WHEN the Overhead Railway Company in 1891 decided to employ electric traction for their trains, the Electric Construction Corporation, of Wolverhampton, tendered for the equipment of the line, and secured an order for the complete installation, comprising boilers, engines, steam-pipes, dynamos, rolling-stock, station-lighting and signals. The plant was required to run a three-minutes' service on a double line 6 miles in length, and to accomplish this distance in twenty-nine minutes, including

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... ops of half-a-minute a t each one of thirteen stations. Each train was to consist of two cars, each car carrying fifty-six passengers, and being of an estimated weight of 12 tons 10 cwt. without motors. To meet this service, twenty trains running a t one time would be necessary, and in considering the power required at the dynamos, the subject was approached from its elementary basis. Curves were drawn to show the energy absorbed by one loaded train at every point in the whole length of the line, assuming various accelerations and intervals during which the brakes might be applied to bring the train to a standstill, the weight of a loaded train, with motors, being assumed to be 34 tons. These curves were modified and checked by the results of experience on ordinary railways, until results were obtained which would meet the service required. I n most cases the stations were so near one another (in one instance under 300 yards, and in others 400 yards) that the brakes had to be applied long before the train could attain a uniform speed, the greater part of the energy supplied to the motors being expended in accelerating the motion of the train, which was required by the specification to attain a speed of 30 miles per hour, if necessary. From these curves i t was an easy matter to calculate the power required for the whole service. This gave, allowing for the various electrical losses which were capable of being estimated, 1,200 to 1,400 amperes a t 500 volts, Downloaded by [ Purdue Univ Lib TSS] on [15/09/16].