This section is from the book "Cyclopedia Of Architecture, Carpentry, And Building", by James C. et al. Also available from Amazon: Cyclopedia Of Architecture, Carpentry And Building.
This method consists in the use of a strip of wood which is applied to the back of the several pieces to be held together and prevented from slipping by means of glue. The strip, however, is let into the pieces a little way in a special manner known as dovetailing, which prevents it from pulling out, and gives it an especially strong hold on them. Fig. 84 shows this arrangement both in elevation and in section. It is useful in making up large panels from narrow boards. In this method, only one of the pieces must be glued to the strip, the others being left free to move.
Another method of accomplishing this same result is by the use of a strip which sets against the back of the pieces to be joined, but is not let into them at all, Fig. 85. It is held in place by means of screws which go through slotted holes in the strip. This is in order that the pieces may have a chance to swell or shrink without bulging or splitting. It is usually customary to employ brass slots which are let into the wood. These resist much better the wear of the screws and prevent them from working loose. If, however, the strip is of very hard wood this is not always necessary.
A third method is that shown in Fig. 86. This is sometimes called the "button" method on account of the use of the small side pieces or buttons which fit over the center strip and hold the pieces of board together, at the same time allowing them to swell or shrink freely. Only the small pieces are screwed to the boards, the center strip being fastened to one of the pieces only. This arrangement takes up a little more room than the others and looks somewhat more clumsy but is quite satisfactory otherwise. In all three of the methods described, the strip should be from 3 to 4 inches wide.
Fig. 84. Method of Binding Boards Together by Means of Dovetail Key.