Surveying ; a manual of practical instruction in the art of plane surveying, including plotting, leveling, triangulation, line running, cross-sectioning, traversing, and other details of field work (1910)
American School of Correspondence, Phillips, Alfred Edward, 1863- [from old catalog] · Chicago, American school of correspondence · leaf 111
The three-screw leveling base is necessarily larger and differsin detail from the four-screw. The upper plate carrying the screwsis permanently attached to the instrument; and the lower ends of lOf) PLANE 8UBVEYING the screws rest upon the trixjod casting, to which it is attaclicd bya singk center… … Fig. 70. The four-screw base commends itself from the fact that it canquickly be leveled approximately; and, no matter how much thethreads are worn, the instrument can be brought to a solid bearing. PLANE SUEYEYING 101 The three-screw base, however, is more easily manipulated, and alldanger of…
Surveying
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