Joints Used In Timber Framing. In figs. 313, 314, we illustrate different methods of joining flooring boards together. For "folding floors," the joints first on the left hand in fig. 313, and c in fig. 314, both boards being nailed to the joints at their edges, but when the boards are rebated, as at b in fig. 314, or centre drawing on fig. 313, or tongued and grooved as in third drawing in fig. 313 and a in fig. 314, only one edge or board is nailed down. Flooring boards vary in breadth from 5 to 9 inches, with a varying thickness of from ¾ to 2 inches; a general average being 1 to 1¼ inches. The methods of joining the joists of a floor to the wall are various, a common method is illustrated in fig, 315, a the flooring joist, b the wall plate on which a groove is cut, c the wall plate, to allow the lower edge of the joist to pass into it, the depth of the groove, as at d, being equal to the depth to which the joist is to enter. In fig. 316 another method is illustrated, a part being cut out on the face of the wall plate, as in fig. 315, of same width as the thickness of the joist, but a rib, a a, is left in the centre, across its breadth; this goes into a groove b, cut in the lower edge of the joist, and of the same depth as the rib a a; a cross section of the wall plate is shown at c d, showing the rib a a . Dovetail joints are sometimes used in connecting joists with wall plates, the best form being that illustrated in fig. 316, well known as the " swallow-tail" joint. In this a part is cut out in the upper face of the wall plate as at e e, the end of the joist on its lower edge being formed of the corresponding shape, as at f f; the side elevation of this is shown at g, and a cross section on the line h h at i. Wall plates are joined together in the direction of their lengths by the "half-lap " joint at a b, fig. 317, and at the corner of the wall, as at c, by the same half-lap joint, of which a side elevation is at d, one of the plates at e, or they may be joined by the "mitre" joint, as at f. Joists are jointed to "trimmer joists," by the joint in fig. 318; the tenon a, in place of stopping short, as at the dotted line, may be extended through the trimming joist b b, as at c, and secured by a "pin" d, as shown. The ends of "binding joists" are secured to the faces of "girders" by a joint of the same kind, which is called a "tusk tenon," as illustrated on fig. 319. The usual depth of the tenon a is one-sixth of the whole depth of the binding joist b; and the plate of the tenon c is one-third of the depth of the joist measured from its lower side. The "ceiling joists" a, fig. 320, are joined to the "binding joists" b b; a notch c is cut out of the lower edge of the binding joist, into which the ceiling joist a is passed; c shows the under side of binding joist with notch e cut out of it. Another method is adopted in which a chase or sunk part a, fig. 321, is cut out, in a horizontal direction, on one face of the binding joist b, near its lower edge, the end of the ceiling joist c being provided with a projecting part or tenon d passing into the chase or mortice a.