A tool or instrument used for making aper ures in wood, metal, or other hard substances. They are of various shapes, too common to workmen to need description; but one of a very peculiar and effective kind, represented above, was brought from Germany by Mr. Donkin, and is described in the Transactions of the Society of Arts. Fig. 1 is a front view of the boring bit; a a the cutting edge; b b a thread or fin, winding round the back, which: acts as a screw to draw the bit into the wood. Fig. 2 is a side view of the same. The instrument is very simple, enters the wood rapidly, and forms a clean hole.