Mechanical drawing self-taught: comprising instructions in the selection and preparation of drawing instruments. Elementary instruction in practical mechanical drawing. Together with examples in simple geometry and elementary mechanism, including screw threads, gear wheels, mechanical motions, engines and boilers (1889)
called thumbtacks. These are forced through the paperinto the board at each corner, as in Figure Fig. 13.14 at/ On account of the large diameter of thestems of these thumb tacks, which unduly pierce anddamage the board, and on account also of their heads,by reason of their thickness, coming in the… … rig. 14. than thumb tacks. The objection to ordinary tacks isthat they are more difficult to remove, but they are, asstated, more desirable for use.
Mechanical drawing
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.
