A drawing of a Trevithick railway locomotive, believed to be his Coalbrookdale locomotive of 1803. The Penydarren engine was probably similar.
Image: Science Museum/SSPL

The Penydarren locomotive

Trevithick turned his interest to railway locomotion. In 1802 he oversaw the building of an experimental locomotive at Coalbrookdale, but it is not known if this ever ran.

A year later he designed a locomotive for Samuel Homfray, the owner of Penydarren Ironworks in south Wales. On 21 February 1804 this locomotive successfully hauled a load along the nearby Merthyr Tramroad. This was the first steam-hauled train in the world. In Trevithick's own words, 'we have plenty of steam and power'.