Temporary Adjustment of a level machine

Temporary Adjustment of a level machine

Temporary adjustment of a level machine involves setting up, leveling and elimination of parallax.

1. Setting up of level machine :

 Level machine can be set at any point on the ground. The things that need to be considered for setting up of a level machine are listed below.
a. Instrument is not too low or too high to facilitate reading on a benchmark.
b. Length of back sight should not be less than 98m.
c. Back sight distance and fore sight distance should be equal.
d. Fixing the instrument over the tripod with clamp screw.
e. The instrument is placed at convenient height with legs spread well apart (horizontal). This can be done by keeping any two legs constant and varying only one leg.

2. Leveling up

Leveling can be done with the help of leveling screws or foot screws.
Procedure to level :
a. Turn the telescope such that level tube is parallel to the line joining any of the two foot screws.
b. Then, bring the bubble to the center by simultaneous inward or outward moving of foot screws. Then, rotate the telescope and balance bubble by third screw.

3. Focusing the eye piece:

Focusing of the eye piece is vital to eliminate invisibility of cross hairs. In order to do this, paper is placed in front of objective till the cross-hair seems distinct.

4. Focusing the objective:

This is done to bring the image of the object to the plane of cross-hairs. It is done by directing the level machine on the staff and turning the focusing screw until image appears clear.