The theory and practice of surveying. Designed for the use of surveyors and engineers generally, but especially for the use of students in engineering (1886)
Johnson, J. B. (John Butler), 1850-1902 · New York, J. Wiley & sons · leaf 327
theupper edges and lead weights attached to the lower edges ofthe vanes. These serve to give the desired tension on the 296 SURVEYING. connecting cord and to maintain the float in an upright posi-tion, even though the cord is drawn out of the vertical by-faster upper currents. The vanes should be… … FlG. 73. drical in plan, and carries a small flag. The tension on thecord should be from one to five pounds, according to the sizeof the floats. The cord itself should be of woven silk and assmall as possible, so as to exercise a minimum influence on themotion of the lower float. Wire is not…
Surveying
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