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The bit, one of the most useful of tools, is operated by means of a crank turned by hand, the pressure requisite to force it into the substance that is being cut being given by the person who uses it pressing with his chest against a broad piece on the end of the crank ; to do this requires a great amount of leaning, or stooping forward, and it is a very unhealthy operation, inducing many chest complaints. The bit-holder represented in our engravings is one by which, with a very slight stoop, in fact scarcely any, the pressure can be given to the perpendicular bit, and the rotation is made easier. . Fig. 1 is a perspective holder, B, and bit-holder, C, a bit, D, being shown in C. The brace and bit-holders have each a head worked on them in the form of a hevel wheel, c and d, (seen in the section,) which work freely together in the space afforded by the swell, e, in the casting, A. By this means, the brace can be made to turn the bit at any angle with respect to its own axis of rotation, by having the angle of the casting made accordingly. On the swell, e, are two projections, f, one on each side, which slide in a slot in the adjustable rest, E,—a most convenient attachment to the bit-holder, but not a necessary adjunct, as it can be used view of the whole, Fig. 2 being a section of the same. Similar letters of reference indicate the same parts in each. A is a hollow casting of the shape represented, and made in two parts, connected together by the screws, a. The plane parts of A, indicated by b, form journals for the brace- with or without the rest. This rest is of the shape shown in Fig. 4, Fig. 3 being a side view of it. A screw and nut, g, passes through a hole in A, which holds the rest to the casting; and it has two small wheels or friction rollers, h, one at each end, which much facilitate its motion downwards as the bit descends in the stuff; when boring in corners or awkward places, it can be removed. It is the invention of Benjamin B. Hill and Samuel W. Adams, of Chicopee, Mass., and was patented January 5, 1858. Further information may be obtained by addressing as above.
