Wallis, Rolland S. [from old catalog], Iowa state college of agriculture and mechanic arts, Ames. Dept. of engineering extension. [from old catalog] · Ames, Iowa, Engineering extension department, Iowa state college · leaf 20
Fig. 20-—Standard protractor. The beginner should obtain copies of the trade catalogues of firmsmakin- drafting and engineering instruments and supplies, and shouldstudy these to familiarize himself with the nature of the various de-vices on the market. Space limitations make it impossible to list…
Mechanical drawing
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