A treatise on surveying ; in which the theory and practice are fully explained (1860)
Alsop, Samuel · Philadelphia, E. C. & J. Biddle & co. · leaf 55
requireddistance. 119. Angles. Angles may be laid off by a protractor.This is usually a semicircle of metal, the arc of which isdivided into degrees. To use it, place it with the centre atthe point at which the angle is to be made, and the straightedge coincident with the given line; then with a… … 120. By the Scale of Chords. The scale of chords,which is engraved on the ivory scales contained in a boxof instruments, may also be used for making angles. Forthis purpose take from the scale the chord of 60° for aradius. With the point A, at which the angle is to be made, asa centre, and that…
Surveying
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