concerning the unpredictable consequences of sea air on iron telescopes; the power of the cube-square law; the Incorporation of Hammermen; the nature of insight; and the long-term effects of financial bubbles

THE FINEST ANCHORAGE IN the Caribbean is found on the southeastern coast of Jamaica, behind an eight-mile-long sandbar that protects the harbor from tropical storms. At the western tip of the sandbar, the original Spanish colonizers built a town they called Santiago, and which the island’s English conquerors subsequently renamed Port Royal, retaining it as a base for privateering until it was destroyed by an earthquake in 1692. Kingston, on the mainland side of the harbor, was built as a refuge for survivors of the earthquake. It proved an attractive destination for refugees of another disaster, the Jacobite Rebellions of the early eighteenth century (the fruitless attempts to return the Stuart kings to the throne following the Glorious Revolution of 1688), which resulted in, among other things, the emigration of thousands of Scots to the island.* In 1747, one of them1 (a Scot, not a Jacobite), Alexander Macfarlane, a merchant, a judge, a mathematician, and yet another of those “gentlemen, free and unconfin’d” who could style themselves Fellows of the Royal Society, acquired several dozen state-of-the-art astronomical instruments from another Scot named Colin Campbell. Campbell was not merely a countryman, but a fellow alumnus of Glasgow University, so it was scarcely surprising that when Macfarlane died in 1755, his collection was bequeathed to their alma mater.

The ships that traveled from the Caribbean to Britain had a good deal more experience carrying sugar than they did telescopes and quadrants, whose iron components were not improved by several weeks exposure to salt air. Which is why, when the Macfarlane collection arrived in Glasgow in 1756, the university hired an artificer, just returned from London, “to clean them and to put them in the best order2 for preserving them from being spoilt.”

James Watt was then twenty years old, and events had been preparing him for his new job almost since he was born, in Greenock, a borough just to the west of Glasgow on the River Clyde. Or even before. Scotland had formally joined the United Kingdom in 1707, but remained distinct from its southern neighbor in a number of relevant ways: poorer, but more literate, and far less inhibited by the presence of an established church that was turning Oxford and Cambridge into vocational schools for the clergy. The combination of relative poverty, and opportunity in British possessions around the world, explained the particularly Scottish enthusiasm for education: if the nation’s most ambitious and smartest sons had to seek their fortunes elsewhere—and they did; during the eighteenth century,3 as many as six thousand trained Scottish doctors left the country in search of employment, and not just in Jamaica—the most valuable property they could take with them was between their ears.

As a result, even members of Scotland’s artisan classes were better educated than was the case almost anywhere else in Europe—a bit of good fortune for them, but even more so for Britain’s ability to maintain its head start on the development of steam power. A 1704 Proposal for the Reformation of Schools and Universities proposed a curriculum in mathematics that would seem daunting to a twenty-first-century honors student: “the first six, with the eleventh and twelfth Books4 of Euclid, the Elements of Algebra, [and] the Plain and Spherical Trigonometry” followed by “The Laws of Motion, Mechanicks, Hydrostaticks, Opticks … and Experimental Philosophy.” Watt, in particular, was taught an impressive amount by a cousin: “John Marr, mathematician,” as he appeared in Greenock’s census.

Like Marr, Watt’s grandfather had been a teacher of mathematics, navigation, and astronomy; his father was a carpenter specializing in shipbuilding who supplemented his income by surveying the land around Greenock, but both were famed for their skill in the repair of delicate instruments. And so, therefore, was James, though whether his combination of mathematical and mechanical aptitude was genetic or the result of early training is as unknowable as it is irrelevant, since all memoirs of Watt’s childhood suffer from the sort of retrospective adulation that nations habitually bestow on their heroes’ early years. Watt certainly seems to have been a bright and precocious boy, but his childhood history is decorated by a truckload of conveniently postdated reminiscences (see Cherry Tree, George Washington’s). In Watt’s case, the best one is the story of his aunt’s recollection of young James’s obsession with the way a teakettle lid was forced upward by steam—suspicious on the face of it, since, as we have seen, the expansive force of steam was not precisely central to the operation of early steam engines. In any event, he certainly benefited from being given the full run of his father’s workshop, with its hammers, chisels, adzes, block and tackles, and so on.

When Watt’s mother died in 1753, the seventeen-year-old was sent to Glasgow to learn the trade of a “mathematical instrument maker,” and though he could find no teacher, he did eventually encounter Robert Dick, a doctor and the professor of natural philosophy at the University of Glasgow. Dick was unable to provide training, but he did advise Watt to seek a teacher in London, for which he supplied a letter of introduction. Taking both the advice and the letter, Watt left Scotland on June 7, 1755, arriving in London twelve days later.

The city, then home to more than 600,000 residents, was already the largest outside of Asia, and easily the dirtiest. Though London owes much of its finest architecture to the fire of 1666, which cleared the way for the buildings of Christopher Wren and Robert Hooke, the overwhelming bulk of the city’s buildings were constructed to somewhat lower standards than St. Paul’s. Moreover, it was still, as of the date of Watt’s arrival, using the Thames for both sewage discharge and drinking water, which partly explains why so much of poor London slaked its thirst with gin, a distilled spirit made from fermenting grain that was so bad it couldn’t even be used to make beer. The Hogarthian enthusiasm for the cheap liquor was such that Henry Fielding—novelist, do-gooder, and pioneer of London’s first police force—wrote, “it is the principal sustenance5 (if it may be so called) of more than a hundred thousand people in this metropolis. Many of these Wretches there are, who swallow Pints of this Poison within the Twenty Four Hours: the Dreadfull Effects of which I have the Misfortune every Day to see, and to smell too.” With its large and unwashed populace, its untreated sewage, and the miasma caused by burning nearly two-thirds of the world’s output of decidedly dirty coal, the city literally stank.

The smells were part of the cost of supporting the world’s most robust commercial and manufacturing economies, but while the former was dominated by newly created speculative ventures, funds, and trading syndicates, the latter had a more medieval flavor. In London, as in most cities of Europe, the making of things had long been the prerogative of guilds, those ancient federations of autonomous workshops whose grip on activities such as weaving cloth, making jewelry, and working metals imposed very substantial costs on the city’s economy.

Some of those costs were borne by the guilds’ prospective membership in the form of free labor and apprentice fees, paid in return for both training and a de facto license to practice the skills acquired. The training, of course, is what James Watt had traveled to London to acquire, from the city’s Worshipful Company of Clockmakers. That particular guild was not a true medieval organization; it had been founded “only” in 1631,6 just in time to define its exclusive franchise as embracing not only clocks but all forms of mathematical instruments. Partly as a result, they were considerably more welcoming of innovation than the more ancient organizations; when Watt arrived in London, their most illustrious member, John Harrison, was not only improving on his prizewinning marine chronometer, which he had invented as a solution to the problem of calculating longitude at sea, but also had previously created new versions of both clock escapements and pendulums. Unfortunately for Watt, Harrison’s guild was just as jealous of their territorial prerogatives as any thirteenth-century goldsmith; their bylaws prohibited any member from employing—and, especially, training—any “foreigners, alien or English”7 unless they were bound to the member as apprentices.

As a result, the first thing Watt learned in London was that he did not qualify for a “normal” apprenticeship. He was too old, for one thing. And even had he been closer to the usual age of apprentices, he had no interest in spending seven years as one. On the other hand, his willingness to leave London8 once trained was a huge advantage, since the guild rules were explicitly designed to eliminate unauthorized competitors only within the city. He was also, by training and aptitude, already far more useful to a master clockmaker than a fourteen-year-old still picking hay out of his ears. The combination was evidently appealing enough that John Morgan, a member of the Company in good standing, agreed to take Watt on as a trainee in return for a year of free labor plus twenty guineas. By all accounts, he got a bargain: Since his “apprentice” had neither an interest in frivolity, nor the funds to indulge one, he did nothing but work. Watt was attempting to crowd seven years of training into one, and he succeeded. Most of his training was in fine brasswork, building sectors, dividers, and compasses; even a Hadley quadrant with a telescope and three mirrors. He boasted to his father that he had mastered an extremely precise “French joint”—a hinge in which one channel folds into another like a fine bound book. By the time he returned to Glasgow in 1756, he was certified “to work as well as most journeymen”9 and was qualified to build and repair the machines representing the eighteenth century’s most advanced technology.

Glasgow was then barely a town by London standards, home to around fifteen thousand people, but it was a “large, stately, and well-built city10 … one of the cleanliest, most beautiful, and best-built cities in Great Britain” in the words of Daniel Defoe,* who visited in 1724 to report on Scotland’s integration with England. It was also, in Defoe’s words, “a city of business [with] the face of foreign as well as domestick trade” and a textile manufacturing center specializing in “stuff cross-striped with yellow, red, and other mixtures” (i.e. plaid), which meant that it was also home to its own guilds, just as jealous of their prerogatives as their London counterparts. In the case of Watt’s newfound skills, the barrier to entry was manned by the rather fearsome-sounding “Incorporation of Hammermen,” who, in the time-honored practice of every guild, weren’t enthusiastic about recognizing a competitor who had failed to go through an approved apprenticeship. So when his former patron, Professor Dick, in need of someone to repair the sea-damaged Macfarlane collection, offered a payment of £5, and more important, permitted him to set up shop as “Mathematical Instrument Maker to the University,” it was truly a godsend.

It is almost irresistibly tempting to see Watt’s life as the embodiment of the entire Industrial Revolution. An improbable number of events in his life exemplify the great themes of British technological ascendancy. One, of course, was his early experience with the reactionary nature of a guild economy, whose raison d’être was the medieval belief that the acquisition of knowledge was a zero-sum game; put another way, the belief that expertise lost value whenever it was shared. Another, as we shall see, was his future as the world’s most prominent and articulate defender of the innovator’s property rights. But the most seductive of all was Watt’s simultaneous residence in the worlds of pure and applied science—of physics and engineering. The word “residence” is not used figuratively: The workshop that the university offered its new Mathematical Instrument Maker was in the university’s courtyard, on Glasgow’s High Street, a bare stone’s throw from the Department of Natural Philosophy.*

He almost immediately started collecting admirers. One of his first friends among the university’s “natural philosophers” was the mathematician and physicist John Robison, who was therefore in a privileged position to observe Watt in the years before his great achievements. Nearly forty years later he would recall that “every thing became Science11 in [Watt’s] hands … he learned the German language in order to peruse Leopold’s Theatricum Mechanicum [an encyclopedia of mechanical engineering] … every new thing that came into his hands became a subject of serious and systematical study, and terminated in some branch of Science.” He continued:

Allow me to give an instance.12 A Mason Lodge in Glasgow wanted an Organ [and] tho’ we all knew that he did not know one musical note from another, he was asked if he could build this Organ…. He then began to study the philosophical theory of Music. Fortunately, no book was at hand but the most refined of all, and the only one that can be said to contain any theory at all, Smith’s Harmonics. Before Mr. Watt had half-finished this Organ, he and I were completely masters of that most refined and beautiful Theory of the Beats of imperfect Consonances. He found that by these Beats it would be possible for him, totally ignorant of Music, to tune this Organ according to any System of temperament, and he did so, to the delight and astonishment of our best performers…. And in playing with this he made an Observation which, had it then been known, would have terminated a dispute between the first Mathematicians of Europe, Euler and d’Alembert, and which completely establishes the theory of Daniel Bernoulli about the mechanism of the vibration of Musical Chords….

Watt may have been comfortable in the rarefied company of mathematicians like Bernoulli and Leonhard Euler; the business alluded to by Robison is the discovery that any of the overtones of an organ pipe produce frequencies that are exact multiples of the pipe’s base pitch. However, like Newcomen (but unlike Boyle, or even Savery), he was as preoccupied by his desire to earn a living as by his passion for discovery. Like an ever-growing percentage of his countrymen in the newly United Kingdom, Watt had acquired the tools necessary for scientific invention—the hands of a master craftsman, and a brain schooled in mathematical reasoning—without the independent income that could put those tools to work exclusively for the betterment of mankind. As a result, in 1759, Watt became half of a partnership with John Craig manufacturing optical instruments. In 1763, he became shareholder in the Delftfield Pottery Company. And every year, he spent a portion of the spring and summer working as a surveyor for the roads and canals just starting to crisscross Britain.

It was upon his return from a surveying trip, in the winter of 1763, that Watt was asked to repair a model of a Newcomen engine in the possession of the university by John Anderson,* who had become Glasgow’s professor of natural philosophy with the death of Robert Dick in 1757. “Repair” is something of a misnomer; the model was not broken, but unlike a full-sized engine, it stopped working after only two or three strokes. Anderson had been importuning the university’s new instrument maker for at least four years before Watt “set about repairing it13 as a mere mechanician.” Shortly thereafter, he realized that the problem was intrinsic to the size of the model, since “the toy cylinder exposed a greater surface14 to condense the steam in proportion to its content.” Watt had intuited the presence of a cube-square problem.

The so-called cube-square law is a recognition of the fact that the surface of any solid object increases in size far more slowly than its volume. Thus, a cube with four-inch sides has a surface area of ninety-six square inches and a volume of sixty-four cubic inches, while an eight-inch cube has a surface of 384 square inches, but a volume of 512 cubic inches. Doubling the cube’s edge increases its surface area fourfold, but its volume eight times.

The cube-square law is yet another bequest from the Scientific Revolution to the Industrial; for a change, one with a clear provenance. The phenomenon was first documented in the final book of Galileo Galilei, the 1638 Dialogues Concerning the Two New Sciences, in which Galileo’s alter ego, the imaginary “Salviato,” demonstrates it to the Aristotelian loyalist “Sagredo” and the dim-minded “Simplicio” (Galileo’s choice of names was as heavy-handed as Dickens’s). The cube-square law has huge implications for construction, for engineering, and even for biomechanics; it is the reason, for example, that an elephant’s legs are so much larger in cross-section than a dog’s. More relevantly for the history of steam power, it reveals the most obvious weakness of scale models, which is that a structure’s performance can degrade substantially when it is blown up to twenty times its original size. Designs that work when small—a bridge made of toothpicks, for example—can easily fail as the weight to be borne increases disproportionately faster than the strength of the “timbers” bearing it.

But the problem also operates in reverse. The cube-square law can just as easily cause a design to fail when it is miniaturized. This was Watt’s initial insight about the model Newcomen engine. Because the scale model, still in the Hunterian Museum at the university, was using far more steam than could be accounted for by any science or experience Watt (or anyone else) had, his first assumption was that the problem was one of the scale itself, specifically the fact that in a small engine the interior surface was far larger in proportion to the volume; if the heat loss was proportional to surface, then the difference could perhaps be explained.

Explaining it took two years.

Watt’s experiments from 1763 to 1765 were an object lesson in the primacy of measurement over intuition, since recognizing the existence of heat loss matters a good deal less than knowing its magnitude; suspecting the nature of the problem wasn’t the same as understanding it. Watt needed to calculate exactly how much heat was being lost in the Newcomen design, and that meant converting general theories about steam into precise measurements, which were, to be kind, thin on the ground at the time, even for such elementary benchmarks as the boiling point of water.

Obviously, the story of steam demands constant reference to that benchmark, which even a bright ten-year-old knows is precisely 212°F, or 100°C, at normal atmospheric pressure. However, as with many such bits of common knowledge, it turns out to be a bit more complicated. Boiling occurs when a liquid’s vapor pressure reaches atmospheric pressure, but while vapor pressure is proportional to heat, it isn’t the same throughout a volume of liquid. Boiling temperatures change depending on the material containing the liquid, since water adheres better to metal than to glass and can therefore boil at a somewhat lower temperature in a metal vessel. The temperature can increase or decrease with the shape of the container, the presence of dissolved air, the location of the heat source, and, of course, the amount of air pressure. Thus, the “normal” boiling temperature of water—100°C—can climb as high as 200°C, as an obsessively competitive scientist named Georg Krebs demonstrated in 1869. Most textbooks plot a “boiling curve”15 with the boundary between liquid and gas a moving target depending on at least four different variables.

Even in Watt’s time, the clear line between liquid and vaporized water was pretty fuzzy. A thermometer dating from the 1750s is marked with two different “boyling” temperatures;16 at 204, water “begins to boyle,” and then at 212, “boyles vehemently,” a distinction that dates back to Isaac Newton. The measurement problem was acute enough17 that in 1776 the Royal Society appointed a committee, headed by Henry Cavendish (better known as the discoverer of hydrogen) in order to establish the “fixed points” of thermometers.

Watt began his researches on the Newcomen engine fourteen years before the Cavendish committee delivered its conclusions in 1777 and was, in consequence, working with a clunkier set of measurements. He wasn’t, however, completely in the dark. Toward the end of his life, Watt himself provided an inventory of the basic knowledge already in circulation before his first great innovation. One small example of it18 was the twenty-year-old discovery, by the physician William Cullen (Joseph Black’s teacher, and yet another member of the remarkable faculty of the University of Glasgow), that water boiled at a lower temperature in a vacuum, thus releasing steam that would degrade the cylinder’s vacuum. This turned out to be critical, because the fact that the Newcomen engine operated in a vacuum meant that cooling the steam to the point of condensation required cooling it to temperatures even lower than 100°C/212°F. In order to calculate how much lower, Watt needed to develop an exact scale showing how changes in pressure map to boiling temperatures. Most important, he needed an accurate way of measuring the volume of steam produced by vaporizing a given volume of water, and the water condensed from a measured amount of steam. Watt was a demon for measurement, and he spent months computing the volume of steam as compared to water, the quantity of steam used by a single stroke of a Newcomen engine, the quantity of water needed to condense it, and so on. As a case in point, though Samuel Moreland had estimated that boiling a given volume of water would produce steam that would fill a space 2,000 times greater, J. T. Desaguliers calculated the number as 14,000, and Watt needed to find out for himself. In one of his notebooks,19 he describes an experiment in which he boiled an ounce of water in a “Florence Flask,” forced the air and water out, and compared before and after weights, concluding that the accurate relationship between liquid and solid volumes was 1,849 times. Once deriving the critical relationship between the phases of water, as Watt later recalled,

I mentioned it to my friend Dr. Black,20 who then explained to me his doctrine of latent heat…. I thus stumbled upon one of the material facts by which that beautiful theory is supported…. Although Dr. Black’s theory of latent heat did not suggest my improvements on the steam-engine … the correct modes of reasoning, and of making experiments of which he set me the example, certainly conduced very much to facilitate the progress of my inventions.

Nothing is more common in the history of science than independent discovery of the same phenomenon, unless it is a fight over priority. To this day, historians debate how much prior awareness of the theory of latent heat was in Watt’s possession, but they miss Black’s real contribution, which anyone can see by examining the columns of neat script that attest to Watt’s careful recording of experimental results. Watt didn’t discover the existence of latent heat21 from Black, at least not directly; but he rediscovered it entirely through exposure to the diligent experimental habits of professors such as Black, John Robison, and Robert Dick.

In the end, it was the habits of recording and comparing results, time after time, that proved truly indispensable for Watt’s “rediscovery” of Joseph Black’s conjecture of latent heat, one that puzzled not only Watt, but generations of physics students ever since. Boil a quart of water, turning it into steam; it takes up a bit more than 1,800 times the space it did when liquid. But an atmospheric steam engine doesn’t want steam, it wants a vacuum, so it has to condense that steam back into water. Newcomen did so by injecting a stream of water into the sealed cylinder of his engine, but he never measured the amount needed. Watt, diligent experimentalist that he was, did: It took up to six quarts of water at room temperature to condense the steam. A year into the process, Watt had not only rediscovered Black’s theory, he was finally able to quantify it. The exhaustive process of experimenting, measuring, and experimenting again had allowed him to calculate how much steam was necessary for each piston stroke, and how much the Newcomen engine was actually generating. He now had quantities he could measure.

The measurements showed him where the problem was. The engine depended on steam’s filling the cylinder before it was ready to produce a vacuum. But every time fresh steam was admitted into the now cooled cylinder, it didn’t expand; it just continued to condense, turning back into water until the cylinder heated up to the temperature of the steam itself. Heating the cylinder walls22 wasted up to three-quarters of the steam, or even more: In one test made in 1765, Watt found that an old-style engine was boiling more than three times as much water to heat the cylinder as it was using to create a vacuum.

The problem was exacerbated by the fact of the vacuum itself, which effectively lowered the vaporization temperature of the water, in the same way that water boils at a much lower temperature at high altitudes: lower pressure, lower boiling temperature. The water, which needed to be heated to 100°C/212°F to boil at normal pressure, needed only half that to boil in a vacuum. And if water turns to steam at relatively lukewarm temperatures, then condensing it requires either a modest amount of very cold water (obviously impractical without refrigeration) or a huge amount at room temperature, which degraded the engine’s efficiency even further.

The Newcomen engine was caught between fundamentally incompatible goals: The engine should use as little water as possible to condense the steam (in order to avoid cooling the cylinder), but as much water as possible to make sure that condensation occurred rather than more vaporization. Put another way: The cylinder needed to be kept at a constant 212°F/100°C (to avoid condensation that didn’t create a vacuum) and it needed to be kept at a constant 100°F/45°C (to avoid vaporization). Watt, in Usher’s terms, had perceived an “unsatisfactory pattern.”

Still, after two years of measurement, analysis, and experiment, the unsatisfactory pattern was all he had. Frustrating though that was, he kept at it, to satisfy not merely his curiosity, but also his wallet; in his own words, his mind “ran on making engines cheap23 as well as good.” From the beginning, Watt recognized the problem in terms of wasted fuel, which meant wasted money, and therefore an opportunity. An idea that could significantly reduce that waste was clearly going to make someone rich. That someone didn’t need to be a skilled artisan. He didn’t have to live in a culture that had only recently articulated a property right in ideas and drafted legislation protecting that right. Scientists and philosophers, as we have seen, had been paving the way for centuries before Watt, or even Newcomen. Eighteenth-century Britain wasn’t any more hospitable to their brilliant innovations than anywhere else; but it was a lot more hospitable to innovators who couldn’t afford to invest years of their lives with no hope of material gain. Watt was brilliant, unusually so. But he was also emblematic of hundreds, soon to be thousands, of men like himself, each of them searching for a “eureka” moment.

ALFRED NORTH WHITEHEAD FAMOUSLY wrote that the most important invention of the Industrial Revolution was invention itself. A number of others compete for second place, but the insight that came to James Watt in the spring of 1765 has a lot of support. By then, he had tried dozens of different ways to find a cylinder that would both heat up and cool down rapidly, even trying different materials for the cylinder itself, experimenting with brass, cast iron, and even wood “soaked in linseed oil, and baked to dryness,” each trial repeated half a dozen times. Nothing had worked, until he had his epiphany,* one he later described as the realization that since

steam was an elastic body24 it would rush into a vacuum, and if a communication were made between the cylinder and an exhausted vessel it would rush into it, and might be there condensed without cooling the cylinder. I then saw that I must get rid of the condensed steam and injection-water if I used a jet as in Newcomen’s engine. Two ways of doing this occurred to me. First, the water might be run off by a descending pipe, if an outlet could be got at the depth of thirty-five or thirty-six feet, and any air might be extracted by a small pump. The second was to make the pump large enough to extract both water and air….

What he had envisioned was simple enough: a second chamber, connected to the cylinder by a pipe, through which the steam would flow. When it arrived in the new chamber, already surrounded by cool water, the steam would condense, a vacuum would be formed, and atmospheric pressure would pull the piston down—but the cylinder in which the piston traveled could stay hot as a new jet of steam entered it. One chamber would stay cool, the other hot, each time the engine cycled.

The separate condenser would prove not only central to the development of steam power and the entire Industrial Revolution that ran on it, but also an utterly necessary step on the way to the very different sort of engine that powered Rocket. It is also, happily, a rich test case of the mutually reinforcing relationship between abstract theorizing and rule-of-thumb engineering. Literally rule-of-thumb: As with all mechanical inventions, the insight that inspired the separate condenser could be visualized, but it wasn’t worth much of anything until it could also be handled—note the linguistic clue. The human eye can see things that don’t yet exist, but making them requires the human hand, and it was now time for Watt to return to his university workshop and let his skilled hands turn his insight into a model.

That year training on brass compasses and quadrants in London now proved its worth. Within weeks, he had handcrafted all the components for an engine: two cylinders, one piped to a boiler and containing a piston with a valve on the bottom to vent excess water, the other a ten-inch-long brass syringe with a diameter of 1¾″ containing two ten-inch tin “straws” each about ⅙″ in diameter, and a hand-operated air pump with a ¾″ diameter.

Fig. 3: The “stovepipe” on the left is Watt’s separate condenser. Four years after his brainstorm on Glasgow Green, this was the result: a working cylinder that didn’t need to be cooled and reheated for each stroke, thus doubling the utility of Newcomen’s design. Science Museum / Science & Society Picture Library

The two cylinders were connected by a horizontal pipe, and the syringe immersed in a cistern of cold water. Watt lit his boiler and let the steam flow into the piston cylinder, closed the steam cock, and pumped out the air in the syringe, thus pulling in the steam, which immediately condensed around the cold tin straws. The piston in the cylinder immediately lifted a weight of 18 pounds; a cylinder holding barely a pint of water was raising a weight equivalent to more than two gallons. Watt, a perfectionist by temperament, education, and training, had finally (though briefly) satisfied himself. Thirty years later, he would describe the model as being “nearly as perfect25 … as any which have been made since that time.” He was not normally an especially confident man—perfectionists rarely are—but in April 1765 he was optimistic enough to write to his friend James Lind, “I can think of nothing else26 but this Machine. I hope to have the decisive tryal before I see you….”

It is not known when he actually saw Lind, but by the summer of 1765, on the back of £1,000 borrowed from Joseph Black, “the invention was complete27 … a large model, with an outer cylinder and wooden case, was immediately constructed, and the experiments made with it served to verify the expectations I had formed, and to place the advantage of the invention beyond the reach of doubt.”

The time had come for the next step. And the next step was going to cost money—a lot more than he could borrow from colleagues at the university. Watt needed capital. Investment capital, however, wasn’t easy to find in 1765 Britain; and it was a lot harder than it had been fifty years earlier. The reason was one of the greatest financial bubbles in history, the collapse of the South Seas Company.

THE SOUTH SEAS COMPANY had been incorporated in 1711, with a charter that granted what was potentially a far more lucrative monopoly than anything Edward Coke had contemplated a century earlier. In return for buying £10 million of government debt, the Company was given exclusive trading rights throughout Central and South America, whose bounty included wool, rum, sugar, and, most profitably, slaves. Promoted like an eighteenth-century Enron, the South Seas Company offered not only the promise of unimaginable wealth, but stock that could be purchased by virtually anyone. This was both a novel and an appealing idea in a time when the world’s largest corporation, the British East India Company, had fewer than five hundred investors. Since, however, the Company’s only real asset was the British government’s promise of access to ports that were entirely controlled by the Spaniards, making money from trading proved difficult. The Company was, even so, brilliant at promoting its own prosperity, placing newspaper stories, hosting parties, and maintaining luxurious offices in the most expensive buildings in London. In January 1720, stock was issued at a par price of £100 a share; by August, at the peak of the bubble, when the average British artisan was earning less than £100 a year, a single share of the Company traded for £1,000. And even worse, it inspired other businesses to issue stock on what might be called speculative ventures, including a company capitalized at £1 million in order to produce a perpetual motion machine. One of the more candid styled itself “A Company for carrying on an undertaking28 of great advantage, but no one to know what it is.”

The result, once the bubble burst and the dust cleared, was that Parliament essentially barred the issuing of stock for any business purpose, which limited the potential pool of investors to what would today be called venture capitalists. In the case of Watt’s invention, this meant partnering with an entrepreneur with both ready cash and a liking for technology.

John Roebuck was then a forty-seven-year-old serial entrepreneur who had started half a dozen different businesses, each of them intending to exploit a technological innovation, including the first industrial refinery that manufactured sulfuric acid* by combining sulfur dioxide with oxygen and the resulting compound with water, all in a lead-lined chamber. The acid refinery prompted his first patent application, but by no means his last. By the time he met Watt in 1765, he was also master of one of the world’s most innovative forges, the legendary Carron Ironworks, and holder of patent number 780—the number of patents granted annually was still, a century after the Statute on Monopolies, measured in dozens—for a new process for making bar iron.

A correspondence between the ambitious young instrument maker and the nearly twenty years older businessman began in the summer of 1765, prompted by Joseph Black, who counted both as friends. In September, Watt wrote to Roebuck inviting an investment in his discovery that producing steam within a vacuum was dramatically more efficient than producing it in air, his excitement such that “I am going on with the Modell29 of the Machine as fast as possible and hope to have it finished in another week.”

Rereading the letters, it is impossible to miss the tension present from the beginning. Roebuck fancied himself at least as gifted a scientist as Watt, and insisted on an extreme form of due diligence, demanding to see Watt’s drawings, notes, and models. He demanded that Watt try to create a vacuum without a jet of water condensing the steam, and even urged him to discard the separate condenser, which was, after all, the point of the entire exercise. Watt, for his part, was generally courteous, but convinced of both his own talent and of the power of the separate condenser. For months, the two engaged in the sort of epistolary courtship that puts one in mind of the way that porcupines mate. Only when Roebuck, who was nothing if not intelligent enough to recognize Watt’s gifts, satisfied himself that the separate condenser promised everything Watt believed, did he agree to a partnership. The terms of the agreement obligated Roebuck to absorb all future expenses related to building a machine that would, in Watt’s words, produce the same amount of work for half the amount of fuel. He further agreed to pay off Watt’s debt to Black in return for two-thirds of future profits.

Watt’s frustrations were just beginning. Vacuum is notoriously unstable, but it needed to be kept intact in order for the engine to do its work. Newcomen’s vacuum seal had been nothing more than a leather collar with a layer of water on top, but Watt had to avoid using it on his own engine, since the water would, of necessity, cool the hot cylinder and so eliminate most of the advantage of the separate condenser. But everything else he tried was either too porous—steam escaped and air entered—or created too much friction in the cylinder, costing a huge amount of energy. As a result, he tried dozens of combinations30 of materials for both piston and cylinder: wood, tin, copper, and cast iron, in square and round shapes, sealed with leather, cloth, cork, oakum, asbestos, and numerous alloys of lead, and lubricated with mercury, graphite, tallow, manure, and vegetable oil. “Cotton was proposed31 by my friend Chaillet; I thought of trying it but was deterred first by its price, secondly, by the very thing you have found: that it could not be easily made to cohere without glue or weaving the substances. I have hopes of pasteboard … mixed with dung; I propose to separate the gall and sand from the dung by washing. I have found by experiment that for making joints steam tight, there is nothing equal to it as it is of no consequence whether the joint be naturally round or not….”

While pasteboard finally worked well enough, it did nothing to solve the central mechanical problem, which was getting the piston to fit into the cylinder as tightly as possible with as little friction as possible—as usual, two objectives fundamentally in conflict with each other. Over the first two years of experimentation, Watt built, again by hand, three models, each with a different cylinder: the original, with a cylinder of 1¾″ brass, but no steam jacket; a 1⅖″ cylinder with steam jacket; and one five or six inches long with a steam jacket made of wood. The tin straws, which worked as a surface condenser, were discarded because of difficulties with consistency and replaced by jet condensers similar to those used by Newcomen.

Not all, or even most, of the revisions—in a nod to Usher’s stages of invention, perhaps better to call them “critical revisions”—were the inspirations of a solitary inventor. A friend, Dr. William Small,* advised by letter, “Dear Jim … Let me suggest a method32 of making your wheel and valves tight: Let the valve frame be made easy for the groove and about half thick; put a ply of pasteboard below the frame … and place it in the groove in its proper place, then lay a ring of pasteboard all around each side of the groove and over each valve frame, taking care no pasteboard projects over the frames or grooves….”

By 1768, Watt, three years into his deal with Roebuck, acknowledged that “what I knew about the steam engine33 [in 1765] was but a trifle to what I know now.” His frustrations were growing pronounced. Any slight defect in any component was enough to compromise the design, and therefore the designer’s temper. Newcomen’s engine had only to be better than a horse-driven pump; Watt’s had to be better than Newcomen’s, and that meant cheaper. The unforgiving arithmetic of coal obliged him to produce not merely an elegant design, but one that consumed less fuel, and virtually anything less than perfection in the boring of the cylinder or the strength of the solder consumed more.

Watt’s perfectionist habits, which had given rigor to his early experiments and made the original separate condensing model work so encouragingly, were no longer much of an advantage. Because while Watt could build a small model to the most exacting specifications, a larger, and therefore practical, version needed a design that could be executed by others; “my principal hindrance34 in erecting engines,” he wrote to Roebuck in 1765, “is always the smith-work.” Supposedly, the smiths at Roebuck’s Carron foundry were the best in England, but even their skills were not up to making a cylinder to tolerances that resulted in one that was (a) perfectly round (so that the piston would fill it) and (b) airtight.

Watt’s only “relief amidst [his] vexations”35 was, perversely enough, the need to make a living. Though Roebuck was paying the expenses while Watt was attempting to produce a working engine, and had even set the inventor up in a workshop at Kinneil, near the town of Borrowstounness (more popularly, Bo’ness) in central Scotland, he was not paying Watt a salary. To support his family—in 1764, Watt had married his cousin, Margaret Miller, who would give him five children before her death in 1772—the inventor adopted his father’s trade, surveying the canals of northern England, which, he wrote, “have given me health and spirits36 beyond what I commonly enjoy at this dreary season…. Hire yourself to somebody for a ploughman; it will cure ennui.”

At Kinneil, however, the pressure was unrelenting. By the middle of 1768, Watt had built an eighteen-inch cylinder out of tin, but the same malleability that made it an excellent material for sealing in the vacuum also made it something less than robust. Roebuck didn’t care. He badly wanted some indication that his investment would be redeemed sometime soon, and he insisted that Watt apply for a patent. And so, in January 1769, Watt, somewhat reluctantly, traveled to London, where, despite the still imperfect design of his engine, he had been granted patent number 913 for “a method of lessening the consumption of steam and fuel in fire-engines.” His first meeting after collecting the document from the Great Seal Patent Office was with neither Roebuck—the man who had financed the patent—nor Joseph Black, the friend who had inspired it, but with a Birmingham manufacturer named Matthew Boulton.

BOULTON WAS THEN THIRTY-NINE years old, eight years older than Watt, born into a family that made small metal goods: buckles, buttons, graters, household tools—“toys,” in the vernacular of the day. When he was still in his teens, he entered the family business, most of whose functions were, typically for the time, jobbed out to others: raw materials were bought from one firm, sales handled by another, transportation by a third. Sometimes the other firms were dependable, sometimes not. But they were always costly, which seemed to Boulton an opportunity. By the time he was twenty-five, he had not only enlarged the business but was in the process of changing it irrevocably. Determined to integrate all possible aspects of manufacturing, Boulton moved the metal stamping operations from one water mill to another, starting construction in 1762 on what would become the world’s largest and most famous factory with the relatively modest outlay of £9,000.* Eventually settling two miles from the center of the city of Birmingham, the Soho Manufactory would grow to include workshops, showrooms, stores, offices, worker dormitories, and design studios. It also incorporated a decidedly progressive bent in workforce relations: Boulton used no child labor, and he even offered his laborers, in return for one-sixtieth of their wages, social insurance that paid benefits in the event of illness or injury.

By the time he was thirty, he was already acknowledged as not only a visionary businessman, but also a hugely successful one. Soho’s output of jewelry, silverware, and gilt decorative products, as well as the traditional iron and tin “toys,” made Boulton, in the words of Josiah Wedgwood (himself a rather remarkable story in the history of ceramics), “the Most compleat Manufacturer37 of Metals in England.” And he was more. James Watt is very likely the best known of all the inventors associated with the introduction of steam power. Partly this is because his life is such a useful bit of shorthand for the entire world of invention that fueled the perpetual innovation machine we call the Industrial Revolution. But the unique elements that made Britain so hospitable to inventions produced by her artisan class, including the legal and cultural incentives articulated in Coke’s Statute and Locke’s Treatises, were only half of the transaction. Increasing the supply of inventors by permitting them to sell their ideas was useless without a market in which those ideas could be sold. And since ideas don’t sell themselves any better than anything does, someone needed to sell them. If James Watt was primus inter pares on the supply side of the steam economy, Matthew Boulton was unquestionably the man best equipped to introduce him to those willing to pay for his supply of ideas.

Watt had already visited the Soho Manufactory once before, in 1767. It is not known whether Watt, whose distaste for dealmaking was one of his most consistent affects—“I would rather face a loaded cannon38 than settle an account or make a bargain”—managed to drop the hint that his partnership might be subject to improvement, but nothing came of it for more than a year, during which Roebuck’s fortunes deteriorated dramatically. In one of the most reliable tropes of his life, Roebuck’s talent for finding innovative business opportunities was sabotaged by his chronic inability to make them pay off, and his investment in a coal mine was, literally, underwater. He needed cash, and thought he knew the best way to get it.

In December 1768, at the same moment that Watt’s patent application was moving through the London bureaucracy, Roebuck sent a letter to Boulton offering to sell him an exclusive franchise for the Watt engine in three English counties: Warwick, Stafford, and Derby; Boulton declined. In January, Watt, in possession of his first patent, stopped in Birmingham on his way back to Scotland; one can only guess what they discussed, but there can be little doubt that both Watt’s plans and Roebuck’s offer were shared. In the event, on February 7, 1769, Boulton sent James Watt a letter that read in part:

I was excited by two motivs39 [sic] to offer you my assistance which were love of you, and love of a money-getting ingenious project. I presum’d that your engine would require mony [sic], very accurate workmanship, and extensive correspondence, and the best means … of doing the invention justice would be to keep the executive part out of the hands of the multitude of empirical Engineers who from ignorance, want of experience … would be very liable to produce bad and inaccurate workmanship…. My idea was to settle a manufactory near to my own by the side of our Canal [i.e. in Birmingham] where I could erect all the conveniences necessary for the completion of Engines and from which Manufactory We would serve all the World with Engines of all sizes … it would not be worth my while to make for three Countys only, but I find it very worth while to make for all the World….” (emphasis added)

James Watt’s new engine was a visionary leap—the separate condenser alone doubled the amount of useful work that the Newcomen engine could extract from a given amount of fuel—but its place in history depended on more than Watt’s engineering brilliance, perfectionist temperament, or even the grant of a property right to the idea. Watt (and, for that matter, Roebuck) would have been happy to grow prosperous replacing the Newcomen engines at England’s coal mines. Changing the world demanded a far larger ambition, and Matthew Boulton was just the man to supply it. It’s no coincidence that Boulton’s grandiloquent promise to “make for all the world” (one that he would, in the event, redeem), like Albert Einstein’s 1939 letter to Franklin Roosevelt warning about possible German development of the atomic bomb, was written in response to a history-shaking example of what is a very nearly universal human phenomenon: the flash of inventive insight.

The nature of which is the subject of chapter 6.

* Place names like Aberdeen and Culloden testify to the Scottish influence on Jamaican history.

* It wasn’t Defoe’s first comment on the new world being created in Britain. In his 1697 Essay on Projects, he named his era “the Projecting Age,” by which he meant the “projectors” who sought to build commercial empires supported by patents and monopolies (and, to be fair, “projects” like overhyped investments, about which more below).

* And only yards away from the Department of Moral Philosophy, where Adam Smith, whom we will meet in chapter 11, had held a professorship since 1751.

* Anderson, whose nickname among the university’s students was “Jolly Jack Phosphorus,” is a fascinating character in his own right: A professor of Hebrew and Semitic languages as well as natural philosophy, he is best remembered as an early advocate of higher education for artisans and craftsmen, for whom he held classes throughout his forty years at Glasgow. So dedicated was he to this underutilized national resource that his estate was used to found Anderson College, now part of the University of Strathclyde.

* For more about the nature of that flash of insight, see chapter 6.

* An entire book—be undismayed, not this one—could be written on the history of sulfuric acid as a symbol for the evolution of modern civilization. Under the name “oil of vitriol,” it was the most important weapon in the arsenal of medieval alchemists—the original philosopher’s stone—and remains critical not only for producing fertilizer and bleaching textiles, but as a precursor chemical for sodium carbonate, which is essential for the manufacture of both paper and glass. Even now, a number of international economists use its production as a proxy for a nation’s level of industrial development.

* Small would have been a key asset in any game of eighteenth-century “Six Degrees of Kevin Bacon” as a correspondent of Watt, a friend of Benjamin Franklin, and, before his return to Scotland from North America, Thomas Jefferson’s onetime professor at the College of William & Mary.

* Modest indeed—a fraction of what he would eventually spend on rejiggering Watt’s patent.

You can support our site by clicking on this link and watching the advertisement.

If you find an error or have any questions, please email us at Thank you!