[Illustration: Fig. 25.]

114. _Q._--These remarks apply to all paddle vessels?

_A._--They do. With respect to the side lever engine, it may be described
to be such a modification of the land beam engine already described, as
will enable it to be got below the deck of a vessel. With this view,
instead of a single beam being placed overhead, two beams are used, one of
which is set on each side of the engine as low down as possible. The cross
head which engages the piston rod is made somewhat longer than the diameter
of the cylinder, and two great links or rods proceed one from each end of
the cross head to one of the side levers or beams. A similar cross bar at
the other end of the beams serves to connect them together and to the
connecting rod which, proceeding from thence upwards, engages the crank,
and thereby turns round the paddle wheels.

115. _Q._--Will you further illustrate this general description by an
example?

[Illustration: Fig. 26.]

_Q._--Fig. 26 is a side elevation of a side lever engine; x x represent the
beams or keelsons to which the engines are attached, and on which the
boilers rest. The engines are tied down by strong bolts passing through the
bottom of the vessel, but the boiler keeps its position by its weight
alone. The condenser and air pump are worked off the side levers by means
of side rods and a cross head. A strong gudgeon, called the _main centre_,
passes through the condenser at K, the projecting ends of which serve to
support the side levers or beams. L is the piston rod, which, by means of
the cross head and side rods, is connected to the side levers or beams, one