Appleton's dictionary of machines, mechanics, engine-work, and engineering (1861)
Appleton, firm, publishers, New York. (1852, D. Appleton & Co.) · New York : D. Appleton · leaf 176
t theextreme ends, and a little up the sides also. The same kind of shaft is sometimes made as in Fig. 516, with a plain conical point, with two scoringcutters and two chisel edges, which receive their obliquity from the slope of the worm: it is as it werea double centre-bit, or one with two lips… … ^ur but it is in this form very effective in Hunters patent stone-boring machine, intended for stones notharder than sandstones ; the drill is worked by a cross, guided by a tube, and forced in by a screw cutupon the shaft carrying the drill; so that the stone is not ground to powder, but cast off…
Mechanical engineering
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