Discussion Levelling

Discussion Levelling is operation the comparison of heights of point o n the surface of the earth.In levelling,the things that we have to measure me asure is the backsight and the foresight.We have start the levelling from the Bukit Ayer until reached the mosque.It is about 4.817 km.Then we continue from moaque until Bukit Ayer back.So back.S o the total distance is double.In levelling there a re two methods of calculating level.The first one is collimation method and the second one is Rise-andR ise-andFall method.Our group have choose Rise-and-Fall method to calculate the level.We have measure the backsight and the foresight . Then ,we have to take tak e backsight minus foresight.If the answer is positive,it known as rise but if the answer is ne gative ,it known as fall.We have to calculate all the backsight and foresight. Based on the result that we have calculated for the levelling,finally we get the level which is 999.8 74.It is only 0.126 to 1000 100 0 km.It is because due to the error that may occurred during carry c arry this experiment.The error may occurred when t aking the measurement due to parallax error.To prevent this error,we have to take the repeated readings and fine the average.Then,when holding the stuff,the bubble of the stuff may not be in the middle of the circle.This make the stuff do not n ot vertically straight.To prevent this error,we have to make sure that the bubble is in the middle of the circle.Besides that,the autolevel also have the bubble to show the stability and accuracy.We have to make sure that,the bubble at the autolevel also is in the middle of the circle.This is because,alon g the road,the surface of the road is not  plane.There is up and down in road.Furthermore,using the Rise-and-Fall method,it is laborious and several calculations.This system is suitable for fly leveling where the y are no intermediate sights.In Malaysia the common practice is the rise and fall s ystem due to its simplicity and standardization.