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 376
he target carries a vernier,by which smaller spacesmay be measured thanthose into which therod is divided. It maybe placed on the side ofan aperture, in the faceof the target, throughwhich the divisions onthe rod can be seen, orcarried on the back orside of the rod by thetarget-clamp. 532. The New… … Up to six feet and a 362 LEVELING. half the target is used as on other rods. For greater heights, thetarget is fixed at six and a half feet, and the back part of the rod,which carries the target, is shoved up (Fig. 386) until the target isbisected by the cross-hairs. Its height is then read off on…
Surveying
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