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 21
Fig. 22.—Movable-arm protractor. grave the graduations on the under side so that they are in direct con-tact with the surface of the drawing. Two improved patterns of thesemi-circular type are shown (Fig. 21), as well as a good movable arm … Fig. 23.—Full-circle protractor. type (Fig. 22) for the mechanical draftsman. In the plotting of sur-veyors notes the topographical draftsman usually finds the full-circletype (Fig. 23) convenient. 19 Beam Compasses.-This instrument (Fig. 24) is used when it is neces-sary to draw circular ares of…
Mechanical drawing
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