During temporary adjustment, centering the Theodolite over the instrument station is one of the

Explanation:

Temporary Adjustment of Theodolite:

Firstly, Instrument is at set-up at concerned station, Then

1. Centering: To place the vertical axis exactly over the station mark

2. Levelling: Levelling adjustment of the theodolite is done using levelling screws or foot screws. The objective of levelling in surveying is to make the vertical axis of the instrument truly vertical.

3. Elimination of Parallax: Parallax is the condition arising when the image formed by the objective is not in the plane of crosshairs. This one of the important steps in the temporary adjustment of theodolite or telescope.

Additional Information

The permanent adjustment of a transit theodolite can be done through the following processes:

1.  Adjustment of the horizontal or trunnion axis
2. Adjustment of the vertical axis
3. Adjustment of plate level
4. Adjustment of the line of sight/line of collimation
5. Adjustment of altitude bubble and vertical index frame.