The Screwdriver (A.) is one of the most important tools in a carpenter's kit, and to be of use should be of finely tempered steel; for, if too soft, it will turn over, and if too hard, it will break. The edge should be as thick as the slot of a screw will allow, in order to have as much strength as possible.

(B.) A round-handled screwdriver is not so satisfactory as one with an elliptical or polygonal handle, as it is impossible to obtain as good a grip upon the former as upon the latter; a round handle, planed flat upon the two opposite sides, is quite commonly used.

(C.) Ratchet screwdrivers are useful in many places where it is difficult to use two hands, and there are patent quick-action screwdrivers on the market which are suitable only for certain kinds of light work, as what is gained in speed is lost in power. The screwdriver bit is a short screwdriver blade, tanged to fit a bitbrace; it is essential in doing economical work, as screws may be driven much more rapidly than by hand, and it is also valuable on account of its greater leverage in driving heavy screws.