Centering and Leveling of instruments,procedure for centering and leveling (by plate vial method) of the theodolite.

 

Centering and Leveling of instruments,

   It help the surveyor to make counter map of land surface or sea surface. It help surveyor to lay a ground level on which they can built a building. It help pipe transport engineer to ensure appropriate slope of land that will allow smooth movement of liquid.

Leveling is a method or element of land surveying which deals with determining points on land surface above sea level. The points of known height are called benchmarks and they are determined from an assumed zero height point at sea level called datum.

procedure for centering and leveling (by plate vial method) of the theodolite.

     Procedure:

1. Set up the theodolite at A and level it accurately with Plate Vial Method.

2. Direct the telescope toward P and bisect it accurately. Clamp both the planes. Read the vertical angle.

3. On Station A with the vertical angle 90 degree in case of face left, and the plate vial in the Centre of the run, take the reading on the staff kept at nearby B.M.

4. Transit the telescope so that the line of sight is reversed. Mark the second instrument station B on the ground. Measured the distance AB accurately. Setup theodolite at station B and repeat steps (1) and (2) for both face observation for vertical angle . The mean values should be adopted.

5. On station B with the vertical angle 90 degree in case of face left, and the plate vial in the Centre of the run, take the reading on the staff kept at nearby B.M.

Result: The RL of top of the object (P) when its base was inaccessible was found to be………….feet.