A treatise on levelling, topography, and higher surveying (1876)
Gillespie, W. M. (William Mitchell), 1816-1868, Staley, Cady, b. 1840, ed · New York, D. Appleton and company · leaf 90
COMPOUND ANGULAR LEVELLING. 71 Otherwise, find height of D above A, and subtract itfrom B C. (111.) By Angular Co-ordinates in several Planes. Onirreg-ular ground, when the distance between the two points isunknown, the operations for finding it by the various methodsof L. S., Part VIL, Chapter… … At A measure the vertical angle of elevation, B A C. Alsomeasure the horizontal angle, C A D, to some point, D, andmeasure horizontally the distance, A D. At D measure thehorizontal angle ADC. Then : AC = AD sin. ADCsin. A C D B C = A C . tang. B A C t> n — a -r sm* ADC. tang- B A Csm. A C D…
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