Trevithicks high pressure stationary engine no 14, c 1805.

UNITED KINGDOM - JUNE 19: In 1802 Richard Trevithick (1771-1833) and Andrew Vivian obtained a patent for high-pressure, non-condensing engines. Trevithick went on to develop this particular engine three years afterwards, which used steam pressures of approximately 50 pounds per square inch. It was built by Hazledine & Co of Bridgnorth, Shropshire, who had a reputation for high-quality work, and was probably used for pumping, winding or driving machinery. Previously, all steam engines were low pressure machines with a small power output in relation to their size. High pressure engines were more compact than their predecessors, making the application of steam in the form of railway locomotives practicable. (Photo by SSPL/Getty Images)