Richard Trevithick was a young engineer but was responsible for one of the most important of all inventions - the first steam locomotive. In 1795, when he was only 25 years old, Trevithick was building working models of high-pressure steam engines. Cornish tin and Welsh coal miners used his early engines to power carts from 1800, and, in 1804 his first steam locomotive, the Penydarren, was unveiled and ran at the heart-stopping speed of 5 m.p.h. The most revolutionary feature of Trevithick's 1804 locomotive was the fact that it had smooth wheels operating on smooth metal rails. Until Trevithick's achievement, engineers has said it was impossible to run an engine on non-geared track, but he had proved them wrong and the golden era of the steam locomotive had begun.