The Industrial Revolution in Europe could not have taken place without the work of James Watt, who is commonly credited with inventing the steam engine.
Watt was born in Greenock, Scotland, on January 19, 1736. At an early age he helped his father build ships and was exposed to the various technologies being developed at the time. In 1755, he left for London to study the craft of instrument making. He began working with steam in 1764 when Glasgow University, for which he worked, brought him a Newcomen engine for repair.
Watt not only repaired the engine, but he also began improving on it. He noted, for example, that the engine wasted time cooling the piston chamber during every cycle. Within five years Watt built a demonstration model that he patented as "a new method of lessening the consumption of steam and fuel in fire engines." This model introduced a second chamber where the condensing cycle took place, leaving the steam chamber hot and ready for a new batch of steam.
Watt's work with steam caught the attention of English engineer Matthew Boulton. In 1775 Watt entered a partnership with Boulton, whose factory was widely respected for its quality metalwork, plating, and silversmithing. Watt was continually searching for ways to improve existing technology. One of his innovations was the 1772 micrometer. This invention helped John Wilkinson perfect a boring machine that could drill cylinders with unprecedented uniformity, a necessary step towards Watt's next development--introducing steam on both sides of the piston . This innovation forced the piston in both directions rather than allowing atmospheric pressure to complete the condensation/vacuum cycle in its own time. These were the engines that he and Boulton began to market in 1775.
In 1781 Watt devised mechanical attachments to convert the rocking motion of the piston to a rotary movement that could more easily be used to power machinery. It was this step perhaps more than any other that led the steam engine to the forefront of Europe's Industrial Revolution. It was used to pump bellows for blast furnaces, to power huge hammers for shaping and strengthening forged metals, and to turn machinery at textile mills. For the first time, mills and factories were not limited to locations near streams or windy plains.
In 1788 Watt unveiled another major contribution to the realm of instrumentation and machine control by introducing the centrifugal governor. Since a similar device had been in use in windmills, Watt made no effort to apply for a patent. Still, it became commonly known as the Watt governor. Its importance centered around its automatic control of steam output. The governor consisted of two metal spheres mounted on a vertical rod that was spun by the engine's output of steam. The faster the rod spun, the farther the two spheres were thrown outward by centrifugal force. The farther the spheres were thrown, the more they choked off the steam outlet. As steam output decreased, so did intake as well as the engine's power output. As power and steam output decreased, the slower the spheres rotated, re-opening the steam outlet and beginning the reverse of the process. Engine output and speed could be controlled and adjusted between these two limits.
By 1790 Watt's engines had nearly replaced Newcomen's engines which were, for the most part, at least fifty years old. By this time Watt had added many other improvements such as a new type of condenser that used a system of tubes instead of one large chamber, an air pump to maintain a vacuum in the condenser, a jacket and "stuffing box" to prevent steam from escaping where the piston rod passed through the cylinder, a sun and planet gear that introduced rotary power to a generation of mills in Soho, and the later crankshaft that replaced this gear.
Watt's other ideas include the steam radiator heater, an office copying press, and a device that could reproduce sculptured busts.
Watt retired in 1800. He received an honorary doctorate degree from Glasgow University and was elected to the Royal Society. He died near Birmingham, England, on August 19, 1819, a successful and respected inventor whose contributions are used to this day. He is buried beside his former business partner, Matthew Boulton.