Elements of surveying and levelling; with descriptions of the instruments and the necessary tables (1870)
Davies, Charles, 1798-1876 · New York and Chicago, A. S. Barnes & Company · leaf 117
is, it is theangle ICB = GBC. And generally, A reverse-hearing, or hack-sight, is aliuays equal to the for^-tuard-bearing, and differs from it only i7i loth of the letters lyvMch it is designated. 77. In taking the bearings with the compass, there are twosources of error. 1st. The inaccuracy of the… … To guard against these sources of error, the reyerse-bearingshould be taken at every station: if this and the forward-bearing are of the same value, the work-is probably right; butif they differ considerably, they should both be taken again. 78. In passing over the courseAB, the northing is found…
Surveying
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