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
ssibly a field-glass. He starts thewatch when the float reaches the upper section, walks to thelower section, and stops the watch when the float passes thisrange-line. The near range consists of a plumb-line, or wire 298 SURVEYING. suspended vertically; and the observer stands several feet backof… … Fig. 74. much as twenty per cent in their times of passage, showinggreat irregularity in the velocity of different parts of the samefilament. This is due to internal movements in the water,such as boils, eddies, etc. It is for this reason that greatrefinement in such observations is useless. A…
Surveying
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