Leveling
4.1 Introduction
•The elevation of a point: vertical distance
between point and a reference level surface
called datum.
•Datum: If a whole series of heights is given
relative to a plane, this plane is called a datum. In
topographical work the used datum is the mean
sea level (MSL)
•+ve if above MSL such as Jerusalem
•-ve if below MSL such as Jericho.