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
348 LEVELING. A small hole at one end, and a horizontal cross-hair at the other,give the desired level line. It is used by holding it in the hand.Fig. 363 is an approved form, made by Young, of Philadelphia.The improvement consists in the patent Locke sight, whichenables the near cross-hair to be…
Surveying
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