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 142
rd, appear together on looking through theprism, and the division with which the thread coincides, when theneedle is at rest, is the Bearing of whatever object the threadmay bisect, i. e. is the angle which the line of sight makes with thedirection of the needle. The prism is mounted with a hinge… … 136 COMPASS SURVEYING. [PAKT Itl slide on or off the siglit-vane, E ; and it may be reversed at pie*Bure, that is, tui-ned face downwards; it can also be inclined atany angle, by means of its joint, d; and it will remain stationaryon any part of the vane, by the friction of its slides. Its use is…
Surveying
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