<P> A steam turbine is a device that extracts thermal energy from pressurized steam and uses it to do mechanical work on a rotating output shaft . Its modern manifestation was invented by Sir Charles Parsons in 1884 . </P> <P> Because the turbine generates rotary motion, it is particularly suited to be used to drive an electrical generator--about 90% of all electricity generation in the United States in the year 1996 was by use of steam turbines . The steam turbine is a form of heat engine that derives much of its improvement in thermodynamic efficiency from the use of multiple stages in the expansion of the steam, which results in a closer approach to the ideal reversible expansion process . </P> <P> The first device that may be classified as a reaction steam turbine was little more than a toy, the classic Aeolipile, described in the 1st century by Hero of Alexandria in Roman Egypt . In 1551, Taqi al - Din in Ottoman Egypt described a steam turbine with the practical application of rotating a spit . Steam turbines were also described by the Italian Giovanni Branca (1629) and John Wilkins in England (1648). The devices described by Taqi al - Din and Wilkins are today known as steam jacks . In 1672 an impulse steam turbine driven car was designed by Ferdinand Verbiest . A more modern version of this car was produced some time in the late 18th century by an unknown German mechanic . In 1775 at Soho James Watt designed a reaction turbine that was put to work there . In 1827 the Frenchmen Real and Pichon patented and constructed a compound impulse turbine . </P> <P> The modern steam turbine was invented in 1884 by Sir Charles Parsons, whose first model was connected to a dynamo that generated 7.5 kW (10 hp) of electricity . The invention of Parsons' steam turbine made cheap and plentiful electricity possible and revolutionized marine transport and naval warfare . Parsons' design was a reaction type . His patent was licensed and the turbine scaled - up shortly after by an American, George Westinghouse . The Parsons turbine also turned out to be easy to scale up . Parsons had the satisfaction of seeing his invention adopted for all major world power stations, and the size of generators had increased from his first 7.5 kW set up to units of 50,000 kW capacity . Within Parson's lifetime, the generating capacity of a unit was scaled up by about 10,000 times, and the total output from turbo - generators constructed by his firm C.A. Parsons and Company and by their licensees, for land purposes alone, had exceeded thirty million horse - power . </P>

Who described the basic mechanism of steam reaction