of the same tubing as the barrel, sliding in a collar, C,
soldered to E. The bottom of D and top of E are bevelled to force the
packing against the plunger. The plates A and B, soldered to D and C
respectively, are drawn together by three or more screws. A brass door-knob
makes a convenient top for the plunger. When the knob touches A, the bottom
of the plunger must not come lower than the top of the delivery pipe, lest
the water flow should be impeded and the valve, V, injured. Round off the
end of the plunger, so that it may be replaced easily and without
disarranging the packing if pulled out of the pump.

The valves are gun-metal balls, for which seats have been prepared by
hammering in steel cycle balls of the same size. Be careful to select balls
considerably larger than the bore of the pipes on which they rest, to avoid
all possibility of jamming. An eighth of an inch or so above the ball,
cross wires should be soldered in to prevent the ball rising too far from
its seat.

[Illustration: FIG. 110.]

A convenient mounting for a hand pump is shown in Fig. 110. The plate, F,
of the pump is screwed to a wooden base resting on a framework of bent
sheet zinc, which is attached to the bottom of a zinc water tray. The
delivery pipe, G, will be protected against undue strains if secured by a
strap to the side of the wooden base.

The same pump is easily adapted to be worked by a lever, which makes the
work of pumping easier. Fig. 111 gives details of the top of the plunger
and the links, B. A slot must be cut in the plunger for the lever, A, to
pass through, and the sides bored for a pivot pin. The links are straddled
(see sketch of end view) to prevent the back end of the lever wobbling from
side to side.

[Illustration: FIG. 111.--Details of lever for force pump.]

A Steam Pump.--The pump illustrated in Fig. 112 belongs to what is
probably the simplest self-contained type, as no fly wheel, crank, or
eccentric is needed for operating the valve.

The steam cylinder and the pump are set in line with one another (in the
case shown, horizontally), and half as far apart again as the stroke of the
cylinder. The plunger is either a continuation of the piston rod, or
attached to it.

[Illustration: FIG. 112--View of steam pump, showing details.]

An arm, S, fixed at right angles to the piston rod, has a forked end which
moves along the rod. This rod is connected with the slide valve through the
rocking arm, R1 and the