instead of along
its sides as in No. 34. It is used in ornamental joints as well as in
carpentry.

_No. 36. A fox-tail tenon_, Fig. 266, is a blind mortise-and-tenon in
which the mortise is made slightly wider at the bottom than the width
of the tenon. Wedges are driven into saw kerfs in the tenon before
inserting into the mortise; then when it is driven home the wedges
spread out the tenon and make it fill out the mortise. It is used in
strong doors and also where the mortised member is already in place so
that a wedged mortise-and-tenon is impossible.

_No. 37. A dovetail mortise-and-tenon_, Fig. 266, is a thru
mortise-and-tenon beveled on one side so as to form half a dovetail.
The corresponding side of the mortise is also beveled and made wide
enough so that when the tenon is pressed well up against its beveled
side a wedge may be driven into the space left on the straight side.
It is used to tenon a beam into a post especially where the post is
fixed against a wall. It is also used in machinery frames which are
made of wood.

_No. 38. A pinned mortise-and-tenon_, Fig. 267, is one in which a pin
is driven thru holes bored thru the mortised beam and thru the tenon
to keep them from drawing apart. It is used in heavy framing as in
bridges, in wagon-making, in window-sash, etc.

_No. 39. A keyed mortise-and-tenon_, Fig. 267, is one in which the
tenon protrudes thru the mortise far enough to receive a removable
key and thus be drawn up tight to the mortised member. It is used in
work-benches and in ornamental joints like knock-down bookcases and in
other mission furniture.

The keyed mortise-and-tenon is made as in a thru mortise-and-tenon,
except that before cutting the tenons the holes for wedges should be
laid out thus: measuring from the shoulder of the tenon, locate by
superposition or measurement the outside of the mortised member.
Deduct from this 1/16" and square a fine pencil-line across the face
and opposite side. This line will be the inside of the hole for the
wedge, and the 1/16" is deducted to make sure that the key wedges
against the mortised member. On the upper surface of the tenon, lay
off toward the end the width of the wedge at this point, A B, Fig.
252, and square across. On the under surface, lay off the width of the
wedge at this point, C D, and square across.

[Illustration: Fig. 252. Keyed Mortise-and-Tenon Joint.]

Gage the sides of the wedge hole on both upper and lower surfaces of