A pantograph (or "pan" or "panto") is an apparatus mounted on the roof of an electric train, tram or electric bus to collect power through contact with an overhead line. By contrast, battery electric buses and trains are charged at charging stations. The pantograph is a common type of current collector; typically, a single or double wire is used, with the return current running through the rails. The term stems from the resemblance of some styles to the mechanical pantographs used for copying handwriting and drawings. Invention The pantograph, with a low-friction, replaceable graphite contact strip or "shoe" to minimise lateral stress on the contact wire, first appeared in the late 19th century. Early versions include the bow collector, invented in 1889 by Walter Reichel, chief engineer at Siemens & Halske in Germany, and a flat slide-pantograph first used in 1895 by the Baltimore and Ohio Railroad The familiar diamond-shaped roller pantograph was devised and patented by John Q. Brown of the Key System shops for their commuter trains which ran between San Francisco and the East Bay section of the San Francisco Bay Area in California. They appear in photographs of the first day of service, 26 October 1903. For many decades thereafter, the same diamond shape was used by electric-rail systems around the world and remains in use by some today. The pantograph was an improvement on the simple trolley pole, which prevailed up to that time, primarily because the pantograph allows an electric-rail vehicle to travel at much higher speeds without losing contact with the overhead lines, e.g. due to dewirement of the trolley pole. Notwithstanding this, trolley pole current collection was used successfully at up to on the Electroliner vehicles of the Chicago North Shore and Milwaukee Railroad, also known as the North Shore Line. Modern use The most common type of pantograph today is the so-called half-pantograph (sometimes 'Z'-shaped), which evolved to provide a more compact and responsive single-arm design at high speeds as trains got faster. Louis Faiveley invented this type of pantograph in 1955. The half-pantograph can be seen in use on everything from very fast trains (such as the TGV) to low-speed urban tram systems. The design operates with equal efficiency in either direction of motion, as demonstrated by the Swiss and Austrian railways whose newest high performance locomotives, the Re 460 and Taurus, operate with them set in the opposite direction.