No. 65. A plain brace joint is one in which the brace is simply mitered and nailed into place. It is used for bracket supports.
Fig. 269-65 Brace
No. 66. A housed brace joint is a joint in which the brace is housed into the rectangular members except that the outer end of the mortise is cut at right angles and the inner end diagonally to receive the brace which is cut to correspond. It is much stronger than 65.
Fig. 269-66 Housed brace