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 110
the whole is attachedto the tri^xxl by screwing to a casting firmly attached to thelegs. The vertical axis is furnished with a hook, to which maybe attaclied a ]ilund>-liiie for tlie accurate centering of the instrn- PLANE SURVEYINa 90 uieiit. A shifting cent(^r is also provided, by nieausof… … 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…
Surveying
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