The curvature of the earth is taken into consideration if the limit of survey is

Bench marks are fixed by

An example for a level surface is

In plane tabling, the instrument used to measure horizontal and vertical distances directly, is known as

"Cross-section" and "Longitudinal sectioning" is

The box of prismatic compass is made of

All level reading are taken to:

The direction of steepest slope on the contour, is

Reciprocal levelling eliminates