21
Angle measuring
1.
Turn the instrument until the vertical cross hair line is in
front of A and read off the horizontal circle scale. This is
angle α.
2.
Turn the instrument until the vertical cross hair line is in
front of B and read off the horizontal circle scale. This is
angle β.
3.
The angle AOB =
γ = α – β.
CHECKING AND ADJUSTING
Spirit level
1.
Centre the bubble in the spirit level with the levelling knob.
2.
Now turn the instrument 180°. The bubble should not move, and should stay centred. If the bubble
moves, the spirit level must be adjusted.
3.
Turn the levelling knob until the bubble has moved half way back to the centre of the level. Turn
both adjuster screws on the spirit level with a hex key until the bubble is fully centred.
4.
Repeat this procedure until the bubble remains completely centred when the instrument is turned
180°.