A treatise on land-surveying; comprising the theory developed from five elementary principles; and the practice with the chain alone, the compass, the transit, the theodolite, the plane table, &c. Illustrated by four hundred engravings, and a magnetic chart (1875)
Gillespie, W. M. (William Mitchell), 1816-1868 · New York, D. Appleton · leaf 234
instrument (sonamed by its introducers, Messrs. Gurley, and shown inFig. 224), the Vernier-plate, which carries the standardsand telescope, is under the plate which carries the grad-uated circle, and the compass is attached to the latter.By this arrangement, when the Vernier is set at any angle,ihe… … to allow for magnet- ^s- ^-^i- ic variation, and thus to run out a line with true bearings, as in Art. (312), or to run out old lines, allowing for the secular variation, as in Art. (321). The instrument mayalso be used like thecommonEngineersTransit. The compass,however, will then notorive the…
Surveying
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