Thomas Savery (1650-1715)Thomas Savery was an English military engineer and inventor who in 1698, patented the first crude steam engine, based on Denis Papin"s Digester or pressure cooker of 1679.Thomas Savery had been working on solving the problem of pumping water out of coal mines, his machine consisted of a closed vessel filled with water into which steam under pressure was introduced. This forced the water upwards and out of the mine shaft. Then a cold water sprinkler was used to condense the steam. This created a vacuum which sucked more water out of the mine shaft through a bottom valve.Thomas Newcomen (1663-1729)Illustration of Thomas Newcomen"s Engine circa 1712Thomas Newcomen was an English blacksmith, who invented the atmospheric steam engine, an improvement over Thomas Slavery"s previous design.The Newcomen steam engine used the force of atmospheric pressure to do the work. Thomas Newcomen"s engine pumped steam into a cylinder. The steam was then condensed by cold water which created a vacuum on the inside of the cylinder. The resulting atmospheric pressure operated a piston, creating downward strokes. In Newcomen"s engine the intensity of pressure was not limited by the pressure of the steam, unlike what Thomas Savery had patented in 1698.In 1712, Thomas Newcomen together with John Calley built their first engine on top of a water filled mine shaft and used it to pump water out of the mine. The Newcomen engine was the predecessor to the Watt engine and it was one of the most interesting pieces of technology developed during the 1700"s.Thomas Savery later worked with Thomas Newcomen on the atmospheric steam engine. Among Savery"s other inventions was an odometer for ships, a device that measured distance traveled.James Watt was a Scottish inventor and mechanical engineer, born in Greenock, who was renowned for his improvements of the steam engine. In 1765, James Watt while working for the University of Glasgow was assigned the task of repairing a Newcomen engine, which was deemed inefficient but the best steam engine of its time. That started the inventor to work on several improvements to Newcomen"s design.Most notable was Watt"s 1769 patent for a separate condenser connected to a cylinder by a valve. Unlike Newcomen"s engine, Watt"s design had a condenser that could be cool while the cylinder was hot. Watt"s engine soon became the dominant design for all modern steam engines and helped bring about the Industrial Revolution.A unit of power called the Watt was named after James Watt. the Watt symbol is W, and it is equal to 1/746 of a horsepower, or one Volt times one Amp.全部都在这里了。最后是瓦特的那部分改进。如果需要前面的也有，那就非常长了。蒸汽机从发明到瓦特那里正是开始使用，中间差不多200年。不过我们现在讨论的蒸汽机基本可以认为是瓦特发明的，虽然他只是改进，但是确实划时代的改进。
