5 and 7, the angle should be oblique enough to give the greatest leverage.
In a tusk tenon, Fig.

267, No.

40, the tenon is made but one-sixth the thickness of the timber, whereas the tusk is made much larger.
Where a mortise is to be cut in a timber bearing weight, it should be cut in the neutral axis, where the cutting of fibres will weaken it least.
In the mortise-and-tenon of a table-rail, Fig.

267, No.

43, there should be a wide shoulder above the tenon of the rail so that the top of the leg above the mortise will not shear out.