lat side of Y, square this line across the face and on
the edges as for a simple dado. Lay out the thickness of Y on the face
of X by superposition or otherwise and square the face and edges, not
with a knife but with a sharp pencil point. Gage the required depth on
the edges. Now with the bevel-square as already set, lay out the angle
A C D on the edges of X, and across the face at C score a line with
knife and try-square. Cut out grooves in the waste for the saw as in
a simple dado, and saw to the proper depth and at the proper angle.
Chisel or rout out the waste and when complete, fit the pieces
together.

[Illustration: Fig. 250. Laying Out a Dovetail Joint.]

_No. 29. A gain joint_, Fig. 266, is a dado which runs only partly
across one member, X. In order to make the edges of both members flush
and to conceal the blind end of the gain, the corner of the other
member, Y, is correspondingly notched out. In book shelves a gain
gives a better appearance than a dado.

A gain joint is laid out in the same way as the dado, except that the
lines are not carried clear across the face of X, and only one edge is
squared and gaged to the required depth. Knife grooves are made in the
waste for starting the saw as in the dado. Before sawing, the blind
end of the gain is to be chiseled out for a little space so as to give
play for the back-saw in cutting down to the required depth. To avoid
sawing too deep at the blind end, the sawing and chiseling out of
waste may be carried on alternately, a little at a time, till the
required depth is reached. It is easy to measure the depth of the cut
by means of a small nail projecting the proper amount from a trial
stick, Fig. 251. The use of the router, Fig. 122, p. 83, facilitates
the cutting, and insures an even depth.

[Illustration: Fig. 251. Depth-gage for Dado.]

MORTISE-AND-TENON JOINTS

The tenon in its simplest form is made by dividing the end of a piece
of wood into three parts and cutting out rectangular pieces on both
sides of the part left in the middle. The mortise is the rectangular
hole cut to receive the tenon and is made slightly deeper than the
tenon is long. The sides of the tenon and of the mortise are called
"cheeks" and the "shoulders" of the tenon are the parts abutting
against the mortised piece.

_No. 30. A stub mortise-and-tenon_, Fig. 266, is made by cutting only
two sides of the tenon beam. It was formerly used for lower ends of
studding or other upr