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 31
A B 29. This instrument is used to lay down, or protractangles. It may also be used to measure angles included be-tween lines, already drawn upon paper. SEC. II.] GEOMETRICAL CONSTRUCTIONS. 29 It consists of a brass semicircle, ABC, divided to half de-grees. The degrees are numbered from 0 to 180,,…
Surveying
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