ight pieces to prevent lateral motion.

_No. 31. A thru mortise-and-tenon_, Fig. 266, is made by cutting the
mortise clear thru one member and by cutting the depth of the tenon
equal to or more than the thickness of the mortised member. The cheeks
of the tenon may be cut on two or four sides. It is used in window
sashes.

A thru mortise-and-tenon joint is made in the same way as a blind
mortise-and-tenon (see below), except that the mortise is laid out on
the two opposite surfaces, and the boring and cutting are done from
both, cutting first from one side and then from the other.

_No. 32. A blind mortise-and-tenon_, Fig. 266, is similar to the simple
mortise-and-tenon described in 30. The tenon does not extend thru the
mortised member and the cheeks of the tenon may be cut on two or four
sides.

To make a blind mortise-and-tenon, first make the tenon thus: Locate
accurately with a knife point the shoulders of the tenon and square
entirely around the piece. On the working edge near the end mark the
thickness of the tenon. Set the marking-gage at the proper distance
from the working face to one cheek of the tenon and gage the end and
the two edges between the end and the knife-lines. Reset the gage to
mark the thickness of the tenon and gage that in the same way from the
working face. Then mark and gage the width of the tenon in the same
way. Whenever there are several tenons of the same size to be cut,
they should all be laid out together, that is the marking-gage set
once to mark all face cheeks and once to mark all back cheeks. If a
mortise-gage is available, use that. Always mark from the working face
or working edge. Cut out a triangular groove on the waste side of the
knife lines (at the shoulders) as in cutting a dado, Fig. 91, p. 66.

In cutting the tenon, first rip-saw just outside the gaged lines,
then crosscut at the shoulder lines. Do all the rip-sawing before the
crosscutting. If the pieces are small the back-saw may be used for
all cuts. It is well to chamfer the arrises at the end of the tenon to
insure its starting easily into the mortise.

Locate the ends of the mortise and square lines across with a sharp
pencil in order to avoid leaving knife marks on the finished piece.
Then locate the sides of the mortise from the thickness of the tenon,
already determined, and gage between the cross lines. As in the case
of like tenons, if there are a number of mortises all alike, set the
gage only twice for