The rabbets are cut out with a rabbeting-plane before mitering and assembling.
The principle disadvantage of a mitered joint is that, if the wood shrinks at all, it opens at the inside corners, as in Fig.

289, because wood shrinks sidewise but not lengthwise.
[Illustration: Fig.289.The Way a Mitered Joint Opens on Account of Shrinkage.] In window sashes, the dovetail joint, Fig.

267, No.

47, is the common one at the upper end of the lower sash and the lower end of the upper sash, and the mortise-and-tenon joint modified is used at the lower end of the lower and upper end of the upper sash.

The glass takes the place of the panel.