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 172
the angles at a and b with any simple ratioto each other. In the figure, this ratio is -J-, the angles at a andb being respectively of 30° and 60°. So much being done, mark the points b, C, a on the edge ofa slip of paper, and then adjust the position of the slip by trial. 114 FREE-HAND GEOMETRICAL… … Then, assuming any points, as n and p, equidistant from C forconvenience, draw nm&n&pr perpendicular to A B ; and drawO n and Ojy, and note their intersections, nx and^ with ax bvAlso note gx. Finally, at nx el9 p, draw perpendiculars to ax b19and make n1?n1 = n?ri; c101 = C O ; px r1-=jpr.…
Geometrical drawing · Mechanical drawing
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