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 144
hts. Measure the vertical angle be-tween the top of the object and a mark at the height of theeye, as with a theodolite or transit, and then calculate theheight as in Part II., Art. (98). Otherwise. Set the index at 45°, and walk backward tillthe mark and the top of the object are brought to… … When the Base is inaccessible: Make C = 45°, and D =26°34. Then CD = AB. So, too, if C = 26° 34, andD = 18° 26/. This may be used when a river flows along the base of ahill whose height is desired, or in any other like circumstance. (199,) To observe Altitudes in an artificial Horizon, In this Fig.…
Surveying
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