The pump cylinders, 8 × 12 inches, have a computed capacity of 700 gallons per minute at 140 pounds water pressure. The pump, besides its other special features, is claimed to be rust proof throughout so that it will not get out of ready running condition. [Illustration: FIG. 243.] ELECTRIC-MINING PUMPS. The electric system has especial conveniences for mine pumping because of its adaptability to long transmissions of power; electric power can be transmitted to almost any distance, and the pumps can be supplied with either direct or alternating current motors. A mining outfit can be easily divided into a number of parts, to facilitate lowering into a mine, after which the assembling of the parts is a simple operation. Stationary pumps for mine use are made in two classes: first, vertical pumps having cylinders in a vertical position in which the over all height is comparatively great and the horizontal dimensions as small as possible; second, horizontal pumps with cylinders in a horizontal position and having for cross dimensions the over all length. The class of pump to be selected, of course, depends upon the limitations of the location. In either case, the motor used for driving the pump is mounted on an extension of the pump base, making a self-contained and compact outfit. Engraving, Fig. 243, represents a Quintuplex pump used principally in mining operations, or wherever large quantities of water are to be delivered under high pressure in the shortest possible space of time. The pump here shown was designed to deliver 225 gallons of water per minute under a head of 1,200 feet. It has five plungers 4 inches in diameter each and having a uniform stroke of 12 inches. These pumps driven by electric motors it is said represent the most economical method of transmitting power, as compared with the best designs of steam pumps. An efficiency of 80 per cent. is claimed for these pumps. NOTE.—It is interesting to know that in one of the largest electric pumping installations which has ever been made for mining work, the power is carried 2,500 feet underground at a potential of 3,500 volts and then transformed into 220 volts at the motors. No trouble has thus far resulted from the high voltage or any other cause; in regard to danger from underground electric pumps, it can be stated that accidents due to the use of electricity in such installations are almost unknown. _Induction motors are arranged to operate without moving contacts._ They are therefore free from sparks and can be used in mines where the presence of gases compels the use of safety lamps. Fig. 244 exhibits an electric induction motor operating a 5-1/2 × 8 portable track pump. Portability is an important feature in all pumps for mine use; and, as track pumps may be put into service immediately at any point on a system of tracks, they meet this requirement better than pumps of any other form.