38 and 39, may weaken rather than strengthen a joint if they are so placed or are so large as to shear or crush their way thru the timber.
9.

_Place each abutting surface in a joint as nearly as possible perpendicular to the pressure which it has to transmit._ Illustrations of this principle are as follows: the angle in a strut joint, Fig.

266, No.

62, should be equally divided between the two beams.
The thrust joint, Fig.

268, No.