A treatise on surveying, comprising the theory and the practice (1906)
Gillespie, William Mitchell, 1816-1868, Staley, Cady, 1840- · New York D. Appleton · leaf 36
38represent a convenientform of signal whenthe instrument has tohe elevated only 12or 15 feet. It is com-posed of two inde-pendent parts, tripodand scaffold, the sameas with the largerstructures. Figs. 439 and 440showconvenient formsof signals for tertiarytriangulation or thesmaller secondary.The… … 26 GEODESY. braces make it more stable and rigid than the signal with but threebraces, particularly when the ground is rocky and winds strong.The signal shown in Figs. 441 to 443 is also very convenient, par-ticularly for low signals. Fig. 441 represents the signal as framed on the ground; Fig.442…
Surveying
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