See Also: Boiler, Boiler - Water Tube Type
Savery, Watt (see Watt, James), and Newcomen Steam Engines all operated at Pressures only slightly above atmospheric pressure. In 1800 the American inventor
Oliver Evans built a high-pressure steam engine utilizing a forerunner of the
fire-tube boiler. Evans's boiler consisted of two cylindrical shells, one inside the
other; Water occupied the region between them. The fire grate and flue were housed inside
the inner cylinder, permitting a rapid increase in steam pressure.
Simultaneously but independently, the British engineer (see Engineer - You Might Be One If ... ) Richard Trevithick developed a similar Cornish boiler. The first major improvement over Evans's and Trevithick's boilers was
the fire-tube Lancashire Boiler, patented in 1845 by the British engineer Sir William Fairbairn, in which hot
combustion Gases were passed through tubes inserted into the water container, increasing the
surface area through which Heat could be transferred. Fire-tube boilers were limited in capacity and pressure
and were also, sometimes, dangerously explosive (see Explosive).