but offset to the west of centre for clearance reasons. Although the use of electricity to power trains had been experimented with during the previous decade, and small-scale operations had been implemented, the C&SLR was the first major railway in the world to adopt it as a means of motive power. The system operated using electric locomotives built by Mather & Platt collecting a voltage of 500 volts (actually +500 volts in the northbound tunnel and −500 volts in the southbound) from the third rail and pulling several carriages. A depot and generating station were constructed at Stockwell. Owing to the limited capacity of the generators, the stations were originally illuminated by gas. The depot was on the surface, and trains requiring maintenance were initially hauled up via a ramp although, following a runaway accident, a lift was soon installed. In practice, most rolling stock and locomotives went to the surface only for major maintenance. To avoid the need to purchase agreements for running under surface buildings, the tunnels were bored underneath public roads, where construction could be carried out without charge. At the northern end of the railway, the need to pass deep beneath the bed of the River Thames and the medieval street pattern of the City of London constrained the arrangement of the tunnels on the approach to King William Street station. Because of the proximity of the station to the river, steeply inclined tunnels were built to the west of the station. Because of the narrow street under which they ran, they were bored one above the other rather than side by side as elsewhere. The outbound tunnel was the lower and steeper of the two. The tunnels converged immediately before the station, which was in one large tunnel and comprised a single track with a platform on each side. The other terminus at Stockwell was also constructed in a single tunnel but with tracks on each side of a central platform. Opening The railway was officially opened by Edward, Prince of Wales (later Edward VII) on 4 November 1890, and was opened to the public on 18 December 1890. Initially, it had stations at: Stockwell The Oval (now Oval) Kennington Elephant & Castle Borough King William Street At the opening the Prince of Wales gave the following speech: The original service was operated by trains composed of an engine and three carriages. Thirty-two passengers could