e inclined surfaces being for this purpose equivalent to the
operation of a ball and socket bearing.

Figure 314 gives a side and an edge view of the connecting rod, the rod
being in section in the edge view, and the brasses in section lined in
both views.

The cross-head pin, it will be observed, is tapered, and is drawn home
in the cross-head by a bolt; the sides of the pin are flattened somewhat
where the journal is, so that the pin may not wear oval, as it is apt to
do, because of the pull and thrust strain of the rod brasses falling
mainly upon the top and bottom of the journal, where the most wear
therefore takes place. The brasses at the crossed end are set up by a
wedge adjustable by means of the screw bolts shown. The cross-head wrist
pin being removable from the cross-head enables the upper end of the rod
to have a solid end, since it can be passed into place in the crossed
and the wrist pin inserted through the two. The lower ends of the
connecting-rod and the crank-pin possess a peculiar feature, inasmuch as
by enlarging the diameter of the crank-pin, the ends of the brasses
overlap, to a certain extent, the ends of the journal, thus holding the
oil and affording increased lubrication. The segments that partly
envelop the cross-head pin and crank-pin, and are section lined in two
directions, producing crossing section lines, or small squares, show
that the brasses are lined with babbitt metal, which is represented by
this kind of cross-hatching. These drawings are sufficiently open and
clear to form very good examples to copy and to trace on tracing paper.

[Illustration: Fig. 315.]

[Illustration: Fig. 316. (Page 296.)]

[Illustration: Fig. 317.]

Figures 315, 316 and 317 represent, in place upon its setting, a 200
horse-power horizontal steam-boiler for a stationary engine, and are the
design of William H. Hoffman. The cross-sectional view of the boiler
shell in Figure 315 shows the arrangement of the tubes, which, having
clear or unobstructed passages between the vertical rows of tubes,
permits the steam to rise freely and assists the circulation of the
water. The dry pipe (which is also shown in Figure 316) is a perforated
pipe through which the steam passes to the engine cylinder, its object
being to carry off the steam as dry as possible; that is to say, without
its carrying away with the steam any entrained water that may be
held in suspension. Figure 316 is a side elevation with the setting
sh