Blessing, George F. (George Frederick), 1875-1921, Darling, Lewis A. (Lewis Andrew) · New York, J. Wiley & sons; [etc., etc.] · leaf 154
ses the proper relation of distances, i.e., lengths of lines, issecured by making comparisons. The relative width of a partis compared to its length, and if a detail on the machine is one-fourth as long as the over-all dimension, it should be drawn one-fourth as long as the over-all on the drawing.… … Fig. 90. —Estimating Proportion by Means of the Eye and a Pencil. and bring it in line with the end of the part being measured;move the thumb along the pencil until it sights the opposite end.This length along the pencil is then compared with the length ofthe over-all dimension similarly measured.…
Mechanical drawing
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