Elements of plane and solid free-hand geometrical drawing, with lettering; and some elements of geometrical ornamental design, including the principals of harmonic angular ratios, etc. In three parts ... for draughtsmen and artisans; and teachers and students of industrial and mechanical drawing (1878)
Warren, S. Edward (Samuel Edward), 1831-1909 · New York, J. Wiley & sons · leaf 38
GEOMETKICAL DRxVWING. Elementary Examjples. - Ex. ^^. Bisect a right angle, in each of the positions given inEx. 33. To do this, sketch carefully a quarter circle betweenthe sides of the angle and mark the middle point of this arc.Then join this middle point with the vertex of the angle asseen in… … The protractor is a semi-circular instrument, whose semi-circu.lar edge is divided into 180 degrees. A right angle is an angleof 90°. Half a right angle is 45°, hence if we place the straightside of the protractor on one side of the angle, and its centre, C,marked by a notch, at the point or…
Geometrical drawing · Mechanical drawing
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