A treatise on levelling, topography, and higher surveying (1876)
Gillespie, W. M. (William Mitchell), 1816-1868, Staley, Cady, b. 1840, ed · New York, D. Appleton and company · leaf 74
nce of 100°. Thezenith distance is preferable in important and complicatedoperations, as avoiding the ambiguity of the other mode ofnotation. (89.) Instruments. All contain a divided circle, or arc,placed vertically, and a level or plumb line. By these ismeasured the desired vertical angle made by… … Fig. TO. Fig. 71.
Surveying
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