In further explanation of joiner’s work, we will briefly describe the mode of making a drawing-board, requiring to be _true_, _plane_, and _square_. Suppose the board is intended to be so wide as to require three boards side by side to make it: these three boards being sawn out of the right length, their edges are first planed perfectly straight and smooth, so that when any two are placed side by side, the edges touching, those edges may touch or fit together accurately for their whole length; this accuracy of joint is obtained by testing the edge after each time the plane is applied, by a straight-edge, or rule, known to be _true_. There are two modes of proceeding to make these joints firm: one by _dowelling_, that is, by inserting short pieces of hard wood, as oak or wainscot, let for half their length into a mortise cut in the edges of the boards that are to fit together; these mortises, being, of course, made opposite each other, these dowels prevent the boards from rising up or starting from their places when the work is finished. Instead of short dowels, a strip, the whole length of the boards, is let into each joint, half the strip lying in a ploughed groove, made in the middle of the corresponding edges of the two boards. But, besides those precautions, the joints are well glued up. There are two modes by which this board may be strengthened, to prevent its _warping_ or _casting_ by the drying or shrinking of the wood. A cross-piece of deal, or better still, of wainscot, is fixed across the ends of the boards, these ends being double rebated or _tongued_, to fit into a groove made in the cross-piece to receive the tongue; these cross-pieces prevent the long boards from warping, since the cross-pieces would have no tendency to alter their figure in the direction of their grain. If, however, the board be larger, _keying_ is better than this clamping. Keying consists in attaching two stout cross-pieces at the back of the boards, the faces of which pieces are worked so as to fit, and are glued into a dovetail-shaped groove cut across the direction of the boards at their back to receive the keys, as will be understood from the annexed sketch. [Illustration] When the board is made, and the glued joints quite dry, the face is planed perfectly smooth and level, and the edges made truly square, or at right angles; if the board be keyed, the back must be planed smooth before the keys are put in. The flooring-boards in the better kinds of houses are often _dowelled_ in the manner above described, and the ends of the flooring-boards are tongued and grooved to fit together, to prevent the boards from starting up from the joists and becoming uneven.