Dumpy level needs two adjustments :-
1 Permanent adjustments:-
permanent adjustments needs only when the fundamental relation between parts of instruments or lines get disturbed.
2 Temporary adjustments:-
temporary adjustments for a level consists of the following:-
1 Setting up level
In this operation, dumpy level is taken out from the box by holding in right hand and fixed at the top of tripod stand by turning round only with the left hand. then tripod legs are so adjusted that the instrument is at the convenient height and the level remain stable.
2 Levelling up:-
Telescope should be parallel to two legs and press the third leg into the ground so that longitudinal bubble was brought to center approximately. Then accurate levelling is done by moving any pair of foot screw inward or outward and brought the bubble tube in center. Then move the telescope at 90 degree in clockwise direction. If there is an error then try to remove it by adjusting the third foot screw.
3 Focusing and elimination of parallax:-
Parallax is a condition, when image from the object glass does not felled in plane of the cross- hairs.It is eliminated by focusing the eye piece inward or outward direction till the cross hair are seen sharply. It i also removed by focusing the object by moving focusing screw till the image appears clear and sharply.