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 43
(43.) BourdalouesLevel. This is a modifi-cation of Egaults. Thetelescope carries a steelprism near each end;one of which rests on a knife-edge, and the other on thespherical top of an adjusting-screw. (44.) Lenoirs Level. In this, the telescope carries, at eachend, a steel block, whose upper and… … perfectly parallel. They are placed on a brass circle, whichis made level by reversing a level placed upon the telescope. RODS. 25 (45.) Fig. Fig. 29. Tripods. These consist of three legs, shod with iron,and connected by joints at thetop. There are many differentforms, the most common of whichis…
Surveying
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