7. CHECKS AND ADJUSTMENTS
19
1 Set the instrument halfway between two points, A
and B, 30 to 50m apart. Take readings a1 and b1.
2 Set the instrument at a point 2 m from point A.
Take readings a2 and b2.
Leave the telescope sighted on point B.
Calculate
b2’ = a2 - (a1 - b1)
If b2’ = b2, the horizontal cross-line is normal and
no adjustment is necessary.
When b2’ and b2 are different, adjust the cross-line
as follows:
7.3 RETICLE CROSS-LINE (LINE OF SIGHT)
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