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6 HORIZOTAL ANGLE MEASUREMENTS
This instrument is equipped with a horizontal dial which can be used for horizontal
angle measurement. Every 1° with a graduation, every 10° with a mark in the dial, and
the graduation increases from 0° to 350° in clockwise direction.
(1)First
，
set up and level the instrument in start point C. Second, sight the telescope to
backsight point A, and rotate the horizontal tangent screw until crosshair is accurately
on the staff at point A. Rotate the horizontal dial at 0°.
(2)Sight the telescope to point B, and adjust the horizontal tangent, until the crosshair
is accurately on the staff at point B. And the angle reading is angle between target A
and target B, i.e.
∠
ACB.
Optical Distance Measure
