Arrninulators. or storage batteries, are used to a limited extent for the operation of elec tric railways. By this method the stored energy, conveyed to a motor in the form of current., sets it in motion, and with it the ear. Looked at from the standpoint of convenience and applirobility. the propulsion of tram-cars through the medium of accumulators must he conceded to be second to no other. The batteries occupy no valuable space, being stowed under the seats, while the motor can be placed under the ear body. London, Brussels, Paris, New York, Philadelphia, Boston, Washington, and San Francisco, have all seen tram cars run by accumulators. In Berlin, Mr. A. Reckenzaun made a successful demonstration with his motor applied to street ears, and deriving current from accumulators. Fig. 22 shows the ear, in part sectional elevation. The various arrangements may be classed under the following headings, viz. : 1. The battery. 2. The motors. 3. Transmitting gear. 4. Speed regulation. 5. The brakes.
(1) The battery consisted of GO cells, each weighing 40 lbs., and with a capacity of 150 ampere-hours. They were piaced on a board under the seats of the car, resting on rollers, so that they could be readily run in and out. There were two rows of 15 cells each under each seat. They were coupled in series, and hence gave an electromotive force of from 110 to 120 volts.
The storage batteries were changed every two or four hours, according to the length of the trip, and the change could be performed in about three minutes, not occupying more time than a change of horses.
(2) The electric motors employed were of the Reckenzaun model. They weighed 420 lbs., and were capable of delivering from four to nine horse-power. At 120 volts their efficiency was 75 per cent., and at the nominal speed of 7 miles per hour they made 1,000 revolutions per minute. lint this speed could be raised to 10 miles per hour.
(3) The car body was mounted upon two trucks, each of which carried a motor and worm gearing was employed to transmit power from the armature shaft to the axles of the wheels.
(4) Changes in speed were effected by different combinations between the whole battery and the two motors.
Two forms of brake could be brought into play on the ear : the ordinary mechanical, and the electrical brakes. The latter were called into action automatically when the switch cut off the battery current. The motors were then converted into dynamos which generated a current that was sent into the coils on the brake-shoes, magnetizing them so that they were attracted by, and pressed against, the wheels. At the same time the resistance encountered by the armature turning in the magnetic field also acted powerfully to retard the speed, and both these acting together brought the car rapidly to a halt.
THE PoRTELeCTRie SYSTEM, invented by J. T. Williams, is designed for the rapid convey ance of mail and express matter between distant points. The carrier, Fig. 2:1, is a hollow,
cylindrical projectile of wrought-iron, with ogival ends, the cylindrical portion being 8 ft, long and 10 in. in diameter, the length 12 ft. over all, and the weight, approximately, 500 lbs. It has capacity to contain, say, 10,000 letters, weighing, per haps, 175 lbs, It is provided with two flanged wheels above, and two underneath, all of which, being fitted with ball bearings, revolve with very slight friction. The propelling power is derived from a series of hollow helices of insulated copper wire, each of which encircles the track and carrier, Fig. 24. These are fixed along the permanent way at inter vals. A contact wheel, mounted upon the carrier, and running in contact with the upper track-rail :which is divided into sections, and utilized as an electric conductor). connects the several helices in succession with the source of electricity as the carrier moves forward upon the track. The actual cost of the electric power required to propel the carrier at 150 miles per hou r is claimed to be five cents per horse-power hour. including cost of attendance at stations. The mere cost of power for propelling a carrier from Boston to New York would, therefore, not exceed seventy-five cents per trip. Excessive estimates of the cost of a double-track line, making liberal allowances in all directions, do not exceed 835,000 per mile, or about $7,000, 000 for a line between Boston and New York. It has been proposed to use this system for speedy mail delivery in New York City.
TELPHERAGE.—Telpherage is the name given to a system devised by the late Prof. Fleem ing Jenkin, and worked out by Professors Ayrton and Perry, of transportation of goods and passengers by overhead suspended cars driven by electric motors. Generically considered, a telpher line system consists of a rod or rail track of considerable length, suspended several feet from the ground, connected with a source of electricity placed at some convenient place at or near the course of the track, and traversed by an electro-locomotive which derives its motive power electrically from the track. draws a number of small holders of ireight or passengers, and is controlled, as to its motion, from a place or places other than itself, On the telpher line built at Weston, England, the wire is five-eighths of an inch in diameter.
The load is carried in seven skips. the first being seen in Fig. 25. About half a ton can be put into each skip and a speed obtained of six miles an hour. The principle of the system of telpherage is best shown forth in a commercial line that was put into operation at Glyude, England, to carry clay from a pit to the Glynde railway siding, whence it was delivered into trucks and taken by rail to its ultimate destination.