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 141
(194.) To measure a Line, one End being inaccessible. A B be the required line, and B the inaccessible point. Let Fig. 154. … At A set off a perpendicular, A C, by Art. (192). Thenset the index at 45°, and walk backward from A in the lineC A prolonged, looking by direct vision at C, until you arriveat some point, D, from which B is seen by reflection to coincidewith d Then isAD^AB. If more convenient, after setting off…
Surveying
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
