As in the case of Van Depoele, whose perfection of the underrunning trolley was contested legally, Sprague's great contribution to electric traction, the suspension of the motor directly upon the axle, had finally to be sustained by the United States courts. Sprague's method was to hang the motor under the car directly upon the axle, by an extension or solid bearing attached directly to the motor. This plan of constructing the motor, together with numerous other improvements, principally in the direction of lightness, simplicity, and adaptability, soon superseded all pre-existing methods of construction. Thus Van Depoele's method of taking the current from the wire, and Sprague's method of utilizing it in the propulsion of the car, must be regarded as epoch-marking steps in the history of electric traction. Sprague's invention demonstrated the validity of his contention, now universally accepted, that motors should be placed under each car instead of being used on locomotives. STORAGE-BATTERY SYSTEMS From the earliest attempts at solving the question of electric traction, efforts were made to produce some form of storage battery whereby the cars might be made independent of a distant generating plant. The advantages of a self-contained vehicle are so obvious that it is not surprising to find the inventors persistent in their attempts at producing practical cars of this type. Such battery cars would not require the dangerous, expensive, and cumbrous system of overhead wires, or the more sightly but also more expensive system of conduits. With such a system of cars the elaborate mains and feeders for bringing the current to the track from the power-house, and for effecting the return circuit, could be dispensed with. Moreover, the independent action of such cars over a system where the power is furnished from a single source, where the stoppage of the current stops every car along the line, is inestimable. Between the years 1880 and 1883 many storage-battery cars were built and put in service both in European and American cities. Probably the most important one of these lines was that which was built by the Belgian, Mr. E. Julien, in New York city, in 1887-8. On the Fourth Avenue road something like a dozen storage-battery cars were put in operation for a considerable time, and later, improved modifications of these cars were operated in Philadelphia under the direction of Mr. Anthony Rackenzaun, of Vienna. But despite the apparent simplicity of the storage-battery idea, innumerable difficulties were perpetually presenting themselves in its practical application. Despite the disheartening results, however, storage-battery cars were not entirely abandoned in practice until 1903, New York city being the last to surrender, as it had been about the last to adopt them.