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 494
712. To measure Heights. Measure the vertical angle betweenthe top of the object and a mark at the height of the eye, as witha theodolite or transit, and then calculate the height as in Part II,Art. 578. Otherwise. Set the index at 45°, and walk backward till themark and the top of the object are… … When the base is inaccessible: Make C = 45°, and D = 26° 34.Then C D = A B. So, too, if 0 = 26° 34, and D = 18° 26. This may be used when a river flows along the base of a hillwhose height is desired, or in any other like circumstance. 480 MARITIME OR HYDRO GRAPHICAL SURVEYING. 713. To observe…
Surveying
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