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 172
he mirrors /and c in succession, they havingan angle of 450 with each other. By this means a line may belocated at right angles to a given line at a given point, or apoint in a given line may be found in the perpendicular to thisline from a given point. THE PLANIMETER. 143. The Planimeter is an… … Fig. 35. of the best of which will be described. The instrument hascome to be a necessity in all kinds of surveying and engineer-ing work where irregular areas have to be evaluated. It isimportant that the student should thoroughly understand itsprinciples, that he may use it with the greatest…
Surveying
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