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MODERN STEAM PRACTICE.
the exit of the fluid. The weighted lever is so arranged that the plugrod lifts the plunger and weight, and the cataract rod for disengag-
a, Cast-iron box. b, Plunger. c, Intet valve. d, Plug rod. e, Lever. f, Weight.
G, Regulating spindle and valve.
ing the valves ascends as the plunger and weight descend, themotion being changed by a lever; the cataract rod for lifting thepaul is jointed at one end of the lever, and the rod passing down tothe arm for the weight and plunger at the other end.
In some examples of the plunger type, when two cataracts are used,the plug-rod tappet acts on the two levers for lifting the plungerssimultaneously; on the centre of motion of the levers a groovedwheel is fixed, and the lever for the cataract pump is connected bymeans of a chain wound round the wheels, and as the tappet orplug rod comes in contact with the levers the wheels are partiallyturned round, pulling one end of the cataract lever down, andraising the other end, to which the plunger and weight are fitted.Some arrangements of cataract pumps have a solid piston, or onefitted with cupped leather washers, and on the top of the piston roda crosshead and side rods passing down under the floor of theengine house, and in communication with the mechanism for liftingthe piston and weight placed on the top of the crosshead. A centralmetallic valve is placed at the bottom of the pump, and a tap islikewise fitted for regulating the ejection of the oil, which is gene-rally used when the cataract is placed on the engine-room floor.This type of cataract has likewise a reservoir for receiving and sup-plying the oil; and as leakage past the piston ring occurs afterbeing long in use, an air passage is formed above the piston incommunication with the reservoir, and any oil passing the piston is