Scottish engineer and inventor James Watt invented the steam engine, a machine that revolutionized industry.
Scottish engineer and inventor James Watt developed the steam engine, a machine that was instrumental to the rise of the Industrial Revolution of the late eighteenth and early nineteenth centuries in Europe. His improvements to existing steam engine technology produced a faster, more efficient machine that could more easily power heavier machinery. Throughout his life Watt experimented and improved on his engine, refining systems that provide the basis for many industrial engines used today.
James Watt was born on January 19, 1736, in the small town of Greenock, Scotland. His father made a living however he could, working variously as a merchant, a carpenter, and a government administrator. Young Watt frequently assisted his father as a carpenter and from an early age enjoyed carpenter's tools more than books. He was a physically weak child who experienced long periods of illness, so he did not begin his education at the usual age. Even when he did enroll, illness frequently kept him from class. Watt demonstrated a keen ability to learn on his own, however, and as he played with carpenter's tools he learned and applied mathematical concepts.
In his teens, Watt was sent to a commercial school, where he studied Latin, Greek, and mathematics. At home he experimented with chemicals and created new tools and by the age of fifteen had found a way to make a simple electric motor. Watt spent a year at the University of Glasgow in Scotland, where he studied to become a mathematical instrument maker. He then moved to London and worked for a man named John Morgan, making accurate quadrants (tools for measuring the altitude of stars) and parallel rulers.
"Inventor" of the steam engine
Watt returned to Scotland when he was twenty. He took a job at the University of Glasgow, cleaning and repairing scientific instruments. It was at Glasgow that he first became interested in steam power. Though Watt is often credited with the "invention" of the steam engine--and he certainly deserves credit for making steam power popular and for adapting it to many uses--earlier inventors had experimented with steam power. In fact, steam engines were already popular in one of England's largest industries, coal mining. They were used to power pumps to keep the mines from flooding, and they were economical because low-grade coal, which they used for fuel, was readily available.
The use of steam to power machines initially depended on the ability to create a vacuum. For instance, the engines used to pump water from the mines were based on expansion and suction effects achieved by generating and then condensing steam to create a vacuum. The process was begun when water was heated in the boiler chamber until its steam filled the chamber. This created an expansion that forced out any water or air inside the chamber. A valve was then closed, after which cold water was sprayed over the chamber; this chilled and condensed the steam inside to form the vacuum. When the valves were reopened, water was forced up from the mine, and the process could then be repeated.
British engineer Thomas Newcomen introduced a steam pump in 1712 that operated on the same principle, but he increased efficiency by setting a moving piston inside a cylinder, a technique still used today. A cylinder, a long, thin, closed chamber separate from the boiler, replaced the large, open boiler chamber; and a piston, a sliding piece that fits in the cylinder, was used to create motion instead of a vacuum. Newcomen's design was significant in its capacity to produce motion to power a machine. The motion created allowed the engine to sustain its own movement; earlier steam-powered machines required that their water and steam valves be constantly monitored and manipulated.
But Newcomen's engines had a number of weaknesses, which Watt soon recognized and set about to improve. Newcomen's engine is called an atmospheric engine because its motion relies on atmospheric pressure rather than on counterweights or the force of steam itself. Steam was admitted to the underside of a piston, then, at a determined point in the cycle, a jet of water was injected to the same area to condense the steam and create a vacuum. The atmospheric pressure in the open end of the cylinder then forced the piston back down, producing a power stroke. Newcomen's machine was capable of twelve strokes per minute.
Watt determined that Newcomen's engine wasted time by cooling the piston chamber during every cycle. Newcomen's engine--as did other early steam pumps--injected steam on only one side of the cylinder and employed atmospheric pressure and vacuums to reset the piston in position. These earlier engines suffered in efficiency because heat was lost during the procedure, which made reheating necessary at the beginning of each cycle. In 1769, Watt obtained a patent on an engine design that included sealing the engine's cylinder and installing steam valves on both ends, innovations that would leave the steam chamber always hot and always ready for a new batch of steam, thereby allowing a large pump to be driven back and forth faster than Newcomen's twelve strokes a minute.
But Watt found it difficult to seal the cylinders because those available were still bored (drilled) as they had been in Newcomen's time, sixty years earlier, and would not seal tightly enough for Watt's purpose. To address this problem, Watt entered into a partnership in 1773 with businessman Matthew Boulton, who financed and organized a search for techniques to manufacture a well-sealed cylinder. Two years later English industrialist and inventor John Wilkinson perfected a boring machine that could drill cylinders with unprecedented uniformity.
Watt's refined steam engine design used one-third less fuel than a comparable Newcomen engine. Watt and Boulton began to market these engines, and in 1775 several of them were sold to operate water pumps and, during the next year, two more were installed in coal mines.
Initiates the Industrial Revolution
Over the next fifteen years Watt continued to experiment with and improve upon steam engine technology. He introduced the centrifugal governor, which became known as the Watt governor, a device that could control and adjust steam output and engine speed. He devised a new type of condenser that used a system of tubes instead of one large chamber, and an air pump that maintained a vacuum in the condenser. But his most impressive innovation was attaching a flywheel to the engine. Flywheels, heavy wheels that control speed in machinery with which they revolve, accomplished two tasks: they allowed the engine to run more smoothly by creating a more constant load, and they converted the conventional back-and-forth power stroke into a circular (rotary) motion that could be adapted more readily 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.
By 1790, Watt's engines had nearly replaced Newcomen's engines, which were, for the most part, decades old. Ten years later, at age sixty-four, Watt sold his interests in his company to his son, James. Despite his success, Watt is said to have been melancholy and withdrawn by nature. He had warm friendships but hated to meet face-to-face with anyone in business negotiations. In his old age, however, he demonstrated a desire to share his knowledge and reminisce about his past successes. The watt, a metric unit of power, is named for him.
Watt died on August 19, 1819, near Birmingham, England. He is buried beside his former business partner, Matthew Boulton.
- Crane, William D, The Man Who Transformed the World: James Watt, Messner, 1963.
- Holt, L. T. C., Thomas Newcomen: The Prehistory of the Steam Engine, Dawlish MacDonald, 1963.
- Quackenbush, Robert, Watt Got You Started, Mr. Fulton?: A Story of James Watt and Robert Fulton, Prentice-Hall, 1982.
- Smiles, S., Lives of Boulton and Watt, Murray, 1865.
- Storer, J. D., A Simple History of the Steam Engine, John Baker, 1969.