Watt's Steam Engine

Date 1765-1769

Watt’s improved steam engine ushered in the low-cost, efficient use of steam power for coal mining and manufacturing and permitted the extraordinary development and diffusion of the Industrial Revolution.

Locale Glasgow, Scotland

Key Figures

• James Watt (1736-1819), Scottish engineer
• Joseph Black (1728-1799), a professor of chemistry at the University of Glasgow
• Matthew Boulton (1728-1809), owner of the Soho engineering works in Birmingham, England
• Thomas Newcomen (1663-1729), inventor of an earlier steam engine called the “atmospheric engine”
• John Robison (1739-1805), a lecturer and later professor of chemistry at the University of Glasgow
• John Roebuck (1718-1794), owner of the Carron ironworks in Scotland

Summary of Event

James Watt was the son of a Scottish architect and shipbuilder. He began his career in 1757 as a maker of scientific instruments on the staff of the University of Glasgow. While there he attended the lectures of Joseph Black, who was developing his theory of latent heat, and he also became well acquainted with John Robison, a brilliant young chemist. Robison directed his attention to the problems of existing steam engines, and when Watt was asked, during the winter of 1763-1764, to repair a model of the Newcomen engine, he was led to a critical study of its workings.

The Newcomen engine, which had been in use in England since the second decade of the eighteenth century, had been designed to pump water from deep mines, but in time it came to be used in ore smelters, ironworks, and textile mills. Although the engine worked and was regarded by many as one of the marvels of the age, it had many defects, and increasing use of it emphasized its shortcomings.

The principal problem was that it operated on atmospheric pressure alone. Steam from a boiler entered a cylinder and raised a piston balanced by a counterweight; a jet of cold water forced into the cylinder then condensed the steam, and the piston returned on a downward stroke through the force of atmospheric pressure, each cycle requiring about four seconds. Newcomen’s engine was highly inefficient by modern standards. It operated at atmospheric pressure or less, did not use the expansive force of steam to pull or to push anything, and wasted about 99 percent of its fuel. Critics complained that it took an iron mine to build a Newcomen engine and a coal mine to keep it going.

Watt designed improvements that were so fundamental that they constituted a series of separate inventions and rendered atmospheric engines obsolete, though many remained in use well into the nineteenth century. Watt had been interested in steam since 1761, with experiments in high-pressure steam. Watt realized that, to save fuel required for constantly reheating the cooled Newcomen cylinder, the steam should be condensed away from the cylinder, allowing it to remain hot. Black was able to help Watt apply the former’s concept of latent heat to the problem of keeping the cylinder hot in the atmospheric engine. This “separate condenser,” invented in 1765, was the first improvement on Newcomen’s engine, and it saved three-fourths of the fuel.

Watt was a tireless, perhaps compulsive engineer. The steam engine and subsequent design improvements provoked his mind unceasingly. Over the next four years, finding time between assignments in his new career as land surveyor, Watt made two additional improvements. One was an air pump that exhausted condensed steam, and the second was enclosing the upper end of the cylinder and building a steam-tight gland around the piston. Steam, instead of air, was then used to push down the piston. Watt also designed a heat jacket for the cylinder to contain its heat.

Significance

The first Watt engine, patented in 1769, was the first model in a new age of steam. It was a single-acting engine used as a pump and built at an ironworks in Scotland owned by Watt’s partner, John Roebuck. The necessity of close tolerances in piston and cylinders required precision machining beyond available technology. The caster John Wilkinson was eventually able to satisfy Watt’s demands for more precisely machined engine parts. Matthew Boulton, owner of the Soho engineering works in Birmingham, became Watt’s partner in 1775, and he saw the possibilities for engines that would do more than pump. He persuaded Watt to develop an engine with a rotating motion through a system of intermeshed gears, and then an engine with the piston being alternately supplied on opposite sides with steam and vacuum. This engine was patented in 1782. Watt’s engines did not immediately eclipse atmospheric engines, especially where cheap coal was readily at hand. Yet where coal was scarce, as in Cornwall, Watt’s engines were a tremendous boon to mining, iron production, and manufacturing.

The firm of Watt and Boulton prospered for years, supplying steam engines of many types and designs for various industries. There were about five hundred Watt and Boulton engines in service by 1800. Expiration of the inventor’s original patents in that year caused a rush on the part of other inventors to introduce new and improved steam engines. Watt gave up active participation in the firm in that year, having contributed more than any other individual to the age of industrial power.

Bibliography

Dickinson, H. W. James Watt and the Steam Engine. Oxford, England: Clarendon Press, 1927. Although dated, this work combines biography and technical explication and also helpfully relates Watt’s relationship to the scientific community at the University of Glasgow.

Landes, David S. The Unbound Prometheus: Technical Change and Industrial Development in Western Europe from 1750 to the Present. London: Cambridge University Press, 1960. Reprinted many times, this volume is a noted treatment of technological innovation and entrepreneurship, interpreting Watt’s work from a long-term, European perspective.

Marsden, Ben. Watt’s Perfect Engine: Steam and the Age of Invention. New York: Columbia University Press, 2002. A nontechnical biography of Watt. In Marsden’s opinion, Watt was less an innovator than a practical businessman with an interest in natural philosophy. Marsden describes how Watt developed the steam condenser to make Newcomen’s engine more efficient.

Nahum, Andrew. James Watt and the Power of Steam. East Sussex, England: Wayland, 1981. A short biography that handily introduces technical aspects to the general reader.

Rolt, L. T. C. James Watt. New York: Arco, 1963. This fine, concise biography also puts Watt into the context of British manufacturing at the end of the eighteenth century.

Tann, Jennifer. “Introduction.” In The Engine Partnership, 1775-1825. Vol. 1 in The Selected Papers of Boulton and Watt. Cambridge, Mass.: MIT Press, 1981. In addition to helping the reader discover Watt from his own words, Tann has also contributed greatly to precise knowledge of his business dealings and the diffusion of Watt engines across Europe.

Uglow, Jenny. The Lunar Men: Five Friends Whose Curiosity Changed the World. New York: Farrar, Straus, Giroux, 2002. Watt, his partner Matthew Boulton, and scientist Joseph Priestley were among the founders of the Lunar Society of Birmingham. Uglow’s book describes how the organization invented new products, advanced science, and worked on other projects that ushered in the Industrial Revolution.