Jamison, Alpha Pierce. [from old catalog] · New York, J. Wiley & sons; · leaf 113
through the center of each leg. To facilitate the use of the instrument and to minimize the wear and tear, instead of opening and closing the tool by meansof the thumb-screw, it is well to proceed as follows: To close thepen, hold it between the thumb and the first finger of the righthand, press… … Fig. 50. DRAWING TOOLS AND MATERIALS. 95 and with the left hand stay the legs, and operate the nut withthe thumb of the right hand; when the nut is approximately atthe desired position, permit the legs to spread gently until thenut prevents further movement. This operation requires muchcaution to…
Mechanical drawing
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