A treatise on surveying, comprising the theory and the practice ; (1887)
Gillespie, W. M. (William Mitchell), 1816-1868, Staley, Cady, 1840- [from old catalog] ed · New York, D. Appleton and company · leaf 246
hed to the axis of thetelescope, and a micrometer-screw, by means of which the move-ment of the arm, and consequently of the telescope, can be accu-rately measured. The arm is placed on the inside of one of the standards, and isattac led to the telescope axis by means of a clamp-screw, so thatit… … is clamped to the axis by the screw D. M is the micrometer-screw.A is a lip projecting from a plate fastened to the standards. The screw is accurately cut, so that one revolution of the screwwill cause the horizontal cross-hair of the telescope to move over agiven space (say one foot) on a rod held…
Surveying
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