Practical engineering drawing and third angle projection, for students in scientific, technical and manual training schools and for ... draughtsmen .. (1897)
Willson, Frederick Newton, 1855-1939 · Princeton, N.J., The author · leaf 37
30 THEORETICAL AND PRACTICAL GRAPHICS. … PLANE PROBLEMS. 31 by trial and error is often resorted to, and even for ordinary cases it is by no means to bedespised. By it the di\iders are set by guess to the probable chord of the desired arc, and, sup-posing a heptagon wanted, the chord is stepped off seven times around the circumference;…
Mechanical drawing · Lettering
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