boiler-room (Fig. 91). Similar drains are fitted aft, draining into the engine-rooms. At the forward end we notice that two pipes, 8 in. diameter, are used, and into these we have pipes leading from barbette, submerged torpedo-room, torpedo-tubes, chain lockers, etc. The forward and after drains, and also the main drain, each have connection to a sea valve for flushing purposes. The wing

compartments and inner coal-bunkers are drained on to the top of the inner bottom, as shown in Figs. 91 and 93.

When a flat requires draining, a valve, as Fig. 99, is fitted. Above the flat there is a strainer with screw-down valve, and below the flat a flap valve to act as non-return.

Pumping. For freeing the ship of ordinary quantities of water, a main suction is fitted above the inner bottom, extending nearly the whole of the ship's length. Screw-down valves, marked S in Fig. 92, are fitted on this main suction at each main transverse bulkhead in order to preserve the watertightness of the bulkhead in the event of the pipe being damaged on either side. Fig. 92 shows a portion of this main suction. Pipes are taken from it to the doublebottom compartments, and on each of these branches a valve, F, is fitted, which under ordinary circumstances acts as a screw-down non-return valve. The valve, however, can be unlocked and lifted off its seat, when it will allow the compartment to be flooded (see Fig. 97 for construction of valve). The double bottom between Nos. 2 and 4 longitudinals is drained through S.V. on No. 2 longitudinal, as shown in Fig. 93, to the suction at the middle line (except in way of the portion of the double bottom used for the reserve feed water). Suctions are also led from the main suction to shallow pockets in the engine and boiler-room bilges; these suctions have a S.D.N.R. valve, without the flooding arrangement shown in Fig. 97. A suction is also taken from these pockets, independent of the main suction, direct to the steam pumps. Mud pockets, M, are placed at intervals on the main suction as shown. This main suction also has branches to the bottom of the ship, forward and aft of the double bottom, as shown in Fig. 92. The main suction is connected with the steam pumps in the engine-room, so that any desired compartment may be pumped out by the use of the steam pumps of the ship.

Downton Pumps.-A connection is also made with each of the four 9-in. Downton hand pumps. These are placed in recesses in the ammunition passages (Fig. 93). Each Downton is geared to work from either the main or middle decks, as most convenient, by means of long cranks, on to which a number of men can be placed.

HOSE

DELIVERY

SUCTION

FIG. 94.-Downton pump.

The Downton is a double-acting pump, shown in outline in Fig. 94. There are four valves, A, B, C, and D, all opening upwards. A piston works up and down as shown. Suppose water is in the tail pipe and the piston comes down. This causes B to close and A to open, so that air is forced up the left-hand side of the pump. This action creates a partial vacuum above the piston, and water

will rise and fill the upper part of the piston chamber. During the upward movement this water is forced up through the valve C, the valve D closing. The water which then collects below the piston is forced away during the downward stroke. In this way a continuous flow of water is delivered either overboard through the discharge or into the rising main (Fig. 93).

Fig. 95 shows in diagram the various leads from a Downton pump. There are three valves, viz.

1. A screw-down (S.D.) valve connecting to the Kingston valve (K) (see Fig. 98 for construction of a Kingston).

2. A screw-down non-return and flood (S.D.N.R. and F.) valve (Fig. 97) connecting to the main suction (M).

3. A S.D. valve connected to the tail pipe of the pump. The pump has

(i.) A discharge overboard through S.D. valve (D).

(ii.) A discharge into a rising main with a branch into the fire main.

The branch to the fire main has a N.R. valve, E, so arranged