and is, moreover, more readily dealt with in the lathe than the
whole cylinder casting would be.

The liner is virtually a cast-iron tube, with a specially shaped flange
at either end. At the back end the joint between it and the cylinder
casting has to be very carefully made. This is a water _and_ explosion
joint; hence it has not only to prevent water entering the cylinder from
the water-jacket, but also to be sufficiently strong to withstand the
pressure generated in the cylinder when the charge is fired. For this
purpose specially prepared coppered asbestos rings are used, which will
stand both water and intense heat. Sometimes a copper ring alone is
employed to make the joint. At the front end the liner is just a good
fit, and enters the bed easily, and a couple of bolts fitted in
corresponding lugs on the liner, pass through the back end of cylinder
casting, so that by tightening up these the joint at back end is made
secure. A small groove is cut on a flange, and a rubber ring, of about
1/4-in. sectional diameter, is inserted here when the liner is fitted
into the cylinder casting. This makes the water-jacket joint at the
front end.

[Illustration: FIG. 3.]

[Illustration: FIG. 5.]

[Illustration: FIG. 4.]

Lugs are provided on the bed and cylinder castings, and are bored to
receive steel bolts--three are sufficient, provided the metal in and
around these lugs is not pinched. In some cases a continuous flange is
provided on both bed and cylinder, and a number of bolts inserted all
the way round. This, however, is unnecessary, and has a somewhat clumsy
appearance. When these bolts are tightened up, the cylinder and liner
are clamped firmly to the bed; but the liner being free at the open end,
can expand longitudinally without causing stresses in the cylinder
casting.

The combustion chamber K is virtually part of the cylinder, and has
approximately equal to one-fourth the total volume of the cylinder. The
shape varies somewhat in different makes of engines; in some it is
rectangular, with all the corners well rounded off; in others it is
practically a continuation of the cylinder, _i.e._, it is circular in
cross-section, with the back end more or less spherical; while, again,
it is made slightly oval in cross-section; but in every case the corners
should be _well_ curved and rounded off, so that there is no one part
which is liable to become heated disproportionately with the rest of the
casting; in fact,