Staking out point heights

 in an excavation,  point B is to be set out at a height ∆H =1.00 metre below street level (point A).  

1- set up the level so that the sighting distances to A and B are about the same. 

2- set up the staff at A and read off the backsight R = 1.305.  

3-  set up the staff at B and read off the foresight V = 2.520. the difference h from the requested height at B is calculated as : h = V - R - ∆H = 2.520 - 1.305 - 1.00 = + 0.215 m 

4- Drive in a post at B and mark the requested height (0.215m above ground level). 

in another frequently -used method. the requested staff reading is calculated in advance: 

V= R -∆H=1.305 -(- 1.000) = 2.305 

the levelling staff is then moved upwards or down-wards until the required value can be read off with the level.