Leveling is a branch of surveying. The object of which:
I. To find the elevations of give points with respect to a given or assumed datum
II. To establish to point at a given elevations or at difference elevations with respect to a given or assume datum
The first operation is required to enable the works to be destined wild the second operation is required in the setting out of all kinds of engineering works. Leveling deals with measurement in vertical plumes.
Level surfaceA leveling surface is define as a curved surface which at each point is perpendicular to a directions of gravity at the point the surface of a steel water is a truly level surface. any surface pararal to the mean spheroidal of the earth is there for a level surface.
Level lineA level line is a line laying in a leveling surface. it is there for normal to the plumb line at all points.
Horizontal plane - Horizontal plane true a point is a plane tangential to the level surface at that point. It is there for perpendicular to the plumb line through the point.
It is strength line tangential to the level line at a point. It is also perpendicular to the plumb line through the point