute diameter, enable uS to determine the force of gravitation at ita surfallea. A heavy body would fall through 17.7 fpet per second on Mercury. snd a pound of matter removed from the earth to the planet would weigh 1,106 pounds• . These are the elements of Mercury for mean, noon, Gn>eQo wicht 1st Jan. 1801.

Mean BidetealreYolution,

87 d. 23 h. 15 m. 43 a. .9 Mean longitude, 1660 00' 48 .6 Longitude of perihelion, 7421 46.9 Annoalmotion of the line of apaid... 5.8 Vitto, referred to the ecliptic, 55.9 Longitude of the aacending node, - 450 37' 30 .9 Motion of ditto, west per annum, 7.8 Ditto, east. referred to the ecliptic, 4t.8 Mean orbital motion in a aolar day, 4°05' 32.8 Inclination of orbit. - 7 00 10 .0 Eccentricity of orbit, half major, axis unity 0.210,5IH.41K Decrease of ditto, in a century, 0,000,003,868 Greatest equation of center, 23039' 61".0 Increase of ditto, in a century, 1.8 14 h. 05 Ill. 28 B. .3 A"ieal rotation. Mean apparent diameter, 6".9 , True diameter (3140 miles) earth .. unity, o .398 160 12' 00" Minimum elongation, 28 48 00 Maximum ditto, . 0,01\.1 Volume earth a8 unity, )1_ BOn as unity, 0,000,000,4936 Mean distance (36, 000,000 mi1ea) earthsuonity, \ Q,387088 I H

-

229

VENUS. -THII;RJ: are but -few perllonl who have not observed a beautiful elar in the welt, a little -after aunset, called the etJening ,'ar. Tbis atar" Venua. It ia the aecond planet from the aun. It il tbe brightelt ..tar in the firmament, and on this account easily distinguilhed from the other planeta. _ If we obll8l'V8 thia planet for several daya, we Ihall fi'od that it doea not remain conltantly at the 88me distance from the lun, but that it appeara to approach, or recede from him, at the rate of about three-fifths of a degree enry day; and that it il lometimes on the 88It aide of him, and eometimea on the weat, thue continually oecillating backward and forward between certain limite.. . _ As Venul never depal1ll quite 48° from the lun, it ia never teen at midnight, nor In oppolition to that luminary; being viai. ble only about three hourII after aunset, and 88 long before IUnriee, accordiug as ita right aacension ia greater or leea thau that of the SUIl. At first we behold it onfy a few minutea after sunset; the next evening we hardly diecover any aensible change in ita position; but after a few days, we perceive that it haa (allen considerably behind the aun, and that it continues to depart farther and farther from him, setting later and later every evening, ontil the diatance between it and the son, is eqoal to - a little more than half the apace from the horizon to the zenith, or aboot 46°. It now begine to retum toward the Iun, making the same daily progrese that it did in separating from him, and to set earlier and earlier every suoceechng eVl'ning, on til it finally Beta witb the sun, and is lost in the spfendor of his light. A few days after the phenomena we have now described, we perceivp., in the morning, near the eastern horizon, a bri~ht itar which was not visible before. This also is Venus, whIch is now called the momi'!!f atar. It departs farther and farther from the sun, riaing a hule earlier every day, ontil it is BeP-n about 46° west of bim, where it appearll ltationary for a few days; then it reaumes ita course toward I the Bon, appearing later and later every morning, ontil it risea with the Bon, and we cease to behold it. In a few days, the eVflning star again appears in the weet, very near the setting son, and the same phenomena are again exhibited. Such are the visible appeaJ'oo anoel of Venol. Venus revolvel about the lun from west to east in 924f days, at the distance of about 68,OO~ of milee, moving in her

V

230

GEOGRAPHY 010' THE HEAVENS.

orbit at the rate of eighty thousand miles an hour. She tume around on her axis once in 23 hours, 21 minutes, and 7 seconda. 'l'hus her day is about 25 Jninutes shorter than ours, while her year i. equal to of our months, or 32 weeks. The mean di8tance of the esrth from the 8un, i. estimated at 95,000.000 of miles, and that of Venull being 68,000,000, the diameter of the 8un, all lleen from VenulI, will be to hill diameter a8 aeenfrom the earth, all 95 to 68, and the surface of biB disk 811 the lICJuare of 95 to tbe lIquare of 68, drst ill, all 9025 to 4626, or 88 2 to 1 nearly. The intensity of light and heat being , inversely as the aquare. of their distances from tbe aun, VenUl receives twice aa mucb light and beat 88 the esrth. Her orbit is within the orbit of the earth; for if it were not, 8he would be seen 811 ot'tt!n in opposition to the lIun, as in conJunction with him; but she W811 never lleen rising in the ea.t, whilll the sun was setting in, the weat. Nor wa, she ever I88n in quadrature, or on the meridian,. when the 8un waa either rislng or setting. Mercury being about 230 from the 8un, and Venus 4&0, the orbit of VeDns must be outaide of the orbit of Mercury. ' . The true diameter of Venus ia 7700 miles; but her afllJflf'tfll diameter and brightneas are conatantly varying, accoMing to ber diatance from the earth. When Venua and the earth are on tbe aame aide of the 8un, her diatance from the earth ia only 1l6,OOO,000 ()f miles; when they are on opposite sides of the 8un, ber diatance ia 164,000,000 of miles. Were the whole of ber enlightened hemisphere turned towarda ua, when ahe i, nearest, ahe would exhibit a light and brilliancy twenty-fin times greater than abe generally does, and appear IilLe a amall brilliant moon; but, at that time, ber dark hemisphere ia turned towards the earth.

7'

When Venus approaches ne8lllllt to the earth, her appart:nl or , observed diameter, is 61".2; when lIloat remote it i. only 9".6: _ 61".2+11".6==6,. hence when neareet the earth, her apparent diameter is 6, times greater than when most distant, and the swfaee of her diak (6,)l or nearly 41 times greater. In this work, the apparent size of the ' Jieavenly bodies ia eatim"ted from the apparent IUrface of tbeir disks, whieb is alWlY. proportional to the aqUare8 of their apparent diamete.... When Venua'a right ascension is less than that of the aun, .h. riaes before him; when greater, ahe aP:reara a&r his aelling. She continues alternately morning an evening atar, for a period of 292 dava, each time. To thoae who are but Iitd" acquainted with astronomy, it will aeem atrange, at first, that Venua should apparently continue longer OD the eaat or west e,ide of the aUD, than the whole time

231

VENUS.

of her periodical revolution around him. But it may be eaaity undellltood, when it ia considered, that while Venua movee around the auo, at the rate of about 10 36' of !ingular motion per day, the eartb followil at the rate of 59'; so tbat Venua actually gaina on the eartb, only 37' in a day. . N ow it is evident that both plaDete will appear to keep OD the same aide of the IlUD. until Venus hu gain8il balf her orbit, or 1800 in advance of the ear;th; and thill at a mean rate, will require 299 daYlI, since, 292X37'=10804', or lSOO neatly. Mercury and Venus are can~ In/mar. planets, because their orbits alii within the earth's orbit, or between it and the BUD. 'The other, planets are denom,inated Buperiar, because their' orbits are without or beyond the orbit of the earth. AI the orhite of Mercury and Venus lie within the earth'l orbit, it ia plain, that onee in every aynodical revolution, each of these pll!>oets will be in conjunction on the aame side of the lun. 10 the former case, the planet ia said to be in its irferiar cOfIj_ lion, and in the latter cue, in its auperiar COfIjtmdiOfl; aa io the following figure. CO"IU"CTIOJf AND OPPOSITIOJf

or

TH& PLAJfl:T8.

·In almost all works on astronomy, Mercury and Vennl are denominated fftferi&r planetB. ltnd th~ oth~r. auplrior. But as the"" t~rms are employed, not to expre •• the rei alive ..zc of the planeta. but to md,cate tbeir ,""ali"" :;apect to tbe earth, it would be beller to adopt Ibe term. i,,1Mior aud

'232

GEOGRAPHY OF THE HEAVENS.

The pt'riod of VenUll'. Iynodical revolution, is found in the same iDaDnet 88 that of Mercury; namely, by dividing the whole circumference of her orbit by her mean relatiw: motion in a day. ThUll, VenUll's abBoiute mean ,daily motion, is 10 86'7".S, the eB~. if 69' 8~.8, and their dilfereuce 36' 69".6. Divide 3600 by 86' 69".6, and 'it gives 683.920; or nearly 684 days, fill' Vmus's synodical revolution, 111 the period in which abe is twice in cenjunctioo with the IlIlrth. ' Venus pasBes froRl h~r inrenor to ber s~perior conjDnction in about 290J days. At her inferior conjunction, she is i6,OOO,OOO of miles from the earth; at her superior conjunction, 164,000,000 of miles. It might be expected that ber brilliancy would be proportionally increased, iD the ~)De case, and diminished, in the other; and so it would be, were it not that her enlightened hemisphere is turned more and more from DS, as she appro~hes the earth, and comes more and more into view as sbe recedes from it. It is to this cause alone tbat we must attributfl the uniformity of ber splendor as it usually appears to the naked eye. Mercury and Venus present to us, successively, tbe varioDs shapes and appearances of the moon; waxing and waning through different pha8e8, from tbe beaDtifUl crescent to tbe full rounded orb. This fact ahows, tbat they revolve around the 8un, and between the sun and the eartb. Let the pupil endeavor to explain thele phaees on any other suppoaition, and he will be convinced that the system of Ptolemy ia enoneous, wbile that of Copernicua ia confirmed. It should be remarked. however, that Venul is never _ wben she is entirely full, except once or twice in a century, when she JlIIM5 directly over the sun'. disk. At every other conjunction, abe is either behind tile sun, or so near him 88 to be hidden by the splendor of his light. From ber inferior to ber auperior conjunction, Venus appeall on the west side of the aun, and is tben our morning star; from ber superior to her inferior conjunction ahe appears on tbe east side of the aun, and is tben our evening star. Like Mercury, she sometimes seems to be stationary. Her apparent motion, like his, is sometimes rapid; at one time, direct, and at another, retrograde..; vibrating alterriatelv back. wards and forwards, from west to east, and from east to west. These vibrations appear to extend from 45° to 47°, on each side of the sun. ' Consequently abe never appears in the eastern borizon, more than three hours befi>re sunrise, nor continues longer in the western horizon, after sunset. Any star nr planet, therefore, however brilliant it may appear. which is seen earlier or later than this, cannot be VenUll.

VENUS.

.

I

In paNing from her western to her eastern elongation; ber motion i. from we.t to east. in tile ",.tIer rf'lIe .ip I it is !.hentie called dirtt:' motion. In paNing from her eastern to her w88terD elongation. her motion with respect to !.he earth, i. from east to west, COfIJrary to the order of !.he signs; it is !.hence denominated retrograde motion. Her motion appears quickest about the time of her conjunctiona. and she _ma stationary, at her elongations. She is brightest about thirty.six days before and after her inferior conjunction. when her light i. so great as to projeel a visible shadow in the night, and sometimes she is visible eveD at nooHay. DIRKCT

.urn

UTII08UDK MOTIOK.

fa the forqoi .... linre, the outer circle repre ...nta the eanh'a orbit. and the inner circle, Ihatof V"nue, while abe movea around the aun. in the order o{Ihe lenera ... b. c, tl, &e. Wben Vellua ia at ... Ihe il in ber inferior conjunction, belWp.en the earth and lun; and il in a situation umiler to that of lhtl moon al ber chanp, being tben invilible, becau... her dark bemil~here is towards the earth. At c, abe. appeara half enlightened to the earth. Ioke the moon in her Ir.t quarter; at d, she appears almolt full, her enlightened aide being then almoat directly towards llie earth; at •. Ihe is in her luperlor conjunction. and would appear quite full, w~re sbe not dirtctly hAillil Ibe aun, or 00 near him .. to be bIdden by tbe Iplendor of hia light; atf, ahe appears to be on the deere.... ; and at 6, only half enlightened, like tbe moon in her laBt quarter i .tn, abe diIBppeara again between the earth and the ann. I .. moving from 6 to .. Me _rna to go """""'.... in the he. vena, beeau... ahe movea contrary to the order of the aigna. In torni.... the arc of the circle from retrograde to direct motion, or from direct to retrograde) ahe appea,. nearlT atation&ry for a fe ... oIafs i l>"c81118, in the former c ..... aDe ia goiDg almoat cliJeetly j'rrJIA the earth,

v2

234

GEOGRAPHY OF THE HEAVENS.

and ill lhe latter coming 111-* iL As she describes a Dinah la'll"r portion or her orbit in SOing from • to " than from, to c, she appears much lonll"f dir-cl Ihan retrograde. At a melLD rate, her relrorrada1ionl are accomplialled in fony·two daYI.

Ifthe orbit or Venus lay exactly in the plane of the earth's orbit, she would pass centrally ailross the sun's disk, like a dark round lipot. at e'f'fl1 inferior conjunction; but as one half of hf!r orbit lies about 31 abo'f'e the ecliptic, and the other half as far below it, she will always J?ass the sun a very little abo'f'e or below it, except when her lDferior conjunction happens in, or . near. one of ber nodes; in which case she will make a transit. This phenomenon, thf!refore, is of 'f'ery rare CK'oCurrence: it can happen only twioe ill a eentury; because it IS only twice in that time that any number of complete revolutions or Venus, are just or nearly equal to a certain number or the earth's revol.u tions.

The principle which W8I i1lutrat.ed in predicting the &ranIIita of Mercmy spplies equally wen to thoae of Venus; that is, we must find such seIII of numbers, (representing complete revolutions of the earth and Venus). as shall be to each other in the ratio of theit periodical times, pr as 365.266 is to 224.7. - Thus; the motion of Venus, in one Julian year, ill 11106591".62. that of the earth fpr the same period being h9627"'45, the ratio will be A. the two terms ofthia fraction cannot be reduced by a common divlaor, we must multiply them by BUch numbers as will make one a multiple of the other; accordingly, thirteen tinIIlII tbe denominator.will be nearly equal to eight times the numerator; and 475 times the denominator will equal 291 times the numerator. By combining these two periods and their multiples by addition and aubtrsction, we shall obtain the period of aU the transits that have ever happened. ThUll: 291--8X7-235. another period; and 291-6Xe =243. another period. and 10 on. Whence we find that, 8 periodical revolutions of the earth, sre equal to 13 ofVenuL 2311 periodical revolutions of the earth, equal to 382 of Venus. 243 periodical revolutions of the earth, are equal to 395 of Venus. 211 I periodical revolutions of the earth, are equal to 408 of Venu•• 291 periodical revolutions.of the earth, sre equal to 476 of Venus. Hence a transit of Venus may happen at the IIIIJII8 node. after an interval of eight years; but if- it do not happen then, it cannot take place again. at the same node, in Ie88 than 236 yesra. The orbit of Venus Cl'0II8ea the ecliptic near the middle of Gemini and Sagittarius; and these points mark the position of her nodes. At present her ascending node is m the 14th degree of Gemini, and her descending node, in the same degree of Sagittarius.

HUtV".H.

are

The earth passes her ascending node in the be-ginning of December, and her descending node. in the beginning of June. Hence, the transits of VellUS, for ages to "ome, will happen in December and June. The first transit ever known to have been Been by any homan being, took plaee at the ascending uode,

rHE SOLAR S"~TEM . ' .. '

23b

December 4th,!639.. leto this date; we .add 235 years, we Bhall have the time of the next transit at the 'liamenode, which will accord!ngly happen in 1874. There will b~ another at the Bame node In 1882, eight years afterwarda. It IS not more certain tbat this phenomenon will recur, than that the event itself w ill engross the attention of all the astronomers then living upon tbe earth. It will be anticipated, and provided for, and observed, in every inhabited quarter of the globe, with an intensity of solicitude which no natursl phenomenon since the creation, has ever excited. " Thfl reason why a transit of Venus should excite so great an interest, is, because it may be expected t,o sol ve an important problem in astronomy, which has never yet been satisfactorily done:_ problem whose solution wi\) make known to us the lIlagnitudes and masses of all the planets, the true dimensiona of their orbits, their rates of motion around the Bun, arid their respective distances from the Bon, and from each other. b may be expected, in short, to furnish a universal standard of astronomical measure. Another consideration will render the ohservation of tbis transit peculiarly favorable; and tltat is, astronomers will be supplied with better instruments, and more lICCurate means of obll8rvstioD, than on aD~ former ocoaaion. • This pheaomenoa was In. witneued by HoMOz, a yoang genlleman aboat twenly~ne yean of age livingl in an obscure village fifteea mile. north of Liverpool. The tablel Kepler, conllruCled upon llie oboervalionl of Tycho Drabe, indicated a lranlil of Venul in utll. bUI aone WBI oboerved. Horroz, withoul much Blliltanee from boob and .nllrnmenlll, leI himoelf 10 inquire inlO the error of the lable., and found thai oaeh a I!henomenoa mighl be ezpecled 10 happea in 1639. He repealed hil calcwauonl daring thil inlerval, with 'all the cafefulnell and enlhulium of a echolar ambiliDul of being the Irst 10 prediCI and ob..rve a celeltial phenomenon, which, from the creation oflhe world, had never been wilnelled. Confidenl of Ihe reoall, he communicaled hil e:.:pecled lriumph 10 a confidential friend residing in Mancheller, and delired him 10 walch tilr the evenl, and to take ob..rvation.. 80 anltioul WBI Borroz DOl 10 fail ofwitneuiDg il himoelf,lhal he COJ1Imenced hiB oblervallonl the day before il was ezpectertunity would occur. He had been wailing tilr the evenl with th" Iboal ardenl anticipation tilr eight yearo, and the ...ull promiled lIIuch benefil 10 the ocience. N"'''';''''''''''~' .u lliu, III1mtz 1Ieiec....,.....,." Au oN"""';""', ..ntl.wit:e rep..... 10 1ft. """". God,the Greal Aothor of Ihe b' I worldl he delighted 10 conlemplale. en h.B duty WBI IItnI perform:tand he bad relurned 10 hi. chamber,lhe oecond time! hiB love of oeieace was rratiAed with fnil BUCcellj and he law whal no mortal eye had ob..rved before ! Ii any Ihinr can add inlerell 10 \hiB incidenl, it illhe modeBly with which the yoong Bllronomer apolDlrizes 10 the world, tilr ",.....u... hil oblelvBtionl at all• •• I observed il," oayl he t " from IUUri ... till nine o'clock, agaia a little betilre len, and IBllly al noon, anC! from one 10 Iwo o'clock; Ihe rell oilhe day beina devoted 10 higher dutie.. wblch mipl nol be aeglected for theI8 putimea.-

ol

"tIUf'

236

GEOGRAPHY OF THE HEAVENS.

So important, aay. Sir John He1'8Chel, have these obaenationa appeated to utronomell, that at the last transit of Venus, in 1769, etpeditioDB _ fitted out, on the most efficient acale, by the British, French. RIIfIIian, and other governments, to the remotest corners of the globe, for the ex~ 'purpoee of making them. 'fbe celebrated expedition of Captain Cook 110 Otaheite, WIllI one of them. The general result of all the observations III8de on this IIlOIlt memorable' OIlC8IIion, giveS ~".1i776 for the BUD'. horizontal parallax.

The phenomena of the Beasons, of each of tbe planete, like those of the earth, depend' upon the inclination of the axiB of the planet. to the plane of ils orbiL The inclination of the axis of Vf'nUB to the plane of her orbit, though Dot precisely known, iB commonly estimated at 75°: 'wbich is more than tbree times as great as the inclination of the eartb's axis to the plane of the ecliptic., The north pole of Venus'R axis inclines towards the SlOth degree' of Aq uarlUII; the eartb's, towards the beginning of Cancer; consequently, the northern parts of Venus bave summer in tbe signs where those of the earth have winter, and vice versa. The declination of the sun on each side of her equator, must be equal to the inclination of ber axis; and if this extends to '15°, her tropics are only 15° from her poles, and her polar circles 15° from her eq uator. It follows, also, that the sun must change his declination more in one day at Venus, than in fi,ve days on the earth; and consequently, tbat he never shines vertically on the same places for two days in succellsion. This may perhaps be providentially ordered, to pre,vent too great effect of tbe sun's heat, which, on the supposition that it is in inverse proportion to the square flf the distance, is twice as great on this planet as it is on the earth. . . At each pole, 'the sun nontinues half a year. without setting in .,ummer, and as long without rising in winter; consequently, the polar inhabitants of Venus, like those of the earth, have only one day and one night in the year; with this difference, that the polar days and nights of Venus are not quite two-thirds as long as ours, Between ber polar circles, which are but 15° from her f>quator. there are two winters, two summers, two springs, and two autumns, every year. But because the sun stays for some time near 'the tropics, and pasHes BO quickly over the equator, the winters in tbat zone will be almosl twice as long as the summers. When viewed through a good telescope, Venus exhibits not only all the moon-like phases of Mercury, but al80 a variety of inequalities on her, snrface; dark spots, and brilliant shades, bills, and valleys, and elevated mountains. But on account of 8That ia,

MV 'II v".",',,-, or aiXIeeD week.. ,

237

VENU8.

the great density of her atmosphere, these inequalities are per. ceived with more diJIiculty than those upon the other planets. The mountains of Venus, like those of Mercury and the moon. are highest in the southern hemisphere. Aeeording to M. Schroeter, a celebrated German astronomer, who spent more than ten yeare in observation upon this planet. some of her mountains rise to the enormous hight o( from ten to twenty-two miles.· The observations of Dr. Hersehel do not indioate so great an altitude; and he thinks, that in general they are conBiderabll overrated. He estimates the diameter of Venus at 8,649 miles; making ber bulk more than one-aixth larger than that of the esrtb. Several eminent astronomere affirm, that they have repeatedly Been Venus attended by Il satellite, and they have given circumstantial dataila of ita size and app~rance, ita periodical revolutiou and ita distance from her. It ia said to reeemble our moon in ita phases, ita distance, and ita magnitude. Other astronomers deny the existence of such a body. becaus8 it was not seen with Venus ,ou the sun's disk, at the transits of 1761, and 1769. The general elememe ohbis planet (or the epoch lat January. 1801, are as follows: . , ,Mean sidereal revolution, 224 d. 16 b. 49 m. 081.00 Mean synodical revolution in BOlar day.. 683.92 Mean'longitude, 11 0 33' 03".110 Mean daily motion in orbit, 1 36 07 .80 , Longitude of perihelion, 128 43 63 .10 W. motion ofapaides per annum, " ' 02 .70 E. .. .. referred to the ecliptic, 47 .40 Inclination of orbit, 8 sa 28 .6 Ann~ increue of do., 00 .6 Longitude of ucending node, 74 64 12 .9 W. motion of do. per annum, 17 .6' E. .. "referred to the ecliptic, 32 .5 Eccentricity of orbit, half maj. axis 88 unity, ' • 0.00686074 .Decrease of do. in a century, 0.000062711 Greatest equation of center, 47' 10".00 Annual decreue of do., • 00 .25 Rotation on axis, 23 b. 21 m. 07s.2 Mean apparent diameter, 16".9 Diameter at superior conjunction, .6 Diameter at inferior conjunction, • l' 0 I ".2 True diameter (7700 miles) earth'. 88 unity, o. r,7e Volume earth'. unity. • 0.927 )fa. suo's 88 unity, • • O.o0000246:i8 Mean ~ce from the sun, (611,000,000 miles). earth'.? 0.723:1316

(I"

ft.

88 UDlty.

5,

• let, I!U16 mile. j lid, 18.9'7 mile. j 3d, 11.44 mile. j 4th, 10.84 mile ••

~38

GEOGRAPHY OF THE HEAVENS.

THE EARTH.

Tn earth is the place from whicb all our observations of the beavenly bodies must necessarily be made. The appa~nt motions of these bodies being very considerably sffected by her figure. motions, and dimensions, these bold an important place in astronomical Icience. It will, therefore, be proper to consider, fint, some of the methods by whicb tbey bave been determined. If, atanding on the sea-shore, in a clear day, we view a Ihip leaving the coast, in any direeiion, Ute bull, or body of tbe vessel, lint disappean; afterward the rigging, and, lastly, the top of the mut vanishes .from our sight. Those on board tbe ship observe that the coast lirst linka below .the horizon, then tha buildings, and, lutly, the tallest spirea of the city, which they are lesving. Now these phenomena are evidently caused by the convuity of the water which is between the eye and the object; for, were the surface of the _ merely an extended plain, the largest objectd would be viaible the longest, and the amallest disappear fint. Again, navlpton have aailed quite around the earth, and thus proved ita convexity. Fentinaud Mage1Ian, a Portug\Jee, _ the ftnd who carried this eoterprise into execution. He embarked from Beville, in Spain, and ~ ted biB courae toward the west. .After a long voyage, he descried the ClOIItinent of America. Nat finding an ~ to enable him to continue Ilia courae in a W8IIterly direction, be aaiIed along the coast toward the 1OUth, until, coming to ita IOUthem extremity, be aaiIed vound it, and found himIeIf in the great Southern Ocean. He then reawned his COJII8B toward the weal After aome time, be arrived at the Molucca Islands, in the EfJlltem HemirpAere; and, BBiling continually toward the west, be made Europe from the eut,-anmng at the place from which he set out.· The next who circumnavigated the earth, 11'88 Sir Francia Drake, who ailed from Plymouth, December 13, 1677, with five smaIl veasels, and arrived at the _ place, September 26,1680. Since that time, the cireumnavigation of the earth baa been perlimned by Cavendish, Uord.,., N oort, Sharten, Heremitea, Dampier, Woodea, Rogers, Sehovten, Rogge.-ill, Lord AII8OII, Byron. Carteret, Wa\Iia, BouP,inville, Cook, KiDg. Clerk. Vaneouver, and many otbeJa. • Magellan I&Iled 110m Se"iIIe. in Spain, Auguat 10, 1519, in a ahip called tile Victory) accompanied by four olher "e.... I•. 1n April. ISIll, he _a killed in a .kirm,ah with Ibe nauve., al Ihe i.land of &lite. or Uv, 80metimea called Malan, one or Ibe Philippine.. One of hia ve_l., however. arrived at 8t. J Ilcar, near Seville, ~p"'mber 7. 11!119.

THE EARTH.

~39

These navigatore, by Bailing in a westerly direction, allowance being made for promontories, &0., arrived at the country they Baileil from. Hence, the earth muat be either cylindrical or globular. It cannot be cylindrical, beQause,' if BO, the meridian distances would all be equal to each other, which is COBtrary to observation. The figure of the earth is, therefore, .pherical.' " The convexity of the earth, north and BOUth, is, proved by the altitude of the pole, and of the circumpolar stare, which is found uniformly to increase aa we approach them, while the inclination to the horizon, of the circles described by all the stara, gradually dimi~i8he.. While proceeding in a southerly dire.,. tion, tbe reveree of this takes place. The altitude of the pole, and of the circumpolar stare, continually decreaBes; and all the stare describe circles whOle inclination to the horizon increases with the distance. Whence we derive thiB general truth: TIN altifude 0fIe pole, and tIN depreNion rf tIN otlNr, at any place OR the earth , IIU",,~, iB equal to lIN latitude rf that place. Another proof of the convexity of tbe earth's surface ia, that the higher the eye ia raised, the furtber is the view extended. An obaerver may Bee the Betting SUD from the top of a house, or any cODsiderable emhience, after he haa cealed to be visible to those below. The eurvatale of the earth for one mile is eight inches; and this cUr. vature inc:re&E8 with the aquare of the distance. From this general law, it will be easy to ~te the distance at which any oi!ject, whoeehight is given, may be - . or to determine the bight of an object, when the ~ceism~ , 1. To find the bight of an ol!iect when the distsace is given. RULK. Find tIN MJ1.II1In of ~ dW_ in mi/u, and talu two-tAiTd8 of that number for tIN higlat in fed. Ell. 1. How high muat the eye of an obaerver be raised, to 888 the IIUIface of the ocean, at the distance of 3 miles ! ,Ana. The square of 3 feet is 9 feet, and f of 9 feet is 6 k Ell. 2. Suppose a penon can juat 888 the top of a spire, over an elltended plain of 10 miles, how high is the ateeplel .Am. 'fhe square of lOis 100, and ., of 100 is 661 feet. 2. To find the distance when the bight is given. Run. Itu:rea.e tIN h!gh/, in fed 0M-h0Jj, and ~ tIN MjfM1I"t root, ~ tIN rli8tan«, in miIi6. • Ex. 1. How filr can a penon 888 the IIIU'fiIce of It plaintowhoae eye is elevated 6 feet above it! .AM. 6, increased by ita ~ is 9, and the square root of 9 is :I: the distance is, then, 3 mil... Ell. 2. To what distance can a penon 888 a light-bouae wboee hight ill 96 feet &om the level of the ocean ! ,Ana. 96, increased ~ ita ~ ill 1«, and the square root of 1« is 12: the distanceia, therefOre, 121Oilea. 3. To find the cumature of the earth when it exceeds a mile. RULL Multiply the MjfM1I"t olllie dW_ by .000126.

'I.

240

GEOGRAPHY OF THE HEAVENS •.

Although it appears. from the preceding. facts. that the earth is spherical. yet it is not a perfect sphell!. lC it were, the length of the degrees of latitude. flom the equator to the poles, would be uniformly tbe same; but it has heen found, by tbe most careful .measurement, that, as we go from the equator toward the pole8, the length increiJlu with the latitude. TheIle measurements have been made by the IDOIIt eminent mathemll-

·ticiaos of di8innt counIriee, _ in· varioua pWiea, from the equator to the arclil; circle. They have found that a ,degree of latitude at the aretic circle WIUI nine 3i:.cIeentluJ of a .mile longer than a degne at the equator. and that the ratio of inc:resse, Cor the ink!rmediate de~ WIllI nearly • the squares of the sines of the latit]l@. Thus the theory of Sir . . . Newton WIUI confirmed, that the bod)' of the earth was more rounded and convex between the tropics,. but. C9l18iderably ftattened toward tbe

poles.

ol.':::J!...

lAIiIi..r..

i~....i: :!~I or-...... 68.732 Bouguer,

Peru, Equator j Pennsylvania, 390 12' 00" N.· Its1y, 43 01 00 ..i France, 46 00 00 . England, 51 29 Ii4I Sweden. 66 20 10

I

68.896 68.898 6JMIM 69.146 69.292

M8IIOIl and Dixon, Boeoovieh and LemsUe Delambre and Mechain

Mudge, Swamberg.

These measurements ~rove tbe earth to be an oblate .pl&eroitl, whose longest or equ'tonal diameter i. 7924 milea, and the p0lar diameter. 7898 mil8ll. The mean diameter is. therefore, about 7911. and their di1rerenee 26 miles. The French Academy have determined that the mean diameter of the earth. from the 45th degree of north latitude. to the opposite degree of south latitude. is, tJCetWGtelY. 7919 miles. . If !be earth were an exact sphere, ita diameIP.r mipl be determined by ita curvature, from a lin,le mea.ureTbn.. in the adjoininK Ipre. _ bave A B equal menl. to 1 mile, and B D equill to 8 incbe .. t.o find A F~ or B Eo which doe. nol oenliblf dill'er from A Eo lillce B D i. only 8 inch.... Now, illl a pro{'O"ilion of Euclid, (B. 3, prop. 38,) that, wben, from a poml wilhoul a circle, IWO Iinel be drawn, one cutting and the other touching it, the IOIlcbin~ line ~B AI i. a mean proportioDal between the ::i:~ ine ( EI and thaI part of it (B DI without the

CllJ' Fig 10

A

B • D

.

B D: B A:: B A: BEor A Every nearly. That il. I mile beiD« equal to 63380 !nchel. E 8 : 63300 : ,63300 : 501811110 incbes. or 79UO mil.... This is ~ nearly what the ID08C elaborate ealculatioDB make

earth's equatorial diameter.

.

the

The earth, conaidered as .a/lanet, occupies a favored rank in the solar system. It plesse the all wise Creator to assign ita poailion 8IJlong the heavenly bodies where nearly all the sisll'r planets are visible to the naked eye. It is situated neXI 10 Venua, aDd is the third planet from the SIlD.

241 To the IICboIar who, for the lint time, taItea up a book 0Jl 1IIItronom1. doubt ~m "Z?F?Fge £md th" "?Frth d~_ ?FiSn the d:avekk&n n"::,,llies. kk'or Wm" can "}dleBJ' un lin" th"" s"e wi", f,,;r and seemingly immeasurable extent, and the stars, which appear but 118 will

~ta~'fkk~: ~ ~;~~~~~, "~~ thetb:~~kk";:! !:,~ea: ,:~~~:~~~ change of place, as we view them at dilferellt hoUrs of the day or night, at dUli!rent _ _ of the year. '

or

It f"""es f'",md sun, ]'fOm ",est tQ }Ist, in 36n "aYI, 5 hours, 48 minutes. and 48 Becond" ; 'and turna. the same way, ho"'14,56 m!kkutef"kknd 4 14",00"", '1'&'14 form"f its "dis, in call'''l its ,fw,nual t14otiot" 14nd ""kkBeI t"e vicilsitudes of the season8. The latter i8 called ita diurtUli motion, Iliid produces 8U""14t8iokk 14f da,1 14nd The ",ean di"tan"" she sun i8 ahQUt 95,000,000 'of miles; it, consequflntly, moves in its orbit at the mean rete of hd,OOO ¥"ilAS hd"t, It" equr;t,;,rial diamew,,,r 79h,h miles, turn" ;,n its uis at the rate of ltt40 miles an hour. Thus, the earth, on which 1\'e stand, and which hal 8enred ~h; aa"" ',;1 th" ;mshw,k"n {o,mdatioo rEf th:: firm::::: Itrueturss. i evp.ry moment rurning swiftly on its center, and, at the same time, moving onward with great rapidity through the empty "t'ace. , This compound motion il to be understood of tbe wlwk eariJa, with all that it holds within it8lubstance, or sustains, upon ita "mrfact;-->{)f lolid mast of tht; oem'Ll: whier: flo~Ei around it, of the air that rl'sts upon and of the clouds which float abovA it in the air. Th;:; the kk';rth. comm::n with !Ill tr:e plEi;:ets, ,,,volvffi around the sun as a center, is a fact which resta upon the clearest demonstrations of philosophy. That it revolves, like them, d+,on own t,tis. it t tru,h ,,;hicr: every titing tttd seHi"g Sttt iIlulltrates, and which very many phenomena concur to establish. ~ither the earth 1tl0!P.~ around its axis every !~y, o~ tJu w~~ ,;tttvertft movr;t aro,mrr It thA tm",. r ""re IS thlttil opinion that can be formed on this point. Either the earth must revolvA on its axis Avery 24 bours, to produce the alternate, SU,,= ,:ftSSiM' r,f dc'+, and ,fight, tht fLUn, mOOD, §,l"nets, tt,met§" fixed stars, and tbe whole freme of the uDivers!! itself, mUlt movl' around the earth, in the same time, To thtt !%tUer ;ttt,e tit r,e thft fact, ;t"tJuld to a "n tittil wisdom of the Surreme Architect, whose laws are universal harmony. As wei might the beetle, that in a moment t"ms baH, ima"ine tht, r:eave;tEi aDd ea,,+' bad made revoh,~ ti~n in the same insta~t. It i~ evident, that iD proportion to ~. distance of the celesual bod II'S from the earth, musi, t'D thAd ,mPPOtiiion, ilie "',pidity their mOvet§dDts. The thett,

W

242

GEOGIlAPIIY OF 'l'IIE IlEAVD8.

woold moyeat the Jate of more tIwa roar hundred thousand mil. in a minute; the DRrest B1ara, at the iDconcei....ble velocity of foorteen bundred milliOO8 of miletl ia a ___ ; ;mel the moet distant luminaries., with a degree of .wiftness whicb DO numben coold eJ:preu._d aU this to saTe tbe little globe we tread opon from turning .fely OD hs uia ia M hCRDII. The idea of Ibe heaveDtl revolriDg about die earda, ia eucombprPd with innumerable other difficulties. We will meDtion only 008 more. It is e81;imated on iood authority, that there are risible, by _ _ c( gIaaaea. DO leIIII than one ItvndrctJ ..Ili_ tf.,.., ICaUered at all poeaible diataDces in the beaRDS above. beaeath, and around 118. Now. ia it in the least degree probable, that the velocitietl of all th_ bodiea should be 80 ,..golated. tha&, thoogh deacribing circlea so very diff'ereDt In dim_ions, they .hootd complete their reYolutioD8 in enctly the lame In short, there is DO more reaSOD to suppose that the heaRDS r~volve around the earth, thaa there is to 10Ppose that they revoln around each of the other plaDell, separately, and at the BalD& time; linee the same apparent revoluaoD is common liD them all, for they all appear to revolve UPOD their axea, in differeDt period.. The rotatiOD of the earth determiDel the length of the day, and may be regarded as ODe of the mOlt importaDt elementl iD astronomical science. It serves as a uDivenai measure of time, and forms the .tlDdard of comparisOD for the revolutioD of the celetltial bodi8l, for all ages, past and to conie. Theory allll observation CODcur in proving. that among the iDDumerabfe vici.simdee that prevail throughout ereatioD, the period of tbe earth'l diumat rotltion i. immutable. The earth performs one complete revolutioD OD itl WI in . 23 boun, 56 minuteB, and 4.09 secoDds, of lolar time. This is called a ~ day. bl!('1luse, iD that time, the ltan appear to complete ODe revolutioD Iround the eartb. But as the earth advancee almOlt a degree ealtward iD im orbit, iD lbe time tbat it tllrDl eutward arollnd itl axia, it i. plain that jU11 ODe rotatioD Dever briDgs the lame meridian arouDd from the lun to th(\ IUD agaiD; so that the earth r&o quires as moch more than one comprete revolutioD OD itl nis to complete a lOW day. as it bas gODe forward iD tbat time. Hence in every natural or 101ar day, the earth performs one complete revolution OD its axis, and the 365thpart of another revolution. Consequently, in 365 dayl, the earth tuma 366 timel around itl axis. And as every revollltioD of the earth OD itl axis completes a sidereal day. there mllSI be 366 sidel'f'lll daya iD a year. And. gt'nerally, since the rotation oCany planE't about itl axis il tbe leDgth of a sidereal day at that planet, the

0_

1ime'

THe EARTH•

.number of sidereal day. will always exceed &he number of solII' days, by one, let thllt number be wbatit may, one revolution being lost in tbe course of lin annual revolution. Tbis difference between the sidereal and solar days may be Uh,lstrated by referring to a watch or clock. When botb hands eet out togetber, at 12 o'clock for instance, the minDte band muat trav!'l more tban a wbole circle before it will overtake &he hour hand, tbat is, before they will come into conjunction again. In tbe same manner, if' a man travel around the earth. eastwardly, no matter in what time, be will reckon one day more, on his arrival at the place whence he aet out, than they do who remain at rest; while tbe man who travel a around the earlll fDeatwardly will have one day Ie... From whieh it is ma~ifest, that, if two persona start from the same pl~ce at the same time, but go in contrary directiona, the one traveling eaatward and th~ other westward, and eacb goes completely around the glo~e. although they ahould both arrive again at tbe v.ery same bour at the same place from wbicb I.bey let out, yet Ihey will dillgree two whole days in their reckoning. Should the day of their return, to tbe man who traveled westwardly, be Monday, to t.he man who traveled ~aatwardly, it woul~ be ~ednesday; wbJle to those who remalDed at tbe place' Itself, It would, be Tuesday. Nor ia it neceeaary, in order to produce the gain or los8 of a day, that the journey be performed either on tbe equator, or on any parallel of latitude; It is sufficient for the purpose, that all tbe meridians.of the eartb be passed through, ea8tward or westward. The time, al80, occupied in the journey, is equally unimportant; the gain or 108s of a day being tbe same, whetber the eartb be traveled around in 24 years, or in as many bours. h is al80 evident, tbat if the eartb turned around its axia but once in a year, and if the revolution waa performed tbe aame way a8 its revolution around tbe aun, there would be perpetual day on one aide of. it, and perpetual night on the other. From tbeae &eta the pupil will readily comprehend the principles involved . in a curious problem which appeared a few ylllml ago: It W8I gravely reported ~ an American IIhip, that, in sailing over the ocean, it chanced to find /lIZ Sundays in F elwulJry. The jw:t W88 insisted on, and a solution demanded. -There is nothing abaurcl in this.-The man who travels around the earth, eastwardly. will _ tbe sun go down 8 IiUle earlier every succeeding day, than if he bad remained at rest; or • earlier lhan they do who live at the place from which he let out. The fuller he travels toward the rising sun, the sooner will it appear above the horizon in the morning, 110 much the sooner will it set in the evening. What he thUII ~IlS in time, win bear the aame proportion to a solar dHY. 88 the distance traveled does to the' circumference of the earth.-A. the Fobe is 3600 in circumference, the sun will appear to move over one

PU4

GEOGRAPHY OF ',.HE HEAn;!"!!.

t.rent:Y-bIrth put m ita '8Ulface, or minutes to

140 every hour, which is four

otAe ~-Collsequently.

,the IUD will rise, come to the meridian, and set, INr minutes BOOner,,, a pLace 10 east of us, than iI "ill with ua; al . . clilltance of 20, the BUD will rUe and IBl eight minutes aocmar; altlle cIiBtIplce of a.o, twelve minutes BOOner, and 80 on. Nqw tho! man who t.."els one degree to U1e eaR, the lint day, wi. have the ..un on bii lDeridian four minutea BOODeI' than we do who ... at rest; Hnd the aecond day, eight minutea BOO'-, and on the third .y,

twelve .minutea aooner, and 80 on; each lucte..aive, dal being compleltd i>ur minutes earlM-l' than the I'l'I'ceding, until he amvea again at the place from which he etarted; w hen this ,,,-'D1inual gain of four minu.... a day will have amounted to a whole day in advcmce of our timr; he having "'en the SUn rUe and Bet once more than we have. Coosequently, U1e day on Which he arriV~8 at holDf', wh8tev~r day of the wet'k it may be, is one day in ad'varice of 0Ul'B, and he must needs li"e that da~' o,'er by calling that day by the same name, in order to make the IIIlCOWlta hannoniIIr. ' If this eboold be the last day of Pebnmry in a biMenile year, it would aJ.o be the _ _ day of the week that U1e Jir81 was, and be six timea repeated; and if it ahould happen on Sunday, be would, under th_ cin:umtltlDcee, have .u ~WMlays in Pehruuy. , Again : -Wh__ the man who trayel. at lhe rate or one degreP to the eut, will hav~ all biB daye four minutes Mort". tbaD oum, St.,' on the contrary, the man who travels at the same rate toward the 'W"', will ha\'8 all biB day. four minutea longer than 01lI'l, When he hu,finisbed the circuit of U1e earth and arrived at the pL&ce iiom whirh he &st .., oUt, be will have eeen the .un rUe and IBl onee _ than we have. Comequently, the day he Fte home will be om day aft". the lillie of that place: tOr which reuon,'if he amvee at home OD Saturday, actordo ing to biB own account, he will have to call the next day Monday; Sunday having gone by before he reached home. Thus, on whatever day of the week JlIIluary should end, in commOD yeam, he would find the __ day repeated only three timeII in Pebruary. It JlIIluary ended OIl Sunday, he 'Would, under these cireumBlaDcea, find OIlly three & . day. in Ftbruory. "

.m.

The earth's motion about its axis being perfectly equable and lIIiform in e"fery part of its annual revolution, the sidereal, day. are always of the .ame length, but the solar or natural day. rarr very considerably at dltrerent times of the year. This fllnation is owing to two distinct causes: the inclination of the earth's axis to its orbit, and the inequality of its motion around 41e Bun. Prom these two causes it is, that the time ,shown by • well regulated clock, and that of a true sun-dial, are Bcarcely ,v .. r the same. The difference between them, which sometimllll .Dlounts to 16~ minutes, is called the Equation rf Time, or the "'iuation of solar days. • The difterence between _

and apparent time, or, in oUier word., ~ may be further Ihown by the

Ifltween Equinoctial and Ediptil;

245 Igure which repeaiuta the circle.of the &pbere. Let it be fiJBt premieed, that tquinodial time is clock time; and that ecliptic ti me i, IIOIar or apparent time. It appears that from Aries to Cancer, the SUD in the ecliptic comes to the meridian before the equinoctial ."n; from CIUlCt'T to Libra, after it; from Libra to Caprlcl.m be/we it; alld lrom Capricorn to .-\ riN, after it. Jf we DO~ce what months the SUD.is in these oevenll quarter&, we ehall 6nd that Ii'Om the ~5th of lJect'mher to the I lith of April, and from the 16th of June to the lilt of September, the clock fa.tUr than the lIIJIlodial; and that, from the 1Ath of April to the 16th of lune, and from the 1lit of September to the 26th of Decemher, tbe "'No dial is futer than the clock. .

I.

EQUATION

C!r TIME.

If

..

It is a universal fact, that, while nona of the planets are perfect spheres. none of their orbits are perfect circles. The planets all revolve about the sun. in ellipses of different deIJreea of eccentricity; having the Bun, not in the center of the elhpse, t, Ilt in one of its foci.

A...L-_,...---C>--t""-t B

w2

The figure AD B E is an",...,. Tbe line A B i. called the trans.ene axis, and the line drawn tbrougb the middle of this line, and perpendicular to it, i. tbe conjDgate axis. The point C. tbe middlr. of the Iran .. verle axi .. \I tbe ....,.,. of the ellipse. Tbe points F and f, equallr distant from C, are called the fori. C F, the distance from tbe eenter to one of the foci, is called the eccentricity. The orbito of the plaueto beinl( el. Ii...... having the lun in one of the foCI, If A B DEbe the orbit of a planet, with the IU 10 the foelJ.l F, when the planet it ..

246

GEOGRAPHY OF TJlE HEAVENS.

the _ j and ....lien lit tJie point B, in ita qAJiool, e>r at ita greatelt diatance tiom the lall. The dil'el'8llat in theoe ,liltancel il evidently equal to F f, tbat iL equal to twice tbe ecC811tricity o( ita orbit. In evel'J revolation, a planet paaoe. through ill perihelioD and aphelion. The eccentricity of tbe eartb'l orbit i. about one and a half millionl of milel: hence Ihe is three millionll of mile. Bearer the aun in hot perih~lion than in her aphelion. Now, all Ihe lun remains fixed in the low.~ (OCUI of the earth'l orbit. it iI .uy 10 pareeiTe that a line. paRling centrall)" through the lIun at right angle, with the lon....r axil o( the orbit. will divide it illto two \uleqnal aegrnenlL PrteUtl, fA'" U .. divi40tJ ." tAr . .inocML J

·tIIe poiat A, it will be.m ile ,.;Aolioit, Or _

That pol1iOD of the earth'. orbit which lies abooe the sun, or nortA of the equinoctial, contains about 184 degrees; while that

portion of it which lies be/QW thll sun, or _tA of the equinoctial, contains o~ly 176 degrees.. 'I'rus fact showl why the lun cootinues about eight days longer on the north side of tbe equator in sumaler, than it doea on the BOUth side·in wintar.

.

.

The points of the eanh', oibit which correspond to its greatest and least dietaDceiI from the BUn, are call8d-th~ former, the a~ee, and the latter, the perigee; two Greek worda, the former of which lignifies.fn1m 1M eortA, and the latter, abtJut tile earlh. Tbeae points are also designetad by the common liliiii8 of apridu.. . The earth being in ita perihelion about the let of January, and in its aphelion the 1st of July, we are three millioDs of miles nearer tbe slln.in winter than in midsummer. The reason why we have not, as might be expep.ted, the hottest weather WhPD the earth is nearest the sun, is, becau.se tbe sun, at that time, having retreated to the southern tropic, shines so obliquely 00 the nortbern hemisphere, that its rays have scarcely half the pffeet of tbe summer sun; and, continuing but a short time above the horizon, less beat is accumulated by day than is dissipated by night. . As the earth performs ita annual rnolution around the IUn, the position of Its axis remains invariably the same,-always pointing to the north pole of the heavens, and always maintainmgthe same inclination to its orbit. This seems to be providentially ordered for the benefit Of mankind. If the axis of the ea rth al ways pointed to the center of its orbit, all external obo jp.ct8 would appear to whirl about our heads in an inexplicable maze. N olhing would appear permanent. '.l'he mariner could no longer direct hill Clourse by the stars, and every index in nature would mislead uil. The following is a summary of our knowledge of the earth, as a planet; epoch, 1st January, 1801: Mean dill$ance from the IUn (95,000,000 miles), itll radius U(lity, 239M Distance at peribelion, mean distance unity, . - 0.09832 Distance at aphelion, mean dietaDC!! unity, 1.0168 Mean aideml revolu&iDn, in IOIar day., 386.2663612

THE EARTH.

troPaI

M.n J'imJlution, in ~ da~. Mean a.nomalistic revOlution, in solar daya, Entire revolution of the SUD '8 perigee, in solar day..

847

886."124"

866.1696981 7.645,798 1000 89' 10".2 1 01 09 .9 o 1i9 08 .83

Mean longitude, conected 20" fur aberration, Motion in perihelion, in a mean solar day, • Mean ~otion, in a mean solar day, Mean motion in a sidereal day" o 68 68 .64 Motion in aphelion, in a mean solar day, o fl7 11 .5 Mean longitude of perihelion, -, ' 99 30 05 .0 E, motion of line of aptsides, per annum, 11 .8 Ditto, refilned to the ecliptic, • 1 01 .9 Complete tropiclal revolution of apei.dea in years, 20,98. Obliquity of eeliptic,' _ • ISO 27' 116".6 Annual diminution ofdiUo, 0;457 Semi axis,major of nat,lion; 9.4 Annual lunHoIar pn!Cl8IIBion, 60 .• Genera1 pMCeaion in 1ongitude, ~ 60 .1 (~omplete revolution of equinoxes, in yeara, 2111!68 Lunar nutation in longitude, ,_ 17".679 Solar nutation in longitude, 1 .137 Eccentricity of orbit, semi axis major as unity, 0.016783588 Decrease of ditto in 100 yean, , 0.00004163 Diurnal acceleration of sidereal or mean solar time, S' 66".91 From the vernal equinox to the summer solstice, 92 d. 21 h. 50 m. From the summer sohttice to the autumnal equinox, 9lt IS 44 Prom the autumnal equinox to the winter solstice, 89 16 44 From the winter solstice to the vernal equinox, 89 01 33 MaE, sun as unity, •' 0.0000028173 Volume, • 1.0 Density, sun as unity, 8.9326 Denllity, water as unity, 6.6t47 Mean diameter (equatorial, 7924, polar, 7898), in miles, 7916 Centrifugal £ 'fee at the equator, 0.00346 'I'ime of paaage of light from tbe sun, 8 m. lS ...3 Motiop of earth, in orbit, in the same time. 110".26

THE MOON. THERe il no object within the'scope of astronomical oble"alion which aWords greater variety of interesting .investigation than the various phases and motions of th" moon. From them, the astronomer ascertains the form of the earth, the vicissitudes of the tides, the caURes of eclipses and ~aultationl, the distance of t\le sunf and, consequently, the magnitude of tpe solar, system. l'hese phenomena, which are perfectly obvious 10 theuDllJsisted.

248

GEOGRAPHY 01' THE HEAVENS.

eye, Ben'ed as a ltandard of meaillrement to al nations, until the adnoeement of science taught them the advantages of solar ume. It is to these phpnomtina that the navigator is iudf!bied for thatlrecision of knowledge which guides him with wellgrounde confidence through thll pathle8B ocean. The Hebrews, the Greeks, the Romans, and, in general, all the ancients, used to assemble at the t.ime of new or full moon. to discharge the duties ofpi~ty and gratitude, for her unwenried attendance on die earth. Bnd all her manifold use•• When the moon, after having been in oonjunotion with the lun. emerges from his rays. she fir8~ appears in the evening, a little aner SUl\8et, lib a fine luminous crescent, wiili its convex lide toward the sun. If we observe her ilie neltt evening, we find her about 13° further east of ,the sun than on the preceding evening. and her crescent of light eensiblyaulmented. Repealing thesll obsl'rvatioD8. we pl'reeive that sbe departs further and further from the sun, liS her enlightened surface cornea more and more Into view, u'ntil she arrivAs at her jlrJl quarter, and comes to the meridian 'at sUlIset. She has then finished her COUfliS from the new to the full, and half her enlightened hemisphere il turned toward the earlh. After her first quarter, she appears more and more giblJou., as she recedes further and further from the sun, until she 'hal completed just half her' revolution around the earth, and is seeD rising in the east when the sun is setting in the west. Sba then ~resents her enlightened orb full to our view, and is said to be In oppositiOflI because she is then on the opposite side of the earth with respect to the sun. , In the first half of her orbit, she appears to paIS over our heads through the upper hemisphere; she now descends below the I'8ltern horizon. to pass through that part of her orbil which lie. in the lower hemisphere. After her tOil, she wanes through the same chllnges of appearance as before, but in an inverted order; and we _ her in the morninlt like a fine thread of light, a little west of the rising sun. For the next two or three days, she is lost to our view, rising and setting in coojumtion with the sun; after which. she passes over, by reason of her daily motinn, to the taBt side of the sun, and- we bllhold her again a new moon, as before. In changing sides with the slln. she changes al80 the direction of her crescent. Before her conjunction, it was turned to thtl east; it is now turned toward the west. '1'hese ditrerent appearances of the moon are called her pluuta. They prove that she shines nnt by any light of her own; if she did. being globular. WII should always s~ her a round, full orb. like the slln. _ The moon Is a satellite to the earth, about which she revolves, in an elliptiCal orbit, in 29 days. 12 honrs, 44 minutes, and 3

TIlE MOON.

249

eeeonds: the tiDle which elapsetl between one new moon, and anoth .. r. Thi8 i8 called her ayfllJdic revolution. Her revolution from any fixed star to the same star again i8 called her periodit. or "idereIJl revolution. It is accompli8hed in 27 daY8, 7 hoors, 43 minutes, and 111 seconds; but, in this tiJIle, the earth has advanced nearly as .many degrCtl in hor orbit, con8equently, the moon, at the end of one complete revolution, mUBt go al mall,. df'grees further, before she will COUIII again into the same P,"",Ition with respect to the Ion Ind the earth. 'rhe moon i, the neuest of all thlheavenly bodies, being 30 times the diameter of the eartb, or 240,000 miles, distant from Ull. Her mean daily molion, in her orbit, is nearly 14 times Sl great as the earth'B; Bince she not only accompsnies the earth around tbe 8un every year, bot, i~ the Dleanlime, performs nearly 13 revolutions aboot the earth. ' Although the apparent motion of the moon, in her orbit, is greater thlln that of any other heavenly body, since she pa.- over, .t a mean rate, DO Ieee than ISO 10' 36 in • day; ret this is to be understood .. H

aI/gular motiort-motion in. ama1l orbit, and, therefon!, embracing a great Dumber of tJesr-, and but comparatively few miles.

'rbe moon, though apparently as large a9 the 8un, is tbe 8malle8t of all the heavenly bodie8 that are visible to tbe naked eye. Her diamettor is but2162 miles; consequently, ber surface .is 13 time8 less than that of the earth, and her bulk 49 times leas. It would require 70,000,000 of such bodies to eqoal the volume of the sun. The reason why she appears as large a9 the sun, wben, in trotb, sbe is so much less, IS because sbe is 400 times nearer to us than the sun. ' The moon revolves onee on her axis, exactly in the time tbat she performs ber revolution around the earth. 1'his is evident from her always presenting the same Bide to the earth; for if she bad no rotation upon an axitl, every part of her surface woold be pre.ented to a Ipectator on the earth, in the course of her synodical revolutiop. It follows, then, that there ia but 0fIe day tmd fligAt in Aer year, containing, both together, 29 day., lla hours, 44 minutes, and 3 seconds. A. the moon, while revolving aboot the earth, is carried with it at the 1Iame time around the sun, her path is extremely irregular, and very different from what it seems to be. Like a point in the wheel of a carria~, moving over a convex road, the moon will deacribe a succe8Slon of epicycloidal curves, which art' always concave toward the Bun, not very onlike their presentation in the following figure. ,

~l)O

GEOGRA PHY

OF

THE HEAVENS.

THII: MOON'S MOTIUN.

Lel.ltU B repre.eDI a portion of the earth... orllil; and •• ell. tbe Inoar orbiL Wheo Ih& earth ia a' t, Ibe now mooo il al .; and while \he earth .1 moviog from •• 10 illl"'"ilion .1 reprelODled in Ihe figure, the moon baa moved through h.lf ber orbit, {rom. 10 e, where ohe io full; 10, while ·Ihe earth i. moving {rom ita pre ... nl poaitioO.lo II, Ihe mooo describes lbe olber bal{ of ber orbiL (rom e 10 .. wbere sbe i. agaio in conjunction.. .

As the moon turns on her axis only as sbe. moves around the . earth, it is plain that the inhabitants of one balf of the lunar world are totally deprived of the sight oftbe earth,.UDless they· traYel to the opposite hemispbere. This we may presume tbey will do, were It only to view eo sublime a spectacle; for it ill certain that, from the moon, tbe earth appears len lima larger than any other body in the universe. .; , As the moon enlighten!! the earth, by reftecting the liJ.bt of the sun, 80 likewise the earth illuminates the moon, exhibiting to her the same phases that she does to 08, only in a contrary order. And, as the surface of the earth is 13 times as large as tbe surface of the moon, the earth, when full to the moon, will appear 13 times as large as the foil moon to os. 1'hat side of thtl moon, therefore, which is toward the earth, may be said fo have no darkness at all, the eartb constantly shining opon it with extraordinary splendor when tbe sun is abeent; it therefore enjoys successively two weeks of illumination from tbe sun, and two weeks of !lartb-Iight from the 8ftrtb. The other side of the moon bae ahemately a fortnigbt's light, and a fortnight's darkness. As the earth revolves on its axis, tbe several continents, spas,

'PID MOON.

.0

251

aad iet.ad., appear &0 &he lanar inbabhauw like many IPOtl, of dilferent forlDa aod bllightlHlllt alternately moving over ita .lurf4C8. being more I)r leal brilliant, as they are leen through intervening cloudl. By thlllle Ipo\l, the lunarianl can not only determine the period of the earth'_ rotation, JUlt as we do that of' the -1lBo bnt they may aI_o dad the longitude of their places, as we dod the latitude of OUll. , As the full moon alway. happ8D8 when the moon il directly oppoaite the Iun, all the full mOO8l in our wimer, mUlt happen when the moon ie on the norlA lide of the equinoctial, beCause tI&m tbe lun' is on the IOIIlA lide of it; coDBequently, at the north pole of the earth, there will' be a fortnight's moon-light and a fortnight's darko... by toms, for a periocl of lix monthl, aod the lame will be the fact during the IUO'_ abll8DC8 the other six months, at the lOuth pole. The moon's axis being inclined only about lio to her orbit, ahe can have no 8Ilnsible diversity of _sons;' £rom which we may infer, that her atlnosphere il mild and uniform. The quantity of light wltich we derive from the moon when full, ia an888t three hundied Lltouland times less than that of the sun.When viewed through a good te18BCOpll, the moon presents' a moat. wonderful and interesting aspect. Heaides the large dark spo\l, wbich 8J8 visible to the nakec1 eye, W8 perceive extensive valleys, Ibelving rocks, and long ridp of elevated mountaine, projecting their shadows on the plaIRs below. Single mounlains occasionally rise to a great hight, while circular hollows, . more than tlaree milea deep, seem excavated in the plainl. Her mountain scenllry bears a striking resemblance to the towering sublimity aud terrific ruggedness of the Alpine reogions, or of the Appenine•• after which some' of her mountains have been uarned, and of the Cordilleras of our own continent.Huge massel 'of rock rising precipitously from the plains, lift their ppaked summits to an immense higbt in the air, while s\lapeless crags hanl{ over their projecting sides, and 888m on the eve of being preCipitated into the tremendous chasm below. Around the base of these frightful eminen08l, are _trewed numeroul loose and unconnected fragments. whicb time seema to have detached from their parent mass; and when we exallline the rents and ravines wbich accompany the overbanging clilfs. the beholder expects every moment that thel are to be torn from their base, and that the proces!! of destructive separation whicb ht!' had onl:ycontemplated in ita effecta, is about to be elthibited before him in all its l8Ility. -Thil i~ Monl. Boaqaer'. infefl'lllce. from hi. e][perim~nh.•• at1tted h,· ,.. Plo.ee, in hil work, II. 019. The nolult or Dr. WolJlllton'. eoml.'utHtlnn.· Wft. dill'erenL proreuor Leahe makfll the litrht of the mnnn 1110 000 IImPlle.. 'thai IhaI of \he IU'.: it ....u formerly reckoned 100,000 time. 1_

'158

GEOGRAPIlY 01' TIlB HEAVENS•

. The r a . of nlouDtUu nlled the ApfHlRines. "hietI travell8l a portion of the ..- ' a disk. from north-eut to aoath,-west, ._ of which some pug are .visible to "'e naked eye, rise with a precipitout aDd cram froIK from the level of tbe Mare Imlwiu"" or Sea of sbowera. - ID abie extensiYe range are _era) ridget wbose summits" ha" a perpeadicufar elevation of feur miltltl, aud more; and though tbe), often deacend to 8 much· lower h!vel, they prelent an ina..,.ble barrier on the north-east, while on "'e sooth-weet they "nk,in pa\le 4eeliYity to the plaiM. There is one reIIlukabie featare in the moon'" lurface, whieb bears no analogy ,to any tbibg obeervable on the eartb. This is the cireular CBftlies which 11ppesr in every part of ber disk. Some of these immense cavens are nearly folJl' miles deep, and forty miles in diamet.er. They lire most numeroul in""tbe southwestern part. At they reBect the 8un'I rays more copiollsly. ahfe, reader this put of her lurface more brilliant thaD any other. They present liD DI JUIIlily 'he same appearance as our earth millht he .upposed to present to the moon, if all our great lakea and seu were dried .p. '. . The number of, ~bble spets on the moon, wbose latitude and lougit.ude· have been accurately determined, nceedl two hundred. TIle nllllfher of aea.e and lakel. al "'ey were formerly considered, whose It>D~ and breadth are known, il between twenty and. thirty; whale the number of peake and mountaina, whose perpendicuIJr elevation varies from a fourth of a mile to five miles in hi,ht, and Wh088 bases are from one to leventy miles iD length, II uot Ie.. "'an one hundred and fifty. t , Graphical views. of these natural appearance&, accom= with miIJ. ute and familiar de9Criptioos,eonstitute wbatiscalled . apAy;utwo Greek words, whicb mean the li8liiii thing in mprd to the IDOOD, • Geography does in regard til the earth. An idea of lome of these scenel may he formed by conceiv'lng a plain of about a hundred miles in circumference. encircled by a range of mountainti, ofyarious forms. three miles in pl'lr' pendicolar·higbt, and having a mountliin near the center, whose top reaehel a DiHe and a half above the level of the plain. From the top of' "'is central mountain. the whole plain. with all Its scenery, would be distiuctly visible, and the view would be bounded only by a lofty amphitheater of mountains, rearing their I~mmits to the Iky. • The D8!D" oe a luuar IpOI. t Brewoter'a ~l,. The beat mape oe the _ n hitherto publiahed, are thOle by Mldler and Beer; bUI the mOllt curlou. and eomplete repreoenl.. lioD of the leleocollic and natlll'lli 8ppe8ran~a oe the moon. i. 10 be IOen 011 au.'-"· T"n,- 'J'e'" !:tee a1ao BIfmoIropMa, by C. PIUDL .

TIlE MOON.

253

Tbe bright apota of the moon are tbe mountainous ",gions ; while the dark 1fI0ta are the plainl, or more level parts of· her lunace. There may be rivera or small lakes on this planet; but it is generally thought, by astronomftra of the present day, that there are no seas or large collections of watt-r. al was formerly lupposed. Some of these mountains and deep "Heys are viaible to the naked eye; and many more are visible through a telescope of but moderate powers. A telescope which magDlfies only 8 hundred times, will show a s:l'0t on the moon's surface, whose diameter is twelve hundred an twenty-three yards; and one which magnifi ..s a thousand' times, will enable us to perceive any enlightened ohject on her surface whose dimension. are only a hnndred and tWllnty-two yards, which does not much exceed the dhnensionl of some of our public edifices, as for instance, the Capitol at Washington. or SL Paul's Cathedral. Professor Frauenhofer, of Munich, recently announced that he had discovered a lunar edifice. resembling afurtijko.tion. together with .etlerallinu tf road. The celebrated astronomllr Schroeter. conjectuff's the existence of a great city on the east side of th.. monn. a little north of her equator, an extensive canal in another plac... and fields of vegetation in another. But no reliance is to be placed on these conjectures.

BOLAR AND LUNAR ECLIPSES.

Or all the phenomena of th" heavens. there are none which engage the attention of mankind more than ecl.ips!'!s of the sun and moon; and to those who arll unacquaint!'!d with astronomy, nothing appeara more wonderful than the accuracy wj.th which they can be predicted. In the early ages of antiquity th!'!y wllre regarded as alarming deviations from the established laws of nature, presaging great public calamities, and other tokens of the divine displeasure. In China, the prediction and obaemmee rI ecIit- are made a mattet rI lltate policy. in order to operate on the fears of the ignorant, and im pose on them a superstitious re~ard for the occult wisdom of their ru\era In Mexico, the natives fast and a1Bict thl!Dlselve8 during eclipses, unde! an apprehension that the Great Spirit is in deep sutJerance. Some of the northern tribes rllndisnl have imagined that the moon hed been wouncJ. ed in a quarrel; and others, that &he was about to be _allowed by a huge fish.

It 11'88 by availing himself of these superatitious notionR that Culumbu., when shipwrecked on the island of Jamaicp, extricated himself and crew fiom a most embarrassing condition. Being driven to great distress for want of proviIioua, and the natives refuaiDg him any IIIIistance, when all

.'

26;'

GEOGRAPHY OF THE HEAVENS.

hoPe .emed to be ent ~ 'be ~ himIeIf mtheir IIIIpI!nICiticm ill regard to eclipaee. Having a.eJIIbJed the principal men of the iaImd, be remoillltrated against their inhumanity, .. being oJImsive' to the Great Spirit, and told them that a great plague waa even then ready to fiill upon them, and aa a token of it, they would that night _ the moon hide ber fiu:e in anger., and put on a dreadfully dark and threatening aapec:t. ThiB "artifice' had the desired eftIItt; for tIie ecli~ had no 1I0OII8I' begun than the frightened barbarians came running with all kind. mproviaicma, and thrOwing tllelJlllllv88 at the at of Columbus, implored his furgiV8Jl8llLAIrna"."fJJI. vol. I, 65 c., v. 2. An eclipse of the aun takea place, when the dark body of the moon. passing directly between the eartli and the sun, intercepts ·his light. This can happen only at the instant 0(-.0 mOOD, or when the moon is in conjunction; for it ia only theD that abe passes between us and the sun. ' , A,n eclipse of the moon takes place when tbe dark body of the earth." coming ~tween ,ber and tbe sun, ,intercepta bis ligbt, and throws a shadow on tlte moon. Thia ran bappen only at the time of full moon, or whE'n the mOOD ia in opposition; for it ia only then that the eartb is between ber and tbe lun. Aa every planet belonging to the aolar aystem, both primaty and secondary, derives its light from the aun, it muat cast a ahadow toward tbat part of the heavens whicb is opposite to the sun. This sbadow IS of course nothing but a'privation of ligbt in th" splice hid from the slln by tbe opake body, and will be proportioned to the magnitude of thl' lIun and planet. If tbe aun and planet WE're both of the same magnitude, tbe form of the shadow cast by the plan!"t. would be that of a cJ lindel;, and of the same diameter as th!" Bun or planet. If the planet were larger than the sun, the shadow would continually diverge, and gtp.w larger and larger; but as the sun is much larger than aOJ of the planets. the shadows which they cast must converge to a point in the form of a cone; the lengtb of which will be proportional to the size and distance of the planet from the sun. The ~ mthe IOn is lOch, that the shadow east by each of the primary planets always CCIJlverge& to a point before it reach8B any other planet; 80 that not one of the primary planets can eclipse another. The shadow of any planet which is accompanied by .tellitea, IIIIIY, on certain occasions, eclipse ita .tellites; but it is not'Iong enough to eclipse any .fther body., The shadow of a .tellite, or moon, may alao, on certain OCcasions, fall on the primary, 'and eclipse it. When the sun is at hi!! greate.t distance from the earth, aDd thor moon ,at her letut di8ta:nce~ her IIhadow is sufficiently long to lI'ltch the, earth, and extend 19,000 miles beyond. Wben the lun is at his letut diatanc6 from the earth, and the moon Ilt her

ECLIPSES.

trealal, ber Ihadow will not reach the eartb'a lunace by

20,000

Dliles. So that wben the aDn and moon are at their _

distances: the cone of the moon'a sbadow will terminate a liule before it reacbea the earth's surface. In tbe former caae, if a conjunction take place when the center of tbe moon comes in a direct line between the centera of tbe aun andeartb, tbe dark shadow of the Rloon will fall centrally upon the earth, and cover a circular area.of T75 mileS iii diameter. To all places lying within thia dark spot, the aUD will be totally' eclipsed, aa illustrated by the figure. . ICLIP8l1:a OJ' TRI aUJ'"

In COIIII!qU8IlCl8 of the earth'. motion during the eclipse, this c;ircuIar _ becomeI a continued belt over the earth'. 1IIIrlice; being, at the broadeII&, 175 miles wide. This belt is, bowever, mely 80 broad, and often dwindlea to a mere nominal line, without total darb_. In March, this line extends- itself from 8. W. to N. E., and ill September, from N. W. to 8. E. In June, the central line ia a curve, going tirat to the N. E., and then to the 8. E.; in December, on the contrary, tirat &0 the 8. E., and then to the N. E. To all places within 2000 miles, at leut, of the central line, the eclipse will be vUa"ble; and the nearer the lliace of oblervation ia to the line, the larger will be the eclipse. In winter, if the central trace be but a little northward of the equatorl and in 1J1IIIIID8J', if it be 21)0 N. latitude, the eclipse will be visible all OVIll' the northern hemi8pbere. A. a general rule, though liable to many modifications, we may observe, thet pJacea from 200 to 250 miles from the central line, will be 11 digita eclipsed; from thence to 500 uilleB, 10 digita; and 80 on, diminiabing one digit in about 2.'10 milea. . If, in either of tbe otber casea, a conjunction take place when tbe moon's center is directly between the centera of the sun and earth, aa before, the moon will then be too distant to cover tbe entire face of the aun, and thpre will be aeen, all around ber dark body. 8 slender nbg of dazzling light. . .

258

GEOGRAPHY OF THE HEAVEN8.

Tbi8 may be iJI1JIImted by the ingoing figure. 8uppoae C D to reo p - t a put of the earth'. orbit, and the moon'. llladow to terminate at the vertex V. The IIIIIIIIllI(l8ce between ef win represent the breadth of the IWIIinowI ring which will be -riaibIe all &round the dadr. bod,. of the moon. Such ... the edipae of February 12, 1831, which J--.I over the 8OU~ ~ from.8. W. to N. E. It was the aunu1sr eclip..e ever ~sibIe m .the Umted SIateL Alcmg the path of thia eclipae, the lumie_ rmg remained pedi!ct and unbroken tOr the .pace of two minutes From the IDOII& elaborate calculation.. com~ed with a long aeries of observations, the length of the moon'. shadow m eclipaes, and her distsnl"ll &om the Bun at the IIUIIII time, vary within the limits of the foUowing table:

I!lIIl

Le~ of BhadoW,/ DilL of mooD. Leut Mean Ore.telt

fiT..

Length of Bhatlow in 1Length 1 Di.tance in / Di ... ...;ce semidiameters. in IDllel. semidiameteu. in milel.

1 118.

&9.'

'53056= 1

55 1228.(99 ~M 1 110.

236._

63.862

211.148 1138.300 1152..638

Thus it appears that the length of the eone of the moon's llbadow, in eclipses, varies &om 228,499 to 236,292 miles; being 7.793 miIea Icmger in the one case, than in the other. The iqequality of her distsnces from the earth is much greater; they vary &om 221,148 to 262,638 miles, making a difJimmce of 31,490 miIea.

!lthough • central eclipSft of the lun can never be total to any Ipot on the earth more than 175 miles broad; yet the space over which the sun will be more or less partially eclipsed, il Dearly 5000 milel broad. The section of the moon'. shadow, or her ~umill'll, at the earib'. BUJIo lace, in eclipaes, is tar &om being alway. circular. If the conjunction happen when the center of the moon is a little ahooe or a little 1ieIow the 60e joining the centers of the earth and Bun, as is moat frequently the case, the shadow win be projected ~ over the earth's aurfilce, and thus cover a much larger apace. To produce a partial ecli~ it is not neceBlry thet the lIbadow should reach the earth; it is sutlicieilt that the apparent diatance between the Bun and moon be not greater than the BUm of their aemidiameten.

If tbe moon performed her revolution io the same path in which the sun appeara to move; in other words, if her orbit lay ezactly in the plane of the earth's orbit, the .Iun would be eclipsed at the time of every new moon, and the moon at the time of every full. Bot one half of the moon's orbit lies about 50 on the north &ide of the ecliptic, and the other half as far on the south side of it; and, consequently, the moon's orbit only croSBeS the earth', orbit in lwo opposite pointa, called lhe moon's Dodel.

257

ECLIPsEs.

When the mOOn is in ooe of these points, or nearly so. at the time of the fleW moon, the aon .will be eclipsed. Wben she ia in one of them, or nearly ao, at the time of full moon, the moon will be eclipsed. But at all other new moons, the moon eitber passes above or below the Bun, as 888n from tbe earth; and, at all other full moons. Ibe either passes abo.e or below the earth'a shadow; and, consequently, there can be no eclip~. If the moon be _tl!l in one of her nodes at the time of her change. tbe lun will. be centrally eclipsed. If Ihe be 11° from her node at the time of her chanr, tbe lun will appear at the equator to be about 11 digits ecllpled. If sbe be 3° frolD her node at the time of her cbange. tbe lun will be 10 digits eclipsed, and 10 on; a digit being tbe twelftb part of the sun's diameter. But when tbe moon is about 18° from ber node. she w:lll just touch the outer edge of the lun. at the time of ber c~ngfl, witbout producing any eclipse. Tbese are called the ecliptic limiu. Between these limits, an eclipse is doubtful, and requires a more exact calculation. The mean ec1iptieJimit for the IUD ill 1610 on esch aide of the

ilode;

the mean ecliptic limit for the moon ill 10010 on esch aide of the node. In the former cue, then, there are sao about esch. node, making, in aU, 660 out of 3600, in which eclq- of the IOD may happen: in the latter caae, there are 21 0 about each node, making, in all, 420 out of 3600 , in which eclipM of the moon OIUally 0ClCIIJ'. 'l'he proportion of the lOW to the lunar ec\iples, therefore, ill u 66 to 42, or u 11 to. 7. Yat there are more Yiaible eclipM of the moon, at any given place, than of the BUn; beca1llll a lunar ec1ipee ill visible to a whole hemisphere, a eo1ar eclipse only to a amall portion of it. . . The greatest possible duration of tbe annutar appearance of a aolar ecliple, il 12 minutes and 24 seconds; and tbfl greatest poslible time during wbich the sun can be totslly eclipsed, to any part of tbe worlil, is 7 minutel and 58 secondl. The moon fIlay continue totslly eclipsed for one hour and tbree quartan. Eclipsel of the sun always begin on hili weltern edge; and end on bis ealtern; but all eclip881 of the moon commence on her I'astern edge, and end on her western. . If the moon. at the time of !ler opposition. be exactly in ber Dode. she will pass througb tbe center of tbe earth's Ibadow, and be totelly eclipled. If. at tbe time of her opposition; ahe be witbin 6° of ber node. Ibe will still P8lS throu~b tbe earth's shadow. thougb not centrally, and .be totally eclipsed:. but if ahe be 12° from ber node, she will only jl1st toucb the eartb's sbadow, and pass it witbout being eclipsed. . . The duration of lunar ec1it-. therefore, dependa upon the dIJIi,renc. between the diameter of the moon and that IIBC&ion Of the earth'. Bbadow

x2

.

258

GEOGRAPHY OF THE REAVEN8.

duougb. which abe ~ . When an eeIi}le of the moon is both total and central, ita duration is the 10Dplt poaible, IIIJIOIItlting nearly to .hoan; but the duration of all eelipees not central qriat with her cIiBIaQce 60m the node. aCLI..a. or TWa

11001'.

The tlitImder of the earth'. shadow, at the distance of the moon, ia Dearly three times as large aa the diameter of the moon; and the length of the earth's abadow ia nearly four times Sf:! ~I'f'at 8S tbe di8tanCII of the mOOD; exceeding it in the same ratio thllt the diameter of the eartb d088 the diameter of the moon, which is aa 3.663 to 1.

I

''''''lqtb of .... _ .. _ ..... \fo ....._ at ....._ of DIam_.,1IIo ... ...,o, .... lIItdeet .. tbe ..r. . . . ezhihlterl ia lbe .,UowlDtlable, """0..

1 1

Moon at the apogee Son allhe peri... Moon al b~r m~an dialanc.· Moon at Ihe per'g.oe I\I00n at Ihe apoge~ Son at hi. mean diltance Moon at ber m.all dlltalle. Moon at the perigee Moon aL tbe apogee Moon al her meBj.diIlRnc. Son at the apogee Moon at the per:gee

I

6.~rJ

6.7&.1

8.~J

5.270

5.7\)9 8.3'8 6.308 &.gj6

ILoooth .,

'be

....1""" ill...,.

J

f J

&12,217 8Ii6 5:17 !Q1,9119

6385

The firIIt column of figures ex~ the diameter of the earth'. shadow at the moon: and 88 the diameter of the moon is only. 2162 milea, it is evident that it can alway. be comprehended by the shadow, which is more than twice 88 broad 88 the disI! of the moon. .

The time which .elap888 between two succ888ive chaDges of the moon. is called a Lunation, wbich, at a mean rate, is about 291 dayR. Ir 12 lunar months were exactly equal to the 12 solar months, tbe moon's node8 would always oecuP1 the same points in the ecliptic, and all eclipses would bappen ID tbe 8ame months of tbe year, 8S i8 the Ca8f' with the transita of Mercury and Venua: but, in 12 lunations, or lunar months, tbere are only 3M day!!; and in this time the moon has passed tbrough both her nodes. hut has not quite accomplished her revolution around the 8un: the consequence is, that the moon's nodes fall back iD the ecliptic at the rate of about 19jO annually; so that the eelipslIl! happen sooner every year by about 19 day •• As thl! moon pa8ses from onA of hllr nodes to the otber in 173 da18, there i. just thi. period between two succ88sive eclipaea

ECLIPSES.

259

of tbe sun, or of the mooD. In wbatever time of tbe yesr, then, we have eclipses at eitber Dode, we may be sure tIIat in 173 day. afterwards, we shall bave eclipses at the other node. :\s the moon'. nodes fiaII back, or Ntrograde in the ecliptic, at the rate of 19!0 every year, they will colllJllet& a backWard revolution entirely around the el'liptic to the IllUDe pumt again, in 18 yean 2t1i day.; in which time there would alway. be a regular period of ec\ipBes, if any compJete number of lunations were finished without a mnainder. But this neYer happens; for if both the sun and moon mould start from a line of conjunclion with either of the nodes in any point of the ecliptic, the IIUIl would perform 18 annual revolutions and 2220 of another, while the moon would perform 230 InnatioQa, and 860 of another, before the node would come around to the same point of the ecliptic again; so that the IIUIl would then be 1380 from the node, and the moon 860 &om the san. But after 223 lunations, or 18 years 11 day..• 7 houra, 42 minutes, and 31 seconds, the aun, moon, and earth, will return so nearly in the ..me po
aun, and 29 "fthe moon. The number of eclipses in anyone year, cannot be less than two, nor more than Benn, In the former ease, they will both be of the sun; and in the latter, there will be five of tbe 8un, and two of the moon-those of tbe moon will he total. There are sometimes six: but the usual number is four: two of tbe aunt and two of the moon. The cause of this variety ia thus IlCC01UIted for. Although the sun usually paaI8II by both nodes only once in a year, be may Jl888 the same node aguin a little befilre the end of the year. In consequence of the retrograde motion of the· moon's nodes, be will come to either of them 173 day. after passing the other. He may, therefore, return to the same node in about 346 days. having thus pused one node tIJJi« and the other _ , making each time, at each, an eclipae of both the sun and the moon, or Biz in all. And, since 121unationa, or 8M day. nom the fir,t eclipse in thf' beginning of the year,leave room for another new moon before the close of the year, and llinee this new moon may tall within the ecliptic limit, it ia poaaible for the sun to be eelipaed again. Thus there may be Be11e1I ecIi.- in the same year. Again: when the moon changes in either of hf'r nodes, abe caHoot come within the lunar ecliptic limit at the next full, (though if she be • If there are f - leap yean in thI. intef'f.al, add 11 day.; bllt if there .,.. ",.., add only teD daYL

280

GEOGRAPHY OF THE HEAVENS.

·

foil ill one 01. her DOdea, ahe may come into the . . . ediptic limit Ii her next cAange, and llix montha afterwarda, she.will change near the node; thus making only two eclipaea. The following is a 1m of all the BOlar eclipees th.. t will be visible in. Europe and ADBica during the remainder of the ~'nt century.

other

TN.

-

Mar. July ISM May Mar. 1858 IH511 Jl11y July 18110 1861 Dec. 1863 May Oct. 1885 Ocl. 1866 1867 Mar. l'eb. 1868 Aug. 1869 Dt-c. 1870 May 1873 11174 . Ocl. Sept. 1875

1848 1861

Il\sit. 1IaJ·... - . I! 7 III A. M. ~ 148 A. M ;It ttl 4ll1l P. M. 11t 1& 614 A. M. 29 I! 3Il P. M. 18 193 A. M 31 730A.M 4t 11 lOP. M. ~ 19 • 10 A. M. 3. . I> 1~ 1110 AM. A. M'I 0 S 2810 0 AM. 7 II 21 A. M. 11Il· 22 II 0 A. M' ~ 30A.M. 10 4 0 A. M 19 II 116 A. M. III

T

a

I

-Year.. -Mrdh. -I

m' .... _.

o;po..

~f

Mar. 25 411 P. ltl. July 4 &6 P. M. July 111 II OA.M. Dec. 31 ? 30 A. M. III May 17 1 OA.M. Mar 16 035 A.M. 8l Aug. 29 630A.M. Ill. Aug. I~ 10 o P. M. June 11 3 o A.M. 1~91 June S 0 o Mer. 0111 P. M. 81 1-112 ! Oo.t. 1891i . I\lar. ~ 4 o A.M. 0 0 Mer. 9 Aug. lriU6 July 1111 9 8 A. M. 4l 1M 13 DOMer. June 1899 \ May 128 8 9 A. M. 11 1900

111711 1878 1879 1880 1>-81 lass 18116 1887 1890

•

I

•

The ecHJ- 01 18M, 1869, 1876, and 1900, will be very large. In th088 of 1868, 1861, 1873, 1875, and 1880, the wn wiN rise ec/ipiltd. Th088 of 1854 and 1876, will be annuiur. The dolar can cootiDue this table, or exteDd it backward, by adding or subtracting the CbaIdean period of 18 yeara, 11 days, 7 hours, 54 miDutea and 31 second.. . '!'he lunar elements fur the lit of Jan. ISO I, are .. folloWl: 29.9.76 Mean distance (237,000 milea) earth eq. diam. .. unity, Mean sidereailevolution, BOlar days, • 27 d. 7 h. 43 m. 11.6 L Mean tropical" "" 27 7 43 04.7 Mean synodical" ".. 29 12 « 02.87 Mean longitude, 1180 17' 08".3 13 10 36 .0 Mean motion in a mean BOlar day, Mean long. of perigee, • 2660 10' 7".4 Mean motion ofapsides, in a ao1ar day, ' . . 6' '1".0 Sidereal rev. 01 apsides, ill mean BOlar days, 3232.6763 Tropical revolution of ditto, 3231.47'() 1 Mean anomaly, 2120 6' 69".9 Motion of ditto, ill a mean ao1ar day, 130.064991 17 d. 13 h. 18 m. 37,4 L Mean linomaliatic revolution, ill BOlar days Inclin.tion of orbit, 50 8' 47".9 A_nding node, 13 63 17.7 Motion of ditto, in a mean BOlar day, 3 10.8 ~Nai revolution of nodes, 6793.39108 Synodical revolution of ditto, :U6.6198!;l Revolution from node to node, 27 d. 6 h. 6 m. 36 .. Et'CBntricity of orbit, . 0.06'8442 Greatest equation of center, 60 17' 12".7

261

ECLIPSES.

tncIiruI&ion of axis. Madmum evectioa, Maximum ftriation, Maxim1Jlll lJlllual equation, Minimum horizoDtai parallax, Meandiu.o, Maximum ditto, Maximum app. diam.. Mean ditto, Minimum ditto, Mean diameter (about 2160 miles) earth'. u unit,.,

VoIulDll,earth88unity,

M....

DeDaity,

-

-.

-

10 30'10".S· 1 20 29 .9 36 42.0 11 12.0 6S 48.0 67 00 .9 01 24.0 33 31 .1 31 07 .0 29 21 .9 3.ti6:1 I ''T

0.01252 0.61.')

MARS is the first of the exterior planets, its orbit lying immediately without, or beyOfld, that of the earth, while tbole of Mercury and Venuaare witAi... . Mllfs appears to the naked eye, of a fine ruddy compll'xion ; reaembling, in !lolor, and apparent magnitude, the atar Antares, Dear which it frelJuently passes, It exhibits its greatest .brilIiancy ahout the time that it rill88 when the sun sets, and sets when the sun rill88; because it' is then nearest the earth. It is lea.t brilliant when it rill88 and sets with the aun; for then it i8 five times farther removed from U8 than in the former ease. I ts distance from tbe earth at its nearest approach is about fifty nlilliona of milea. Its greate.t distance from us is abollt two hundred and forty millions of miles. In the former case, it appear8 nearly twenty-live timealarger than in the latter. When' it ri8e8 before the Bun, it is our morning atar; when it sets after the 8un, it ia our evening atar. The distance of all the planets from the earth. whether they be interim or exterior planets, varies within the limits of the diameters of their orbits • ror when a planet is in that point of its orbit which is nearest the earth, it is evidently nearer by the whole diameter of ita orbit, than when it is in the opposite point, on the other side of its orbit. The appDI't.f1t diamekr ·of the planet will alao vary for the IRme l8IIIIOD, and to'the _ degree. Mar8 ia aometimel leen in opposition.to the sun, and 8ometimes in superior conjunction with him; sometimes gibbous, bllt DOver horned. In conjunction, it is never seen to paBB over the

262

·

GEOGRAPHY OF THE HEAVEN&.

lun'l dilk, like Mercury and Venul. Thil pro~es not only that ita orbit is u:ltrtor to the· eartb'l orbit, but tbat it i8 an opue body, Ibining only by tbe reflection of the lun. The motio~ of Mari through the COD8tellationl of tbe zodiac is but little more .tban laalf 81 great as that of the earth.; it being trenerally about fifty-seven days in passing ovpr one lIilJll, which IS at the rate of a little more than half a degree each day. ThuI, if we kfloW wbat conltellation Mars entera to day, we may conclude diat two monthl hence it will be in the next cODtiteliation ; fourmontlJl heol,e, in the next; six months, in the next, and 80 On. Mars performs hil revolution around the sun in oile year and ten and a half months, at the di8tance of a hundred and fortyfive million8 of milel; moving in ita orbit at the mean rate of fifty-five thousand miles an hour. Ita diurnal rotation oli ita axil II performed in twenty-four hours, thirty·seven minutes, and twenty-one and a third seconds; which makea itl day about forty-four minutes longer than ours. Its mean Bidereal revolution

is perfcmned in 1186.9796458 BOlar day.;

or in 686 day., 23 hoora, 30 minutes, 41.4 IIIICOJlda. Its Iynodical revo-

lution ill performed in 779.936 BOlar days; or in 779 day., 22 hows, 27 minutes, and 60 aeconda.

Ita form is that of an oblate spheroid, whose folar di~meter is to ita equatorial, as fifteen is to sixteen, near y. ItB mean diameter is 4222 miles. Ita bulk, therefore. is seven timel leu than that of the earth; and being fifty millions of miles farther from the 8un, it receivea from him only half 88 mucb light and heat. The inclination of ita axi8 to the plane of ita orbit, is about 28fo. Consequently, ita BeaBons mUlt be very 8imilar to those of the earth. Indeed, the analogy between Mars and the earth is greater than tbe analogy between the earth and any other planet of the lolar system. Their diurnal motion. and of courae the length of their daYB and nighta, are nearly the Bame; the obliquity of their ecliptiCB, on which the sealons depend, are not very different; anil, of all the superior planet8, the distance of Mars from the Bun is by far the nearest to that of the earth ; nor is the length of ita year greatly different from ourB, when compared with the years of Jupiter, Saturn, and Herschel. 'ro a spectator on this planet. the earth will appear alternately, as a morning and eveni!lg star; and will exhibit aU the . phases of the moon, just as Mercury and Venus do to U8; and· sometimes, like them, will appellr to pau over the lIun's disk like a dark round spot. Our moon will never appear more than II qtlGf'Itr qf II degree from the earth, although her distance froul

263 it is i40,OOO mil.. If Mars be attended by a satellite, it is too small to be seen by the moet powerful telescopee. When it is COIIIidered t!lat Vest&, the ImaUeat of the IIIteroida, which ie _ mid " !&all times the cIiatance of Man from UB, and only 169 miles in diameter, is peroeivable in the open apace. and that without the ~ of a more COD8piCUOUB body to point it out, we may reuonably

oooc1ude that Man is without a moon. The progn!IIi 01 Man in the heavens. and indeed of all the IUperior plan. . will, lib Mercury and Venna, IOmetimea appear direct, aome. timea ~ and IOmetimea be will _m ltationary. When a superior planet first becomes mible in the ~ing, welt 01 the sun, a little after its conjUDdion, its mOOon is direct, and a110 IIIOIt rapid. When it iB first _ eut 01 the lUll, in tbe evening, IOOD after ita opposition, its motion is rehvJ&mde. The. retrograde IIICm!IDentI and stations, III they appear to a apectBtor from the earth, are common to all the plane... and demonIItrate the truth of the Copernican lYatam. •

The telescopic pHenomena of Mars aft'ord p8C.'uliar intereat to astronomers. They behold its disk diversified with numerous irregular and variable apots, and ornamented witb zones aDd belta of varying brilliancy, that form, and diRappear, by tuma. Zones of intenae brightnllss are to be seen in its polar regiona, subject, however, to gradual changea. That of tbe aouthern pole ia much tbe moat brilliant. Dr. Herscbel 8Upp0888 that tbey are produced by tbe reftection of tbe aun'a ligbt from the frozen regioD8. and that the melting of tbese maa888 of polar ice ia the caule of the variation in tbeir magnitude and appearance. " He waa the more confirmed in these opiniona by observing, tbat after tbe expoaure of the IUIDinoua zone about the nortb" pole to a 8ummer of eight montbs. it waa conaiderably dureued. while that on the BOuth pole, wbich had been in total darknes8 during eight months. had conaiderably i_tilled. " He observed, further. that when this spot was most luminous, the disk of Mars did not appe~r exactly round, and tbat the brigM part of its aouthem limb seemed to be swollen or arched out beyond tbe proper curve. The extraordlDary hight and density of the atmospbere of Mars. are luppoaed to be the caule of the remarkable rednesa of its light. It has been found by experiment, that when a beam of white light paa888 tbrough any colorle.. transparent medium, ita color inclines to red; in proJ?omon to the density of the medium, and the space through WhlCb it has traveled. Thua the 8un, moon, and stara, apllear of a reddish color when near the horizon; and every luminoua object, seen through a mist, i8 of a rnddy bue.

264

GEOGRAPHY OF THE HEAVENS.

This pbenomeoon may be th11l explainech-Tbe momentum of the red, or Ieut refrauaibIe ra,., being greater than that of the violet. 01' IDOI& refrangible raya, the former will make their way through the rtlI!i.atinc medium, while the latter are either re8ected or abeorbed. The color of the betJm, thendOre, when it JI!IIChes the eye, mWlt partake of the c:olor • of the Ieut reIia,ogibIe raya, aod this color muat mer- with the w. taDce. '!'he dim light, therefOre, by which Man ia illuminated, haviug to pa.- twice through ita ~ere before it JI!IIChes the earth, mWlt be deprived of a great proportion of ita violet raya, aod COIIIIIMI.lkmtly then be red. Dr. Brewater IUPJIOIIeII that the diflerence'bf color among the other planeta, and even the fixed stara, ia owing to the diflerent bights aod denaitiea of their atmospheres. The elliptical e1ementa of Mala, for Jan. lilt, 1801, are as follows:

Mean distance (142,000,000 miles), earth'. as unity, •• 1.6236923 Mean aid. 1e9.,. . . . . . . . . . . . 686 d. 23 h. 30 m. 41.4 L Mean &yo. do., in BOlar days, • • •• 779.936 Long. of perihelion.. . . . • • 3320 2:)' 66".6 Motion cir apaidea, E. per. an., .' • • • • • 16".8 .. Rpparent for preceasion, • • • I' 05".1f Inclination of orbit, • • • • • • 10 51' 06".~ .-\nl1ual decrease of do., • • • • • • 0".014 Long. of ABC. node.. • • • • • 480 0' 03".5 Motilln of do. w. per annum, • • • • • • • • 13".It .. .. •• E. refilrred to the ecIiptic,. • • • • • 26".tI • 0.0933070 Eccentricity of orbit. Semi maj. axia unity, • Secularincreaae of do., • • • 0.00090176 Greate- t equation of center, • • 10° 40' 60" Annual decTe&Be of do., • • • • • 0".37 Rotation on axia.. • • 114 h. 37 m. lID.6 .. Inclination ofaxia. • • • 300 18' 10".8 Mean app. diam... • • • • 8".19 Diam. at conjunction, • • • • .3".80 • • • •

18.J8

True diam. (4100 miles). earth as unity, Volume, earth as unity, • • • • • • • M.... IIUD as unity, • • • • • • • •

..

.. oppoaition,. • •

0.617 • • • • 0.1386 • 0.0000003927

THE ASTEROIDS, OR TELESCOPIC PLANETS. AacC!m11l'8 higher in the solar system, we find, between the orbite of Mara and Jupiter. a cluster of nine small planete. which present a variety of anomalies that distinguish them from all the older planete of the system. They were all discovered withia the present centufJ.

THE ASTEROIDS.

The dalell of their diIcovery, IIIIIl the _ _ of their ~ ani

fOllow.:

•

.

Veres, January 1, 180 I, by M. Piazi, of Palermo. Pallas, March 28, 1802, by M. Olben, of BJeD1811. Juno. September 1,1804, by M. Harding, of Brelllllll. Vesta, March 29, 1807, by M. Olben, of BJeD1811. Astrea, 8th December, 1846, by Heneke, of I>nD-a. Hebe, 6th July. 1114,7, .. .. .. .. Iris, 13th Auguat, 1114,7, by Hind, of LoodoD. Flora, 18th Oct., 1114,7, .. .. .. .. Metis, 26th Apri1, 1848, by Graham, of 8ligo.

The scientific Bod". entertained the .opinion. that the planetary distanl'M, above ~ercury, formed a geometrical aerietl, each exterior orbit being double the distance of its next interior one, from the sun; a fact which obtain. with remarkable exactness between Jupiter, Saturn, and Herschel.. But this law seemed to be interrupted between Mars and Jupiter. Hence he inferred, that there wa. a planet wanting in that inteT\'al; which is now happily supplied by the discovery of the four .tar-jorm planets, occupying the very space where the unexplained vacancy pr,," aented a strong objection to his theory. These bodie. ere muc1& trmIJller in size than the older planetsthey all revolve at _IV t1ae _ diltaru:u from the sun, and perform their revolutionslD _Iy t1ae_ perioda.-their orbits are mucb more ~, and bave a mue1& greater ifll!lifltJlion to the ecliptic.-and what is altogether singular. except in the case of comets-nearly aU crOll _1& oJ1acr I so that tbere IS even a polli/Jjlity that two of these bodies ma1' some time, in the court18 of tbeir revolutions, come into colliSion. The orbit of Veata is eccentric. that sbe i. sometime. farther from the sun than either Ceres, Pallas, or Juno, although ber mean distance is mallY millions of mile. less than tbeirs. The orbit of VIISta crossetl the orbits of all the other three, in two oppOIite points. From these and otber eireumstancee, many eminent astronomers are of opinion, that these four planets are the. fragments of a large celetlual body which once revolved between Mars snd Jupiter. and which burst asunder by lOme ~mendous convul-

.0

I

a AceordinglO him, the diltance.oCthe planeta may be ezprelled nearly .. 6:>lIowI: the eiU'lh'a cliltanC" &om the IUD being ID. Mercury ••••••••••••••• " d Alteroidl •••••••••••• c:=28 Venul, ••••••••••••••• ':mJl =7 Jupiter••••••••••••• ·.4 'x'lll =62 The Earth, ••••• ...... • 1=10 Salurn.... ••• .. • .... •• =1110 Man, ................ =111 Henchel............ ·4+3XIll ...... Comparing 1M..... alael with the actaal mean dillancel DC the planell froIB tbe aan. we eanuot but remark the near agreement, and can eoareely helitate 10 pronounce tbal the relpeetive distancel of Ihe ~Ianets from the sun, were aaoigned according to R law. althou(rh we are enurel, ignorant of the exact law, and oflbe reatOn Cor that Illw.-Bri..w.,·, EIImeitII. p. 88.

Y

'!m)(!l

_

GEOGRAPHY OF THE HEAVENS.

aion, or BOrne external nolenee. The discover, of Ceres hy Piazzi, on the first day of the preaellt century, drew the attention of all the astronomers of the age to that region of the sky, and every inch of it was minutely explored. The consequence was, that, in the year following, Dr. OIbers, of Bremen, announced to the world the discoyery of Pallas, situated not many de~rees from Ceres, and very much reaemblinl1 it in size. . From this discovery, Dr. Olbers first concelyed the idea that these bodies might be the fragments of a former world. and if 80, that other portions of it might be found either in tbe same neighborhood. or elae, baving diverged from the same point, •• they ought to have two common points of reunion, or two nodes in opposite regious of the heavens throu1h which all the planetary fragments must sooner or later pass.' . .'One of these nodes ·he found to be, in the constellation Virgo, and the opposite one, in the Whale; aDd it is a remarkable coincidence that it was in the neighborhood of the latter constellation that Mr. Harding discovered the planet Juno. In order. therefore, to detect tbe remaining fragments, if allY existed, Dr. Olbers examined, tbree times eyery year, alf the small stsrs in Virgo, and the Whale; and it was actually in tbe constellation Virgo, that he discovered the planet Vesta. .some astronomers think it not unlikely tbat otber fragments of a similar description may hereafler be dlscoyered. Dr. Brewster attribute& the fall of meteoric atones to the smaller fragments of these bodies happening to come witbin tbe sphere onhe earth's attraction. Met.eoric atones, or what are generally termed aerolite3, are atofl.ee which IOID8I;imes fiill from t~ upper regions of the ~.here, upon the earth. '!'he substance of which tbey are composed, IS, for the most part, metalIit: I but the ore of which it consista iB not to be fuund in tM aatne _titumt ~ in any known substance upon the earth. Their fiill ia generally ~ by a luminous appearance, a hlaaing noise, and a low! explosion; and, when fuund immediately after their descent, they are al_yehot, and UBUaIly cxmnd with a black· crust, indieating a IItaIe of exterior tu.ion. Their size variee from that of ama1l fragments of inconaidmable weight, to that of the most ponderous _ . They have been fiIund to weigh from 300 pounds to ae'feral tons; and they have descended to the earth with •.furce lIIllBcient to bury them many feet under the sur&ce. . . ~ome have supposed that the, are projected from volCan08ll in the moon; others, that they proceed from volcanoes on the earth; while othel1l imagiRe that they are generated in the regions of the atmosphere ; bat the truth, probably, iB not yet ucerlained. In lOme inatances, these atonea 00""' penetrated through the roo& of houaes, and. prom deatnloo ti'fe to the inhabitants. If we carefully compute the foroe of gravity in the moon, we shall find, tbBt if • body were projected tiom her surliloe with a momentum that

TH& AST&ROIDII.

'Would ca_ it to move at the rUe of 8,!l!)O ht in the &at II8COIId of time, and in the directiOli of a line joining the cent.era at the earth and moon, it would not fall again to the surface of the mooD; but would become a aatellite to the earth. Such an impulae migh" indeed, cause it, even after many revolutiona, to fall to the earth. 1'he faU, therefore, of tbMe IItmea, from the air, may be IUlOOWlted for in this manner. Mr. Harte calculates, that even a velocity of 6000 feet in a _ d , • wooId be· nfticient to carry a body projected from the surface of the DlOOIl beyond the power of her at&ndion. If 110, a prQjectile force three timeII grea_ than that at a cannon, woald carry a lioJy from the moon beyaad the point of equal attraction, and _ it to reach the earth. A fOrce equal to thia ia often elerted by oar volcanoeI, and by mbtenanean Iteam. Hence, there ia no imJlOllllibility in the -auppoaition of their coming from the moon; but yet I think the theory of aerial cooaolida1ion the _ plaulible. Of the old .steroids we ptM8nt the following noticea: Vea&a appears like a lltar of the 5th or 6th magnitude, shining 'With a pure steady radiance, and is tbe only one of the aateroids which can be diacemed by the naked eye. JUlfO, the next planet in order after Vesta, revolves around the san in foar years, four and a half monthe, at the mean distance of two hundred and fifty-foar millions of miles, moving in her orbit at the rate of forty-one thouaand milea an hour. Her diameter ia estimated at 1393 milee. This woold make her magnitude a hondred and eighty-three tim.. I... than the earth's. The light and heat which ahe receiv.. from the sun ia Beven ~mes 188a than that received. by the earth. The eccentricity of ber orbit is 80 great, that ber greateat dis!apce from the sun ia nearly double ber least distance; eo that, wben ehe is in ber perilNliort, she ia nearer the sun by a bundred and thirty milliona of miles, tban wben she is in her aplNliun. This great eccentricity has a corresponding effllCt upon her rate of motion; for being so much nearer, and therefore ao macb more powerfally attracted by tbe sun at ODe time thaD at Bnother, abe moves through that half of her orbit wbich is nearelt tha aUD, in one balf of the time that Ibe oecupiea in comp\etinjf tbe otber half. According to Schroeter, the diameter of JWlO ia 1425 miIea; and abe is arrounded by an atmospbenl more denee than that of any nf the other planetI. 8cIuoeter alIO remarb, that the ftriatioo in her briU~ ia chie8y owing to certain changes in the denaity of her atmoIpbere; at the 88IJle time be thinb it not improbable that the. chaagaI may ariae from a diurnal revolution on her axiL . ellRIIS, the planet next in ordAr af'ter Juno. re.,ol.,... about the Ian in four years, seven and a tbird monthe, lit tbe mean distance of two hundred and sixty-three and a half willious of milll",

26M

GEOGRAPHY OF THE HEAVEN8.

moving in ber orbit at tbe rate of forty-one thouaand milpa aD bOllr. Her diameter ia eatimated at 1582 milea, wbicb makes ber magnitude a bundred and twenty-five times leas tban the eartb's. The intensity of the Iigbt and beat wbich she receives from the alln, ia about Beven and a balf times 1888 than that of those received by the eartb. Cerea shines witb a ruddy color, and appears to be only abou' the size of a atar of the eighth magnitllde. Conseqllently she is never seen by tbe n~ked eye. She ia aurrounded by a species of cloudy or nebulous light, wbich gives her aomewbat the appearance of a comet, forming, according to Scbroeter, an atmosphere aix hundred and Beventy-five milea in hight. Ceres, as has t-n IBid, _ the tint diacovered of die uteroid&. A& her diacovery, aatronolDtll'l congratulated themselvea upon the hlU'lDODY of the lIYatem being II!IIIoJed. TIley bad long wanted a planet to tiD up the great void between Man and Jupiter, in order to make the .,.... complete in their own eyell; but the auooesaive diaeoveries of Pllll.. and Juno again introdoced confusion. and presented a difficulty which tbey were unable to 101"." till Dr. Olben auggestod the idea that these BIIIaII anomalous bodiee were merely the liagmente of. larger planet, whieh bad been exploded by aome ~vulsion. Among tht- most able and decided advocates of this hy . is Dr. Brewster, of Edinburgh.

P ALLAa, tbe next planet in order after Cerea, performs her re1'0lution arollnd the alln in four years. &eYen and two-third months, at the mean distance of two hundred and sixty-follr millions of miles, moving in her orbit at tbe rate of forty-one thouaand miles an bour. Her diameter ia eatimated at 2025 miles, which is but liul", less than tbat of our moon. It ia a singular and very remarkable phenomenon in the solar syatem, that two planets, (Cerel! and Pallas.) nearly of the same aize. ahollid be aituated at equal distancea from the sun, revolve about bim in tbe aame period. and in orbita tbat intersect each other. The diffeJ'PDC8 In tbe respective diatances of Ceres and Pallas is less than a million of miles. The difference in their sidereal revolutions, according to aome aatronomera, hi but a single day!

The calculation of the latitude and longitude of the BlltProids, is a labor of extreme difficulty, requiring more than four hundred equation. to reduce their anomalous p"rturbations to the true place. This anfrom the want of auxiliary tables, and flom the filet Ihat the elementa of the a&ar·form planets, are very imperfectly determined. Whether any of the asteroids baa a rotation on its axis, remains to be ascertained. The tDlIowing table exlnDits the present ....te of knowledge with reference to the aateroids. The longitudes are referred to the mean equinox, JIIII. 1. UM8, except Metis, which iB fur April 30, 1848.

TBB ABTBROID8.

Name •.

I Flon,

'Vella,

3 bia, 4 Metia, II Hebe,

6 Albea, 7 JUlIO,

8 llereB, II pan.,

NameL

BeY. ill Sid. da,... 1198.16 18S5.st 1346.16 13016.010 1876.26 11110.75 1694.68 1880.96 1686.66

Bpoob.

I Flon,

1MB Jan.

S V8I&a, 3Iria,

1847 18017 1848 1847 1847 1847 1848 1848

01 Mea., 5 Hebe, 6 AIIIlea,

7 Juno,

8 c-,

9 PaIlu,

1.0

April,

01.0 Sept. 1.0 April, 80.0 July, 10.0 March, 16.0 July, 9.5 March, 12.0 March, 4.0

Aph. Dial.

Peri. DiaL

loM7l16 1.671997

1.936886

1.86&244. 1.150346 1.884262

1.908567 8.060943 8.349368 1.979798 3.438811

1.986888 1.092456 1.998166 1.658746 I.I068CK

M"an -air.

Lour. uc. node.

36058' 32".0 810 46 101 .7 198 18 87.2 loll 601 11 .82 1701 601 01.8 63 80 49 .3 158 0602.1 21 MOO.6 24 57 sa.4

1100 18' 50".8 103 II 01 .8 269 015 19 .6 68 29 40.4 138 01044 .8 141 29 19 .1 170 53 51 .0 80 47 17 .9 171 012 II .8

u ....n,-ContiRued. Name..

.1 Flon, 2 V8I&a, 3 Iria,

01 Mea., 6 Hebe, 6 Aatrea, 7Juno, 8 Ceree,

9 P.uu.

Long uc. ROdeo-Long. 0( Perihelion.

'f7O 26' ol9".1 tl2 16 It.4 118 1836.6 4 to t7.7 123 36 42 .1 6 00 31 .4 116 35 04 .11 298 28 14 .7 61 26 35 .1 Name•. 1 Flora,

IVeata, 8 Iria, 01 Mea., 6 Hebe, 6 AII&leao 7 Juno,

==

Inclinalion.

Aug. or Bccelllrioil,..

50 52' 65".9 70880.3 6 IS 10.9 6 36 t4 .0 101 44 to .3 5 19 17 .1 13 OS 39 .3 10 37 18 .1 301 37 31 .1

go 01' 36".9 6 07 II .6 13 10 60 .1 7 1836.9 11 81 11 .4 10 019 65 .8 101 012 19 .6 01 t4 66 .8 13 601 48.9

111_ d.aily Sid. - .

1086".1100 977 .948 963 .4498 962 .6660 941.37601 867 .8498 811 .7011 770 .9868 768 .8868

From theee eiemlmtll and data,

IOIIlfJ

curioua result. may be obtained

~!~ere:: 10 ~:;~:~ ~:~~ thein:~~~~ ~:~:,~~::::~:!: There are ~ where the orbits are entirely encIoaed the within the other~ viz. Flo£:", &n H~b~~ Iris and Flora in Juno. A.trea and Vesta PaiIa£ In., FLora, I'Flas, ts,ts,~.a Vesta Cer€gg

ODe

The following orbite interlock like the links af a chain, ~

H,L" and

He"", and F§trea. Juno and AIItnla. V,Fgg and A"'~_ Flo"" and tsFrea. Iris and Astrea. PalFb in lkFb

Vesta and Iris. FI,gg, and PFb§b and "ggko. V est&. and Juno. H,L,., and

"",,0.

Ceres an" Juno. Pall.. and Hebe. V gg§b and Hebe. Cergg and Hebe. Pallas in Flora. V,,,,L,, in Fk,la.

In those cases where the orbits interlock with each other, .. the nocIe.

«one orbit on any other are perpetually shifting, the tum, "'~y CO§b", Fhen actuH inter",k:§uon the mal" take suck iime the two planets should be found at the same in this now COOP mon point of their orbits, a collision would tske place~ which~ in co!'~_ :zuen'" "f the "robahl" rotark ",oUon the :m,ving ,'r,jjes, m§uld k:':A ,Yuee a sudden ~and terrific shock. The very1lear equality of the orbital motions would eecure the pIan~ta from any severe collision from their ",e:IOciH", in orbi,,~ If kke knowk,rillge or lheee minute planeta was perfect, it would not be impossible. 10 compute backward or forward and ascertsin the time

:~:t!';e':erbi'r e:f

!'e

u:r&~:~;!kt~!'~~::W\h;hi.~ie~~f ::::'eA!D

. ~e times ?f in~ion ~btained, ~ombinin~theae with the periods of §be "kmrnds U,eIl' ou::ts, It mould r~cr:~cme r::~Able ",mp:m' the mhen ,::lIisi'r: c,f thll hiane§ 10 pla:·r:. By computstions Encke found that about the year A. D. :ll!97, the

;:~orm ~;: ::!!mAt~~c :'~~i:~ "c! of h~a2:~"z::~~r:~:'~:

been attempted. Th:: hypothrL~i, of Ortul'll gahz'l'II 8§,;ngth new ,~t~,oid mfl\'ered. ll}thoL,;h the that the alcillmlion Flora ~hOrtef than periheli~n of Ceres, preaenta a difliCuity which had not before existed.

f fTPITEfTts

is the largest of all the planeta belonging to the solar It may be readily distintsdsh,d from the 6","C£ starll, kkple21:':TILr and magfLi:TIL,de;.

JUPITER

system. It:y ita

to nak21:Y

JUPITER.

271

eye almost as retlplendent as Venus, although it II more than Beyen times her distance from the sun. . When his right aacension il less than that of the lun, he is onr morning star; and appeara in the eastern hflmisphere before the sun rieel; when greater, he il our evening star, and lingers in the western hemisphere after the lun sets. Nothing can be easier than to trace Jupiter among the canstellationlof the zodiac; for in whatever constellation he il seen &ooclay, one year hence he will be seen equally advanced in the na:I conltellation; two yeara hence, in the next; three years hence, in the next, and 10 on; being just a year, at a mean rate, in paning oyer one constellatioD. The exact mean moIion of Jupiter in iii orbit, ill about' OIIe twelfth of a degree in a day; wlW:h IIIIOUI1tII to 0DIy SOO 10' W' in • year. Jupiter il the next planet in the solar IYltem aboTe the uteroidl, and performl hi' annual reyolution around the lun in nearly lSi of our yearll, at the mean distance of ~95 millionl of milea; maTing in hil orbit at the rate of 30,000 ~i1ea an bour. . The exact period of Jupiter'.1idareal re't'OIution 1111 yean, 10 months, 17 day.. 14 houra, 21 mutel, 261118C011d-. HII exact _ diItance from &be Bun is U5,533,837 ume.; COIII8CIuently, &be exact rate of ~ motion in his orbit, is 29.943 ume. per hour.

. He reyolvfll on an axil, which is perpendicular to the plane .of his orbit. in 9 houra, 55 minutea, and 50 secondl; so that his year contains 10.~71 days and nights; each about 5 houralong. His form il that of an oblate spheroid. whoee polar diameter il to its equatorial, 81 13 to 1~. He il therefore considerably more !attened at the polel, than an'y' of the other planets, excep" Saturn. This is cauaed by hil rapid rotation on his axil; forh il a univeraal law, that the equatorial parts of every body reyolving on an axil, will be !"Wollen out in proportion to the denlit1 of the body, and the rapidity of its motton. The di8immee between the polar IDII equatorial diametmw of Jupiter, miles. The difference between &be polar ad equatorial diametera of &be earth, ia oa1y 26 miles. Jupiter, eVen on &be IDOIt _ _ view through • gpod teJeacope, aD'Dl!llrll ~ be oval; &be loager diaJne. tel being parallel to the direction of iili.~t;;lta, which are aIao parallel to

~ 6000

UJ..e ecliptic. this rapid whirl on his Uil, his equatorial inhabitants are earned around at the rate of SI6.5M miles ao hour; which is 1600 miles farther than the equatorial inhabitants of the earth are carried, by its diurnal motion, in ltJmIty.J'our Aourt. the true mean diameter of Jupiter il 86,255 miles; which il Il88rly.ll times greater than the earth'l. Hil volume ii, there-

-B,

i'7~

GEOGRAPHY OF THE HEAVENS.

fore, about Iltirlaft AfHIIlretl pli1es luger tban dlat oC the earth. On account of hi8.great di8tance Crom the lon, the degree of lif{bt and hest which he receive8 from it, il 117 Woes lea dian thal received by the earth. When Jupiter is in conjunction, he liaes, ..ita, and comes to the meridian with the sun; but is never obeerYed to make a transit, or paas OYer the aun's disk; when in opposition, he n- when the 8\Dl . . . BellI when the Bun riaee, and comes to the meridian at midnight, which never happens in the _ of an interior planet. This plOY. that Jupiter nmJI_ m an orbit which is t:IJIerior' to that of the earth.

A8 the variety in 'the seaions DC a planet, and in the length of its daY8 and, nights, depends upon the inclination of its axia to the plane of its orbit, and a8' the axi8 of Jupiter has no inclination, there can be no difference hi hi8' 8ea80ns, on the same parallel8 of latitude, nor any ftriation in the length of his days and nights. hil not to be o:odentood, howeyer, that one tmiJarra _1m preYaill from hi8 equator to his poles; bot that the __ parallel. rf laHlutk on each aide of hil equator, oniformlyenjoy the same sealon. whatever lea80n it may be. Aboot his equatorial regions, there is perpetoalsummer; and at his poles, everlasting winter; but yet equal day and eqoal ntght at each. "his arrangement seems to have been kindly ordered by the beneficent Creator; for had bis axis beeo inclined to his orbit, li,ke that of the earth, his polar wintelR woold bue been alternately a dreadfull,light ,of rill: tltw/mul. Jupiter, when viewed througb a teleecope, appean to be 8U~ rounded by a number pf luminoos sones, usually termed bella, tbat frequ,ently extend qoite around him. These belts are parallel .not.ouly to each otber•. bot, in general, to his equator, which i• • allo neerly parallel to the ecliptic. They are subject, howeyer. to considerable variation, both in breadth and .Dumber. Som.. times eight hays been seen at once; sometimes only one, but more usually three. Dr. Herachel once perceived bil wbole disk covered with small belts. Sometimel these belts continue for month I at a time widl little or no variation, and sometimel a new belt hal been II881l to (orm in a Cew houn. Sometimes they are interrupted in their length; ,and It odler timea, thet appear to spread in widtb, and run into each other, until their readth exceeds 5,000 miles. Bright and dark IpOts are also frequently to be leen in tile belts, whicb uaually diaappear witb tbe belta themselyes, though not alwaYI. for C8IIini obserYed that one ooeupiedthe same position more than 40 yean. Of the _ oC tbese nriable appearancel. but little ia known. The, are gtinera\ly IUppoaed to be nothing mon than atmOlp~ ~ resulting from. or combiDed widl. abe rapid mouoll oCdle planet·upon i&8' axia..

!I_'

.JUPITER.

278

DiftiDent opinioDl haft been enIIeJ1ained by utrooOlDell I'8IIpIIding the of th_ belli and BpOtI.~ _ they have been regvded .. c1ouda. or RI openinp in the • of the planet, ...hiIe other8 imagine that they are of • more permanent nature, and are the nwIuI of pat phyaieal revoIutiouI, which are perpetually agiw.ting and changinf the IIUIface of the planet. The &r.i 01 ~ opiniOlll IlUfticiently expIainII the ftriatioDl in the form and magnitud'e of the 1pOU, and the ~ of the beltl. The apot firat qbaerved by CIIIIIIini, in 1666, Which hal both dilappeared and' zeappeared in the __ form and ~ lion for the Bpace 01"4 a yean, couhrnot potIIibly be occuioned by any I&moIphericai variatioDl, but EeIIIII evidently to be connected with the IIUlfiu:e of the planet. The l"onn of the belt, according to _ utronomen, may be accounted for by IUppoeing that the almotIJIAtn reftectl , more light than the body of the planet, and that the cloud. which float in it, being thrown into palaIIellltrata by the rapidity of ill diurnal motioo, bm regular inttndica, through which are _n ita opeke body. Ol any f1I the permanent . . which may ex.. within the JaIIIJII of the openins. ta1lle

Jupiter ia alao attended by four latellilea or moon., lOme of which are visible to him every hour ofthe night; exhibiting,oa a amall acala and in short periods. moat of the phenomena of'the BOlar aystem. When ,iewed through a teleacop.. the.. satellitea present a moat interesting and beautiful appaarance. The firat aatellite, or that nearest the planet, is 259,000 milel distan& from its center, and revolves around it in 42i houra; and appeara, at the surface of Jupiter, four times larger than our moon doee to 118. Hia second satellite, heiug both smaller and farther dis&ant, appeara about the'lize of oura; the third, IOmewhat less; and the fourth, wbich ia more than a million of miles from him, and takes 16l days.to revol,e arodnd hiDl, appeara only abou& one tAird the diameter of our moon. These satellites luifer frequent eclipses from paaaing through Jupiter'. sbadow; in the aame manner 88 our moon il eclipaed in paaaing through the earth's shadow. The three nearest aatellitel faU into hia abadow, and are eclipaed, in e,ery revolution; but the orbit of the fourth ia 10' much inclined, that it p88888 by its opposition to bim, two yeara in lix, without fallIng into his shadow. By meana of tbese eclipaea, altronomers haye not only diacovered tbat light is 8 minutes and 13 second a in comin~ to us from the sun, but are also enabled to determine tbe longitude of places on the earth with greater facility and exactness than by any other methode yet known. It was long since found, by the moat careful obIIervatiOlll. that when the earth is in that part of her orbit which is nearelt to Jupiter, the eclipeea appear to happen 8' IS" _ than the tables predict; and when in that part of her orbit which is fartbeat from him. 8' IS" later &ban the tableB predict; making a total diffimmce in time, of 16' 26". From the mean of 6000 ecnp- ot.ned by Delambre, thia di-.greement

A4

GEOGRAPHY OF THE HEAVENS.

and esIt:uItztiDn. _ _tUfactiorily.uled at 8' 13", while both _ COJIlIidered equally corNC&. NIIW,. wbeo the eeliJhappen _ than the mbIee, Jupiter i. at hie - - ' approach to the eill1h-when 1ater, at hill greateBt distance; 10 that the tIi&reDee in m. dlBlance8 from the earth, in the two - . i. the &olIole diomder of tI~ earth', orbit, or about 100 millions of miles. Renee, it i. concludeil that litrht iI not itutontaneow, but that it occupiell 16' lMI" in puaing IClOIe the earth'. orbit, or 8' 13" in coming from the IAIIl to the earth; being nearly 12 milliona of milea a minute. • ~...."".

The revolutions of the sstellites about Jupiter are precisely similar to the revolutions of the planets about the SUD. In this respect they are sn epitom~ of the solar sJ8~m, exhibiting, on a smaller scale, the various change. that take place among the planetary worlds. Jupiter, when I88D from hi. D88reat 18tellite, al?paara a tlwtr 14M ti_larJcer than our moon does to us, exhibiting OD a &Csi. of iDoonceinlilfl magnificence, the varying forms of a crescent, a half moon, IL gibbous phase, and a full moon, every fo">"two hours. El_ _ of Jupiter and bi. ..te16tes b Jan Iat, lSOI. PLUln.

Mean aid. JeVolu. (nearly 12 y_), aoIar da"... U8Sd. 14b. OSlO. OS.1iI. " 898.867 Mean I)'noWc leY. IOlar daya, Mean longitude, 1120 15' sa".O Mean orbital mo. in a IOlar day, 4 69 .26 Do. per annum, 80 20 82 .0 Longitude of perihelion, 11 08 M .6 ... nnwd mo. of apsidea eastward, " 6.06 Do. refeIred to the ecliptic. 67.06 Inclination of orbit to the ecliptic:, 1 18 In .3 Annual d _ of 'do. o .128 Longitude bf node 88 18 18 .9 Mo&ion at do. west per .nnum, 16 .8 Ditto east, refeIred to the ecliptic:, " 84 .8 0.0481621 EccenVicity of orbit, half ~ aD nnity, 111CI'8IIII8 of ditto in a centuty, 0.000169860 Greatest equation at center, rP 81' 13".8 Annual increaaa of ditto, o .634 ". Rotation on axis, Db. 56m. 49.71. 8005' 80".0 Inclination of axis to ecliptic, Mean apparent eq. diam. 86.74 Ditto at conjunction, 30.00 46 .88 Ditto at opposition . "" True diam. (00,000 milea_l.J) earth'. cliam. unity, 10 .860 1280.0 Volume, earth'. l1li unity, " " " 0.000934 1,:n Ma~ BUD'S:- unily'l " " " " 0.99239 DeD81ly', BUn • l1li UOlly', " " " Mean distance C485,000,000 mllea), earth'. l1li unity, 6.102776

-mmg

275

JUPITER. ~

8.lTUoLITU.

1:'":"_-.-_---:---,,--1 Finl. second. Third. Fourth. Sid. rey. in .. IOlarda""I~d. 18h.l8m. 3d. ISh. 14m.1d.8h.43iD." Ukl. le~. ;!:IIII. D.\lo for comp'lIation, !~ .'111913'18 3 MIBIOI 7 .1M.W2S 16 6"*1,61, M.an app. dlam. ~"'016 ()I'.IIII 1".~ 1".273 !508 bJ8 33?7 ll800 Ditto in miles. M. .... Jap. as one. 0.0000173 0.0000lI3I 0.0000885 O.OIlOOt27 M. dill JIlp. eq. nod. ul. .0t863 Ut:J47 15 350:/4 26.119~~ Dilloin degreee, 1'&7".92 0"3'07".64 0"04'59".320"8' ~i".48 Ditto in mile., I1lO,OOO 420,000 6711,000 .1.100.000

A IDOIt curiOUI phenomenon with rdmmce to on8 of the satellites of Jupiter, lull _aly been ~ at the Cambridge ob8e"atory, and aIao at the (,'int:inuati oberYatory. In Jllllling IICl(8 the diJIk of 'he p\aDe&, it bu been __ to 10lIl illl ligbt .. if undergoing ecIipae, until it finally becomeI a 6/Qek apot on the diIk of the planet; after pIIIIIiDs otf the disk it _ _ ita liah&.

SATURN. SATUU is situated between the orbita of J upher and Herschel, and Is the moat remote planet from the earth of any that are visible to the naked eye. It may be easily distinguished from thfO fixed stars by ita pale, feeble, and steady light. It resembles the star Fomalhaut, both in color and size, differing from it only in the steadiness and uniformic,y of ita light. From the slowneea of ita monon in ita orbit, the pu pil, throughout the period of hia whole life, may trsce its apparent course among the atars, without any danger of. mistake. Having once .found when it entera a particular constellation, he may easily remember where he is to look for it in IIny subsequent year; because, at a mean rate, it is just two and a half years in Pallaing over a single sign or constallation. Saturn's mean daily motion among the stan is only about 2', the thirtieth part qf II degree, 8atum entered the COIlIIIIllation V"ugo about the beginning c{ 1833, Ind COIltinued ill it until the middle of the year 1835, when he paseed into Libra. Be will continue in that coll8teDation until 1838; and 10 on; occupying .bout 21 yeam in each COJl8telladon, or nearly thirty years

mone JeYOlution.

•

The mean distanee of Saturn f"rom the IUD il nearly double tbal of" Jupiter, being about nine bundred and nine milliOfts or miles. Hil diameter is aboG 82,000 miles; his volume therefore is ekven Atmdred timu greater than the earth's. MoYing in his orbit at the rata of 22,000 mil.. an bour, he requires twentyDine and a hair y.... &0 oomplete Iris circuit around the sun :-

278

GEOGRA.PHY OF THE HEA.VENS.

but hi. diurnal rotltion on hi. axil i. accompli.h~ in ten and a " hlalf houl'l. Hill Yflar, therefore, i. Dearly thirty tim81 as long as ours, while hill day is shorter by more than ODe balf. Hi. year cantlin. about il5,150 of ite own day., wbicb are equal SO 10.759 of our days. ' ' ~be surface of Saturn, like tbat of Jupiter, is diversified with belts and dark apote. Dr. Herschel aometim81 perceived five belts on hia aurface; three of wbich were dark, and two bright. The dark belts have a yellowiah tinge, and' generally cover a broader zone of the planet than those of Jupiter. To the inhabitente of Saturn, tbe aun appears ninety timea l8Is than he appears to tbe earth; and they receive from him only one nimtidA part as much Iigbt and beaL But it is comp'uted that even the fli~tietA part of the sun'. light exceeds the IIlumiuating power of 3,000 full moons, whicb would be abundanti y sufficient for all the purposes of life. The telescopic appearsnce of Saturn is unparalleled. It is even more interesting than Jupiter, with all his moon. and beltL That which eminently distinguisbes this planet from evef1 other in the system, is a magnificent zone or ring, encircling It with perpetual light. The light of the ring is more brilliant than tbe planet itself. It turns around hs center of motion id the same time tbat Saturn tuma on ita axis. When viewed with a JOod telescope, it is found to consist of two concentric rings, diVIded by a darl!. band. By the Ia_ of mechanica, it is impoaaible that the body of the rinp should retain ita position by the adhesion of the particIeB alone; it mWlt necell881'ily revolve with a velocity that will generate centrifugal force ... Scient to balance the attraction of Satum. Obeervation' eonfirma the truth of th_ principles. showing that the ringa rotate about the planet in 10! hOOD, which is considerably Ie. than the time a ";'wllite would tak" to revolve about it at the aame distance. 'fheir plane is inclined to the ecliptic in an angle of 310. In CODIIIlqUllllCe of this obliquity of poaition, they always appear elliptical to us, but with an eccentricity .. variable 88 to appear, ClCCaBionally, like a IItnIight line drswn a<."l'Oll8 the planet; in which _ they are visible only by the aid of superior instruments. Such _ their pooition in April, 1833; for the BUD W88 then paRSing from their ..uth to their north Bide. The ringa intenleCt the ecliptic in two opposite point&, which may be called their node&. Tht-...e pointa . Ill\! in longitude 1700, and 3500. When, therefore, Saturn is in either of these point&, his rings will be invisible to WI. On the contrary, when his longitude is 800, or 2000. the rinp may be _ to the greatest advantage. A. the edpt of the rinp will pteleDt ,lhelllolelvea to the SUD twice in each revolution of the pIanet, it is ObviOUB that the disappearance of them will occur once in about 15 yeara; aubject, however, to the variation dependent on the poaition of the earth at that time. The ful10wing are the dBte8 during the ensuing revolutioBB of the planet, wben ita mean /JeIioantric lonaitude is IIUch that the rings will (if

1838 July, 1847 Dec. 1A55 April, 1863 NOt'.

soc III 8eorpio, 10° of AquariUl,

SOC of Gemini, SOC of Virgo,

North Iide illaminated. In_ble. South Bide illumillated. lnviBible.

The distance between Satum and his inner rintf, is only 11,000 miles; being leas than a tmlla part of the dtlltanee of our moon from the eartb. The breadtb of the dark band, or the interval betweentbe rings, is bardly 3,000 miles.-The breadth of the inner ring, is 20,000 miles. Being only about the same distance from Saturn, it will preBent to bis inhabit,ants a luminous zone, arcbing tbe wbole coneaye vauh from one hemisphere to the other with a broad girdle of light. The ~ost obrious use of this double ring i8, to reSect light upon the ,Planet in tbe absence of the suni what other purpose8 it may be m.... nded to subBerve, is to 118 unknown. The 8un, aa ba8 b..en shown, illuminates one side oC h during 151ea", or one half of the period of tbe planet's revolution i an duriug the next 15 years, the othl'r 8ide i8 enlightened in its tum. Twice in the courae of 30 1ea", there is II sbort interval of time when neither side is enhghtened, and wben, of course, it O88BeS to be visible i-namely, at tbe time when tbe sun I!eaaea to shine on one side, and is abont to sbine on tbe other.· It revolves around ,its axis, and conseqnflnt.ly, around ~aturn, in 1010 hours, which is at the rate of a thousand miles a minute, or 58 times swifter than the revolution of the earth's equator. When viewed from the middle zone of tbe planet, in tbe absence of the sun, tbe rings will appear like vast luminou8 arches. exte!lding along the canop), of heaven, from tbe eastern to the western borizon, exceeding In breadth a bundred times the apparent diameter of our moon. Besidea the rings, Saturn is attended by Beyen satellites, ..hich revolve about bim at difFerent periods and distancea, and reciprocally reSect tbe aun's rays on eacb otber and on the plan.. t. Tbe rings and moons illuminate tbe nigbts oC ,Satum ; \he moona and Saturn enlighten the rings, and tbe planet and rin~ reSect the sun'8 beam8 on the aatellite.. TblJfuurtla oftbee Iatellitea (in the order III their diatance) -ftnt diIeoYeIed by Hun-. 011 the 16th of Mareh, 1856, ad, in bOIlor III • Tbil bap,JM!u, .. _ han alreu., 1howD, whllll 8a1arll1. either in the lIOIh deJree of PilCe&, or the lIOIh de~ of Viqo. When he i. between the.. pomta, or in the lIOIh d.".. either of GeminI or of Saciuariu, hi. rill( appeara moel open 10"., and _ in the form of !Ill OYaJ, whOle kmpat diaDilller II 10 the IhOnelt . . . 10 '' ,

Z

278

GEOGRAPHY

or

THE HEAVENS.

&be cJi8coorenIr, _ C8lIecJ the ~ 8tJIelIiIL TbiJI aateIIite, being the largest of aU, is E8D without much difficulty. CIIIIIini discovered the 1st, lZeI, 3d, and 6th aateJJiteII, between October, 1671, and Maroh, 1684. Dr. Henchel.discovered &be 6th and 7th in 1789. These are nearer to Saturn than 'any of the rest, though, 0 avoid confullion, they are IIIlIDI!d in the order of their discovery.

The sixth and seventh are the smallest of tbe whole; the first and second are the next smallest; the tbird is greater than the first and second; the fourth is the largest of them all; and \he fifth surpasBeB the rest in brightness. Their respective distances from their primary, vary from balf the distance of our moon, to two millions of miles. Their periodic revolutions vary from 1 day to 79 days. The orbits t1f the six inner satellites, that is, the tat, 2d, 3d, 4tb, 6th, and 7th, an lie in the plane of Saturn's rings, and revolve around their outer edge; while the 6th satellite deviates so far from the plane of tbe rings, as sometimes to be seen t!trough the opening between them a~d tbe planet. Laplace imsginBl that the accumulation of matter at Batum'. equator retainI the orbilB of the ftnJt llix satellites in the plane of the equator, in the IllUDe maJIIIer u it retains the rings in that plane. It hu been . . . factorily ucertained, that Batum hu a greater accumulation of matter about biB equator, and consequently that he is more 8att.ened at the poles, than Jupiter, though the velocity of the equatorial parts of the f0rmer is much leas than that of the latter. TbiJI is aufticiently accounted for by the filet, that the "11gB of Batum lie in the plane of biB equator, and act IIIOJe powerfully upon thoae parts of biB IIIU'fiule than upon any other; and thus, while they aid in diminishing the gravity of these parts, also aid the centrifugal force in Battening the polea of the planet. Indeed, had Saturn never revolved upon biB axis, the action of the rings would, of itaeU; have been aufticient to give him the form of an oblate spheroid. Satumian elements, January 1, 180 1 : Mean distance (about 890,000,000 m.ilBl), earth's u one, 9.538786 Mean sid. rev. (lZ9,456 yeara), mean BOlar days, • 10759.1198 Mean synod. rev. in mean BOlar da,... • • 378.090 Mean longitude, • 1350 20' 06".5 Mean orbital motion in a mean BOlar day, t' 00".6 Do. in a BOlar y e a r , · · 120 13' 36".1 Longitude of~lion, • 890 09' 19".8 Ann. mo. ofapsicf8leutwud, 19".4 Ditto refened to ecIi.pIic, • • l' 09".5 Inclination of orbit to ecliptic, to 29' 36".7 Annual deereue of ditto, 0".156 I.ong. of ucend. node, • • 1110 66' 87".40 Motion of do. per an. west, • • • 19".4 " " .. .. .. " eat, ret: to ecliptic, 30".7 Eccentricity half maj. aD 1IIIity,.. 0.0561606

279 0,000312402 Decreue of do. in a century, Greatest equation of center, • • 60 16' 12".00 Annual decreaae of do. 1".279 Rotation on axis, 10 h. 29 m. 16.8 L Inclination of axis to ecliptic, 310 f9' App. diam. at mean dist. from the earth, 16".20 9.982 1'rue diam. (about 7fi06R milea), earth'... unity, 99f•. OO Volume, earth's as unity, Mass, sun's as unity, 0.0002847380 Denaity, SUB'S as unily, 0.650

. . .. . . . . ..

40",096 36.289 34 .476 18,688 17.991 0.408 4.339

Outer diam. of eXterior ring, Inner Outer diam. of inner ring, Inner Equal diam. of planet Breadth of division between the riDgB, Dial of ring from the planet,

Mile•.

178.418 166.271 161.690 117.339 79.160 1.791 19.090

The multiple division of Saturn', rings hu be8n a matter of _ '.' dilpute. There now _mil little doubt that the exterior ring is divided into two rings. Prof. Encke laW the diviBion distinctly, April 26, 1837. On the 25th of May he obtained theae approximate III8UIUIl8 : 40".4116 oUter diam. of ellt. ring, .. II II new division, - 37.471 Inner diam. of outer ring, -. 38.038 Outer diam. of inner ring, 34 .749 26,766 Inner diam. of inner ring, Theae are the only meuures which I have aeen. The third division _ distinctly obaerved on the 7th September, 1843, at Mr. Lassell'. obaervatory, near LiverpooL Since the erection of the Refractor of the Cincinnati Obaematory, the planea of Saturn's rings have been too much inclined to the vieual ray for exact examination. I have never been able to mek8 out the triple division of the ringL It hal been found that the laws of perfect equih'brium require that the center of the rings should not coincide with the center of the planet. Exact Dl8UUrea have shown that this discovery of theozy is verified in nature. There is a alight dillimmce in the 1'8IIpIlCti.ve diste1lCllB from the planet to the inner edge of the ring on the right and left, amounting to about two-tenthll of a eecond of arc. . Saturn is one of the moat magnificent ~ in the heavell8, when _n with a powerful telescope, and never WIB to excite the moat pr0found admiration in the beholder. The aatellitea of Saturn are by no _ _ .. weD !mown .. thOll8 of Jupiter. The two inner aatellitell are among the moat difticult objectII to be ~ in the heavenL The following elementll may be regarded u a near approximation..to the truth. '.

_

GEOGRAPHY IlalelHte.

or

THE HEAVENS.

=--. ........ ---- --'=0Id 80lar Day. -~. La mean

d. h. m.

I

n

m

IV V

VI !-VB

-

11l1&li DiIlaDOe.

Sidereal BnolutioD

.&liii0-

aIIr·

I~

,

DiICOTerer and Dale.

7 0 " 38 3.3111 19.15 120,000 w. Herachel, 1789 8 10853 • .300 31.19 1110,000 1 1 11 IS Ii.IS4 .5.13 190,000 D. CUIIini, • 1684 I I 17 .11 8.819 1 0093 243.0011 .. 3 • 11 25 9.1124 124.S8 340,000 4 1111 II 41 22.0S1 3 26.60 788,000 C. Huygens, 16511 1179 07 56 6U511 918.00 ~97,ooo D. CaBni, • 1671

I

.. . .. ..

. ....

URANUS OR HERSCHEL.

URANUS is the planet next beyond Saturn; to the naked eye. it appears like a stat of only the sixth or seventh magnitude, and of a pale, bluish white; but it can seldom be seen, except in a very fine. clear night, and in the absence of the moon. As it moves over but one degree of its orbit in eighty-five days, it will be MIen yean in passing over one sign or constellation. When first seen by Dr. Herschel, in 1781, it was in the foot of Gemini; 10 liuJt it Aa8 not yet completed one revulution ainu it _ diacotIered 10 be a pJaflel. It is remarkable that this body was obaerved u liar back u 1690. Ia _ _ three IimeII by FIamatead, once by BmdIey,once by Mayer, IIIId ·eleven timea by Lemonnier, who registered it BIIlOIII the 1Itar8; bot DOt one of them supected it to be • pIaneL The inequalities in the motions of Jupiter and Saturn, which could not be accounted for from the mutual attractions of these planets, led astronomer. to suppose that there existed another planet beyond the orbit of Saturn, hy whose action these irreguJarities wflre produced. 'rhis conjecture was confirmed March 13th, 1781, when Dr. Herschel discovered the moliOflB of this body, and thus proved it to be a planet. Herschel is attended by six moons or satellites, which revolve about him in dift"erent periods, and at various distances. Four of them were discovered by Dr. Herschel, and two by his sister, Misl CarolillE' Herschel. It il p088ible that others remain yet to be discovered. UranuI' mean distance from the lun il 1828,000,000 of miles; more than twice the mean distance of Saturn. His sidereal

281

URANUS.

reTolatiou is performed in 8' years and 1 month, and his motion in hi' orbit is 15,600 miles an hour. He is supposed to have a rotation on his axis, in common with the other planets; bat astronomers have not yet been able to obtain any oceular proof of such a motion. His diameter is estimated at 3',000 miles; which would make his volume more than 80 times larger tban the earth's. To his inhabitants, the sun appears only the "2"1-. part as large as he does to us; and of course they receive '"rom him only that small proportion of light and heat. It may be shown, however, that the !fit part of the 8un's light exceeds the illuminating power of 800 full moons. This, added to the light they mllst receive from their 8ix sa&ellitel, will render their days and nights rar from cheerless. But three of the six IIltelli&ee reported by Henchel, have been obeened by those who have followed him. The following elements are for the epoch let January, 1801, reckoning from the mean equinox: Mean Bid. rev. (84.02 yeara),1OIar days, • 30686.821 d. 369.61'>6 " " wynocl. rev. " " "" Mean longitude, 1770 48' 23".0 Mean motion in orbit in a _ BOlar day, . 42".37 Do. per annum, .• • 40 17' 45".16 Long. of perihelion, 16'1 31 16 .10 Annual mo. of aprides east, • 52.60 Inclination of orbit, 0046' 28.44 72 69 36 .30 Long. of ascending node, 14 .16 Ann. mo. of do. eastward, Eccentricity of orbit. Semi axis maj. W1ity, 0.04667938 Greatest equatiou of center. 60 20' 5'7".00 Mean app. diam. (35,000 miles scarcely), • • 4 .00 True mam ., earth's as unity, 4. 344 Mass. sun as unity, • • 0.0000658098 V olume, earth as unity. 82 Density, sun's as unity, • 1.100 Mean di.;tance (I,SOO,OOO,OOO miles), earth's as unity, 19.182390 Henrht'l'JI SatcHilea.

----I

II III

IV V

VI

S ide real Revolution.

d. h. 5 21 8 16 10 23 13 10 38 01 107 16

Renchel'. perioda, of t.wo of

z2

m. s. 26 20 57 47 02 47 !is 29 48 00 39 66 ~

.

Mean Distance .-Semi~ dillmeter == 1 of PJnnet.

13.120 17.022 19.845 22.752 45.607 91.008

IIltellit.es, have been

eonfirmed by

_

GEOGRAPHY OF THE HEA.VUB.

Ilia lIOII, and by Dr. Lemom, of MUDieh; a third CIII8 baa mcently beea ot.erved by 8tri;.ve of PuIkcRa. . • From an exteDllive aeriea of II*IAlI8I, a flattening at the polea, and a protuberance at the equator of tbia .pIanet Iw t-1 det.ectecI, delDOlllltrat,. mg a rotation upon an axis, in IICDOldance with the pneral analogy of

the phmetI.

.

NEPTUNE (naft C.A.LUJI LKnallUa). THIs is the most remote and the latest discovered of all the large planets. The extraordinary circumstances attending its disp.overy, have given to this object an interest which does not attach to any other heavenly body. After the discovery of U ra. nus, in 1781, efforts were made to reduce ita motions to the known laws of gravitation, and an orbit was computed, which, in the outset, it was thought would represent all the obsened places of Uranus, and by which ita future places might be predicted. In a abort time tbis orbit was found to be at fault: tbe planet W\UI gradually leaving it, anll seemed to be under some unknown influence, wbicb involved ita motions in mystery. After tbe lapse of many Tears from the discovery of Uranus, M. Bouvard resumed the Investigation of ita orbit, and finally reached the conclusion that it was impossible to represent at the same time, by any orbit, the old observed places of the planet and the new ones, or those taken after the star was discovered to be a planet. He, therefore, rejected the ancient observations aa more likely to be in error, and adoptinJ tbe recent ones, com· puted an orbit and tables for Uranus, whlcb it was hoped might repl'IIII8nt the future places of the planet. A few years sufficed to show tbat this orbit and these tables were defective. Tbe computed and tbe obsened places of the planet did not agree, and the' difference increased from year to year, until it attracted the attention of many distinguished astronomers. Some were disposed to attribute these irregularities to a relaxation of the AgOroUS laws of gravitation in those remote rel[ions of space; others conceived that Uranus might be attended by some large estellite wbicb was swaying it from its computed orbit: wbile another class conceived the possible ex. istence of a remote unl\iscovered planet, under whose infiuence Uranus was made to break away from ite computed track • . Under these circumstances, a young astronomer, M. LeTerrier, of Paris, as early as 1846, at tbe request of M. Arago, undertook a thorough discussion of the irregularities of Uranus, with a view to understand their cause; and in CBse tbis cause sbould be an u.terior planet, to determill8, from the known irregularities

NEPTUNE.

of U ranua, tbe actual place of tbe unknoWll dieturbing planet at a given epoch. M. Levemer commenced by determining, witb all accuracy, tbe disturbing influence on Uranus, exerted by all the knotcm bodies of the aolar aystem, and ~ore eS)lecialJy the etrects of the large and nearer planets Saturn and Jupiter. His memoir on this subject was presented to the Academy of Sciences of Paris, on the lOth Nov., 1845. On the first of the following June, he read a second memoir before that I~med body, in which he demonstrates that the irregularities of Uranus cannot be explained by any known cauaea; and concludes. that they are due to an unknown planet revolving in an orbit exterior to tbat of Uranus, and as far from Uranus as it is from the sun; and whose place, as ronghly determined, was, on the 1st January, 1847, in longitude 3250 • On the 30th August, 1846, a third memoir wa. read, in which the author fixes the approximate elemE'nts of his theoretical planet, its mass, and its cf0sition for theIst January, 1847, in beliocentric longitude 326 39'. On the 5th October, J846, a fourth and last memoir was presented to the Academy, in which M. Leverrier discussee tbe pOsition of the plane of the orbit of hie unknown planet. These wonderful accounts excited tbe greatest interest among astronomers, yet such was the difficulty of the problem, that few were willing to b"lieve that Leverrier's computation would ever lead to the discovery of his imaginary planet. These misgivlnge were soon dissipated. On the Ist of Sept., 1846, M. Leverrier wrote to bis friend Dr. Galle, of Berlin, requesting him to direct his telescope to the place in the heavens which his calculation. had indicated as the place of his planet at that date. This request was immediately complied' with; and on the very first evening of examination, the planet was actually discovered within less than one degree of the place pointed out by M. Leverrier! In the mean time, the publications of Leverrier had brought to lillht the fact, that Mr. Adams, a young geometer of Cambridge, Eng., had discussed the vert same problem, and had reached reaults almost exactly coincident with those of Leverrier. Indeed, Mr. Adams had obtaint>d his results some months previous to M. Leverrier, but having failed to publish them to the world, thus gave to his distinguished rival the priority and right of discovery. The wonderful coincidence of the results obtained by Leverrier and Adams, Sfll!med to fix absolutely the fact of the discovery of the planet from calculation. The news of ite discovery was soon spread throughout the world, and excited every where the deepest mterest. The intelligence rear-hed Cincinnati on the 28th Oct., 1846, and on the same evening the planet was

284

GEOGRAPHY OF THE HEAVENS.

readDy detected by its flUTe with tile great refractor. Ite diameter waa immediately measured. The new rlanet was now followed with IIreat intere8t at all the principa ObSe"afOries in the world, with the view of discoyering how nearly the coml!uted elements before discovery would agree with those determined from actual observation after discovery. As the planet moved extremely 810w, this would hue required a ,long series of years, but for a most important dieeovery made by Mr. S. C. Walker, then at the Washington observatory. After computing an orbit of the new planet from the besl data then in eXl8tence, he traced it backward for fifty or lixty yeara, in the hope of finding that its place had been fixed fong since by lome astronomer who had obse"ed it, believing it to be a fixed 8tsr. His research wal rewarded with a brilliant discovery. Two plaee8 of the planet were obtained from thecatelogue of Lalande, a8 fsr back a81795, which, combined with recent places, gaVE' sufficient date to determine with comparative a"curacy the elements of the orbit of the new planet. A difficulty herf! arose, from the fact that a great dieerepancy tlll.isted between the periodic time of the planet and that computed by M. Leverrier. His computed period was about 217 yeara, - while the periodic time of Neptune i8 about 164. This discrepancy has induced 80me astronomers to assert that the discovery of the planet, after all, was aecidenlal. Thi8 Leverrier denies; and here. for the present, the matter rests. Prof. Pierce of Cambridge, after an elaborate research, finds that all the irregularities of Uranus are most perfectly accounted for by the inftuence of the new planet; 80 that in case this resull may be relied OD, thi8 great problem is DOW absolutely exhau8ted. The following are the elements computed, before discovery, by M. Leverrier: Periodic time, yean, Mean distsnee, esrth • unity, Mean loogitulie, lat Jan., 1847,

Longitude or perihelion, Mean anomaly, Equation of center, Helioeentric longitude, lat Jan., IM7, Radius ftCtor, earth'. unity, M-. Y~n of the BUD'. - . . Adams' ele~entli, computed before disco'Yery : Mean longitude, Oct. 6th, IM6, Longitude of perihelion,

Eccentricity, M-. BUD'•• unity,

117.387 36.1639 81SO

.r ••

1M ," S M 01 68

7 «.9

316 31 33 06

313° Ot' 199 II 0.1t0616 .0.00018000

NEPTUNE.

286

The elements obtained since the diBcoyery of the planet by Mr. Walker, and by using &he place of &he planet observed by Lalande, 1795, are as follows. These will be gradually improved as ob88rvatione are multiplied. Long. perihelion poiat, Long. ucending node, IAclination, Eccentricity. Mean daily lid. muton, Long. Ii epoch, -

470 12' 56".73 m. eq. II1l Jan., 1848. - ISO 06 11.04 m. eq. llIl Jan., 1MB. 1 4668.97 0.00871946

:U".1tM48

_s300 "' 41".at lS m.II1l noon, Greenwieh, Jan., 1848.

Mr. L8_II, of Liverpool. discoyered a satellite to Neptune, on which a snfficient number of obserYBtions haYe bel'n made to determine, with considerable accuracy. the maS8 of the planeL ,'his has been computed by Prof. Pierce, of Cambridge, and i. found to diff'er considerably from that obtained by Leverrier before .Jhe discoYery. From observations on Lassell's satellite by Mr. Bond, of Cambridge, the mass of Neptune is determined to be r..lu of the sun's mass. With this mass Prof. Pierce accounts for all the irregulariti81 of Uranus, and closes, at least for the present, the investigation.

COMETS.

COIRTI, whether viewed as ephemeral meteore, or as substantial bodiN, forming a part of the 80lar .ystem, 8re objects of no ordinary interesL . When, with uninstructed gaze, we look upwards to the clear sky of evening, and behold, among the multitudes of heavenly bodies, one, bJazing with its long train of light, and rnshing onward toward the center of our system, we inaensibly shrink back 8S if in the presence of a supernatural being. But when, with the e:re of astronomy, we follow it through its perihelion, and trace It far off', be,ond the utmost verge of the solar system, till it is 10lt in the Infinity of space, not to return for centuries, we are deeply impressed with a sense of that power which could create and let in motion loch bodies. Comets are diltinguished from the other heavenly bodies, by their appearance and motion. The appearance of tbe planets is globular. and their motion around the sun is nearly in the lame plane, and from weat to ellat; bot the comets have a variety of forma, and their orbits are not confined \0 any particular part of the heavens; nor do they obsene anyone general direcuon.

286

GEOGRAPHY OF THE HEAVENS.

The orbitll of tbe planets approacb nearly to cirell'lI, wblle

,110118 of tbe comets are very elongated elipses. A wire boop, for.flxample, will represent the orbit of a plsnet. Ir two opposite sides of the same boop be extended, so tbat it sball be long and nanow, it will then represent tbe orbit of a cornel. The sun is always in one of the foci of the comet's orbit. There is, howeYer, a practical difficulty of a peculiar nature which embal'l'UE8 the solution of the queetion as to the furm of the cometary orbi... It 10 happens that the only part of the coune of a comet which can ever be viaible, ia a portion throughout which the ellipse, the parabola and hyperbola, 80 closely reeemble each other, that no observations can be obtained with lIIIfficient accuracy to enable UB to distinguish them. In &ct, the obeerved path of any comet, while visible, may belong either to an ellipae, parabola, or hyperbola. That part whicb is usually brigAUr, or more optJIce than tbe otber portions of tbe comet, is caned tbe nuckua. Tbis is aurrounded by an etltJe/op, wbich bas a cloudy. or Aairy appeara,lICt'. Tbese two ,arts constitute tbe body, and. in many inauuicea, the wbole 0 tbe comet. Most of them, however, are attended by a iong train, called the tail; thougb some are without this appendage, and as seen by the naked eye, are not easily distinguisbed from tbe planets. Others, again, bave ito apparent nucleus, and seem to be oo)y globular malses of vapor. Nothing is known with certainty of tbe compoaition of these bodies. Tbe envelop appears to be nothing more tban vapor, becoming more luminous and transparent wben approacbing tbe lun. As tbe comets pass between us and the fixed staTS, their envelops and tails are so tbin, tbat .stars of very small magnitudes may be seen througb tbem. Some comets, having no nucleus, are transparent throughout tbeir whole extenL Tbe Ducleus of a comet sometimes appears opake, and it theD resembles a elanet. Astronomers, \lowever, are Dot agreed upon tbis point. Some affirm that the Ducleus is always transparent, and that comets are in fact Dotbing but a mass of vapor, or less condensed at the center. By others, it is maintained tbat tbe nucleus is sometimes solid and opake. It seems probable, however, tbat tbere are three claBses of comets, viz.: 1st. Thoee whicb have no Ducleus. being transparent tbroughout their wbole extent; 2d. Those which bave a trsnsparent nucleus; and, 3d. Tbose having a nucleus whicb is solid and opake. A comet, wben at a distance from the sun, viewed througb a good telescope, bas the appearance of a dense vapor surrounding the nucleus, and sometimes flowing far into tbe regions of spllce. As it approacbes tbe sun, ita ligbt becomes more brilliant, till it reaches Its perihelion, when ita light is more dazzling than that

COMETS.

287

of any other celestial body, the sun eJ:oepted. In tbis part of ha orbit are Been to the beat adYl.tage the pbenomena of this wonderful body, wbiob baa, from remote antiquity, been the specter of alarm and terror.' . Tbe luminous train of a comet usually loltow. it, as it approacbea the sun, and goa 'b(ore it, wben the comet recedes from tbe SUn; sometimes tbe tail IS considerably curved towards the region to wbich the comet is tending, and in some instances it baa been observed to form a rigM angle with a line drawn from the sun througb tbe center of the comet. The tail of the comet of 1744. formed nearly a quarter of a circle; that of 1689, was curved like a Turkisb sabre. Sometimes the same comet bas several tails. Tbat of 17•• bad, at one time. nO less than liz, which appeared and disappeared in a few days. The comet of 1823 bad, for several days, two tails; one eJ:tending toward the sun, and the other in the opposite direction. . Comets, in passing among and near tbe planets, are materially drawn aaide from their courses, and in some cal88 have thf>ir orbits entirely changed. This is remarkabl, true in regard to Jupiter, wbicb seems by some strange fatahty to be constantly in tbeir way, and to serve as a perpetual stumbling block to tbem. " The ~kable comet of 1770, which W$8 fOund by LenD to reo .mve in a moderate ellipae. in a period of about five yean, actually gat entangled among the II8Ielliles of Jupiter, and thrown out of its orbit by the attracliona of that planet," and bas not been heard of lin_Her.eM1, p. 810. By this extraordinary rencounter, the mouona of _telliles IIUffered not the leut pereeptible derangement ;-a . t proof of the aeriform nature of the comet'. - .

,-

.!:t:::1

It is olear from obserYltion, that comets' contain very Iittle

matter, for they prodoce little or no eft"ect on the motion of tbe planets when passing near those bodies. It is aaid tbat a comet, In 1.5., eclipsed the moon; ao that it must bave been very near the earth; yet no sensible eft"ect waa observed to be produced by this cauae upon the motion of the earth or the moon. Tbe observations of pbilOIOphera upon comets, have aa yet detected nothing of their nature. TJcboBrabe and Appian aupposed their tsils to be produced by the rays of tile sun, transmitted through the nucleua, wbich they supposed to be transparent, and to operate aa a lena. Kepler thougbt they were occasioned by the atmosphere of the comet, driven oft" b>: the fmpulse of the sun's rays. Tbis opinion, witb some 'lDedlfication, W'6 also maintained by Euler. Sir Isaac Newton conjectured tbat they were a thin vapor, rising from the heated nucleus, aa smoke ascends from the eartb; while Dr. Hamilton supposed them to be streama of electricity. .

188 II

GEOGRAPHY OJ' THE HEAVENS.

Tbal the Iuimnoae put of a ....." aJII Sir Joim BencheI,".

~inl in die JIIIlure of a IIIIOke, Cog, 01' cloud, IIU8p8IIded in a trampanmt a~ ill evident tiom a filet wbicll hu been often no&iced, that the portion of the tail where it ClODleII up to, and lIIIlJOunda the

m.:

bead, ill yet 88pIIIIded tiom it by an interval Ie. luminous; as we often _ one layer of clouds laid CYfer another with a considerable clear space between tbem." And again--« It fullowa that the. can only be reganled .. great _ of thin ftpor, au:eptible of being penetrated through their whole aubltance by the 1IIlIlbeame...

Cometa haYe always been considered by the ignorant and superstitioul, as the harbingers oC war, peatilence, and famine. Nor has thi, opinion been, eyen to this day, confined to the unlearned. It was once uniyersal. And when' we examine the dimensions and appearanees of some or these bodies, .we cease to wonder that they produced univeraal alarm. According to the testimony or the early writers, a eomet, which could be seen in daylight with the naked eye, made ita appearance 43 years herore the binh or our Sanour. This date was just after the death of Cesar, and by the Romans"the comet was belieyed to be hi., metamorphosed soul, armed with fire and Tengeance. Thil comet is alrBin mentioned aa appearing in 1106, and then resembling the IUD in brightne8B, being or a great aize, and haTing an immense tail. In the year 140i, a eomet wu aeen, so brilliant as to be dieearned at nocm-day. In 1456, a large eomet made ita appearance. It spread a wider terror than was eyer known berore. The belief was Tery general, among all elassel, that the eom"t would destroy the 8arth, and that the Day or Judgment was at hand! This comet appeared again in the yeare 1531.1807,1682, 1758, and 1835. It pa-.l ita perihelion in NCYfember, 183~, and wil18'1ery 751 yeare thereafter.

At the time or the appearance or this comet, the Turks extended their nctorioul arma across the Hell""pont, Bnd seemed destined to OTerrun all Europe. This added not a little to the general gloom. Under all these impressions, the people seemed totally regard leas or the present, and anxious only for the fu~re. The Romiah Church held, at this time, unbounded away oyer the liYes, and fonunes, and consciences of men. To prepare the world for ita expected doom, Pope Calixtus III ordered the Ave Maria to be repeated three times a day, instead of two. He ordered the church bells to be rung at noon, which was the origin of that practice, so univerBBl in Christian churches. To tbe Ave Maria, the prayer was added-" Lord, saTe us from the DITil, the Turk, and the comet:" and once each day, these &breI' .,bntlxia1!s personages sull'ered a regular excommunicaton.

~89

COMETS'

The pope lind clergy, exhlhiti'ilg 'ul'hl'ear, it R not II. matter that it became the ruling passion of the multitude. The churches and conventa were crowded for confession of ains; and treasures oncoonted were poured into the Apostolic chamber. The comet, after sufferinl some months of daily corsing, and escommonioaUon, began to show signs of retreat, 'and SOOD dieappeared from those eyes in which it found no favor. Joy and tranquillity soon retumt'd to the faithful subjects of the pope, but not so their money and lands. The people, however, became eatisfied that their Iius, and the safety of tbe world, had been cbeaply purchased. The pope, who bad achieved eo aignal a victory over the monilter of the sky, had checked the progress of the Turk, and kep.t for the preBent, his Satannic majesty at a safe distance; wbl!.e thl! church of Rome, retaining her unbonnded wealth, was enabled to continue that inftuence over' her followers whicb she retains, in part, to this day. The comet of 1680 woold bave befOn still more alarminc than that of 1456, had not acience robbed it of its terrors, and hIstory pointed to the signal failure of its predeceBsor. This comet waa of "-larI8lt size, and had a tail whose enormous .length W88 more tbaD mmty-aiz millUlN rf milu. At ita greatest distance, it is 13,000,000 of miles from the aun; and at its nearest approach, only 574,000 miles from hia centar; or about 130,000 miles from his Bunace. In that part of ita orbit which is lIfIarest the 8un. it fiieB with the amazing 8wiftneea of 1,000,000 miles in an hour, and the 8un aB Been from it, appears 27,000 timl!8 larger than it appeara to os; consequently, it i8 then exposed to ft heat 27,000 t~meB I(l'eater &han the solar heat at the earth. This intensity of heat exceeds, several thousand timea, that of red-hot iron, and indefld all the degrees of heat that we are able to produce. A siJDple ma88 of v'apor, exposed to a thousandth part of such a heat, would be at once dissip'ated in space-e pretty strong indication that, however volatile are the elements of which cometa are composed, they are, nevertheless, oapable of enduring an inconceivable intensity of both beat and cold. This is the comet which, according to the reveries of Dr. Whiston, and othera, deluged the world in time of Noah. Whiston waB the friend and BucceSlOr of Newton: but, anxiooe to know more than is revealed, he paased the bounds of sober philoaophy, and preaumed not only to fix the residence of the I iJamneci, but allO the nature of their punisbmenL According to his theory, a 88me, WIll tbe awful prison-hooae in which, aa it wheeled from the remotest regioDl Of darkne18 and cold illto the "lory vicinity of the SDn, hurryinr ita wretched tenantetp the

or wonder

-,'!" ...- :

2.\

990

GEOGRAPHY OF THE IlEA.VENS.

extram.. of periahiug col. aDd deYouring fire. abe Almighty , ~ waa to diapenle the Ie. .riuea of hie juatice. Surb theories mal. be ingenioul, but they hue no basil of facta ,to relt upon. rhey more properly belong to the chimeN. of Astrology, than to the acienee of ARtronomy. When we are told by philosophera of great caution and high reputation, that the fiery train of thl! comet, juat' alluded to, extended from the horison to the zenith; and that of 1774 had, at one time, six tails, each 6,!)OO,000 of miles long; and that another, which appeared lOOn after, had one 40.000,000 of milea long; and wben we conlider also tlte inconceivable velocity with which they speed their Bight through the solar system. we may ceaae to wonder if, in the darker agea, they have been re. garded as evil omenl. But th ... idle phantasies are not peculiar to any ar or coun· try. Evea in our own timea, the bAllutiful comet ,0 1811, the most splendid one of modern times, was generally considered among the superathions, as the dread harbinger of the war which WIS declared in the following spring. It is well known that an indefinite- apprehension ,of a more dreadful catastrophe liltely pervaded both -continents, in anticipation of Biela's comet of 1839. The nueleus of the' comet of 1811, accordinll to observations made near Boston, was 9,617 miles in diameltlr, corresponding nearly to ,the size of the moon. The brilliancy with which it IIhone. waa equal to one-tenth of thst of the moon. 'rbe envelop, or aeriform covering, aurrounding the nunleus, waa 94,000 miles thick, about five hundred times 88 thick as the atmosphere which encircles the earth; making the diameter of the comet, including ita envelop, 50,617 miles. It had a very luminoua tail,whOl8 greatest length waa one Aundred miUi_ tf mila. This comet IDOftd, in ita pen'brlion, with an almost inconceivable WIlocity-fifteen hundred times greater than that of a llaIl burBling 6um the mouth of a cannon. According to RegiomontanWl, the comet of 1471 moved o.,er an are at 1200 in one day. Brydone obeei'Ied a comet at Palermo in 1770, which JIll-'- through 6()0 of 8 great circle in the baa.,. en•. in 24 hours. Another comet, which appeared in 1769, pB8II8II 0'181' 41 0 in the ..rne time. The conjecture at Dr. Halley, therefore, 1I8IIIIIII highly probable, that if a body of IJ1lCh a _, ha~ any CIIIIIIiderabJe density, and movins with BUob • 'I8locity, were to mike oor earth, it would instantly reduce it to chaos, mingling its elements in ruin. The lraD8ient effect of a comet paaring near the earth, could .--Iy amount to any great convuhion, ..ys Dr. Br8Wlller: but if the esrtb WeRI actually to recei.,. a shock 6um one at these bodies, the COIIII8q118DC8I would be awful. A new dimctiao would be pen to its rotary moCion, and it would re'IOI.,. UCRlnd a new ana The.... fiBtlllkilll their beda, ...ould be hurried, by their centrifugal bee, to the new equitorial regions:

COMETS.

291

cenIiDeD..,

WaadII aDd theabodM rJimen aDd miIDaIa, .,ouId be _ _ by the UDivenal rush of the watera to tbe new equator, aDd fmIr1 ves&iae of hUIJIa!l indua&ry and genill8 _Idbe at once delUuyed. ~

The chant'.e8 apinat eucb an eYent, bowever, are 80 very Dump-rolla, that there ia no reason to dread its occurrence. The French government, not long since, called the attention of some of h"r ablest mathematicians and astronomen to the solution. of this problem; that iI, to determine, upon matlaematica/ prineiplu, IW'w »tatlY cAamu tf col_on tlae eart4 w", ~ to. A fter a 'liature examination, they reported,-" W~ bave found that, of IIRl,OOO,OOO of cbances, there is only one unlavorable,-there exists but one which can produce a collision between the two bodies." , .. AdlDittin~, tben," they, .. for a moment, that the comets which may strike the earth with their nucleii, would IIIIDibilate the whole

18,

human race; the danger of death to each individual, reaulting wm the

appearance of an lIf1imoum tDr1ld, would be exactly equal to the riak he would run, if in aD urn th..re wu only one lingle white ball amoug a total number of lSI ,000,000 balla, and that m. condemnation to death would be the ine9itabIe -.eqaence of the white ball being produced at the fint drawing."

We haYe before stated that cometa, nnlike the planeta, observe no one direction in their orbita, but approach to and recede from their great center of atlraction, in every possible direction. Nothing can be more sublime, or better calcul'l1ted to fill the mind with profound astonishment, than to contemplate the revoiutioR of cometa, while in that part of their orbits which comes within tbe aphere of the telescope. Some seem to eome up from the immeallurable deptha below the ecliptic, and, having doubled the heavena' migbty cape, again plunge downward with their fiery trains, "00 the long travel of a thoWland yeaH."

Otbere appear to come down from the zenith of the uni'l'erae to doable their perihelion about tbe aun, and tben reiiscend far , above all buman v i s i o n . ' Othen are dasbing through the solar systfom in ,all possible directions, and apparently without any undiaturbed or un. disturbing patb preacribed by Him wbo gnides and sustains tbem all. Until within a few yeare. it wal univenally believed that the periods of tbeir reyolutiona must neceasarily be of prodigious length; but witbin a few yeart, two comets bave bel'n discov· .ered, whoae revolutions Ire performed, comparatively. witbin onr own neigbborhood. To distinguish them from tbe more remote, they are denominated the comet. qf a .lwrl pn-iod. 1'be first was discovered in the conatellation Aquarius, by two French

191

GEOGRAPHY OF THE HEA.YENS •

••\roDOm81'l, in tbe' year 1786. The lIame comet wall apia observed by Mill Caroline Hers('thfll. iD the conatellatioD CygDUI, in 1795, and agaiD iD 1805. In 1818, Profelaor EncJ[e determiDed the dimeDsions of its orbit, and ~e period of itlt sidereal revolutioD; for whicb reason it bu beeD called .. Er!dtJe'.

annel."

Thia comet performa ita revolution arouDd the SUD in about 3 years aDd 4 mODtha, in aD elliptical orbit which lies wholly within the orbit of Jupiter. Ita _ diatance 'from. the aun is 919,000,000 of miles; tbe eccentricity of ita orbit ia 179,000,000 of milea; cODsequeDLly, it ia 358,000,000, of miles nearer the aUD iD ita perihelion. than it ia iD ita aphelioD. It waa visible throughout the United States in 1825, wheD it presented a fiDl~ appearaDce. It wu also observed at ita Dext return iD 1828; but ita last return to ita perihelioD, on the 6th of May, 1839, waa iDvillible iD the United States, OD account of ita great lOutherD decliDation. The second" Comet ofa ahort period." 111188 observed in 1772; and wal 888n again in 1805. It waa Dot until its .....ppearanee in" 1896, that unonomers were able to determine the elements of ita orbit, and the exact period of ita revolution. Thil was auccessfully accomplished by M. Biela, of Joaet»hstadt; hence it is called Biels', annel. According to observauons made upon it in 1805, b, the celebrated Dr. Olbera, ita diameter, including ita envelop, la 42,280 miles. . It is a curious fact, that the path of Biela'a comet puses very Dear to that of the earth; ao near, tbat at the moment the ceDter of the comet is at the poiDt nearest to the earth's path. the matter of the comet exteDda beyond that path, aDd iDcludes a portion within it. Thus, if the earth were at that point of ita orbit which is Dearest to the path of the comet, at the same momflnt that the comfit should De at that poiDt of ita orbit which is nearest to the path of the earth, the earth would be enveloped in the nebulous atmosphere of the comet. With respect to the eft'ect whicb might be produced upon our atmosphere by such a circumstance, it il impoaaible to oft'er any thing but the m08t vague conjecture. Sir John Herschel waa able to di8tingui8h ltars u miDute a8 tbe 16th or 17th magDitude IArougla 1M body rf 1M comet! Henee it aeema rea80nable to infer. that the Debuioul matter of which it i8 compoaed, mUlt be infinitely more attenuated than ODr atmosphere; 10 that for Ivery/article of cometary matter which we should inhale, we Ihoul iDspire millioDs of panicl" of atmospheric air. This i8 the comet which wal to come into colli8ion with the earth, aDd to blot it out from the solar 8ystem. ID returning to ita perihelioD, November 26th, 1832, it wai computed that it would cr08l tile earth'a orbit at a distanee of only 18,500 miles.

COllETS.

It il erideat that if the earth had been iD tbat pan of her orbit at the _ Ii",,- with the come&, our atmosphere would bave mingled with the atmosphere of the comet, and the two bodies, perha,., bave come in contaCt. But the comet paaaed tbe earth'. orbit Oft the'19th of OctobardD the 8ih degree of Sagit.tariUI, and the earth did Dot arri,. 'at that point until the 30th of November, which wu 81 daYI afterwardl. I{ we mUltlply the 1UIm"r of houre in 3J day .. by 68,000 (tbe velOcity ohhe earth per hour), we maU find that tbe earth YU more theD 11,000,000 miles bebind tbe eomet wbeD it croaaad her orbi&. bl neareet ap'proaeb to the earth, at any time, wy about 51,000,000 of mdes; ill nearest approacb ~ tbe laD, wu about 83,000,000 of miles. Ita mean dilllnce from th,e IUa. or half the 10Dgeat lIil of ill 'orbit, il 337.000,000 of milea. III acceDtrieit, il 153,000,000 of miles; cOll88Cluently, it is 507,000,000 of miles nearer the 10D in ill peribelion than it is in ital aphelion. The period of ita sidereal revolutloD is 1,'60 dayl, or abOllt 6f yean. Up to the beginning of the 17th century, DO correct notiona had been entertained in respect to the path I of comell. Kepler'l first conjecture waS, that they mOTed in Itraight linea; but u that did not agree with obse"atioD, he ne.U concluded that they were ~boIic CU"el, having the lun Dear the vertex, and runoillg mdefiniteI)' iDto tbe regioDI of Ipace at both extremiues. Thl'lre wal notblDg in the obaervauonl of tbe earlier aatronomere to fix their identity, or to lead him to IUlpect that Iny one of them bad ever been _n before; mncb I... that tbey formed a part of tbe IOlar Iyatem, re,olving about the IUD in ellipucal orbill that retorned into themll8lvel. ' Thil grand disoo,ery wu rese"ed for one of tbe mOlt indu .. trioUI and lIfICiool ulronomere that ever lived-thil wu Dr. Halley, the contemporary and friend of Newton. Wben the oomet of 1681 made ill appearance, be I18t himself about obll8"ing it with great care, and fouad there wu .: wonderful resemblance betweeD it and three other comets that he found recorded, the comell of "56, of 1531, and 1607. The umet of their aI?pearaace had been nearly at I¥lual and regalar interval a ; thear perihelion dillancea were nearly the lime; and he finallT. proved them to be one and the lame comet. performing ill circUit aroond the Iun in a period varying a little from 76 yeare. Tbia il tberefore called Halle,', comet. It ia the very lime comet that filled the eutern world with 10 mocb conatfomation in 1456, and became an object of 80 mocb abhorrenoe to the chorch of Rome. The three periodic cometa, Encke'l, Biela'l, and Halley'.. baYe preaented, in their recent returna, lOme extraordinary pbanomena. The periodic time or Encke'a comet appeara to line been regularly _miMWn& ainCl Ita dilcoTery. The dia~

2.6.

194

GEOGRAPHY OF THE HEAVENS.

guilhed astronomer whose Dame it bearl,llfter a rigoroUI eX1lIDiDation ofall the knowD causel whie~ can produce luch In effect, finally reached \be cODolulion that there mUlt exist, throughout the planetary regioDI, a rare medium, cap-able of reailting the motion of the light and p"eoUI comets. ('his ltartling doctrine baa been received with oonliderable favor amoDg the learned, although it involvel Dothing leas than the fiDal deltruetion of the entire .IOlar system. In case a reaistiDg medium exist, no matter how email ha eff'sct OD the plasetl and oomets may be, yet lIince the stability of the eatire system is guaranteAd only on the hypothelilthat the revolutions of the planets are without rellistance. it followl that, sooner or later. the same effeets suppOled to be exhibited by Encke's comet, will be shown by every revolvinlf planet and satellite. and each, in SUCoossioD, will terminate Its cal'l'er by falling into the sun. Reeflnt observations by Sir John Herschel, OD -the physicsl constitution of Hailey's comet during its return in 1835. have revealed lOme truths which may. in the end, accoum for the retardatioD of Eneke's comet, without resorting to the hypothE'sis of a resisting medium. He conceives that the laws of gravitation will not acconnt for certain phenomena presented by Halley's COlllet, and that we will be compellt'd to admit the existence ora repullive force, developed onder certsin circumstances•.among the particles composing the tails and gaseous portions of comfits. During its late return, Biela's comet exhibited the wonderful phenomenon of an actual separation into two distinct portionl. When first discovered, the comet presented its ordinary apptlllrance, but in the coune of the following month, it was found to consist of two distinct parts, each pos_sing all the characteristiCll of a comet. These fragments continued to separate from each other, while they pursued their orbhual career around the sun. ThiB phenomenon Sir John Herachel is disposed to .attribute to the same causeB.which are operating to diminiBh the periodic time of Encke'B comet, and which produced luch sudden and wonderful changeB in the appearance of Halley'l comet, during its retorn in 1835. , The next appearance 'of Biela'B comet will be looked for with great intereRt. At thil time (J~ly. 1~). aBtronomers are on the look-out for Ericke'B colDet. Our koowledge of the phYBical cODBtitutioD of these mysterioul objects, is extremely limited. The number of comets which have been ot.ned aince the ChristiaD era, amounl.l to 700. Searce1y a year has pa8II8d without the obaervalion of one or two. And since multitudes of them mWlt escape obeervatieD, by reasoD of their tzavtmling that part of·the heaVllllll which Is above the horizon in the day time, their whore number is probably many thou-

ADda. Comel.l. 10 eircumatancea, can only become visible by the _

eoineidtmoe ofa.total ecHp.e of the nn-a coiDcidence which happeued, . .. related by Seneca, 60 ytllll'll before ChM, when a IaJp comet_ actually obeened very _ ~ IIUJl. • But M. Arago reuollli in the following 1IWIJlI!l, with respect to the number of comets :-The number of aecertained cometa, which, at their leut diatancee, JlUII within the orbit of Mercury, is thirty. AIIII11IIlin, that the comets are UJIiformly distributed throughout the IOlar system. there will be 117,649 time. u comets included within the olbit at Henchel, u there are within the orbit of Mercury. But u there are 80 within the orbit of Memury, there m\l8t be 3,629,'10 within the orbit of Henchell Of 97 comets whoae elements have been calculated by utron~ S4 ~ between the sun and the orbit of Mercury; 33 between the orbits of Mercury and Venus; 21 between the orbits of VenDS and the Euth; Hi Iletween the orbite of CeJ'IlII and Jupiter. Forty-nine of theIe comets miwe from eaRt to west, and 48 in the opposite direction. , The total number of distinct comets, whoae paths during the_DIe part of their course bad been ucertained. up to the year 1832, _ _ hundred and thirtyo48V8ll.

many

What regions thesll bodiea vi8i&, wben they paS8 beyond ~e limits of our viflw; upon what errands they come, when they again revisit the central parts of our sYlltem; what is the difference between t~eir physical constitution and that of the 8un and planets; and what important ends they are destined to accomplish, in the economy of the universe, are inquiries which naturally arise in the mind. but which surpas8 the limited powers of the h~man understandini a\ present to determine.

118

GIIOGBDBY

or- Tn

RKA-VUL

CHAPTER VIII. THE TJU.N8LATJON OP THE 8UN AND BOLAR 8YBTBK THROUGH 8PACE.

Bnura clOll8d a rapid aUn'ey of &be individual objecta coutituting &be aolar ayatem, we proceed to &be examination of the wonderful discovery made by Sir William Herechel, and recently confirmed b, &be Runian aatronomers, &bat 1M """ Gltefldetl by all AU pI4rtda, ..ullilu, _ t:OIIteU, .. moving IfDiJIly eArougla apaa. It will be remembered, &bat the aun muat be reckoned amonr the fixAd atara; and, indeed. is one of the many millions of atara oomposing the Galaxy, 01 Milky Way. So aoon as the .fsct waa ascertained beyond question, tbat amoDI{ the fixed stara many were found, which after yean of attentive ell:Bmination, actually changed their relative poaitiou in the heavens, it waa not unnatural to conjecture these changes to be the eft'ect of parallax, produced by the movement of the aun and hia lyltelD , of planeta, in lOme direction through the regiou of space. It will be readily leen. that in cue luch a movement of the lun exilta.1lnd should be appreciable in amount, when compared with the diltance of the ltan. ita eft'ect would be to produce aD apparent change among the relative placea of the ltara. in coo8f!Cluence of the fact that the apectator every year viewl &hern from a dift'erent point of absolute apace. The extenaion of &be law of gravitation to the fixed stars, by the diaeovery of binary Iyatema, reduced it to a certainty &bat the ltan exerted a motual inftuence over each other; and froID thil ,eneral attraction which each exerted over every other, it was lmroalible for the IUD to eaeare. The result of &bia ge_ ral attnction would be motion in lOme direction. To demo... Itrate the tru&b of thil conjecture-to determine &be direction. angular velocitV, and actual Jpovement of &be lun and IYltem, have been &be great queltionl for lolution during the laat few yean of aatronomical research. Sir W. Herschel had roughly examined thil lubject; and from a general examination of -the proper motion of the fixed ltan, conoluded &bat the lolar Iyatem was moving toward &be 8OnlteJlation Hercnl... For many yean, &bil theory wal received with comparatively little favor. The IpecnlatiOD was 80

TRANSLATION OF THE SUN TB!l0UGH SPACE.

197

bold, 80 daring, and apparently so Car beyond the leope of aceurate examination, tbat many minds were indisposed to receive it. Within a few yeara, bowever,·tbe liubject baa been taken up by M. Argelander, a Russian astronomer, and the IJrand apooulation of Heraebel bas become a matter of abaolute sClenes. Argelander'a general mechod of determining tbe direction of the aolar metion, may be thua explained, in ita general outlinea. He commenced by f\xin~, with accuracy, the places of five buudred atara, in all the Visible parta of the hea,ens. His own determined placea of these stars were then compared with the r.1acea of the same st8rs determined by preceding astroUOl\lers. rile old position of any star,joined with Ita new position, would give ita direction of apparent motion, and the distance between the two places, combined with the interval between tbe old and Bew observations, would fix the rate of movement per annum. The five bundred selected .tars were then grouped into three classes, according to their annual rate of motion. Tbe Iqost swiftly-moving, comr,osing the first clase, were examined separately in this way. rbe old and new flscea of each star bemg joined, tbe HDe. thus determined in position, made a certain angle with the meridian, which could easily be determined. All· theBe angles wpre computed; and by an examination of their values, it Willi spen tbat their general direction indicated, that in CBse the proper motions of theae atars were occasioned by tbe move·ment of the solar system through space, the direction of that Diotion must be, as Heracbel had aaid, towanl the constellation Heroules. A point in tbis constellation was now selected, as the one ioward which the aun waa moving; and, on thia hypothesis, the directions in which the stars already examined would appear to move, were accurately computed. Now in CBse these computed directions ahould in every inatance 'coincide with the aelual obaerved directiona. it would· demonatrate that the point had been well cbosen, and was the true point required; while a want of coincidence would abowtbat another trial must be made. Tbua did ArJJelander proceed, witb incredible paina, to select anel test one pomt after another, until be obtained one, whicb, better tban all otbera, barmonized all tbe proper motions of bis five hundred atara; and thia was tbe pomt towards which, it DOW became certain, the sun, witb all hia attendanta, was urging his flig 11.&. . A aubaequent inveatigation. by M. Str6ve, baa confirmed Argalander's resulta in the most't'emarkable manner. Having accomplished thia object, M. Striive gave his attention to the determmation of the amoont of angular motion of the Bolar aye-. tern, as seen from the mean diltaDce of the RarI of the lat mil"

198

GEOGRAPHY

or

THE HEAVENS.

Dimde; and by a compl_ and elaborate ipv_tipao., laaUy ucer&ained, that in each year, the lun'langular mouon amountecl to three huodred and thirty-five thounndtha or oDe 1eC00d or arc, or this would be the angle included between two Yiaalil raya, drawn rrom the eye or a apectator removed to tbe mean distance of aten of the 1st magnitude, to the two placea OCCIIpied by the aun at the be~Dning and close of tbe same year. Having learned the value or this distance approximately, we may DOW convert this angular motion into linear movement, aad we reach the following wonderful proposition, via. :-TA. 1Vn. attended . by all Ai. planet., raullite., and coma., i. .weeping thrwgA apace. towartlr'tAt rtar .., in tAt eonrtellation H_lt6, at tAt rate rf tllirtll-thru millionr tlru Atmrlretl and ,Nt" u.-ncI milta irw-lI Sucli1a the latest determination, wUb rererence to the magniicent ayatem with which we are usociated.

,ear.

.

LAW OF UNIVERSAL GRAVITATION. IT ia aaid, tbat Sir Isaac Newton, when he W88 drawiDgto a cloee the demonstration or the great truth, that gravity ia the cause whioh keepa .the heavenly bodiea in their orbita, was 80 mucb agitated wlth tbe magnitude aod importanoe of the diecoyery he W88 about to make, that be was unable to proceed. and desired a rriend to finiah what the intensity of hia reelingB did not allow bim to do. By grantation is meant, that unive~ aal law or attraction, by whicb every particle or matter in _the aystem haa a tendency to every other paniclll. Tbia attraction, or tendency of bodies toward each other, il in proportion to the quantity of matter they con&ain: The earth, being immensely.1arp in compariaon with all other lubatancea in ita vicinity. destroys tbe effect or this attraction between amaller bodies, by brin~ng them all to itself. The attraction or JraYitation ia reciprocal. All bodies not only attraet other bodlea,but are themselves attracwd, and both aecording to theit respective quantities or matter. The aun, the largest bOcly in our a),stem, attracta the esrth and al\ the other planeta, while they In tum attract the SUD. The earth, alao. attracta the moon, and abe in tum aUraata the earth. A ball, thrown upward from the earth, ia brought again to ita surface; . the esrth'l attraction not only counterbalancing that or the ball, but alao produolng a mouon of the ball toward itself. Thia diapQaition, or tendency toward the earth, is manirested in whatever ralla. whether it be a pebble from the hand, or an apple rrom a tree, or an avalancbe rrom a moun&ain. All terres-

LAW 01' GRAVITATION.

Irlti boell., DOt escepdng die waten o( tbe ocean, gnYitate toward the center :f the earth, and it is by the same power that animala on all parts of the globe stand with tbeir f.t pointing to ite center. . . The power of terrestrial gravitation is greateR at the earth'l IUrface, whence it decreaaea both upward and downward; but Dotbotb ways in the aame proportion. It decrea..s upward III lAe ItJU"'" of lAe dillanu. from the earth'. cenler incre.... ; lo.u.at at a diltance from the center equal to twice the ..mi. diameler of the earth, the pYi~~ing force would be only one fourth of wbat it is at the surface. But below the surface, it decreaaea in the dired ratio of the distance _from the center; so that at a diatance of half a lIemi·diameler frpm the cenler, the grllYitatinl( force is bot half what it i, at the aurface. L WeigAt and grtfI?ity, in this case, are synonymoo;,erm". We aaya piece of lead weigbs a pound, or 16 ounces; but if by any means it could be raised 4000 miles above the surlitce of the earth, wbich is about tbe dis~nce of the surface from the center, and con~uently equal to two ..mi-diameters of the earth above ite cenler. it would weigh only one fourth of alound. or foor ouncea; and if the same weigb~ could be raise to an elevatioo of 12,000 miles above the surface, or foor aemi-diameten above the cenwr of the earth, it woold there weigh only one sixteenth of a pound, or one ounce. ' 'I'he lime body, at the center of the earth, being equally attracted in every direction, woold be witbout weight; at 1000 miles from tbe center it would weigh one fourth of a pound; at 2000 miles, one balf of a J?ound; at 3000 miles, tllI'",e fourtbl 'of a pound; and at 4000 mdes, or at the aurface, one pound. It is a unmr.J law rB aUnction, that iU power ~, at tAe .-,uare of tAe dUt_ The of this is aIao true, via. power inemJIa, III tAe IfJfIlIn of tile dUt_ GiviDg to this law the fOrm rB .. pracIiilaI rule, it wiIllbmd th1l8: grtIf1ity of 60diea aboIe lAe "!'fa« of tAe earlA, det:nt.ua in" - duplWde ratio (ur III tAe ~ of llieir ~), ira ~ len of tAe earl1&, from tAe itIrl/a'. ctnUr. That iI, w'ben the gravity is increuing, multiply the weight by the lIIuare of the distance; but wllea the graYity ill ~,difIiM the waight by the 111_ of the cI,iatanca, 8uppGIIB a body weigba 40 pound. at 2000 mil. above the earth'. surface, what would it weigh a' the surfiule, eatimatiDg the earth'. BeIJIi. diameter at 4000 mill!81 From the center to the given bight, is Ii 8B1J1i.diameter: the 111_ of 1i, or 1.Ii, is lUll, whid!, multiplied into the wei,ht (40), gives 90 pounds, the answer. 8u.ppoae a body which weigba 266 pounds upon tbe IDrIice of the eanb, be raiaed to the distance rB the moon (140,000 milea), what would

ne ne

m-.

con_

d_.

be ita weight 1 Thas, 4000)140,000(60 ieJni.diameterI the eqoare rB wlIIch ia 8800. M the pmty, in ttiie - . ia decnIIina. ditride the

'800

GEOGRAPHY OF THE HEAVENS•

dIe.-

of the diIbulee, ad it will give 98OO)2116t1oJttb of a pound, or 1 00-' . 2. To find to wbat hisht a Bi- welpt mUll be l'aiaed to lnee a eertain portion of ita weight. , RULlI_Divide tAt weitllat lit 1M -:t-.lI!l tAt MJUirwl weigAt, tmd utraet tAt MJUII"t root 0/ 1M quolimt. Ex. A Iioy weigba 100 pounds. how high mlJlt he be canied to weigh but 4 pounds! Th-. J00 divided by 4, .givee 26, the aquare root' of which. ill 6 IIBJDi.diameteIII, F 20,000 mil. above the.center.

. we1ght by

Bodies oC equai magnitude, do not always contain equal quantities of matter; a ban oC cQrk, of equal bulk with one DC lead, contains less.matter, because it is more porous. The sun, though /ourt«n lauMreil tlaotuand tiDies larger than the earth, being much less dense, contains a quantity of matter only 355,000 times 88 great, and hence attracts the earth with Ii Corce only 355,000 times greater than that with which the eartb attracts the sun. ' . The quautity of matter in the sun, is '780 times greater than that of all the planets aud satellites belonging to the solar system; consequently their whole united force of attraction is 780 times less upon the sun, than that olthe sun upon them. . The center f gravity DC a body, is that point in which its whole weight IS concentrated, and upon which it would rest, if Creely suspended. IC two weights, olle of tan pounds, the other of one pound, be connected together by a rod eleven Ceet long, nicely poised on a center, and then be thrown into a free rotary motion, the heariest will move in a cirele with a radius oC one Coot, and the lightest will deecribe a circle with a radius DC tell Ceet; the center around which they move is their common center DC gravity. . Thus the sun and planpta move arouod an imaginary poill:t aa a ceoter, always preserving an equilibrium. . If there were but one body in the universe, provided it were DC uniform density, the ceoter of it would be the center of gravity toward which an the sfarrounding pomona would uniformly tend, and they would thereby balance each other. Thus tbe center oC gravity, and the body itself, would forever remain at f8Rt. It would neither move up nor down; there being no other body to draw it in any direction. In this CBse, the terms up and :lawn would have no meaning, except 88 applied to the body 'tself, to express the direction oC the surface Crom the center• . Were the esrth the only body revolving about the suo, as the· un's quantity of matter is 355,000 times 88 great 8S that of the earth, the sun would revolve in a circle equal only to the tlaree lufldred IJndjlfty-Jifle tlaouBandtJl·pan of the earth'a diatance from it: but 88 the planeta in their aeveral orbits vary their positiollll,

LAW 01' GRAVITATIOK.

801

&btl center of gravity ia .not \ah...y. at the ..me clilaanca from the IUn. Tbe quantity of matter in the aun 80 far eueecla that of all the planeta wlether. that were they all on ODe .ide of him. he would Dever be mqre than hia own diameter. fro.m the common center of gravity; the .un. i•• therefore. juatly conaidered aa the center of the ayatem. . The quantity of matter in the 8IlTth being about 80 timn aa great aa that of the moon. their commo. center of gravity ia 80 timea nearer the former tban the latter, which ia about 3000 milea from tbe earth'l center. The 8econdary planeta are loverned by the aame lawl aa their primarin. and both together move around a common oenter of ,ravhy. Every IYltem in the universe il BIIppoeed W revolve. in like manner. around one common cetIter. I

ATTRACTIVE AND PROJECTlLJt FORCES.

Au. limple motion il naturally rectilinear; that is, all boclif!a put in motion would cont,nup. to go forward in Itraight linea, aa long 81 they met with no resiltance or diverting force. On the other hand. the lun. from hie immflDse size. would. by the power of attraction. draw all the planeta to him, if hie attractive force were not counterbalanced by the primitive impulse of the planetary bodies to move in straight line.. . Tbe attractive power of a body drawiag anothflr body toward dae oenter. ia denominated centripetal foru I and tbe tendency of a revolving body to fly from the cp.nter in a tangent line, ia called the projectile or Centrifugal fUf'Ce. The I' oint action of these two central force. ~V88 the pfanete a circu ar motion. and retaine them in their orblta al they revolve, the primariel about the lun, and the eecondariell about their primariel. The degree of the aun'l attractive power at eacb particular planet, whatever be itl distance, il uniformly equal to the centrifugal force of the planet. The nearer any planet is to the aun, the more atrongly is' it attracted by him; the farther any planet is rrom the sun, the lesl is it attracted by him; therefore. thoBe plfllete which are the nearer to the sun mUlt move the (aater in their orbita, in order thareby to acquire centrirugal forces equal to thl! power of the aun'a attraction; and tbose which are the fartber from the aun muat move the slower. in order that they may not have too great a df!gree of centrirugal force. for the wenker attraction of the aun "t '1>0'18 diatances.

2B •

·82

GEOGRAPH Y' OF THE RBAVU&.

The dieoovery of tbeee great trathl, by Kepler and NewtoD, ..tablilhed thl! UIIIVER8AL LAW or. PLAlfI:TUY MOTION; which lDay be atated al Coli OWl. . 1. Every planet monl in ita orbit with a velocity varying nery inltant, in consequence of t.o forces; one tending to the center of the IUn, and the other in the direction of a tangent to ita orbit, arising froll!. the primitiveJmJlulae given at the time it was launched into space. The former II eaUed it.s centripetal, the latter, ita cmtrifugalf-. Sbould the centrifugal force ceaee, dae planet would faIr to the lun by ita gravity; were the lun not", attraet it, it would, lIy oft" from ita orbit in a straight'line. B.· By the time a Jllanet haa reached ita aphelion, or tbat point of itl orbit which II Cartheat from tbe lun, his attraction hilS overcome ita velocity, and draWl it tOward him with luch an accelerated motion, ,that it at last overcomes the lIun's attraction, and Ihoota past him: then gradually decreasing in velocity, it am ves at the perihelion, when the sun's attraction again prevails. 3. However ponderous or light, large or amall, near or.renlote, the planeta may be, their motion is always luch -that imaginary lines joining their centera to the slln, paal over equal areas in equal times: and this ia true not only with respect to the areaa deacribed every hour by, the planet, but the agreement holda, with rigid Ixactness, between the areaa described in the same time, by aU the planeta and cometa belonging to the aolar aystem. From the foregoing princ:iplea, it folJOWII, that tile fiJrce of gravity, and the centrifugal force,.,., mutual opporingpo~ continually acting ag~ the other. ThlJ8, the weight of bodies, on the earth'. equator, is diminU/led by the centrifugal force of her diurnal rotation, in the proportion of one pound for every two hundJed and ninety pounds: tba& l8, bad the earth no motion on her axis, all bodies on the equator would weigh one two hundred and eighty"Tlinth,.part more than they now do. On the contrary, if her diurnal motion were accelerated, the centrifugal force would be proportionally incre8sed, and the weight of bodies at the equator would be, in the aalDe ratio, diminished. Should the earth revolve upon ita axis, with a velocity whicb would make the day but eighty.(our minutes long, instead of twenty-four hours, the centrifugal force would counterbalance that of gravity, and all bodies at the equator would then be abaolutely destitute of weight; and if the centrifugal force were filrther augmented, (the. earth revolving in 1_ time than eighty-four minutes). gra";'tation would be completely overpowered, and all fluids and looIe , subdances near the equator would fiy oft" from the 1IIll'fBce. 'I'he weight of bodiee, either upon the earth, or on any other planet hav· Ing a motion around, ita axis, depends Jointly upon tile mass of the plaDet, and ita diurnal velocity, A body weighing one pound upon tile equator of the earth, would weigh, if removed to tile equator of the ann, 27.91ba. Of Mercury, 1.03 lbe. OrVen1l8, 0.1I81ba. Of tile moon, -tr lb. Of Mara, • Ib. Of Jupiter, 2.716 Iba. Of Saturn, 1.01 lbe.

_me

PUCISlION OJ' THE ZQUIlfOXES.

808

9HAPTER IX. PRECESSION, NUTATION, ABERRATION, PARALLAX, REFRACTION.

. I. attemptiDg to b the pleee olany heaftnly hody, at a giV8D epoch. for ,the purpose of ascertaining its subsequent movements, h is absolutely indisJ'ens~bleto know the precise changes which are affectiog the points or lines to which the heavenly body is referred. and by means of which its place la determined. The longitude and right alC8nsion are both reckoned from the nml! point, viz•.the eertIIJl rquiflOlIf, and in cue this point is not fixed, the~ to know with accuracy the place of a star or planet rllfem.d to the vernal equinox, we muat learn the precise amount of change in the place of this point of refe~nce. If the lun in its apparent annual motion among the bed stars, pused oYer tbe same identical track every year, then the points an which hil orbit cnts the celestial equator would be ever invariable. Thill. howsver, ia not the case. The sun's path among &he fixed stsrs. ill slowly but constantly changing. If a bri,ht slar this year should happen to occupy the exact point in which the aun's path CI'Oll88l the equator in the spring, at the end of one year the sun would come round and would cro88 the equator 10 88 to leave that atar a Iillk to llae etUI. . . This apparent yearly motion of the lun westward. cauaea i& to reach the equinox or to come to the equator earlier than it otherwise would do, and in &hil 'way brings on an equality between the daYI and nights, BOOner than it would have come had the sun's apparent orbit been fixed. Because the snn in this way comes to the equinox at a time ~ng its .forme~ arrival. it has been called a prtUIIiDfi of die equinoxes, while in reality It is a recession or receding of the equinoctial pointl along the equator. We shall now in a few worda trace this extraordinary phenomenon to ita origin, point out its effects, and present ita exact numerical value. The swift rotation of the earth on ita axis, causes a protuberance or elevation around its equatorial regions as we have alread,. seen. This belt of matter heaped up at thto equator. is subjected . to the attractive enl'rgy of the sun and moon, and by their combined action eXflrted on this belt of redundant matter, the solid Mrth is made to reel 8lightly on its axis. Now thf! plane of the earth's equator produced cull from the heannl the equinoctial,

804

GEOGRAPHY OF THE BEAVENII'.

and in eue this plane be in any way deranged or moved, it will cease to cut the ecliptic in its fOfl!ler points. It will be eeeD readily that whatjCYer caulle operates to displace the earth's equator, must operate to chauge the position of tbe equinoctial points. Again: as the earth's axis is ever perpendicular to tbe ftllrlh's equator, it followlI that every change lD the position of the equator, involves a corresponding change in tbe position of tbe earth '8 axis. To exbibit tbis to the eye, take a wooden wheel, pass through its center an axis; and tben let.the wbeeland axis flm.t on still water: [f the wbeel be one half sunk below the Burface of the water, tbe otber balf coining up above tbe surface, then will the axis cease to be vertical, and will become inclined toward .the immersed ponion of thewbeel's rim. Repeat the experiinent at any point of the rim, and it will be fOlind that every motion of the wheel involves a corresponding motion of the axis. The wheel repreaents the earth's equator, the axis that of tbe earth, and the surface of the still water the plane of ~e earth's orbit. [n the long run, the etreet of tile combined action of tbe Bun and moon, on the equator of. the earth, causes it to cut tbe ecliptic in two opposite points, 'which move slowly backward every year, and accomplisb an entire revolution in about 26,000 years. As this motion is repreaented -exactly by the earth'. axis, it follows that in the same period the pole of the equator, or north pole of the beavens, will revolve around the pole of the eclietic. . . 1 he ellact value of precession, aa recently determined by M. Striive, is 50".23449; a quantity of the utmost importance, in the nice investigations of sidereal aatronomy. [n consequence of the motion of the north pole of'tbe beaven.., the bright star Polaris, now nflar tbe pole, will ultimately be left far behind, and at tbe expiration of aboat 12,000 years, th. brilliant star Vega, in the Lyre, will become the polar star. Nutation is a subordinate etrect of the same _general cauaes producing precession. [t was diacovered by Bradley, and is aue to the joint influllnce of the sun and moon on the protuberant mass at the eartb's equator. It nriBB with the configurations of the sun,moon, and moon'l node. and is represented by supposing the extremity of the earth'l axis' to deacribe a minute ellipse in the heavenl, in about nineteen yearl, while it is carried forward in its general revolution about the pole of tbe ecliptic. The exact numerical value of nutation, as determined by BIlICb, Peters, and Lllndahl, is 9".2320• .8berrtUion.-Ir the light which radiatel from a lelf-Iuminous body, or which is reflected from an opake one, pasled instantly from one point in space to any other, however remote, then woalcl luminoul bodi. actually occupy the plaCBB in space,

I

ABERRATION.

whicb, to &he eye. they appear to Ill. ~,laowcYer. il DOt dle. oue. Ligbt baa beeDfound to PlOfI8I8 wida a TClocitJ amain, indeed, but Itill finite, bringing with it certain eft"ecla, which, In &he pJellCnt ltate ofastronomy,oallDOtbe dientganled. The discovery of the fioite velocity of light was made by Roemer, Crom ao aueotive examination of \he eclipl" of 1M eatellitee of Jupiter. It will be remembered that the earth'l orbit, being ... clOl8d wi&bin the orbit of Jupiter, wben tbe earth and Jupiter are in a straight line pusing \hrough the sun, 'alld on \he same lide of the son, they are Dearer each other \hall wben OD oppolite sides of \he IUD, by a di!l\aa4le equal to the diameter of the eartb's orbit, or by nearly 200,000,000 of mil... It _ found that \hose eclipses of Jupiter's eateUhes wbich occurred while the earth and, Jupiter were near each other, came on earlier thall \he computed time; while those occuiring at the time Jupiter and the earth were at their greatelt distance, came on too late for the computed time. For a long time no explanation could be found for thie siogular phenomenon. At lengtb it was found to depend on the relative distances of \he earth aIId Jupiter, and was fina)ly explained by giving to the light which cornea to UI from the eatellitea of that planet, a finite and determined vel. city. AI \he light from the satellites is reflected light, so 8000 as the satellite enters the shadow of Jupiter, the lource of ligbt ie cut off; aIId in case light moved instantly from one point to another, the ecrrpee would take place tbe moment the satellite entered the shadow of its primary. Bllt the stream of light flowing on with a finite velocity, requires a certain time to become exhausted. When Jupiter and tbe eartb are nearest, or in conJunction, the stream is shorter. or has a le88 distance to flow, by Dearly 200,000.000 of mites, than wheD the earth and planet are in opposition, or most remote from eacb other. In \his way it is found that Iigbt requires about sixteen minutes to cross &he diameter of the earth's orbit. The velocity tbus determined has been confirmed, in a remarkable manner, by Bradley's discovery of what has been called the aberration of the fixed stare. Thil is an apparent change in the placea of the fixed stars, due to the Cact that the velocity of light, combined with that of the earth in its orbit, causes th~ fixed stars apparently to d~scribe a minute orbit. in the period of one year. Very extended and minute investigations have revealed the actual velocity ofthe light of the fixed stars: and this velocity is nearly, if not exactly equal, to that of reSected light as dedllced from tbe obeerved ecliplea of Jupiter's eatellites. The numerical value of aberrstion, as lut determined by the RUBsian astro~omers, is 20".50. PlI1'allaz.-This subject bas already been treated, in the cbapter on the distribution and distauce of tbe fixed stare. Th. eft"eet of parallax on the place of ally heavenly body, ie to callie

282

_

GEOGRAPHY

or

THE .HEAVENS.

lHo appear leu I!Ilented above the borizon than it wOlld be if leen frolllthe earth'l center. The apparent plaeea of the lUIIt BlOOn, and planeta, are senlibly aft'ected by parallax; and their we places caD only be obtained from their apparent placel, by oorrecting these for the eft'ect of parallax. ' Rtfraetitm. - The Iigbt which reachel UI from the bentonly bodiel oirly comea to the e.,e of the observer after traveraing the atmosphere, a gaseoUI mechum,which POlsesses tke power of causing a ray of light, while traveraing it, to bend from ita rectilinear path. In Clonlequeaoe of this bending of tIt.e rays of light, called refraction, a star or planet ia seen iD the ·direction of the straight line drawn tangent to the .curved ray of light, at the point where it.enters the eye; and it thUI appears higher above the horizon than it really il. Tb~ a star or planet is seen, by the eye. wbile it i8 yet really below the horizon, in consequence of refraction. The aame cauSe dift'uses the light of day, and gives to UI the twilil[bt of morning and e.ening. The eft'ect of refraction on tbe .pfacea of the he....enly bodies has been carefully ltudied,and tablea have been prepared, sbowing the value of refraction at all elentionl above the borizon, and for all changea of the thermometer and barnmeter. . . To obtain, then, the absolute place -of any heavenly body, from its apparent place, as taken by aD instrument absolutely perfect, we mUlt cor~t ita !Dltrumental, or observ~ place, for precession, nutation, aberratton, parallax, and refraction.. If the lDltrument be not absolutely perfect, then must ita errors be inl'8Itigated, and be allowell for. before a final reliable resuh caD be obtained.

CHAPTER X. .

.

THE TIDES.

THE oceans, and an the seas, are obsened to be incessantly agilated f!lr certain periods of time; first from the eaBt toward the west, and then again from the west toward ~e east. In tbie lBotiOD, which laSIa about aix houl'll, tbe sea gradually swell a ; 80 that entering tbe moutbs of rivers, it drives back the waters toward tbeit source. After a continual flow of aix bours. the seaa seem to rest for about a quarter of an hOllr; tbey then begin to ebb. or retire back sgain from weat to eaat for lix hours more; and the rivers again resume their natural courses. Tben. after a aeeming ,pauae of a quarter of an bour, the ae88 again begin to tlow, as before, and thua alternately. This regular alternate motion of tbe sea constitutes tlu lith_, of wbich tbere are two in 80mething leBs tban twenty-five bours. '.file ancients con.idered the ebbing and flowing of the tides .. one of the greatest mysteries in. nature. and were utterly at a 10118 to account for them. GaJileo and Descartea, and particularly Kepler. made BOme BIleeeeafiJl advances toward 88CeJ'laining the cauee; but Sir IlIIIac Newton was the first who clearly mowed what were the chief agents in producing these motiOllL The cause of tbe tideB, is tbe attraction of the sun and moon, but chietly of tbe moon, upon the waters of tbe ocesn. In virtue of gravitation, the moon, by her attraction, draws, or raisE'll the water toward her; but because the power of attraction diminisbes as the squares of the distance Increase, the waters on the opposite side of the eartb are not eo much attracted as they ~ on the side nearest the moon. That the moon, llllya I3ir John HeracheI, ahould, by her attraction, heap up the waters of the ocean under her, ~ to moat per8Oll8 very natara!; but that the llllme cauae ahould, at the _ time, heap them up 011 the opposite 1Iide, EeDII, to many, palpably abeurd. Yet nothing i. mori! true, nor indeed more evident. when we consider thet it ill not by her wAole attraction, but by the diBilrences of her attractiona at the oppoBite III1I'fiIees and at the center, that the watem are raiaed. ,. That the tides are dependent upon aome known and determinate la,.., evident from the exact time of high water being previoualy given in e'fer! ephemeris, and in many of the COIIlIIIOD a1manllal. . The moon comes fJVfJr1 day later to the meridian than 011 the day preeeding. and her exaet lime is known by ""'aIlation; and the tides in any

u

'lOS

GEOGRAPHY 0., 1;0 REAVENS.

I11III ..,., pi-, will be &JuDd 10 iIIIow the _ rule; happeiDg uactIy 10 much later every day .. the moon _ Jatar 10 the metidiaD. From thia old coafDnnity to the moao.. 0( the JIIOOII, we _ iDduced to look to her .. the eaU88; I11III to ini!r that &be. phennmerw _ qc:ao .woed principa11y by the moon'. aUJaetioa. . .

THE TIDE'.

_e FIG.

I.

Fla. lL

If tbe eartb were at relt, and there were DO attractive illAuence from eitber the lun or moon, it ill obyioul from the principles of gra.yitation, tbat the water, in tbe ocean would be truly ,phelical (al represented by figure 1); but daily obee"atioD proves tbat they are in a state of continual a¥itation. If the earth and moon were without motloD, and tbe earth covered all oyer witb water, the attraction of the meon would raise it up in a beap in that part of the OCt!8n to wbich the mOOD ia vertical, as in figure 2, and there it would, probably, alway' cODtinue; b!1t by tbe rotation of the 'earth upon hI axil, each part of its .urface to which the mOOD is vertical is presented to the action of the moon: wherefore, as the quantity of water aD the whole earth remainl the lame, when the watera are elevated on the lide of the earth under the moon, and on tbe opposite 'ide alIa, it is evident they mUlt recede from the intermediate pointl, and thUI the attraction of tbe moon produce laitlA tIHIter at two opposite placel, and low water at two opposite places OD the earth at the lame time, aa represented by figure 3. Thill is evident from the figure. The _tera eannot riBe in 0IIII pJ-. without falling in another; and therefonl they mu. fall .. low in the horizon, at C and D, .. they rille in the aenith and DIldir. at A I11III B• .. in the foIlowinJ figure.

It haa already beeD Ihown, UDder the amcle gravitation, tha' the earth and moon would fall toward each other, by the power of their mutual attractioD, if there were DO ceDtrifugal Coree &0

THE TIDES.

I

809

pJeve~t them; and tbat \he moon would ran as much' faater toward \he earth \han \he earth would rail toward the moon, aa &he quantitf or matter in \he earth ia greater· than the quantity ot matter In the moon. The iame law determinea alllO the aize of their Jespective orbite around tbE'ir eommon center oC gravity. It follows, then, 88 we have - . that the moon does no& revohoe, ltrictIy speaking, around the earth 88 a center, but around a point betwem them, .which is 80 times nearer the earth than the moon, and conlI!CJ.uently is situated about 3000 miIea from the earth's center. It has also been shoWn. that all bodiee moving in cirolee aequire a centrifugel force proportioned to their respective m_ and velociV' . From the. &ete, some pbiloeophelll account for high water on the IIide of the earth 0pp0IIite to the moon, in the filllowing manner : As the earth and moon move around their common center of gravity, I/IIJt part of tM earlh which is at any time tumed from tM moon, being about 7000 milee farther from the cenler of gravity than the 'lide next the moon, would have a greaUr centrifugal.r- tluJ" 1M . . ntI:l • • At the earth's center, the centrifugal foree Will balance the attractive force; therefore, 88 IIIUdl water is thnYum oil by the centrifugel force on the .we which is turned from the moon, 88 ia ...wed on the Bide nut her by her tdVactiOIl. . From tbe universal )aw, \hat the Coree oC gravity diminishes .a the &quare oC \he distance increases, it reaulta \hat the attractive power oC \he moon decreasell in intensity at every step of tbe descent Cram the zenith to the nadir; and, consequently, that the waters on the zenitb, being more attracted by tbe moon than the earth ia at ita center, move Caster toward the moon than the earth'a center does: and aa the center oC \he earth movea Caater toward \he moon than \he waters about the nadir do, the .waters will be, as it were, left behind, and thua, with Jeapect to \he center, they will be raiied. The reason why the earth aDd waters of our globe do not _ to be 6:ted equally by the moon's attraction, is, that the earthy eubltance of the globe, being firmly united, does not yield to any dilJinnce of the moon's attraclive force; inaomuch that it. upper and lower eurIi&ce mUl& move equally &at toward the moon; whereas the watera, cohering top. therbut very slightly, yieJd to the dift'erent ~ of the moon'. attraI> tive force, at dilimmt distances from her. The leng&h of a lunar day, that is, oC the Interval from one meridian pasaalfB oC the moon to ano\her, being, at a mean rate, 24 hours, 48 mlnutea, and 44 aecondll, the interval between the fux and the reflux of the sea il not, at a mean rate, precill8ly aix houri, but twelflll minutllll and eleven 1IIeOfItla. more, ao that the time of high water doee not happen at the game hour, but is about 49 minutes later every day. The earth revolvea on ita axis In about twenty.four bours; if the mOOD, thereCore, were .•tationary, the _ e part of our globe

.

110

GEOGRAPHY OF THE HEAVENS.

I

would retam beneath it, and there would be two tidea eY., lwellty-four bour.; but while the earth i. tumiul' ODee upon ill axis, the mOOD haa goae forward 13° iu her orbll, which tak.. fort),-aiae minutel more before the same meridiaa is brought .gaan directly under the moon. And heDee every suceeediag day the time of high water will be forty-uine minutes later thaa the preceding. . For example :-8uppoae at any place it be high water at 3 o'clock iu the afternooD, upon the day of DeW 1IIOOIl; the fOllowing day it will be high WIder about .9 minut.ea after 3; the day after. about 38 minutea after.; and 10 OIl till the next new moon. The exad daily mean retudaIion of the tideI iB thoadetermined : . The mean motion of tbe moon, in a IOIar day. i. 13".l763116311 The mean motion of tbe .l1li, ID a IOlar dllY, i. 0 .98564722

Now, lIS 111" ia 10 80 milUltea, 10 i. 11".11107491110 48' W'.

lt il.obrionl that the aUracUon of the IDD mnst produce upon the waters or the ocean a like effect to that of. the moon, thoogh in a leal degree; for the great mue of the lun il more than compensated by ita immeose distance. Neyerthelels. ill effeCt is considerable, and it caa be Ibown, that the hight of the solar tide is to the hight of the lunar tide al i to 5. UeDee the tidea, though conltant, are nol eqnal. They are greatelt wheD the moon il in conjunction with, or in opposition to, the Inn, and least'when ill qnadrature. For, in tbe former cale, the lun and moon set togetber, and the tide will equal the snm of the solar anil· lunar tides, and in the latter they act agaiust each other, and the tide will be the difference. 'rhe former are called apring utI., the latter, fIIGJI tida. Th. Ipring tidea are higbeat when the lun and moon are near the equator, and the moon at her least di.lance from the earth. The neap tidea are lowelt when the moon, in ber first and second quarters, is at ber greatelt diatance from the earth. The geaeral theory of the tidea is thi.: when the moon is neaMat the earth. ber attraction il Itrongest, and the tides are the bighelt; wben Ihe ia farthest from the earth, her attraction is least, and the tidea are the 10wesL From the abon theory, it might be Inpposed that the tid.. would be the highest when the moon was on the meridian. Bnt it il found that iu open seas, where the waler 1Iowl freely, the moon haa generally f)GIUd llal north or lOUt! meridian about tlaree Nnw. wAeta it iI lli~-'" water. The reason iI, that the force by which the moon ratsea th" tide conti_ to act, and consequently the waters continue to riBe after Ihe hal paaaed the meridian• . For the aame reason, the highest tid.., which are produced by the conjunction and oppoaition of the. aun and moon, do not happen on the daya of the full and change; neither do the low..t tides bappen Oil the dayl of their quadratnree.-But the greatelt

THE TIDES.

3ft

tpring lida commonly happen Ii days afIer the new and full moons; and the leut neap lida Ii day. ofter the first and third quarten. The 81IIi and moon, by I'I!88OD or the elliptical form or their orbitI, are

alternately Dearer to and fit.rther &om the earth, than their mean diatanC8lo In ClODII8CI.uence or this, the efII.cacy or the IUn will ftuduate between the e1:ireme8 J9 and 21, taking 20 for ita mean 'f8Iue; and between 4,'J and 69 for·dlat of the moon. Taking into ~unt thiII cause of diJIiII.. ence, the bigheIt spring tide will be to the lowest neap 8.69+21 is til ~19, or 88 8Q to 24, or 10 to 3. The relative _iI!ftu~ce is l1li 51 to 20, or 88 5 to 2, _ly..,...Hu8CAel'• .A8tr. P. 339.

Though the ti'des, in open .et.II, are at the higbest about. tAru Aoun after the moon has passed the meridian, yet tbe waters in tbeir plUlsage tbrough sboals and cbannels, and by striking against capea and headlands, are so retarded that, to different plaoes, the tides hlLppen at all distances of the moon from the meridian; consequently at all houn of the luriar day. In small collections of water, the moon acts at tbe same time on every part; diminishing the gravity of the whole mass. On \bis account there are no sensible tides in lakes, tbey being generally so sma)) that when the moon is vertical, it attracts every part alike; and by rendering all the waters equally ligbt, no part of them can be raised higher than another. The Mediterranean and Baltic seas have very small eleutions, partly for this reason, and partly because the inletS by which they communicate with the ocean are 80 narrow, that they cannot, in so short • a time, either receive or discharge enough, sensibly to raise or. sink their surfaces. . .Of all the cau~es of dUFerence in the bijrht of tides at different places, by far the greatest is local situation. In wide-mouthed . rivers, opening in 'tbe direction of the stream of the tides, and whose channels are growin¥ gradually narrower, the water is accumulated by tbl! contracting banks, until in some instances It rises to the-hight 0(20, 30,and even 50 (eet. . Air being lighter tban water, and the surface of the atmoflphere being nearer to the moon than the surface of the sea, it cannot be dou\ted but that the moon raises mucb hijrher tides in the atmosphere than in the sea. According to SIl John Herschel, the~e tides are, 'by very delicate obse"ations, rendered not only sensible, but me_able. UPon the ~ticin that the waters on the IRIlfiace ~f the moon are of the same speci1ic gravity 88 our own, we might 8IIIiIy determine the hight to which the earth would· raise a li1nar tide, by the known principle, that the attraction orone or these bbdiea on the other'81R1lfiace i8 direc#y 88 ill! quantity of matter, and inwnely 88 itIJ diameter. By making the calculation, we BhaIl find the attracti-ve power of the earth upon the moon to be 11.777 m- BNIier tbIID dlat of the moon upon the earth.

IJS

GEOGRAPHY OF THE IlEAVUS.

CHAP'.I,'ER XI. THE 8EA80N8-DIPFBRENT LENGTHS OF THE DAYS AND NIGHTS.

Tali vici.situdes of the le-.onl and'the unequal lengths of the days and nights, ate occasioned bl the annual revolution 01 the earth around the Iun, with its axil inclined to the plane 01 its orbit. ' The temperature of lUIy part of the earth's surface depend. mainly. if not entirely. upon its expolure to the lun's ray.. Whenever the lun i8 obot7e the horizon of any 'place.. that, plaCE II receiving heat; when the lun i8 below the horizon. it i8 parting with it. by a process which ii' called ri.liation. The quantities of heat thul received and imparted in the course of the year. mUlt balance ear.h other at everyllace, or the equilibrium of temperature would not be 8upporte • Whenever. then, the lun remainl more than twelve houra above the horizon of any place. and lesl beneath, the general temperature of that place will be abo/ltl the mean state; w heD the reverse takes place. the temperature, for the, lame reason, will be below the meaD 8tate. Now the coDtinuance of the lun above the horizoD, of any place, depends entirely upon his declination. or altitude at noon. About the 20th of 'March. when the Inn il in the vernal equinll'&, and consequently hal no declinatiC;lD, he riS88 at lix in the morning and sets at aix in the evening; the day and nigh~ are then equal. alld aa the sun continu,ea as long above onr horiz.on as below it, hia iDllu.ence must k Dearly the same at the aame latitu.dI8s., in buth hemiBphl'rea. From the 20th of March to tbe 21s. oC June. the days grow longer, and the nights ahorter; in the IJ,Orthern hemi8phere the temperature increa8es. and we paBl froBl apring to mid-summer; while the reverse of this takes place in the 80uthern hemisphere. From the Illst of June to the 23d 9f Septembt'r, the days and nights again apcroach to equality, and the excess of temperature in the northern lemisphere above the rqean atate, growa lea8. U also its defect in the southern; ao that, ..,hen the lIun arrivea ai the autumnal equinox, the mean temperature ia llgBin f8atol't'd. From the 23d of September until the 21at of December, our nights grow longer and the daya ahorter, and the cold increases

\

THE SEABOIt'I.

818

.. before it dhninisbed; wbile we pue trom autumn 'to mid winter. in &he nonhem bemispb8Je, aDd the iDbabitants of the NOtbern hemispbere trom spring_ to mid-aummer. From the lUst of December to the 5lOth of Maroh, the cold relaxes u tbe days ~row longer, and we pus from the drearin88s of willter to the mlldneu of spring, wben the se880nl are completed, and the mean temperature is again restored. The 18me vict88itudea tranapire, at the 8Ime ,time, in the louthern hemisphere, but ill a oon&ra7 order.-Thus are produced the four S88lonl of the year. But haYe stated not the only. nor, perbaps, the moat efficient cause in producing the heat of lummer and the cold of winter. If, to lhe iDbabitants of the equator, the lun were to remain 16 hours below their borizon, aDd only 8 bours above it, for every day of the Y9r, it ia certain they would Dever experience the rigors of our winter; lIince it can be demonatrated, that al much heat flllll upon the same area from a W:rlictJl aun, in 8 hours, as would fall from him at an angle of 000, in 16 houra. Now 88 the lun's rays fall m6fIt obliqt.Hly wAeta tM day. are dortut, and moll d&reet1!l wAeta 1M day. are /tmgat, theae two caUSf'S, nalll8ly. the duration and intenlity of the lolar ht'Bt, together. produce the temperature of the ditrerent lea80ns. The reason ,why we have not the hotle8t temperature when the daYI are longest, and the coldeat temperature when the daYI are ehorteet. but in each case about a month afterwards, appears to be, that a body once heated, doea not grow (lold inBtantaneouB!Y. but gradually, and BO of the contrary. Hence. as 'long aB more heat comes from the lun by day than il 10lt by night, the heat will incff'8Be, and wee wna. ' The nortli pole of the earth il denominlted the e/ewdedpole, because it iB a1waYI about galo above a perpendicular to the plane of the equator, and the Bouth pole ia denominated the depr'UIeti pole, because it iB about the 88me diBtance below such perpendicular. AB the Bun cannot Bbine on more than one half the earth'l aurface at a time, it iB plain, that when the earth iB moving through that POrtiOR of ita orbit which liel al1oIIe"lbe aun, ~e elevated pole is in the dark. This requires aix month. that II, until the earth aniyea at the equinox, when the elevated pole emergeB into the light, and the depreaaed pole is turned away trom the Bun for the lame period. Consequently, there are lix monthB-day and Bix montha night, alternately, at the polM. When the aun appears to nl to be in one part of tlui ecliptic, dJe earth, .. 888n from the -BUll, appeara in the point cliametrically oppoaite., Thue, when the aun appeara in the vernal equiDOX at the fim point of mea, the earth is aetaally i. the oppolite equinox at Libra. The daya and nighta are daen equal all OYer the world.

20

.h lite IUD ..".... to lDOYe Dp fia. lite ....... eqaino1 to the 1 8 _ eolltice, da. earth 8O&8aIly ..IW.. fia. the autumaal equinoK dow. to Ibe wiater eoladee. The daYI now length. . in the IlOI1hera bemiapb.... _ ahOrteD iD the aouthem. The IUD il now oyer lite north pole. where it is mid-day, and oppoaile the eouth pole. wbBftl It is mid-uigbL . As the IUD d8lOllllda from lite IUDUDer eolldoe towerd lite autumnal eqaiDoz, the earth uoeuda from Ihe ...iDler aoladoe toward lite yernal eq8iDo:i. Tlafl IBIDmer daya iD-the Dorthem btmlitphere haYiDg wued ahOrler and Iborter, D,W become again or equalleugth iD both bemiapberea. . While the lun appears to moye from the autumDai equiDOx dOWD to the wiDler eolllioe. the earth paeeea up the yernal &qaiDOK to the I_mer eo"doe; the aouth pole com.. iDto the ligb&, the wiDler daYI coDliDuaily aborteD iD the northem bemiapbere, and the Hmmer daya .. regularly iacreue iD length iD th .. lOutheru hemia'phere. . Wbile the aaD appears apia to .-ad from ita winler 101llice to the yemll equiDos:. the earth deacenda rrom the aummer aolatice to the autumual equiDOK. The aummer days now IIhorten in the eoutheru bemiaphere, aud the wiDler daYlleDpeD in the .onhem bemispbere. WheD the IUD pa.... the Yenaal equinox, it ri_ to the arcdc or eleYlted pole, and 88&8 to the an&8rotic pole. When the aUD arriyes at the aammer eolatice. it ia noon at the DOrth pole, and midnight at the aouth pole. WheD the IUD p.... the autumnal P.Cjuinox. it 88&8 to the Dorth pole. and ri_ to the south pole. WheD the IUD arriyea at the winler IOlatioe, it il midDight at the IlOrth pole, and DOOD at the IOUth pole; and wbeD the aUD oomel agam to the yemal eqUiDOX, it CI0888 the day at the ROUth polto. and lightl up the momlug at the north pole. There would, therefore, be 1861 daya dunng which the aUD would not set at the north pole, aDd au equal time during wbich he wODld nIK riee at the aouth pole; and 1781 daya in which be . would not let at the south pole, Dor ri88 at the north pole. At the arctic circle, i30 ~•• from the pole, the longest day ia 24 houta, and goes on increa&lng a8 you approacb the pole. ID latitude 67° 18' it ia 30 days; in Iat. 69° 30' it ia 60 daya, &C. 'rbe aame takes place between the autarctic circle and the south pole. with the exception, that the day iD tbe lime latitude aouth 18 a liule aborte" aince the aun ia Dot 80 long looth of the equator, as at the Dorth of it. .ID thia eatimale nO'lCCO.UDt ia takeD .of the refraction of the atmosphere, whicb, as we sball aee bereafter, increaaea the leqgtb of the day, by makin, the IUD appear more elented above lbe boriloD thau it really II.

rrom

LENGTHS 0:1 DA.T8 AND NlGIIT8.

816

THE IJEASON8-UNEQI1AL LENGTH& OP DAYS AND NIGHTS.

The above cut ~ta &be iDclination of the ~'. uill to ilil orbit in every one of &be twelve IIigBB of the ecliptic, and COIIIIflCluehUy for each month in the year. The BUD enteD &be sign Ariu, or &be vernal eqw. nox,on the 20th of March, when the eanh'. uil inclines neither toward the SUD, nor .from it, but IitlewUe to it; 110 &bat the BUD &ben IIhineI equally upon the eanh fiom pole to pole, and the days and . t a lie 8Y8J)'Where equal. TbiI iii the'bepming of &be lIItnInomical year; it ill allIO the begiJmin of day at tile north pole, which .. jul& co.miDg into light, and tbe of day at the IIOU&b pole, which .. jull png into .

emu-.

:l

,

By tile eanh'. orbital prop-, the BUD appear. to eater tbe IIIIClODd lip, Tauru.r, on the 20th of A pri1, when the north pole, N. baa lIBIl8ibIy advanced into the light, while the 1IOU&b pole, 8, baa been declining tlom it; whereby the day. -.:ome longer &ban the nigbtl in the northern hemisphere, and aborter in the IIOUthem. On the IIld of May. &be BUD appean to enter the Bign Gemini, whea the north pole, N, baa advanced CODIIiderably further into the light, while the sou&b pole, 8, baa ~y declined tlom it; &be IDJDDler da)'l lie DOW wuing longer In the northern hemisphere, and the nighll

1Ihorter.

The 1111& of June, when tile BUD enterI the Bign C_, .. the ftnt day of 1DJDDler, in &be lIIIIronomical year, and the longeIt day in the northern hemiBpbere. The north pole now baa ita greatellt inclination to the BUD, tbe light of wbiDh, as .. ehown by the boundary of light and darkn-, in the &cue, extend8 to.the utmoIt verge of the bdie Circle I the whole of whicll .. included in the enlightened hemisphere of the 8Iltb. and enjoy., at thiI - . COIIIItaDt day duriDa the _plete NVOo

818

·G:r.oGILl.PHY OF TilE BUVOI•

hdioD •of the euth

011 _ uit. The wheIe of the DOrthem Frigid Zcme ill now in tile circle of perpetual illaminalion. On the I3d of July, the BUll entenl the IIign Uo I and 88 the line of the eanh', uia alway. continues parall~1 &0 itaelt; the boundaJy of light

and damae. begina &0 approach nearer &0 the pol., and the length of the day in the northern hemiaphere, which had 'arri~ at _ maximum, begins gradually to decreaae. On the 23d of August, the sun ente\1l the aign V'trgo, increasing the ~cea mentioned in Uo. On the 29d of September, the sun enteJs Ubra, the first of the autumnal aignII, when the eanh'. axie, having the _me inclination·as it had ill the oppoaite sign, .his, ill turned neither from the BUD, nor toward it, but obliquely to it, 110 that the BUll again now shines equally upon the whole of the earth'. BUrlBce from pole to pole. The days and nIghts are _ _ of equal length ~t tha world. On the 23d of October, the BUll entel1l the sign &orpio I the days visihly deereaae in Iengtb in the, DOrthem beiniapbere, and increase in the 1IOUthem. . On thend of November, the BUD entel1l the sign ~arif.Ul, the 1881 of ·the autumnal signs, at which time the boundary of light and dar~_ is at a considerable distance from the north pole, while the south pole baa proportionally advueed into the light; the length of the day continues to increase in the southern hemisphere, and to deeieaae in the northern. On the 21st of December, which is the period of the winter solstice, the BUD enteta the aign Capricorn. At this time, the north pole of the earth'.· uis is turned from the BUn into perpetua\ darkne.; while the IIOUtb poIe, in _ tum, is brought into the -light of the BUD, whereby the whole Antardic region comes into the circle of perpetua\ ilIuminatioa. It is now that the 1Kiuthern bemiapheJe enjoy. all thoae advantages with which the northern hemiapbere 11'88 filvared 011 the 21st of June; while the northern bemiapbae, in _ tum, Ullderaoea the dreariDe. of winter, with IIbort mil niPt& '

da,..

,

lema

AUlt.OU JlGREAtlS.

811

CHAPTER XII. AURORA BOREALIS

Tv. lublime aDd beautiful phenomena prMented by the /JUrIJt"III 6orealie, or norIAem ligltt., I I they are caUed, haYe been in all agel a 4IOuree of admiration and wonder alike to the peasant and the philosOpher. In the regionl of the north, thel1lre regarded by the ignorant with IUperatitiOUI dread, as harblRgera of eyil; while all sgree in placing them among tbe unexplained wondera of natura, These lights, or meteoric coruscations, are more brilliant in the arctic region.. sppearing mOltly in the winter Sf'lIlIOn and in froaty weather. They commonly appellr at twilight near the horizon, and sometimes continoe in that stllte for BeYllral hours without any perceptible motion; aft.f!r which they send forth Itreaml of Itronger light, shooting with great velocity I1p to the paith, emulatiDlf' not unfrequently, the IightDin~ invividn88l, and the rainbow IDcoloring; and .again silently nsing in a compact majestic arch of lteady white light, apparently durable and Immovable, and yet 10 8ftneacent, that while the beholder lookl upon it, it is goDe. . At other times, tbey cover the whole hemisphere witb tbeir flickering and Canutic coruscations. On these occasionl their motions are amazingly quiek, and they astonilh the spectator with rapid changes of form. They break out in placee whera Done were ...n before, skimming briskly along the heavenl; then they are IOddenly extinguished, leaYing behind a uniform dosky track, which again il brilliantly illuminated in .the sllme manner, and al· IOddenly len a dull blank. Some nigh. they aSlume the appeaflllC8 of YIlt columnl; exhibi~ on one lide tlnta of the det'lpe8t yellow, and on the other, mehlngaway till they become undistinguilhable from the lurrounding sky. They han generally a Itrong tremuioul motion from end to end, which continu.. till the whole yanish...· . Maupt>rtuU relatea that, in. Lapland, .. the Iky .u lometimes tinged with ao deep a red. that the conltellation Orion looked as though it were dipped in blood, and that the people faneie4 theT, IIW srmies engaged, fiery chariots, and a thouaand prodigif!8.' ihMlin relatea that, .. in Siberie, on the eoniDea of the ie, ...,

202

8J8

GEOGRAPHY OP THE HEAVENS.

tile spectral forms appear like ruBhing armies; and that the hi... ing crackling noiaea of thole .,rial fire-works so terrify the d0r. and the hUnten, that they fan prostrate on the ground, and will not move while the raging host i, passing." Kergvekfl describes" the night; between I~ltmtl and the Ferro lalands, .. brilli1Lnt'as the day," the heavens being on fire with ftames of red and white light, ohanging to columns and archl's, and at length oonfounded in a b"'lIi~nt o!la~ of ~ones, pyramids, radii, shes'fes, arrows. and globes of fire. Bat the e'fidence of Copt. Parry is of more value tban that the earlier tra'felera, as he examined the phenomena under the most fa~orable circumstances, during a period of twenty-sllven consecutive months, and because his oblenations are IInin:O.uenced by imagination. He speaks of the shifting figures, the spirea and pyramids, the majestio arches, and the sparkling bands and stan which appeared within the arctic circle, as surp..sing his powen of deacril.'tion. They are indeed sufficient to enUat the supentitioas feehngs of any people not fortified by religion and philosophy. ' The eolorl of the polar lights are of various tints. The ray. or bctJme are steel gray, yellowish gray, pea green, celandine green, gold yellow, violet blue, purple, sometimes rose red. crimson red, blood red, gresnishred, orange red,· and lake re4, The areMt are sometimeenearly black, passing into violet blue, gray, gold ,ellow, or white, bounded 1Iy an edge of yellow. The lflller 0 these lights 'fariee in kind as well .. Intensity. Sometimes it is pearly, sometimes imperfer.t1y vitreous, lIometimes metallic. Its degree of intensity varies from a very faint radiance to a light nearly equaling that of the moon. Many theories have been proposed' to acoOUlit for this "Wonderful phenomenOD, but there seems to be none which ia entirel,. ..tisfaotory. One of the first conjectures on record, attributes It to inflammable npon a_nding from t~ esrth into the polar atmosphere, and there ignited by electricity. Dr. Halley objects to this hypothesis, that the cause was inadequate to. produce the eft'eot. He was of opinion that the poles of the earth were in some.wayconneoted with ·the aurora; that the earth was hollow, having within it a magnetio sphere, and that the magnetic eftln'fia, in passing from the nortb to the lOuth, might become visible in the northern hemisphere. . That the aurora boreslis is, to some tIlttel)&, a m....tical phenomenon, is thought, e'f8n by othera, to ~ pretty clesrly established by the fonowing considerations : 1. It has been olisened, that when the aurora appean near the northern ,horison in the form of an aroh, the middle of it ia DOt in the direction of the we north, but in that of the magnetic ...ale at the pi. . of obaematioll; and that when the arch riaee

0'

AUBOIA BOREALIS.

819

toward the _hh, it constantly Crotlle8 the haa"_ at rip& lUIglee, not to the true 1I.agnetie meridian. . 2. When the beams of the aurol'll shoot up ~ al to PUI the .nith, which il lometimea the case, the point of their conYergenCt! is in the direcaon of the prolongation of the dippmr needle at the place of obselVlluon. 3. It h.. allO been obse"ed. that during the appeal'llnce of aa active and brilliant aurora, the magnetic nf'edle ofteu becomee resdels, varies lometimes several degl888, and does not resume its former poaiticn "ntil after several houra. From theae facta it has heen generally inferred, that the aurora ia in some w:ay connected with the magnetism of the earth i and that the simultaneous appearance of the meteor, and the disturb· ance of the needle, are either related as cause and effect, or U the eommon rauU oC lOme more general and unknown cause. Dr. Young, in his lectures, ia very certain that the phenomenon in question is intimately connseled with electro-magnetism, and ascribes the ligla of the aurora to the illuminated agency of electricity upon the magnetioal substance. It may be remarked, in suppOrt of the eJectro.magnetic theory, that in IDIIgIl8tism, the asency of electricity is now clearly eatabliahed; and it am hardly be doubted that the phenomena, both of eleetric:ity and magnetism, are produced by one and the _ cause; inumuch .. magn~ ia1 may be induced by electricity, aud the electric spark baa been drawn from the magnet. Sir John Henchel allo attributes the appearance of the auro;'· to the agency of electricity. Thia wonderful agent, aays be, which we see in intense activity in lightning, and in a feebler and more diffused form traveraing the IIpper regionl of the atmosphere in the northern lights, is preaent, probably, in immenae abundance in every form of matter which aurround. UR, but b.. comee sell8ible only wben 4iaturbed by excitements of peculiar kind..

_

GJ:OGaAPBY or TId IbJ.TENS.

CHAPTER XIII. ASTRONOMICAL INSTRUlIfENT8.

T.. rapid introduction of teleecopes into eebool. and academia, u meaBl of inatruction, demanda lOme notice of lbe cooatruction and modes of uaing theae inatrumenla. The creat adnotage of poa_ing auch meana of a wakening interest and exciting to atudy, will be readily appreciated when we remember that th. acmal aigbt of an ohJect lhrollgh a teleecope for even a aingle mOIDenl, producea an impretlllion, tbrougb the eye. on the mind. that no labored deeeription can ever accompli.h. Tbere are two principal cla_ of teleacopea. the Rifradi"II and &jketing. In the fim c1ua, the light from the object nnder examination falla on a lens of glu., and by refraction ia brouvht to a fOCDl, forming an image of the object which ia thea ina~18d through a powerful magnifying glaaa caJled the ere piece. In the reftectinll teleacope the Iill'ht falla on a mamllia .peculum or highly pohahed mirror of auch form u to rtjlut the light to a fOCIII. where the imagt' formed il examined with a magnifying The la~t te!eacope8 which have ever been conatructed, are of the rejkdlngklnd, and among theae may be mentioned the Great Reftector of Sir William Herechel, the diamp.ter of whose Ipecnlum waa four feet, and ila focal length forty ffleL ' A mnch larger one hu reoeady been conatructed by Lord Roale, an Iriah nobleman of great liberality. Ikill and eeienee. The lpeculam of hil MOBlter Re8ector, u it hu befon termed. ia no I... than lix feet in diameter! and ila focal length il 54 feel. Thia magnificent inltrument hu aocompUabed tbe resolution of a great number of nebule into alars. which bad reaiateci the power of a\lprecedinlJ inatrumeela. Th. larreat reftecting teleacope accurately mounted in tbe world, is that in the observatory of Mr. Laaaelle, near Liverpool. Ila .peculu.. it about 1M inoh" in diam.ter. For many y..rs relecting tel_opes bave heen little uaed for any other purpose than mere gasing, in eonaeqnence of tb..ir nnwieldly ·proportiona, rendering it next to impolaible to mount them with lufticant accuracy and ateadinMa, for the nicer mea.. ures and obaervationl of utranOlDY. Theae difticulti.. 188m to

gI....

ASTRONOMICAL INSTR.UMENT.,.

821

have been IU0C88sfulIy overcome )ly Mr. Lu..Ue, and with dae ., accurate figure which Lord Roue hal been·able to gin to his large specula, re&ctorl may apin come into competition with refractorl u instrumeota for critical obll8rY8tion. The largest and mOllt perfect refracting teleacopes, have been manufactured at the optical institute of Utzschneider and. Frauenhofer, of Munich, Bavaria. Two instruments have been daere constructed. with object gla911ell of about fifteen inchel. diameter. One of these is at the Imperial Ruasian observatory at .Pulkova, nllar St. Peteraburgh; the other is now mounted in the observatory at Cambridge. Ne,w England. The refractor of da\ Cincinnati ob.ervatory has an object glaas of 12 inches diameter, aod a focal length of 17 feet. These lar~ instruments are mounted with all the perfection of art. Then enormous weight is ,so perfectly counterpoised and balanced in every direction, as to be moved by the slightest touch. of the observer. They are provided with delicate machinery, which may be attached to the telescope, and will give to it a motion such as shall exactly follow the apparent diurnal motion of any object under examination. But for this most ingenious and beautiful. contrivance, with high magnifying powers, it would be next to impossible to follow the swift apparent motion of the heavenly bodies. The E~l te~ope, whether ref'racting or reflecting, iI mounted lD such way al to revolve on twe principal aXeS. The one called the polar tJIri&, is precisely 'parallel to the earth's axis; the other, called the deelifitJli01l IS perpendicular to the fitst in all ita positions. By revolving the telelCOpe around the polar axis, WII fo\1ow the diurnal motion of the ,heavenly bodies; by moving the telescope around the declination uis. it is carried north or south, .describing the arc of a declination circle. The two motions combined, en~ble the observer to direct the telescope to any point in the heavens. The HOf!.r Circle, firmly attached to the lower extremity of the polar axis, is divided into hours and minutes of time, and meaaurea with accuracy any motion of the telescope around the Jlolar axis. The Declination Circl., fixed to the declination aXl11, ia divided· into de~ees and minutes of arc, and by Vemiers, into seconds. rendenng it possible to read with accuracy any motion of the telescope arouDd the declination alda. The Micromlter is an instrument 80 contrived 'lUI to mauure, with great accuracy, the relative diatanCeB and poaitions which fall within the field of the teleacope. There are many constructiODS for. this purpose, among them Frauenhofer'a wire micrometer holds a high rank. Two delic.te lpider,' we6a are so adjusted in'the focua of the eye-piece of the. telesco'pe, that they are aeen distinctly, and appear, when i~luminated by a &mall

=-,

322

GEOGRAPHY OJ' TIlE IlEAVUS.

lamp, .. delicate rolden wir'81 draw,. aeroaa the field of view. The machinery bearing theM wires il 10 contrind .. to enable tb. oblerYer te mon them parallel to tbl!lJlMlntl, aad alllO to re.ol.e them around the axil fJf the telllCope. Eacb of thetle motionl il meuured by di.ided _lea, in the moet preeiM man.er; and loeh ia the power of the mierometera attached to the large refractora now in uae, that the I8mi-diameter of a apider'. web mlr be m_ured with great eertai~t)', or an inch ma), be di.ided Into 80,000 equal parte. ' With the micrometer, the distanee aDd angle of poIinon of the doubl. stara, the diameten of the planeta, of the SUll and moon, are accurately measured; and a .ariet)' of delieate obl8r..tions made, which could ,.ot he aceomplished iu an)' other w~.

.

The mounun, of large instrumenta is very expenlive. wbell attended witb all tbe accurate detail necesaary to reDder them ul8ful aa meana of accurate obaer..tion. The amateur astroJlomllr, wbo wllhea bis telesllOp, mounted merel)' for fiDdiDI aad gazin\r' ma)' accomplieh it at a trifting eXpt'Dle. (Fer a deacriptlon of a cheap and conVlnient mounting, eaned the Parallacttc Ladder; aee Mitchel'e Sidereal Meallnger, Vol. III.) The n-aMt IN1ru1llCftl, il a teleacope firmly attached to aD axil perpendicular to that of the teleaeope, and p..eing throup ita center. When thie axia ill 10 placed on permanent lopporte al to be exat't1y level, nd preeiael, eaat and weat, the telel80pe will, in revolving around ita axil, deacribe a great circle paelin, north and louth, or will remain in all poeilioDl in the plane 0 the meridian. The horizontal axis ie composed of two hollow conel of braee or btber material, firmly a"aebed to the tube of the telelcope, on either aide. In the fOCal of the eye-piece, leYeral spiders'.webe are placed at equal diataneetl from each other, and preeiaely .erdeal in poeilion. Theae .are crolsed at right anglea by one horizontal spider'e line. The number of vertical wi,.", al they are ealled, is generally ae.ell. TJ,Ie tranlit inlllmmen' il ulld to determine the right a_nlion of the heannly bodiel, and the prineiple of ita al'plication il e:ltremely lIimple, while ita actnal uae ill attend"d With great ditlieulty, and requirel extraordinary care and Ikill. It will be remembered, that the right aleenlion il meal~red on the equator, from the vernal equinox rennd through 24 houre or 360 dl'greE'I. The inltant when the vernal ..qoinox il on tbe meridianj il the moment marked () boura by a lidereal ~Iock, or at that moment the sidereal day begina. If an object il found to Cf08l the meridian, pallsing the field of the transit Instmment and ita central wire, at one hour aenn minutel eight aDd three-tentbs aeeonda. sidereal time, then will thil be'itl right a_n8ioD in time. To obtain the inltanr of croaainr the middle wire, or tbe m88D

ASTRONOMICA.L INSTRUMENT&.

823

of tbe wh'88, is the critical matter in oblMlrvin, with the transit. The obaen'er 10 places his teleaeope, in declination, that tbe Itar to be oblen'ed will enter tbe field of yiew near the horizontal wire. About the time of ita appearance, be takes the second from tbe clock, and, counting the beati, notea at what beat, and fracllon of • beat, the ltar pasael each of the leven yertieal wires. By adding together these times, and dividinJ by seven, he obtainl the wtant at wbich the star crOised an imaginary wire called tbe _ _ tf ',lie wira. This. corrected, for the nrious enon to which tbe clock and transit in8trument are liable, will give the apparent right ..cen8ioA of the object observed. The priQCi~alerroJ8 of the tran8it, are the following :-18&', error of WDel, an8iAg trom tbe fact that the horizontal axi8 i8 not preciaelyleYel, aDd, iA caae the eaat end ia hiJ,hfl8t, the teleBCope will look too much west, ud the reverse, If the west. end be high. 241., Error of GZi",utA, occasioned by the horizontal al.ia not behlg located precilM'ly east aAd west. If the east end of the axis be a little north of 88st, then the teleacope, looking north of the seAhh, will point west of the meridian; looking aouth of the seAith, it will point east of the meridian. 3d., error of collimation, ariaing from a failure to make the axis of the teleacope preciaely perpendicular to tbe horizontal axis on which it reYoryes. This error may cause the instrument to look either too mooh east or west, a8 the axi8 incline. in the o~e or the other direction. The TrarMit Circle i8 an in8trument like a transit teleacope. beariAg on its horizontal !,xi8 a gradua~d ,circle, by means of wbich the pOlition of the instrum..nt, in declination, may be read with aoourat'y. Such an instrument enables the ob.erver to determine both the right aacension and declination of the object under examination, at the same observation. The8e are ealled filed, or meridian instruments, because, unlike the equatorial, which may be directed to any point in the heavens, they move only in the, plane of the meridian. 1'here are many other ae'ronomical instruments, but our limite will not permit, in this place. a more extended noti('8. The only object haa been, to give to the etudent some idea of the con8truction of the inatrumente uaually found in an astronomiclll obseryatory. In mounling these teleBCopes for BCientifie Ulft, the greatest pains mUBt be taken to secure a firm foundation; such is the delicacy of theae instruments, that nothing abort of the moat IOlid and ieolated foundation, will render their resulte reliable. At the Cincinnati ObserYatory,la"e piers of grouted masonry are founded on the rock, and carReu up to a hight I,litllble to receive the etone colnmna on which the teleacopes are lixed. These pien are entirely ilOlated from the building aDd are BeCured from Inl external action.

814

GEOGRAPHY 01' TO RUVOI.

CHAPTER XIV. QUESTIONS ON THE lIIAPSi TABLES, ETC.

IT has beeD thought uanecelaary, al it il quite impracticable, to Sl'8l8nt a full eet of question8 on each or the constellationl, an othet topics treated in this volume. This would hue increased the sin of the "folume to nearly twice itl preaent dimenlion., without increasiug ita nlue. EveTT judicious teacher will puraue hil own plan of communicating Instruction, and will never confine himself or hie pupils to a set of stereotyped queationa. . We present, therefore, as a mere specimen of the kind of enmination which we dMm important. a series of Questions on the Constellation Cygnus, Map No. 20. Is the Swan a northern or louthern conltellation' In what declination is ita southern limit' How far uorth does it extend' Between what hours of R. A. is it included' How is it bounded on the south, esst, north, west' How is it situated, with reference to. Ly,.,1 How may the conlltellation be recognized in the heavens' What stars constitute the longer piee-e of the Cross 1 What stars the shoNr piece'. What is the name and magnitude of • CYrni 1 How many stars of the third magnitude are contained in the Swan, and their letter namesl Where Bra p., E. and. situated 1 Where is f6 l'ituated 1 Whl're are I, 8, and 1& found 1 What are some of the principal double stars , What aJ'4! the magnitudel and colors of the components of f6 eygni' What remarkable fact in the hiltory of the components of I CYllni 1 What their distance, and probable period of re"folution 1 Gin lome aCOollDt of the diacovery of the parallax of 61 Cygni. What is the distance of this set from our system' • What their period of revolution' What the lum of the masses fJf these stars, compared with the 8un'l UlasS 1 What is th~ distsnce and magnitude of the componenta of 61 Cygni' Why was it selected, by Beaeel, for his reeearchea for parallax' How does its .witt proper motioD accord with Midler's theory of a central sun 1 What remarkable nebule are found in the constellation' What aurious phenomena han been remarkecl in the planetary Debule

QUESTIONS ON THE MAPS, ETC.

. 325

Dear I Cygni 1 What may be said with regard to the magnitude and distance or these objects' A.re they situated in the region

or the fixed stars' How shouhl the chaJ1· or map be held, to make its stars correspon~ to thos~ in the· beavens ,

TABLES. PLA.CES OF THE PLANETS 111'1' JANUARY, lIMO. FROM these places, and the elements of ~he planets given in this work,· the approximats lositions or the planets may be readily computed, so 88 to fin them at any time. . .,

TABLE L Nallllil.

Apparent R. A.

Apparent Dee.

Mercury, 'Venus, MIIN, Vesta, Juno, Pall88, Cerea, Jupitsr, Saturn, Uranul, '

18h. 29m. 23s. 21 33 53 17 03 24 o 12 00 . Ii 16 30 16 33 18 16 39 30 9 37 07 13 26 33 1 08 40

S. 24° 46' 01" S. 16 22 28 S.23 05 40' S.62(00 S. 0 19 00 N. 3 10 00 S. 19 18 00 N.15 10 03 S. 5 57 12 N. 6 37 56

2D

326

GKOGRAPHY OF THE HEAVENS.

TABLE II. 1'0 change -xlnds

\

TABLE III.

fE,!l To change hoUlB, conde, of IIidereal minutes, and tor, or right flfLff'lfffllllli,

right ascensiOffL nutes, and time. DtIg. H. M. DeL MI. M.S. I\I"L

Sec. . Th, Sec.

1

2 3 4 5 6 7 8 9 10

36 37 38 39 40

44 11 12 o 48 13 o 52 14 o 56 15 1 0

41 42 43 44 45

17 18 19 20

1 1 1 1

8 12 16 20

46 47 48 49 50

21 22 23 24 25

1 1 1 1 1

24 28 32 36 40

51 52 53 54 55

26 27 28 29 30

1 44 56 3 1 48 57 3 1 62 58 3 r 56 59 3 2 0 60 4

---4 16

-- -

IH

22 23 24 25 44 32021 48 330,22 52 34022 56 350 23 0 36024

20 0 401 201 01

1

26 27 28 29 30

6 30 645 7 0 7 15 7 30,

66 57 58 59 60

14 0 14 15 14 30 1445 15 0

L~L TITUDE,'

hTrHTED STTrTrTrT~ Tr27

.PLACES

TABLE IV. Longitude with their

The

in Hash-

are reelwned Jirz:r;!z, Green,wick

ne Capital8 (&ala of GovernmmJ) of the Statu and Territ0rit8

art

duignated by Balic LetterB.

,Tapital),.... ·N. Y. . , lZ """a,.. .... .. .. D. c. An....pol..., .............. ( ..... Md. Auburn, ..................... ·N. Y. Auguata, ...................... Ga. A......ta (Stat. House), ........ Me. Baltimore (Battle Monument). ·Md. :.,~,~~ Court Hou.~ .. ·Me. g.zz7",'le (Old CouL . Mas.. .E"Z'~1f. ·N. Y.

42

as

:JY 0 4~

3;j

66 \!8

t4184-1

:19 11 13 44 "7 41 .j j 42,·7 ::E?~77!fl7f:77d . . . . . . . . . . . . . "S. c. ;'2 i?SCE!0:?7Th i£it&te HOUIeL" .)1818. 42 BrialOl (Hotel),.; ••• :·.......... R.I. 413\1 Brooklyn (Navy yard), .. , ..... N. Y. 40 41 Brunswick (College), ......... ·M~. 43 sa Bulfalo, .............. · ........ N. Y. 4:l 53

g::~!~~P..(.~~~;.~~d Hall),·::::C~.· ~.~ 15

i~~~l'!i~~~t~t~~~:~,,:· ... :: ::'i.~ ~ L1z7z:,,,.,wn (Navy Tr".j). . Mas.. CincInnati, .................... Ohio. Col...mbia, ........ • ............ s. c. Col"mbw, .................... Ohio. CotWml (State House), ......... N. H. Dedbam (Court House),,, ...... Mas •. Dmoit, ...................... .. Mich.

2"

as

§

33 :19 43 42 42

111 41 1229 16

24

f:~-;':~:::~~.:?~'.,""7",:·:iE~·· : l: kA",,?,;""

·0..........

.N H 43 ,<" 18 .i~ 44 64 36 0 42 58 38 14 38 34

307"1.", {Court Houae:, .Md .. Eastport, ...................... Me. EcienlOn, ..................... ·N. C. Exeter, ............. , ......... N. H. FnInif"'~ .................... Ky. Fredericksburg, ............... Va.

~::~:;:=~::::

Tr",,,,,z,wn, .. . .. ..

"l},,,,,,,,,,,,, .........

:~l" ~L:

778 Il84 414 661 66

.8. C. :J3 if, .Mas •. 42

68 936 693 110 336

318

GBOGJLAPHY OF THE HEAVENS. Latitude LonBitade, W.., DiaLfrom Nonb. indegreet!. in time. Wub'n.

liII.

07Ii -;-;-;;-~ ~ Hn~

...................... N. Y. U 14 :K 38 Iftil' ................... ·Iucl. 39 5& J .................... ............ M'pi. 31 23 ·M'nri. 38 36 iCennebnnk.................. ·Me. 43 l1li Kinpton...................... U. C. " 8 KnoxTille..................... Tenn. 35 " Lanouter.................... ·Pa. 40. 38 LeJ:iD(to~..................... Xy. 38 8 LiuJ. - . .................... Ark 3& 40 Loekpon, ................... ·N. Y. 43 11 LoBiavWe, ................... Ky. 38 a Lo...ell (St. Ann.. Ch.roh)..... M.... 41 38 48 Lynehbugh................. •• Va. :n 38 Lynn ....................... M.... U 28 Marbleh.ad, ................. ·M.... U ao Middl.to:wn. .................. Conn. 41 3& HU,!::~""'" ........ • .. Ala.

J"-. .....................

M~

.................. Ga,

Mobil., ....................... AI.. MotaIpdior, .................... VL MonomoY'Point Light, ....... ·M.... Mont.... aI, ..................... L. C. Nantuckel(Town Hall), ...... M.... N .....,;u" ......................Tenn. N.tahea. (O..t1e),· .. •...... • .. lII'\)i. Ne.... rk, ...................... N. J. Ne... Bedford (Marinen' Oh.), ·M... Ne...bern, .................... N, O. Ne...burgh, ................... N. Y. Ne...buryport (td Prea. Ch.),· .. M.... Ne...caatle, ................ • .. Del. N.... H _ (CoUep), ......... COnn. Ne ... London, ................ ·COnn. Ne ... Orleana (Oity), .......... La. N""",,", ...................... R.I. N .... Yorlr (City Hall), ........ N. Y. Norfolk (Fanner'a Benk)... • .. '. Va. Northampton (ManaionHollae),M..., Norwicb ...................... COlln. Penaacola, .................... FI.. Peterllbllrgh, .................. Va. Pbiladelplii. (lndepend. HaIl) •• Pa. Pittaburgb .................... Pa. Pittalield (i aL Cong. Churcb), • ·M.... PI.llabllrgh................... N. Y. Plymolltb (Court HOule), ...... M .... Portland (Town HOUle), ....... Me. Ponamollib (Court HOUle), ... ·N. H. POlllhktepaie, ................ N. Y. Princeton, .................... N.J. """'""- (Old CoI.),.......... R. I. Qllel?ec (Cutl.), .......... , ... L. 0. ~............... .... ... N. O. RichoftoftIl (Capitol),.... • ..... Va. Rocheller fR'r Houle), ........ N. Y. Sable (Cape).................. Fla. Sackell'a Harbor, ............ ·N. Y. Seeo, ............. .... • ...... M.. St. Allpatine, ................ Fie. SL Low., ..................... )I'd.

'/3 46 86 &7 86 Ii 10 8 81 8 70. 76 40 83 54 '78' !If) 83 Ii4 111 111111 78 48 86 30 71 18 48 711l1li 70 1I7, 70 ho 71 311 33 7 83 10 ao 40 tiS II " 17 7138 41 39 08 70 1 31 45 31 '/3 36 4110311 70 741 38 II 30 86 411 3 313& III 1M 41 40 48 74 10 41 38 7 70 46 0 3D W 77 II 41 3l 74 1 U 48 10 70 III 0 311 40 76 41 1708 7167 .. 41 !12 71 II 10 67 48 10 841 41111 71 III 14 40 G 40 74 I 8 36 &0 76 18.7 41'185& 7l) 40 41 33 71 7

aa

10 118

87 II

37 13 114 31166 III 40 311 G 118 118 44 G 41 1I7 III 43 31118 43 4 114 41 41 40 II 41 4lI18 411 47 17 3& 47 39 17 43 8 17 14 60 G 68 43 31 118 48 30

77 10

311.

711 10"

30 8

73 17 ao 7'd 118 70 4110 702030 70 411 '/3511 74 all 71 II 68 70 /18 31 78 48 77 18 til 77 III 81 JII 76 til 70 lIS ,81 3CI

..

ao

4 II 4'7 48 II " !If) II 0 311 8311

4U 8

II 8 40 II :Ill 36 Ii 1I!12 IIIJ7 III 8 848 Ii 15 4 II 4Il 0 4 45 15 Ii 17 18 4 43 48 443 lIS 4 lID 38 II as lIO II iii " 4 lID. 440 8.1 4 1I4 10 44030.8 II 47 18.1 II II • 00 40 4 43 44 II 8 10 4 /18 4 443 lIS II 8

lM6 7tII 173 10311 1180

118 ~1I8

118 101

lI34 1088 403 lI!IO 4-'11 118 "1 ._

au

841'

1033 6M

IlOO

l1li1

IlOO

714 1140

1110

••

3IJ7 M

• 48 36 8 0117.3 .. 46 •.11

480 103 301 354 11103 403

• 58 U

..

Ii 1\ 15.1 4 lID 40 4 48 118 6 48 48 1i.1O II 0 43. Ii 10 31 4 &3 10 4 &3 44 4'411 450 41 II 4 43 0 4 lIS 40 , 5810 4 46 43.7 4 43 40.1 6 15 " 6 II 411.11 II 11 t4 II til 0 II 3 48 4 41 44 II 18 10 II 08 14

1117 378 II1II

•

461 6U

1060 144

I. l1li H 638 431

64.

4l1t 301 17Y 3M 7flt 1811 IS 381 407 .. 1M1 _

LATI,UUU, :UTe., OF

IN UNIT:u:u ELLLTES. 32:U Latitude Longitude, West, Di.L from

~ indegreeltin time .. "

Salem (E. I Savannah,

·M,,',," " "" " " "" •••••••• ·G"

~~!r.i:::'~.':~~~);::: ::~li'

Taunton (Court Hou.e), ·······Mu•. Toronto (york), .••••••••••• · •. U. C.

f2::.~::::::: :::: :::::::: :~i!' ~~~"ae(~"O ,:;':fY'r',~::::::::~a

if$~~~""":::::::::Er:

W""SHINGTON (Capitol), .•••.••. D. C. W ubington, .•••••••••.••••••• M'pi. Wheeling, ••• •• •• •• •••. •• . ..• Va. Wilmington, ••••••...• · •••..• ·Del. Wilmington, .••.••..••••••••• ·N. C. Worcester {All' 21"11), ••••••• ·M",," York. •••• Vork, ••••• " "..

·········M"" ·······P,'

2»2

0

19 70 81 73 72

I

jt; 11'1. I.

64 3 56 36

ifT L3 36 f,; ;2 U ;,5 EO i; 24

0"

9~: '~~~ 79 I!O 17 20

74 39 7340 87 42 3 78 31 ,,49 76 13 89 2

~:

68 36 46440 ,6 60 48 is i", 6.9

:~

~,,2

'" """

8

I::~ ~

77148i8U 91 20 6 II 20 SO 49 22 48 75 28 6 I f$2 78 10 5 J 2 40 71 49 " ;6 70 40 i; 40 76 40 ;" 40

W~h'n.

mIle •. 446 662 391 357

m 500 166 383 858 124 383 781

I: 146 264 108

416 . 394 600 87

"

HUNTINGTON AND SAVAGE, . . . . . . . ., ....'I'BIIII'I'. BIIW 1rOaK, PUllLI8B TIUI .oLLOWIM

VALUABLE SCHOOL BOOKS. To which they ftry respectfully IOlicit the attention of Connty and Town fluperintendenta, TJ'WIteetJ, SchOol Committees, Teachen, and othen inter· . . . . in the _ of education.

. AN ELEMENTARY ASTRONOMY, I'or Academies and 8chooll. IDultrated by numerous orllfinal colored dlapamL Adapted to _ witIa or witIIout the author'e LUge Mapa. By H. MATTISON. Pifth Bdition, with Questions and a Glouary. 'nUs Is ODe of the moet comprehensive and splendidlJ: iIIultrated worb 011 .btronoDly ~~ hu ever been publilhed in the United Statel. Ita plan Is 8IninelltlJ: orlJinai and Dhiloaophical. It is conlined to the ~ of the _. ence, or the"",,," that lIave been reached during tile lapse of api, without delineating Ita MytholOSical history. or tracing llie proC8S188 by which these facta haft been alCertained, either by the uee of ili$umenta, or by mathlmatical CII1culatiOJlll. It embodies all the late discoverie., and is equally adapted to p!1vate learnen, the library, and the achoolroom, u it is complete in itaelf; independelit of the larp charta. AI a book of reference it is Invaluable. To this may be added ita perfect adaptation to use ...,Is the larp Maps, (of which tbe IUUltnltions in the book are exact oopies in lDiDiature,l 10 tbat tbe learner baving the Maps. bu on a larp IC8le the l&IIle di~ by which to illustrate the 188lOn at the reeitatio•• tbat bave been preYloUlly studied by tbe pupil in tbe text·book. To .ay nothing of the recommend.. tions that follow. the Ale of lea .....""" copie. of this work, in a little over a ",ar, is a au1llcient proof of ita popularity and intrinlic yalue.

ASTRONOMICAL MAPS, Adapted to uae with the .. EL.arllll,....Y A.,..olloary," and de~ed to iII_ crate the JlechanislD of tbe Heavens. For the use of Public Lecturen, PriYate Learnen, Academies, and ScboolB. By H. MATTISON. Thia aeriel conaiata of Sixteen Mapa, or Celestial Charta. eoiCh IS by 44 lJl('.bes, repreaenting the various ap~arances of the Heavenly Bodie&-tba Sun, Moon, Planeta, Cometa, and Fixed 8tars-&nd iIlus~ting the laws whieb gover. them in their molions, the philosOphy of Tides, EcJipaee, and Tranlita, and indeed all tbe most interesting and wonderful pbenomena 01 the M.echanism of the Heavens. Tbe sixteen Mapa cover an area of neerly 100 square feet. They are priDted upon a black ground, anaweriDg to the aatural appearance of the heavens iii the night, and are beautifully colored and 1D0unted upon elata and rollers. They are oeyond comparison the molt Iplendid and complete aeries of scieDtiIic cbarta eyer published in this country. They are not only invaluable for Seminaries, AClidemies, and tbe higher inltitution. of learning, but at the l&IIle time are 8,dmirably adapted to p0pular uae in Common Schooll. 0... """"""" • .,. of this wor~ have already been aold and fIOne into uae fa diJrerent parta of the oonntry; and the unanimity and oordiality witb whicb they are commended by all wbo bave used Ol'u&mined them, 1& truIt gratifying to tbe pub1ilhen. (See following pap.)

Ln, per eel, ia c_, with cloth bacb, ......................... 820 00 II II ,II OD Itroll&' paper, withoat cloth baob, 15 00 Book. per 50

copy........................................................

o:r Bach Set oC Mapa Is nicely packed in a Wooden Caee, and _

be

.at to order with perfeCt aafety to any pan of the United States or CIIDIIda

HuaIiftpm

4- &'D466'. P~.

n. ."..,.,.

of B"~ of Bc1tooU. 7'rufeU. __ T ......... ~ iIIIIiId,. tA.J.u..;.,

RECOMMENDATIONS

Ha'riDg eDJDined, and IItIveral of .. 1IIItId, the ~nl' A.. IUIil AanoNOIIJC~ M...... by R MaUiaon, _ are prepared to _y, that in our opinion, they are better adapted to the ~ of elementary iDmuctiOll in Aaroaomy, thaD aDy other work or appuatus now before the public. We woold therefore cordially Ie-.unend their introduction into all achoo. where thiB BUbIime 8CieDoe

,.8OJIOIIY

_taught.

Sec.,.

EDWARD COOPER o( Teachers' ABlciatioll, _ N. Y. ALBERT D. WRlGR'!J Principal NormallDst., BrooklyD, N. Y • •IAS. L. McELLIGOTT, Prin. Col. 8cboolL N. Y. city. JAS. R. BOYD, Prin. Je1l"el'8Oll co. Inat., watertown, N. Y. R. K. 8ANFORDL,Teacber Natural Science, lIiddleburJ AcademJ. WyoDUng, N. Y. N. BRITTAN, Principal o(Union School, Lyoll8, N. Y. R. F. HICKS!..County Supt.!. LiYinpton co., N. Y. ALONZO BE..,.BE, County BUpt., Ontario CO., N. Y. HENRY GILLAM, (ormer teacher of MadI. Cayoga Academy, N. Y B. R. McALPINE, Supt. o( Public Schools, Roi:be8ter, N. Y. ELLERY S. TREAT, Prin. Pub. Schoo! No. I, Rocbe8ter, N. Y. WM. BARNES, .. .. .. 5, .. A. F. HALL ...... 7 .. REUBEN JOHNSON, .. .. DANIEL HALLOCK, .. .. II, .. A.. S. GREGORY .. .. .. 14 .. H. G. WINSLOW, Prin. Union School, Mount Morris, N. Y • •• P. BARKER, Prin. Public School No. 10, Brockpo"," N. Y. G. L. FARNA~J Prin. Publio Schdol No. a, Watertown, N. Y. G. R. JACKS01'l, Teacher, Oswego. N. Y. I. PATTERSON, Prin. Public School No." N. Y. city. JULIA B. CLARKE, Teacher of Public Schoo! No. I, Osweso, N. Y.

e:'

p;..,.

..

faa,. lIrrmo:r., Director of tIN Ciftt:itmcdi Ob.rNtory. ID a DeM'to the publi8helll, Prof. M. -18= II Your lleriee of Ma~ are hung up in the public _ption-room 01 the observatory. I am much pleased with your plaD of epeaking to .ile eye; and am confident that th_ ma~ will IIOOJl &ncI their way iDIO every well.oconducted achool."

Prom Pko•• C.wwnr., of BrOlDn lJ"i__ty, .nd·N. BmROP, EaQ., Bapmratetadtmt of PulIlie Be." in Prmlknc., R. L !'10m a brief examination· of Mr. M~ttilcm'l .. E1emeatlllJ AItron-

omy," and the accompBDying Maps, we have formed a favorable opinion of their utility to pupil, iB that branch of ltudy, and have recommellded their iBtroouctioD into the High School of the city of

Provideace. M_All, 1847.

'"'" :bY. lbOlUAD S. Rnr, OIllllfllWUmer of Pili/lie BeAooz. for

tlle Btate of NeVI H_,.lir•• I have examined with great pleaaure, Mr. Mattilloll" ElemenilllJ Astronomy, and Astronomical Mapa, and I think them admirably adapted to IImI8l the attention of the young, and to impart thorough and practical knowledge in the nblime .udy of Astronomy. I admire the arrangement and cl_fication of the Aatroaomy. It explaillll and iU\IIItl"ateI one thing at a time, in a manner 10 clew and interelltinf, that it CaDDot fail of entertaining and improving the student. In view of the excellellciea of the Elementary Aafronomy, and Mapa, I molt cheerfully commend them to an intelligent pnblic, hoping that they will meet with all that n _ which their meritalO richly d8lOrYe. M •• 18, 1847. I '"'"

~. B.uwBL

H. Cox, D. D., of Brooklyn, N. Yo

Th_ Mapa, mathematical and optical, illulltrate the lIoblellt parll of that incomparable lCience j they are accompBDied by an explanatory volame, adapted to them, lucidly arranged, all Conning, I think, an apparatDl for the learner and the ICholar, of rare excellellce and enduring uaefuln-. Reaalta and proceBII8I are there combined, reduced to IIYltem, and digested collll8Cutively in happy order j competent to inIItruct the merchant, the mechanic, the farmer, the inquiaitive youth, the rntlemen of leimre, and aD others who upire after lub\ime knowledge, and are willing IOm!ltimea to look at the heavell& Ladiea who value true knowledge, and who hue \earned how to . think-and there are lOme of this dOlCriptiou-wi!1 prize anch iJIIItrnmental helpa to the acquiaition of lOund and rich information in AItronomy. AA a work of reference, a ,lIeNU".. of knowledge, a profitable am_nt, or an ornamental pDl8Dit, it woald greatly honor .. well .. happily form their mentaJ.character, and nbordiJlate the very gelllll of heaven to their proper decoration .. intellectual and immortal hoiuga I need not add it ill very valuable for lIChoo'" IIWd d8lOrYea the patronage of our countrymen, .. a native productiOD. I IiDcerely _ret" well .. aaticipate ita _ _ May 6,1847.

THE

GEOGRAPHY OF THE HEAVENS, AND CUBS-BOOl[ OF A.8TROJrOJlY. 1 'IOL 18mo. AccampaIecl by a CeleItial AUu, Imperial4t.o., Da.ai, c61ored.

b

admirable work to follow tile .. Bn"If~"'Y An'aolfOIlY" &JIll . . . . ~aONO.I""L M....... The two works together pre_ a more thorouJdl embodimeDl of tile lCleoce than any otllen of tile _ eompua, ill tfie oouatry. colf~a.~. OP Tall "~L4" 1. P!&n exhibitiDI the relative Magnitudes, DistaD,,", aDd POBition of the di1l"erent Bodie. whiel;! compose the Solar S)"IItem. I. The Visible Heavens in January, February, aDd March. I. The Visible Heavens in October, November, and December• ... The Visible Heavena in Jull'! August, and September. II. The Visible Heavena in April., May, and June. II. The Visible Heavens in the South Polar Regiona, for each IDODth III the year. 'T. Tbe Visible Heavens in the North PQlar B.ea10u, for each month III the year. 8. Planisphere of the Whole Heavens, on Mercator', Projection. '

By B. A. BURRITT, A. II. With an Introduction by Tao.... DICK, LL. D., Author of tile "Cluietuul Philosopher," "ritten expreasly for this work. A variety of intereating facts and observations embraclllg the latest improvements in the acience, were derived directly from the French and EIIJlish Observatories, e:qwe"z, for this Class-Book, and are not contained m an! otber. It is now coming generally into use m our princi~ Seminaries, and Is recolljlDended to sehools in general by memben of the Board of EJ:amination of Yalp College, &I a work more needed, and which, it is believed, will be more useful than any other introduced into our .. ln8Iitutiona of Learning, lor a number of years." This book, as its title imports, i. designed to· be to the &tarry heavens what geography is to the earth. Such a Class-Book baa lon~ been neoded. Hitherto, the science of the stare has been but very IIlpelifiClally ItUdied In our schools, for want of proper helps. They have oon\inaed to gaze upon the visible heavens without comprehending what they I&W. They have cut a vacant eye up'
Huntington

4'

Sa"age', Pu6licat'OM.

17

A NATIONAL GEOGRAPHV FOR SCHOOLS, mUltraled by 110 EngraYinp and 80 Stylograpbic Mapa; with a colored ,

GLO •• MAP, OR A lIaw PUR.

One vol. quarto. New and Improved edition.

By S. G. GOODRICH, Author of Peter Parley's Talee. Tbis worlt Ie dee\ped u a l
If"

If".

=

PETER PARLEY'S NEW GEOGRAPHY FOR BEGINNER8. IDIIIInIed with 18 beaIdiI1IJly colored II., .... 110 BllpariDp, .... ~ bOaDd Ia.wr COTen. ~ B to ..,.. 01 die ttIIcltr 0I1tJ1e, or of tile ~• .... pnedcal.-bod mwbich Peter Pv~ p--. to aile e ... jflIU 01 wbicb be writeL NCIC1rItJwtaMl.,. other worb 0 the _YO _ _ "'1Id, tbWlitde work, _ fnll ad _rUe ilia ..y. ~ 10 _ _ iU _ , Ia all ~ where improYemeDla Ia PJ:imuy ed.-cioD are . . . forward. bU been 1a.BqJud.'" II tJaroqIIout tbat BCOQIItry ad ~ CUIad,: it bu ~- tnDIIated. lato ad iii mucb UIed Ia 1'DDce; It bu been JIIIhIlIbeclIa Gnak, ad to -,OlIO yoatb of tbat JWloD. B bu aIIO _ _ traD8Ia&ed by the _ _ _ _ _ Ia Penla, IIId lDtrodaced into &heir 1CIIoo", ad .... been _ _ - ' " r . printed Ia 8idDeJ, New South Wale8. TIWI foreIp _ II ~ of &be ftJae ad.popuIarily of the work; yet it II to be ~ Iba& _ baYe DO ooPJrilbt Jaw to Ifft IIltbon IIId pubIiIIIen the baeIl of IIIIIIl - .

_...u..

ftt.eD8h'e1=

Huntington

t

&WJge'. Pv.6lictmoM.

IU8Iorr 01 Bo&lDical Science. UlCl &lie ~ IiDd CoII1IUtI onraobeCllIIId IlDOrgaDised matter In Nature.

18 ~

1. diaUDnilhed aDd experienced teacber in natural ICIence ..,. 01 dill

. . ar from de~tInA: o&ber worb on &bia subject, Bblillr. my Iewill not be invidious, wlien I aay. Sblt I &binIt it far better adaptjd to . of Ele~ Inat:ructioJi m the ICIence than IIIlJ I have _ _ I am ucb deUabted wi&b the euy UId natural metbod '-" wbleb it In~ ducee the schow to a knowledge 01 the ftrat prinCiples of tbe science. UId &be strict philOllOSlhical arranpment It emplOJ8 in impartinA: ID8truCtIan. TIle whole work Iiu &be impre.. of one practiCally acqiiainteil wi&b the art of leIIcIriDIr. UId adds aDoUier ~f to tile inaJ!f. Ureail.y emtiDJr. tIIIt IaItlUctora 01 in~ce are l8Derally better quaW1ed to pJepare el.1I18JItarI works tban those who have never bad any experience Ia the ~ Of

luchins·" . . . . . . . . . J.1I'l'JIO&,

DB8IGNBD FOB. P1WU.B.Y AND COIIMON 8CHOOLS,

BOTANY FOR BEGINNERS. All III'l'&ODUOTIOII TO . . . . LlllcoLll'I lOToUI1'.

BI' MU. LINCOLN PULP8. I voL 18mo. pp. 150. TblI book 18 lateacled cbteA,. 6:lr the _ 01 priJnery ecbools and the younpr pupils in bJ.sber schools and seminaries. 80 mucb bu, of late, , been iIrrid bJ those who take an interest in &be IUbject 01 education, In fa.or o(InWOduc!Da the Natural Sciences Into Common Schools. &bat it ia to be hoped that tbe time Is DOt far distant w ben plante UId minMaII will be

u familiar objecte of lltUdy Ia our diatrict scbool~ouse u &be 8IlIIlIinx-bool< now il. PerhaPi lOme parent or teacher may be ready to inquire, wnether It is reaommended thet IriIcb Itudiee aball taIui &be piac8 01 re8iinr. epellins. or wrltiDg i by DO _ ; but every teacher boWl that there are many liatle8I IUI4 VllCBDt - . n t s when even &be moat active 01 bls pupils leelll tired of tIIeir monotono1lll punuita, habit UId reapec\ 6:lr &beir teaCber may lead &bem to lit ItIll UId ilo no mischief; but it]a not di1IIcuJ.t to !l8J'C8ive. by &be beavy eye IIIId inanimate countenance. that the intellect ilumbera. These are Ole momente when the ezr:rlenced teacber feels &be nHd of 80me new stimulant. Instead then 0 saying. "Jobn. or Lucy. ~ou have been BiUiJIK idle &bia half bour. wby 408't JI)U mind )'QU1" boOk 1 be wbn unde1'8tand8 the 111IIIIIIII mind is awue that tbls is the very way Itill more to disgust bls pupil. aDd be will auuredly be read}' with some new method of aw8keniDg attention. SUJIPOI!I. then, inltead of a rebuke for idlane., the teacher auld lIIDdly addre. bls pupil u follow8: .. You have been ., lema engqed upon a ceram I8t 01 atudiea, that I peroeive they have beoome ~ lOme; I tIiiDk ollatroclucing a new study lato &be school; to-monow 1...." p •• - - . .. fIeI-.Jr; you mal &bere6:Jre brInjJ with you toomonow all tile Wild lilies} or violet'li. or any kind of common W:iId flower that you can find In &be flelaa." Tbe dec&, one at all aoc1llltomed to the care of children will readily understand. But it may be aaidJ "&bere are many teacbers who _ not c&pable 01 BivIDB a lecture upoil DOteny." To tblj it may be an~ that every teacluir wllo is ID any de.,.. fit to be sueb can 1II1II the .. ~ 6:lr Besume...." even ~ ~ never beard a lecture upon tile IUbjeet 01 botuiy I it willteacb blIIi &be 18ading priDciples, an4 be can a· ~ them to blIi pupila; tbls will be ~ IIJHIII Bo'"" ThouaBDda are iIIfD8 tbls little wort, and iIlve the IIh'OIIIlII* MItimonJ ID

aDr

"favor• . TIle n _ 0I1IiII Beeeber Ia tile Hartford Female 8emInary aayI t"It •• cIear,limple.aDd interuttar ezblbition 01 tile priIIcIpln Of .. _

10

HumiflgWn

4- Savage"

Publicatwr&8 •.

tertalDlDr 1CleDoe, adapted to tile codlprebeoslon of cbUdren, for wboD .., .. deaiped; and fully capable of prepariag tbem for a more enaDded trea __ It is partimIlarly reco1iuDeD4ed ~ Ole iDatructorl. of our common 1ICbool., .. an iJitereatiDi emJ)ioymem for tbe leiaure boul'll of their 8Obol&l'll; II! ... motben, u an ualst8nt to them In the great work of atoriDg their ~, IDIDda with the kDowledp of tile worb of~eir Creator."

PHELP8' NATURAL PHIL080PHY, lOa TIIJI Villi OP ICBOOUl, AOADIIIIla, A1CD P&I1'ATII I T V _

. iull8trated with numeroua EnsraviDp from original deIdpI. By MRS. LINCOLN PHELPS. New EditioD. I vol limo.

PH.ELP8' PHIL080PHY FOR BEGINNERS. I vol.18mo. A teacher of mucb experience, and PrIncipal of one of our lint A~ 1&)"11 of theae worltlr" Tbe aub.lect is treated in a ID8llner blgbly acientific I the ensraviqa deligned for nfuatrating tbe ten are bappil)' cbOl8n and executed:; aDd a degree of fre8bne.. per'Vadea the wbole work wbleb cannot but impart life aDd animation to the atudent of itl pagel. But more than all, we rijoice to _ .. bealthy moral feeling dIftIIaiDI ita fragrance over tile whole."

PHELP8' CHEMISTRY. New Edition. 1 voL limo.

PHELP8' CHEMI8TRY FOR BEGINNERS. 1 voL lSmo. ProrellOr Cuwel1, or Brown University, bariD& eumiDed 80me of "molt important cbaptel'll of th_ worka, 118.)"11 :-" Tbe priDcip\ee or the leienee BpJl8lLf to be atated witb brevity and c1eam_, aDd are bippily illn. tr-' by Iamiliar UIIl well..elected exampiea."

'OlUVBBIIlTr BDmOB OP

DR. WEB8TER'S DICTIONARY: Abridged from tile quarto American Dictionary, with WalIter'1 K.ey to the Pronunciation of Greek, Latin, and Scripture ProJl4lIo-Names, etc. With a Memoir aDd But or tile Author. 1 voL royal duOdecimo. 560 papa.

WEBSTER'8 HIGH-8CHOOL DICTIONARY. limo. 160 pageL The deaigD or thil volume 11 to f'unll.b a vocabulary of the more common words, wbiCh conatltote the body of our language, Wltb numel'OU8 tecbDical' terms In tile 8ciencea aDd Arts, and many woro. and pbruea from other languagee, wblcb are often met with in Englieb boob, With a brief deftDi.. tion of eac'!.Lto wblcb 18 added an accented vocabulary of CLASSICAL, SCRIPTUJUi, aDd MODERN GEOGRAPHIC NAMES. The Ortb~ phy and PronWlciation are made to co~Dd clOl8ly with. tboae editiODl of the work of 'tile author r_ntly reriaed under tile editonbip or Profeilor GOOD.ICB,of.YaIe College; ,

Huntington

4- Savage'. Public4ti0n8.

21

WIBSTBl'8 PlIlI!IlY SCHOOl PIO~ODNClNG DICTIONAIY. With Accented Vocabularies of CI_cal, Scripturel and Modem Gqn. pbical Proper Names. Square 1411110. New ecbtion, reviBed and eoIarpd, correapoJIdiJIg in oitbography to the large worlt of Dr. Webater. Tbia work embraces about ten thoUllllDd more w0rd8 tIum Walker's 8chooI , Dic&ioDary, and 18 8IpCIC.iaJly recommended to the attention of teachen. ~POCJ[ET BDITION, In several *lJ'leI of blDIIiDI-clotb, ~ siI& , and silt emhoUed. Tbia Iaat 18 a yocabuIary of the __ importlnt wordll of our lUlgu.... ho&h 00IIUD0Il and llCientillc, with a CODClIe. pRmitive deftniUon of each word, followed by the derivatiODl of the same word,-thus preleDtinJ the two fea&uru In one, of a deftnill8 Dictionary, and one of the 8JDonym•. The foUo~ ,Tutimonial II IUhIcribed by a Iwse numbilr of the __ di8Iinpjahed men of our country : .. Tlie sub8criben highly appreolue Dr. Webster's purpoae and attempt to , improve the Ell8lish Ilmguaae, by reDderiDa Its orthography more simple, r~. and uniform, and by removiq diJllculties arising from its anomaJi.... Ie 11 wry deliral>le that one atandard dicllonary should be used by the numerous DdllioDl of people who are to inhabit the vaat extent of territory IJe. !,on&inJ to the United State.: as the uae ofauch a atandard may prevent &be formation of dialects In .tatea remote from each other, and impreu upon the 1~1I(8 .....,....." and It II deairable, aIIo, that the acquilition of the language mould be rendered easy, not only to our own citilellll, but to foreignen w~ wiah to pin _ _ to the rich atoreI of acience whicb it contains. We reJoice that the A.....-ic:aa DicIiGury bids fair to become ncb a atandard; and we alnceraly bope that the autlior'l eiementary booka for pr!mary acboola and academiel, will commend themaelve. to the general _ of our feUow·ci&ilens."

,'abiIit,.

THE PRACTI8AL FRENCH TEACHER. By NORIU.N PINNBY, A., It. The leading peeuliartty In tbia work Ie, that It uercl_ the atudent througbout In the constant practice of apeatiDr. The preparation of every ~ II a preparation for speaking the lanfUaae, and every I_n 18 an actual convenatioD In it. Theae conyenationa, too. are progreuive and ."atematic h commenciq i' wltb tbe limple.t elements of the language. and ednncilllJ an easy proce... to the more dilllcuit. The wbole bas been prepared wi a view to overcome the dilllcuitiea whicb an Allierican lIleets ID acqulriq a knowledge of that eo necenary part of a linlIbed education.

KEY TO PINNEY'S PRACTICAL FRENCH TEACHER. TBB I'Dl8T BOO][ Dr FBmfOK; or, A I'rIIcticaJ Introduction to the Readiq, Writing, and 8pea1dq of the Frencb Laquage. By No. . . . I'lIn••y, A.III. PICTORIAL HISTORY OF THE U. STAT~ 1!7 S. G. GooDBlOB' PICTORIAL HISTORY OF FRANCE. by S. b. GOODBIOH. PICTORIAL HISTORY OF ENGLAN~ by S. G. GooDBlCB. PI~RIAL HISTORY OF ROME. by I). G. GooDJUCB. PICTORIAL HISTORY OF GREECE, by S. G. GooDBlCB. The above aeriel of biltorfea, formerly published by lIIesan. 80rin a. Ball.

mPhiladelphia, 18 very eIte~yely introduced into both priyue and publio

ENGINEER'8 '" MECHANIC;8 COMPANIONI IIeDmration of Super8cee aDd 8oIlde; tablet! of Sq_ _ CiIbeI; Square aDd Cube RoOts; Cit'cua\fereIIc aDd Areas of Circlaa; the Meclwdcal Powen; of Steam aDd Steam EJisine8 ; Ullited 8tate8 Weights aDd Meuuree, 6:0. BY 1. M. SCRIBNER, A. J(. 1 YO!. 181M., 140 pep-. Morocco, lilt. with tucb. ThIa work Ia 1UghlJ' recommended ~ aeveral ~ ciYll eqiDeen _ maohiDIaIa; IIIld, u • JIaDual fOr ~ m8chaDia. ia a work 01 Ire&t value. Be8ides the purallOpice already enumerated, it _taIDa • vu& aDIOUII& of valuable mauer, in relation 10 Cen&re& of Gran&y; Gravi&ation of BocIi"!] PeDduluma; Specifio G~ii' S~ WIQllt. _ Cruah of lIlateriala; Water"'WheeJa , H ce; HydrauJil!!j S&atiCa ; Cen&rea of PercUlllon aDd Gyration; F ' ; Hea&; '1'1iblea of weialda ot JIe&alI; Pipes, 8cudIiDp; lnte~; 6:c. 6:c. ' Com~

THE ENGINEER,., CONTRACTOR's, AND SURVEYOR'S

POCKET TABLE-BOOK. BY 1. M. SCRIBNER, A. M. 1M ,..., MIno. Tuck hindbIs, with gUt edp. The aiJoTe work comJlrlaea LorIarithma of NlUIIben, Loprithm1c sin8a _ Tangents, Natural SiDes aDd N"aturai TaDgents ; &he Travene Table,_ .a fUll extensive Nt of t&blea, exhibiting at one view the number 01 Cu· bic Yards conta,ined in lIIlyemblUlkment or cuttiDg,lIIld for lilly bue or elope of IIidea uaual in praclice. Beaidea these eaential tables, the work comprlaea 10 ~ more of Mensuration, Tables, Wi!'ts of Iron, Strength of M_ rialI, Formulu, ~ etc., for.. out RailroIIda, C..... and eurv.. ; mllch 01 wbleb baa never before otrered to the public. aDd aD indlapensabTe to the engineer. Thia book will pro" a great aaviDg of &!me. aDd will enable the new beginner to fUmiah reiults .. iecurate1y (aDd wiIJI much greater rapidity) u tile moat experienced in the profeaaion, without tla aid. The tables of logarithms, eto., _ve been caref\illy corrected aDd co... parII!l with cWrerent eilitiona of the l&1li8 tables; aDd all the tables thr0ughout the book have been reed carefully by proofs four times ; hence the IDOIt implicit con6denee may be placed in theii correctneu.

ana

KAME'8 ELEMENT80F ORITICI8M. I voJ. Svo. ~

The OD1yedftton which received the latelt rerilion of the Aather,

PRE8TON'8 BOOK-KEEPING, DOVBL• .urn ImeL• •RTRY. PRE8TON'8 INTERE8T TABLE8, • per cenL-Larp aDd AlIridpd. 7 per cenL-Larp and Ahridpd.