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 9
Horizontal- / i \ (h) (I) (J) Fig. 6.—The triangles used in combination Pora/le/ Lines -PerpendicularLine , ,-Perpendicular … -Fixed Triangieor Straight Edge --Fixed Triangleor Straight Edge 1 - Fixed Triangle or Straight Edge (a) (b) (c) Fig. 7.—Drawing parallel and perpendicular lines with the triangles.
Mechanical drawing
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