Wentworth, G. A. (George Albert), 1835-1906 · Boston, Ginn · leaf 57
arms withverniers. A rectangular protractor, having the degrees marked off onthree sides of a plane scale, is sometimes used. Often thisform of the protractor is found on the reverse side of thediagonal scale. 48 SURVEYING Constructions. 1. To lay off an angle with the circularprotractor. Place the… … Fig. 30 2. To draiv through a given point a line parallel to a givenline with a right triangle and ruler. Make one of the sides of the triangle coincide with thegiven line, and, placing the ruler against one of the other sides,move the triangle along the ruler until the first side passesthrough the…
Surveying
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