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 363
glass, and containing in addition thereto a reflecting prism, cross-wire, and small spirit-level, the last being shown in the open partof the tube. The eye-lens, as indicated in the cut, is made of two separatepieces, the larger one being the usual concave eye-lens of theopera-glass, the smaller…
Surveying
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