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Steam
The breakthrough in the search for new power sources came in 1698 when Thomas Savery, using the newly discovered concept of vacuum, invented a vacuum-powered mine pumping engine. He called it "The Engine for Raising Water by Fire".
Thomas Newcomen had also been experimenting with steam. Newcomen formed a partnership with Savery and, in 1705, they developed an entirely new form of atmospheric engine.
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Thomas Savery (1650-1715)
In the mid-17th century, a number of European scientists were experimenting with gases and gas pressure. In England, Robert Boyle studied atmospheric pressure and formulated his gas laws. In Germany, Otto Van Guericke was studying the properties of a vacuum, while in France, Denis Papin experimented with pressure vessels.
Thomas Savery was born in Shilstone, Devonshire. As a military engineer he used the results of Papin's work to develop an inverted steam-driven water pump in 1696. Savery raised steam in a boiler. The steam was condensed in a separate container by spraying the container with cold water. As the steam condensed, it created a partial vacuum. This vacuum could be used to suck water up from the bottom of a mine shaft.
Savery patented his invention in 1698 under the title of "New Invention for Raiseing of Water and Occassioning Motion to all sorts of Mill Work by the Impellent Force of Fire". He widely advertised his invention and it aroused much interest. His customers included mine companies and buildings construction firms who needed to pump water to the top floor of large buildings. The major problem with Savery's engine was
that it would weaken if it was put under very high pressure. If the steam pressure reached between 8 and 10 atmospheres, there was a real danger that the engine would blow up. |
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Thomas Newcomen (1663-1729)
Thomas Newcomen was born at Dartmouth, Devonshire. He was an ironmonger by trade and he worked with his assistant, James Culley (or Cawley) who was a plumber. Together Newcomen and Culley spent ten years experimenting with steam engines which could
be used to draw water out of Cornish tin mines. In 1705, they were successful in developing a steam engine which Newcomen described as a "fire engine".
Since Savery held the patent for the steam driven water pump, Thomas Newcomen formed a partnership with him in 1698. In 1712, Newcomen built the first atmospheric steam engine in Staffordshire, in a workshop near Dudley Castle. The improvement made on Savery's original engine was that the intensity of the pressure was not limited by the steam pressure. In fact, it was the atmospheric pressure which pushed the
piston down. The weight of the wooden beam pulled up the piston which allowed steam from the boiler to enter the piston chamber. Cold water, which was stored in a separate tank, was then sprayed over the piston chamber. This condensed the steam and created a partial vacuum which pulled the rocking beam down towards the cylinder. This brought the pumping rod up in the mine shaft. The wooden beam then fell back down under the
influence of atmospheric pressure and the cycle was repeated.
Newcomen's engine was widely used in the tin mines of Cornwall and in mines in the north of England. Although the engine was not very energy-efficient and was expensive, it was not improved upon for over 50 years. |
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