The practical draughtsman's book of industrial design and machinist's and engineer's companion : forming a complete course of mechanical, engineering and architectural drawing . Flg. 14. size and strength, isless liable to legs of the bow-pen compasses arejointed. Fig. 19 is afront elevation of aninstrument preciselysimilar to the last, ex-cept that it has a pen-cil instead of a compasses re-quire to be adjusted to any desired radius by the direct action ofthe hand. In work where great accuracy and minuteness is calledfor, it will often be found a very tedious matter to o
The practical draughtsman's book of industrial design and machinist's and engineer's companion : forming a complete course of mechanical, engineering and architectural drawing . Flg. 14. size and strength, isless liable to legs of the bow-pen compasses arejointed. Fig. 19 is afront elevation of aninstrument preciselysimilar to the last, ex-cept that it has a pen-cil instead of a compasses re-quire to be adjusted to any desired radius by the direct action ofthe hand. In work where great accuracy and minuteness is calledfor, it will often be found a very tedious matter to obtain a trueadjustment in this manner, particularly if the joints of the instru-ment are not in perfect working condition. This difficulty is gotover in what are termed spring, or screw bow compasses. BOOK OF INDUSTRIAL DESIGN. 189 Fig. 20 is a side, and fig. 21 a front view of a pair of pen com-passes of this class. The use of such instruments is confined to Fig. 17. Fig. 18. Fig. 19. Fig. 20. Fig
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Keywords: ., bookcentury1800, booksubjectarchitecturaldrawing, booksubjectmec
