OBJECT AND USES OF LEVELLING
The object is
(i) to find out the elevations of given points with respect to a datum
(ii) to establish the points of needed height below or above the datum line.
Uses of levelling are
(i) to find out or to set the plinth level of a building.
(ii) to decide or set the railway, road ,canal or sewage line alignment.
(iii) to determine or to set different levels of towers, dams etc.
(iv) to find out the capacity of a reservoir.