<P> The first practical mechanical steam engine was introduced by Thomas Newcomen in 1712 . Newcomen apparently conceived his machine quite independently of Savery, but as the latter had taken out a very wide - ranging patent, Newcomen and his associates were obliged to come to an arrangement with him, marketing the engine until 1733 under a joint patent . Newcomen's engine appears to have been based on Papin's experiments carried out 30 years earlier, and employed a piston and cylinder, one end of which was open to the atmosphere above the piston . Steam just above atmospheric pressure (all that the boiler could stand) was introduced into the lower half of the cylinder beneath the piston during the gravity - induced upstroke; the steam was then condensed by a jet of cold water injected into the steam space to produce a partial vacuum; the pressure differential between the atmosphere and the vacuum on either side of the piston displaced it downwards into the cylinder, raising the opposite end of a rocking beam to which was attached a gang of gravity - actuated reciprocating force pumps housed in the mineshaft . The engine's downward power stroke raised the pump, priming it and preparing the pumping stroke . At first the phases were controlled by hand, but within ten years an escapement mechanism had been devised worked by of a vertical plug tree suspended from the rocking beam which rendered the engine self - acting . </P> <P> A number of Newcomen engines were successfully put to use in Britain for draining hitherto unworkable deep mines, with the engine on the surface; these were large machines, requiring a lot of capital to build, and produced about 5 hp . They were extremely inefficient by modern standards, but when located where coal was cheap at pit heads, opened up a great expansion in coal mining by allowing mines to go deeper . Despite their disadvantages, Newcomen engines were reliable and easy to maintain and continued to be used in the coalfields until the early decades of the nineteenth century . By 1729, when Newcomen died, his engines had spread to France, Germany, Austria, Hungary and Sweden . A total of 110 are known to have been built by 1733 when the joint patent expired, of which 14 were abroad . In the 1770s, the engineer John Smeaton built some very large examples and introduced a number of improvements . A total of 1,454 engines had been built by 1800 . </P> <P> A fundamental change in working principles was brought about by James Watt . With the close collaboration of Matthew Boulton, he had succeeded by 1778 in perfecting his steam engine which incorporated a series of radical improvements, notably, the use of a steam jacket around the cylinder to keep it at the temperature of the steam and, most importantly, a steam condenser chamber separate from the piston chamber . These improvements increased engine efficiency by a factor of about five, saving 75% on coal costs . </P> <P> The Newcomen engine could not, at the time, be easily adapted to drive a rotating wheel, although Wasborough and Pickard did succeed in doing so in about 1780 . However, by 1783 the more economical Watt steam engine had been fully developed into a double - acting rotative type with a centrifugal governor, parallel motion and flywheel which meant that it could be used to directly drive the rotary machinery of a factory or mill . Both of Watt's basic engine types were commercially very successful . </P>

Which was not a source of energy introduced during the late 1800's