 Although that experiment ended in failure, in 1802 the Coalbrookdale Company built a locomotive for him, but little is known about it, including whether or not it actually ran.In 1804, he built a successful unnamed rail going steam locomotive for the narrow gauge Merthyr Tramroad in South Wales (sometimes - but incorrectly - called the "Penydarren Tramroad").The Penydarren locomotive used a high-pressure cylinder without a condenser, the exhaust steam being used to assist the draught via the firebox, increasing efficiency even more.