Providing the power for the Industrial Revolution, together with the concept that transformed power into a marketable commodity
James Watt
(1736–1819)
In the International System of Units (SI), the watt is a unit of power commonly used to quantify the rate of energy transfer. If you are an engineer, you know that 1 watt is the transfer of 1 joule (a unit of energy) per second. If you are anyone else, you know that a 100-watt lightbulb is brighter than a 60-watt lightbulb or that a 100-watt amplifier makes music louder than a 30-watt amp. This most basic unit of power is named after James Watt, the Scottish engineer, chemist, and inventor who was asked to fix a 1712 Newcomen steam engine and ended up transforming it into the 1781 Watt steam engine, thereby creating the machine that powered the Industrial Revolution.
This alone is ample reason to name the watt in his honor. But there is more. Having transformed Thomas Newcomen’s engine into something sufficiently practical and efficient to disrupt civilization, Watt borrowed a concept introduced by another early steam-engine tinkerer, Thomas Savery, to market his innovation. Before the watt was accepted as a universally understood unit of power, the unit Watt devised, horsepower, had already become a standard unit for measuring the rate at which work is done. Moreover, if Watt’s steam engine required mechanical genius to create, the concept of horsepower required a combination of philosophical and marketing genius. Having created a profoundly transformative technology, Watt sold it to the world by presenting its value in terms of the very technology—animal power—he had transformed.
The Watt steam engine would fundamentally disrupt human society. Horsepower made the value of that disruption comprehensible to anyone who had ever used a horse to pull a wagon or a plow or turn a grinding wheel in a mill—or who had even watched a horse perform any of these tasks. Watt defined the shockingly new in the language of the comfortably familiar, even as his breakthrough set the universe of the horse on an inexorable course of obsolescence as a work engine.
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James Watt was born in 1736 in the Firth of Clyde seaport of Greenock, Scotland, the son of a shipwright and the grandson of a mathematician. Raised a Presbyterian, Watt grew up into a deist. There was a God, he argued, but it was man who had to get things done on earth. The deity of the deist offers no guidance and no help, but doesn’t interfere either.
Watt struggled through early life, puny, sickly, continually assailed by migraines and toothaches. He was home-schooled early on and then enrolled in Greenock Grammar School, where he excelled at mathematics but had no interest in Greek and Latin. Carpentry he learned from his father—and he took naturally to working with his head and hands. As his father applied his woodworking skills to building ships in the busy seaport town, Watt became interested in their navigation instruments: quadrants, compasses, telescopes, and the like. In his teens, Watt decided he wanted to become an instrument-maker. The decision came none too soon. His father suffered a serious financial loss when a ship he owned was wrecked, his wife died suddenly, and his own health went into freefall. He was pleased that his mechanically inclined son was eager to learn a lucrative trade.
But Watt couldn’t learn it in Greenock. Now eighteen, he went off to Glasgow in 1754, where he called on a relative, who introduced him to Robert Dick, a scientist working at the University of Glasgow. Dick was instantly impressed by the instrument-making skills Watt already possessed, but he also recognized that the young man had a great deal yet to learn, and he counseled him to go to London for training. Watt set off, spending two weeks in the capital seeking an apprenticeship opportunity. He repeatedly ran up against the rules of the instrument-makers’ guild known as the Worshipful Company of Clock-makers: the only apprenticeships offered under the Worshipful Company’s rules lasted seven long—and impoverished—years. At last, however, Watt found John Morgan, whose workshop was in the center of the city and whose attitude toward the rules was highly pliable. He would take Watt on as an apprentice and, what is more, cram into a single year everything he needed to know about the trade of instrument-maker. In return, Watt would serve him during that year for almost no salary at all. He snapped up the offer.
Watt began his accelerated apprenticeship in 1755 and learned fast. Morgan was astounded to see Watt quickly surpass the level of skill of his official apprentice, who had been employed in Morgan’s shop for two years. Watt drove himself hard, working ten hours a day in training and then many additional hours doing minor repair work for slim compensation. Though pressed for cash, his father sent him what little he could when he could, but young Watt began to buckle under the combination of short rations and long hours. Add to this the outbreak of the Seven Years’ War, during which agents of the Royal Navy and British Army were prowling the streets of London looking to “impress” (draft) young men into naval or military service. Fearful of being caught in the dragnet, Watt spent even more time cloistered in the shop to avoid exposure on the streets. After his year was up, he had completed the apprenticeship with flying colors—only to fall dangerously ill.
Sick though he was, Watt felt he had no time to convalesce. Instead, he returned to Glasgow in 1756 and, through his few connections at the university, got some work for the institution. He used the meager proceeds to set up his own shop, only to find that other instrument-makers refused to accept him as one of their profession. They did not complain about the brevity of his apprenticeship, but were outraged that it had been served in London. The truly fine instrument-makers, they declared, were those trained in Glasgow! Fortunately for Watt, however, his work for the university impressed the professors, who prevailed on the institution to provide space for him to set up shop on campus with the official title of “Mathematical Instrument Maker to the University.”
It was a fine position, but the volume of work was still too small to make a decent living. With the town’s instrument-makers against him, Watt looked for related additional employment and began making musical instruments—something in which the other members of his trade had no interest and therefore did not regard him as an unqualified competitor. What gave Watt an edge was that he looked at existing instruments critically, and he identified aspects of their design that could use improvement. He not only repaired or made instruments, he made them better—and this began to draw customers. In 1758, a local architect invested in his business, which enabled him to open a shop in the heart of Glasgow. By 1763, he was well established as a maker of a variety of mechanical products, ranging from musical instruments to toys to the kinds of “mathematical instruments” he made for the university, for whose scientific faculty he continued to work from the small shop on campus.
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Among the luminaries with whom Watt made friends at the university were the physicist and chemist Joseph Black, who made important discoveries concerning the evolving science of thermodynamics, and Adam Smith, whose 1776 An Inquiry into the Nature and Causes of the Wealth of Nations would make him the father of political economy, precursor to modern economics. Another Glasgow professor, John Anderson, was less famous than either Black or Smith, but nevertheless instrumental in applying science to the creation of the technology that enabled the Industrial Revolution, and he was dedicated to the education of the working man. He was also the older brother of one of Watt’s grammar school classmates. In 1763, Anderson came to Watt with a problem. He had a small laboratory model of a Newcomen pump, the first practical steam engine, invented in 1712 by Thomas Newcomen and used chiefly to pump out water from coal mines. Anderson was using the model engine to investigate why the full-size mine pumps were so inefficient, requiring a huge amount of steam to function even minimally. Anderson’s small machine would start up, pump a few strokes, and then stall out. What was wrong, the professor wanted to know.
Watt could tell just by looking at the machine. The boiler was too small to furnish sufficient steam to reheat the cylinder after just a few strokes. But he did not stop with this simple diagnosis. He decided to observe the failure closely. In doing so, he discovered more than a problem with Anderson’s particular Newcomen pump: he discovered why all Newcomen engines, including the full-size pumps, were so inefficient. With each stroke, the cylinder in which the piston moved cooled and had to be reheated. That continual reheating process consumed a great deal of heat—energy that was therefore unavailable to do useful work. Watt understood that what was needed was a means of condensing the steam without cooling the cylinder, and he pondered how to do it. The pondering extended over months and then years of experimentation.
While working on the problem, Watt made himself an expert on the properties and physical dynamics of steam. He discovered something that his friend Professor Black had earlier found out independently, namely what Black called the latent heat of vaporization: the amount of energy that had to be added to a liquid to transform it into a gas or vapor (such as steam). The key, Watt realized, was that the quantity of energy for vaporization, called the enthalpy, was a function of the pressure at which the transformation from liquid to vapor took place. Watt discovered this key in May 1765, fully two years after Anderson had brought him the ailing Newcomen model.
After a moment of inspiration that happened during “a walk on a fine Sabbath afternoon, early in 1765,” as he later wrote, Watt imagined an engine with a separate condenser, in which condensation could take place continually, so that the steam cylinder could be evacuated without cooling in the process. The vapor would rush into the condenser, in which the pressure was approximately equal to the vapor pressure of water. In the meantime, steam would be injected into what Watt later called a “steam jacket” surrounding the cylinder. In this way, the cylinder was kept at or close to the high temperature of the steam that was injected into it from the condenser. The loss of heat was thus minimized, which meant that more of the energy provided by the steam was available for useful work.
Work. That was one thing Watt felt he could not do on the Sabbath. Deist though he was, he observed prevailing custom and, itching to get into his workshop, he nevertheless agonized patiently until Monday morning. Come the dawn, he went to work with great speed. For purposes of an expeditious experiment, he improvised a cylinder and condenser by using a large brass surgeon’s syringe, four inches in diameter and ten inches long. American engineer and professor of mechanical engineering at the Stevens Institute of Technology Robert Henry Thurston described the experiment in his 1878 History of the Growth of the Steam Engine:
At each end [of the syringe] was a pipe leading steam from the boiler, and fitted with a cock to act as a steam-valve. A pipe led also from the top of the cylinder [that is, the syringe] to the condenser, the syringe being inverted and the piston-rod hanging downward for convenience. The condenser was made of two pipes of thin tin plate, 10 or 12 inches long, and about one-sixth of an inch in diameter, standing vertically, and having a connection at the top with a horizontal pipe of larger size, and fitted with a “snifting-valve.” Another vertical pipe, about an inch in diameter, was connected to the condenser, and was fitted with a piston, with a view to using it as an “air-pump.” The whole was set in a cistern of cold water. The piston-rod of the little steam-cylinder was drilled from end to end to permit the water to be removed from the cylinder.
It worked “very satisfactorily, and the perfection of the vacuum was such that the machine lifted a weight of 18 pounds hung upon the piston-rod.” Watt quickly went on to construct a bigger model, which also worked.
The breakthrough had come. Watt was just twenty-nine years old. Nevertheless, his steam engine was not commercialized until eleven years later, as the inventor labored over the details of perfecting a full-scale version. The main problem was that the metalworkers of the day could not machine the piston and cylinder with sufficient precision to create an efficient engine. While Watt struggled trying to solve this problem and secure a patent, his principal backer, an industrialist named John Roebuck, went bankrupt, and Watt himself had to take day jobs as a surveyor and civil engineer to put food on the table. He labored in this way for eight years, during which time another industrialist, Matthew Boulton, purchased Watt’s patent rights, but worked closely with the inventor. He saw what Watt apparently did not see—that the machine under development was much more than an improved water pump: it was a source of energy capable of driving any type of machine that could be attached to it. So Boulton backed Watt financially and, most important, secured for him the services of John “Iron Mad” Wilkinson, who had developed precision boring techniques for making cannons. A cannon was essentially a bored-out cylinder. If Wilkinson could make this, Boulton figured he could make a cylinder precise enough for Watt’s engine.
Boulton was right, Watt perfected the piston and cylinder, and the two men discovered that they made very good business partners. Boulton provided the capital and management expertise, while Watt provided the genius. The first commercial Boulton-Watt engine was purchased in March 1776 by the Bentley Mining Company. It performed astoundingly well, making some fourteen to fifteen strokes per minute and emptying in less than an hour a coal pit 90 feet deep and filled with 57 feet of water.
By the early 1780s, Boulton was urging Watt to develop designs to enable the “Watt-Boulton Steam Pump” to be used in other applications. He wrote to his partner in 1781: “The people in London, Manchester and Birmingham are steam mill mad. I don’t mean to hurry you, but I think in the course of a month or two, we should determine to take out a patent for certain methods of producing rotative motion. . . .” This led to Watt’s invention of a mechanical linkage that converted the reciprocating motion of a rising and falling piston to a rotating motion that could drive anything with a shaft. In addition, Watt continually improved the steam engine itself, always with an eye toward increasing efficiency.
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In 1782, a large sawmill placed an order for a massive Watt-Boulton engine. It had to replace and do the work of a dozen mill horses. Watt therefore set out to quantify how much work a single horse could do. He set up an experiment in which he proved that one horse could lift 33,000 pounds the distance of 1 foot in 1 minute. With this calculation, he now knew how to calculate the required specifications for the new engine: just multiply everything by twelve to get the equivalent of the work of twelve horses.
But Watt also realized that he had found something else. In 1702, Thomas Savery, another early steam-engine inventor, wrote a book called The Miner’s Friend; or, an Engine to Raise Water by Fire, Described. In it, he compared the work his primitive steam pump could do with what horses could do: “So that an engine which will raise as much water as two horses, working together at one time in such a work, can do, and for which there must be constantly kept ten or twelve horses for doing the same. Then I say, such an engine may be made large enough to do the work required in employing eight, ten, fifteen, or twenty horses to be constantly maintained and kept for doing such a work.” Reading this description, Watt formalized horsepower as a unit for measuring the rate at which work is done. He intended it as a tool to promote his engines by quantifying the value they offered in terms familiar to almost everyone living in a century run on horse power. But he succeeded in doing something more: he transformed energy into a commodity. The business in which Watt and Boulton were engaged became, in effect, an energy business—or, more precisely, a work business, since work is the word used to describe the useful application of energy.
From this point forward, the Industrial Revolution was not only driven by steam, but was conceptualized, promoted, and managed in terms of energy and work produced, the cost to produce it, and the profit to be made from it. Civilization hereafter had a new system of value and values, a relentlessly precise combination of physics and economics.