It isn't particularly an instrument in alone but operates in tandem with the above levelling instruments to evaluate vertical peak variances.In this process, trigonometric relations are utilized to locate the elevation of a degree from angle and horizontal distance so, it is known as as trigonometric leveling. It really is also called as oblique le

One other altimeter, known as roving altimeter, is taken towards the points whose elevations are wanted. Readings of your roving altimeter taken at the specified factors are modified afterwards in accordance with variations in temperature plus the like observed in the Manage issue.Datum or surface refers back to the point or floor from which the l