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Captivity of Steam

History of the Steam Engine & James Watt


Engine 489 steaming out of the yard
Alan W Cole/ Photographer's Choice/ Getty Images
Steam engines used to pump water out of mines in England existed when James Watt was born. The discovery that steam could be harnessed and made to work is not credited to James Watt. We do not know exactly who made that discovery, but we do know that the ancient Greeks had crude steam engines. James Watt, however, is credited with inventing the first practical engine. And so the history of the "modern" steam engine often begins with James Watt.

James Watt

We can imagine a young James Watt, sitting by the fireplace in his mother's cottage, intently watching the steam rising from the boiling tea kettle, the beginning of a lifelong fascination with steam.

In 1763, when he was twenty-eight and working as a mathematical-instrument maker at the University of Glasgow, a model of Thomas Newcomen's steam pumping engine was brought into his shop for repairs. James Watt had always been interested in mechanical and scientific instruments, particularly those which dealt with steam. The Newcomen engine must have thrilled him.

James Watt set up the model and watched it in operation. He noted how the alternate heating and cooling of its cylinder wasted power. He concluded, after weeks of experimenting, that in order to make the engine practical, the cylinder had to be kept as hot as the steam which entered it. Yet in order to condense steam there had some cooling taking place. That was challenge the inventor faced.

James Watt's Invention of the Separate Condenser

James Watt came up with the idea of the separate condenser. In his journal the inventor wrote that the idea came to him on a Sunday afternoon in 1765, as he walked across the Glasgow Green. If the steam was condensed in a separate vessel from the cylinder, it would be quite possible to keep the condensing vessel cool and the cylinder hot at the same time. The next morning Watt built a prototype and found that it worked. He added other improvements and built his now famous improved steam engine.

James Watt Partners with Matthew Boulton

After one or two disastrous business experiences, James Watt associated himself with Matthew Boulton, a venture capitalist and owner of the Soho Engineering Works, near Birmingham. The firm of Boulton and Watt became famous, and James Watt lived until August 19, 1819, long enough to see his steam engine become the greatest single factor in the upcoming new industrial era.


Matthew Boulton and James Watt, however, though they were pioneers, were not the only ones working on the development of the steam engine. They had rivals, one was Richard Trevithick in England; another was Oliver Evans of Philadelphia. Independently, both Richard Trevithick and Oliver Evans invented a high-pressure engine. In contrast to Watt's steam engine, where the steam entered the cylinder at only slightly more than atmospheric pressure. Watt clung tenaciously to the low-pressure theory of engines all of his life. Matthew Boulton and James Watt, worried by Richard Trevithick's experiments in high-pressure engines, tried to have the British Parliament pass an act forbidding high pressure on the grounds that the public would be endangered by high-pressure engines exploding.

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