<P> Evidence indicates that there was 6 to 8.5 km long Diolkos paved trackway, which transported boats across the Isthmus of Corinth in Greece from around 600 BC . Wheeled vehicles pulled by men and animals ran in grooves in limestone, which provided the track element, preventing the wagons from leaving the intended route . The Diolkos was in use for over 650 years, until at least the 1st century AD . The paved trackways were also later built in Roman Egypt . </P> <P> Railways reappeared again only in the 14th century . </P> <P> In 1515, Cardinal Matthäus Lang wrote a description of the Reisszug, a funicular railway at the Hohensalzburg Castle in Austria . The line originally used wooden rails and a hemp haulage rope and was operated by human or animal power, through a treadwheel . The line still exists and is operational, although in updated form and is possibly the oldest operational railway . </P> <P> Wagonways (or tramways) using wooden rails, hauled by horses, started appearing in the 1550s to facilitate the transport of ore tubs to and from mines, and soon became very popular in Europe . Such an operation was illustrated in Germany in 1556 by Georgius Agricola (image right) in his work De re metallica . This line used "Hund" carts with unflanged wheels running on wooden planks and a vertical pin on the truck fitting into the gap between the planks to keep it going the right way . The miners called the wagons Hunde ("dogs") from the noise they made on the tracks . </P>

Which one of the following means of transport requires energy