page_title: Watt steam engine
section_title: Introduction
hierarchical_section_title: Watt steam engine / Introduction
caption_attribution_description: English: Photo of model Newcomen steam engine at the University of Glasgow, Scotland, which was repaired by James Watt. He used this model to test his separat condensor, inventing the modern steam engine. Caption (model): In 1764, James Watt. In working to repair this Model, belonging to the Natural Philosophy Class in the University of Glasgow, made the discovery of a separate Condenser, which has identified his name to with that of the Steam Engine. Original caption (book): 'The Newcomen engine, in the repairing of which Watt was led to his great discoveries. Preserved in the University of Glasgow.'
context_page_description: The Watt steam engine, alternatively known as the Boulton and Watt steam engine, was an early steam engine and was one of the driving forces of the Industrial Revolution. James Watt developed the design sporadically from 1763 to 1775 with support from Matthew Boulton. Watt's design saved so much more fuel compared with earlier designs that they were licensed based on the amount of fuel they would save. Watt never ceased developing the steam engine, introducing double-acting designs and various systems for taking off rotary power. Watt's design became synonymous with steam engines, and it was many years before significantly new designs began to replace the basic Watt design.
  The first steam engines, introduced by Thomas Newcomen in 1712, were of the "atmospheric" design. At the end of the power stroke, the weight of the object being moved by the engine, pulled the piston to the top of the cylinder, as steam was introduced. Then the cylinder was cooled by a spray of water, which caused the steam to condense, forming a partial vacuum in the cylinder. Atmospheric pressure on the top of the piston pushed it down, lifting the work object.
context_section_description: In 1698, the English mechanical designer Thomas Savery invented a pumping appliance that used steam to draw water directly from a well by means of a vacuum created by condensing steam. The appliance was also proposed for draining mines, but it could only draw fluid up approximately 25 feet, meaning it had to be located within this distance of the mine floor being drained. As mines became deeper, this was often impractical. It also consumed a large amount of fuel compared with later engines.
  The solution to draining deep mines was found by Thomas Newcomen who developed an "atmospheric" engine that also worked on the vacuum principle. It employed a cylinder containing a movable piston connected by a chain to one end of a rocking beam that worked a mechanical lift pump from its opposite end. At the bottom of each stroke, steam was allowed to enter the cylinder below the piston. As the piston rose within the cylinder, drawn upward by a counterbalance, it drew in steam at atmospheric pressure. At the top of the stroke the steam valve was closed, and cold water was briefly injected into the cylinder as a means of cooling the steam. This water condensed the steam and created a partial vacuum below the piston. The atmospheric pressure outside the engine was then greater than the pressure within the cylinder, thereby pushing the piston into the cylinder. The piston, attached to a chain and in turn attached to one end of the "rocking beam", pulled down the end of the beam, lifting the opposite end of the beam. Hence, the pump deep in the mine attached to opposite end of the beam via ropes and chains was driven. The pump pushed, rather than pulled the column of water upward, hence it could lift water any distance. Once the piston was at the bottom, the cycle repeated.
  The Newcomen engine was more powerful than the Savery engine. For the first time water could be raised from a depth of over 100 yards (91 m).  The first example from 1712 was able to replace a team of 500 horses that had been used to pump out the mine.  Seventy-five Newcomen pumping engines were installed at mines in Britain, France, Holland, Sweden and Russia. In the next fifty years only a few small changes were made to the engine design. It was a great advancement.
  While Newcomen engines brought practical benefits, they were inefficient in terms of the use of energy to power them. The system of alternately sending jets of steam, then cold water into the cylinder meant that the walls of the cylinder were alternately heated, then cooled with each stroke. Each charge of steam introduced would continue condensing until the cylinder approached working temperature once again. So at each stroke part of the potential of the steam was lost.
caption: The model Newcomen engine upon which Watt experimented
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