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 136
neanother. (186.) Description of the Sextant, Fig. 150. The frame isusually of brass, constructed so as to combine strength withlightness. The handle, H, by which it is held, is of wood.AB is a graduated arc; C D, the index-arm, is movable abouta pivot in the centre of the graduated arc. M is a… … horizon-glass, H, is attached perpendicularly to the plane ofthe instrument, and parallel to the index-glass when the indexis at zero. The lower half of this glass is silvered, to make ita reflector, and the upper half is transparent. J1 E is the tel- 118 LEVELLING, TOPOGRAPHY, AND HIGHER…
Surveying
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