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5. Checking and Adjusting Your Instrument
5.1
Circular Level
Set up your instrument properly on the tripod. Adjust the leveling screws to center the bubble into the circle vial.
Turn the telescope 180 degree clockwise, check the bubble position, and then, turn the telescope 180 degree
counterclockwise and check the bubble position again. If the bubble is off center, the circular level needs to be
adjusted.
5.2
Line of Sight
1) Place two rods facing each other at points A and B at a distance of 50 - 80 m apart. Set up your instrument at
point C, which is about halfway between A and B.
2) Sight the rods and take readings on point A as A and from point B as B.
3) Set the instrument at point D, which is about 2 m from point A.
4) Sight the rods at point A, take reading as AA. And then, sight the rod at point B, take reading again as BB.
5) Use the following equation to calculate:
BB' = AA - (A - B)
The instrument is in its perfect condition if BB' = BB, otherwise, it needs adjustment.
