A treatise on surveying, comprising the theory and the practice (1906)
Gillespie, William Mitchell, 1816-1868, Staley, Cady, 1840- · New York D. Appleton · leaf 258
in-sertion of metal plugs for the graduation, asin the above-described rod. The hygroscopicproperties of this rod are as perfect as can bedesired, hence the two greatest objections towood for measuring rods have been overcome, and the rod used by the Coast and Geodetic Survey combines thebest… … 248 PRECISE SPIRIT LEVELING. with a depression (radius of 35 centimetres) in the center for re-ceiving the foot of the rod. Prongs underneath prevent lateralmotion when properly pressed into the ground. It is sometimesnecessary to use a peg in place of the foot plate in order to obtain astable…
Surveying
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