A method of transport for passengers and goods in which wheeled vehicles move along steel tracks, flanges on the steel wheels engaging with the rails and thereby guiding them, so the driver does not have to steer. Each vehicle may be self-powered, or a train of unpowered vehicles, then called rolling stock, may be towed or pushed by a locomotive. In the earliest railways, dating from the sixth century bc, slaves provided the motive power. A funicular railway, the Reißzug, running on wooden rails and drawn by a rope pulled by human or animal power, was installed to bring supplies to the Hohensalzburg Castle, Salzburg, Austria, in around 1500; a funicular still runs along the same route. Horses were also employed to pull trains along rail tracks. Steam locomotives appeared early in the nineteenth century.