Four-way plug cock for steam distribution, 1804.

Drawing (scale 1:2) believed to be by Richard Trevithick (1771-1833). Trevithick was the first to use high presured steam to drive an engine. Until 1800, the weaknes of existing boilers had restricted all engines to being atmospheric ones. Trevithick set about making a cylindrical boiler which could withstand steam at higher presures. This new engine was well suited to driving vehicles. In 1804, Trevithick was responsible for the first succesful railway locomotive.