Setting Up
The tripod legs are properly spread on the ground and the clamp screw of level is released. The level is taken in the right hand and is fixed on the tripod through turning round the lower part along with the left hand. The tripod is then placed on ground in the desired position so in which the level is at a convenient height for sighting. The foot screws are initially turned so that they are in the middle of their run although the legs of tripod are spread such that the level is as nearly horizontal as possibly judged by eye.
Two of the legs are firmly pressed within the ground and the third leg is moved to the left or right until the transverse level bubble is around in the middle. The telescope is brought parallel to the firmly pressed legs of tripod (i.e. the pair of foot screws) and the bubble of major level tube is brought within exact middle position through turning these foot screws either inward or outward concurrently. The telescope is then turned through 90o so that it lies over the third foot screw. The bubble is centered again through turning this third screw only. Rotate the telescope through 90o once again clockwise and check the bubble. If there is any displacement, bring back the bubble in its central position. This cycle of exercise is frequent till the bubble traverses such that it remains in central position for all positions of telescope. In this position, the instrument is considered to be properly positioned and levelled.
If the telescope is turned by 180o and the bubble position from middle is displaced, it indicates that the instrument requires be repairing and correcting by making permanent adjustments.
After levelling the instrument, its focusing is needed. The eye piece and object glass are focused consecutively. The lid is removed from the object glass, and a piece of white paper is to be held before it. The eye piece is moved within or out till the cross-hairs are clearly and distinctly seen. The telescope is then rotated towards the staff. The image of staff is brought among the two vertical hairs of the diaphragm through use of a tangent screw. A focusing screw is then adjusted until the parallax between direct sight of staff and its image is removed. The instrument is now ready for making the measurements, i.e. the line of collimation is now perfectly horizontal.