Practical draughtsmen's work, with numerous engravings and diagrams (1903)
Hasluck, Paul N. (Paul Nooncree), 1854-1931, ed · Philadelphia, D. McKay · leaf 43
■Testing Straightedge. fine-set plane, or glasspaper wrapped round a flat piece of wood.The stock of the square should be exactly at right angles withthe blade, but, as usually constructed, this is rather difficult totest without some true instrument of reference ; and, paradoxicalas it may seem,… … I jt.JL - Fig. 59.—Untrue T-square makes Correct Angles. right angles, as will be seen by Fig. 59, where, of course, thedivergency is greatly exaggerated. In fact, the squareness ofthe T-square is entirely unessential for any work, but the absolutesquareness of the board is most important. It will…
Mechanical drawing
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