Elertrk Pumps.—The numerous applications of electricity to pumping purposes which have been made (iring the last five years simply timonnt in most cases to the attachment to any form of pumping machine of an electric motor. Quite recently such applications have been made to heavy pumping, as for water-works, deep mines, etc. In the latter the power is transmitted from the electric generator on the surface to the motor at the bottom of the mine through copper wires or rods, thus dispensing with the cumbrous reciprocating pump-rods used in the Cornish system of mine pumps. or with the steam pipes used with direct-acting steam-pumps. Fig. 8 illustrates an electric motor applied to a duplex water-works pumping engine. The motor is of the Edison vertical type, arranged with insulated pinion, etc. The water end of the machine is the usual waterworks type, having composition plungers work inn through composition sleeves. The suction valves being placed below and the discharge valves above the plungers, gives the room necessary for a very large amount of valve area and water passages. This reduces the friction of the water as it passes through the pump to a minimum. There is a connection between the discharge of the pump (immediately under
the air chamber) and the suction-chamber with a gate valve on same ; the object of this arrangement is that when starting up the pumping-engine the pressure on the pump can be taken off the valves by letting the water flow back into the suction. The check valve on the discharge nozzle, which is necessary to this arrangement. is not shown by the illustration.
Duty Trials of committee of the Society of Mechanical Engineers, appointed in 1890 to report on a method of duty trials of pumping-engines, recommended that the old unit of duty per 100 lbs. of coal be abolished, and a new unit of 1,000,000 heat units be used in its place. This corresponds to the heat obtained from 100 lbs. of coal which develops 10,000 heat units per lb. The committee give full and explicit directions as to the method of making the various observations, as to the arrangement and use of instruments, and other provisions for the test. The complete report is published in Vol. XI. Trans. A. S. 1‘1. E., and it should be carefully studied prior to making preparations for a test.