The Most Powerful Idea in the World

by William Rosen

  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 h
e 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 i
ncreases 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.