Elements of surveying and navigation : with a description of the instruments and the necessary tables (1847)
Davies, Charles, 1798-1876 · New York : A.S. Barnes & Co. · leaf 31
of a line, with the scale of chords,an angle equal to a given angle. Let AB be the line, and Jl the givenpoint. Take from the scale the chord of 6 0 de- ^^ grees, and with this radius and the point ^^^2_^ \ .^ as a centre, describe the arc BC. Then -^ ^ take from the scale the chord of the given… … 24. This instrument is used to lay down, or protract angles.It may also be used to measure angles included between linesalready drawn upon paper. DESCRIPTION OF INSTRUMENTS. 27 It consists of a brass semicircle ABC divided to half de-grees. The degrees are numbered from 0 to 180, both ways ;that…
Surveying · Navigation
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