Watt steam engine

The Watt steam engine was the next great step in the development of the steam engine after the Newcomen engine. Offering a dramatic increase in fuel efficiency for what was a minor design change, the new design was soon retrofitted to almost all existing Newcomen engines, and then went on to be used in place of most natural power sources such as wind and water. Watt's design became synonymous with steam engines, due in no small part to his partner, Matthew Boulton.

Related Topics:
Steam engine - Newcomen engine - Fuel efficiency - Matthew Boulton

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Newcomen's design was both powerful and useful; the first example from 1711 was able to replace a team of 500 horses that had powered a wheel to pump out a mine. In over fifty years few detail changes had been made to the basic design, seventy-five of which could now be found at mines all over England.

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However effective the system was, it was also expensive to run. It worked by creating a vacuum in a cylinder by condensing steam inside it. This process was normally so slow that the engine was not very effective, so to improve the condensation a small spray of water was introduced when the cylinder was filled with steam. Unfortunately the water also cooled the cylinder walls, so when the next charge of steam was introduced it spent some time simply warming the cylinder back up to boiling temperatures, condensing while this occurred.

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A Scottish instrument maker, James Watt, was given the job in 1763 of repairing a model Newcomen engine for the University of Glasgow, and noted how inefficient it was. In 1765, while wandering across Glasgow Green he conceived the idea of a separate condensing chamber for the steam engine. Watt's idea was to separate the condensation system from the cylinder, moving the cooling water in a second cylinder, C, attached to the main one through a valve V'. When the piston had reached the top of the cylinder, the valve V was closed and V' was opened. Then the steam rushed from the cylinder into the condenser, which was kept cold and under less than atmospheric pressure. At first these valves V and V' had to be operated by hand, but later, it is said, a boy named Potter, whose job it was to turn these valves, connected the valve handles by cords to the beam ED in such a way that the machine became automatic.

Related Topics:
Scottish - James Watt - University of Glasgow - Glasgow Green - Condensation - Valve - Piston - Cylinder

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Watt met Matthew Boulton and became a member of the Lunar Society. He told Bolton about his ideas on improving the engine, and Bolton, an avid entrepreneur, agreed to fund development of a test engine at Soho, near Birmingham. This proved frustrating and Watt repeatedly almost gave up on the project, only to be convinced to continue by the ever-cheery Boulton.

Related Topics:
Matthew Boulton - Lunar Society - Entrepreneur - Soho - Birmingham

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The improvement due to this change was dramatic: Watt's design used about 75% less fuel than a similar Newcomen engine. Since the changes were fairly limited, Boulton and Watt licensed the idea to existing Newcomen engine owners, taking a share of the cost of fuel they saved.

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Watt was unwilling to rest on his laurels, and continued to improve his designs throughout his life. He first turned his attention to providing rotary power from his engines, introducing the sun and planet gear system invented by his employee William Murdoch, and later adopting the more familiar crankshaft seen on most engines today. This allowed the steam engine to be used to replace water wheels, thereby freeing British industry from geographical constraints and becoming one of the main drivers in the industrial revolution.

Related Topics:
Sun and planet gear - William Murdoch - Crankshaft - Water wheel - Industrial revolution

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In order to improve reliability, he introduced the centrifugal governor, automatically controlling steam flow to the engine and keeping it at a steady speed. He also introduced the manometer to measure steam pressure within the engines.

Related Topics:
Centrifugal governor - Manometer

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Watt also continued to work on more advanced versions of the basic engine, introducing the double-acting design which used the steam twice per stroke.

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The oldest working engine in the world is the Smethwick Engine, brought into service in May 1779 and now at Millennium Point in Birmingham (formerly at Birmingham Museum of Science & Industry). The oldest still in its original engine house and still capable of doing the job for which it was installed is the 1812 Boulton and Watt engine at the Crofton Pumping Station. This was designed to pump water for the Kennet and Avon Canal and on certain weekends throughout the year the modern pumps are switched off and the two steam engines at Crofton still perform this function.

Related Topics:
Smethwick Engine - 1779 - Millennium Point - Birmingham - Crofton Pumping Station - Kennet and Avon Canal

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