concerning the many uses of a piston; how the world’s first scientific society was founded at a college with no students; and the inspirational value of armories, Nonconformist preachers, incomplete patterns, and snifting valves

MIDWAY ALONG A LINE of statues that overlooks I. M. Pei’s glass pyramid at the Louvre, near the images of René Descartes and Voltaire, a rather forbidding figure looks down on the Napoleon Court. The man’s right hand, as is traditional, is tucked into his coat. His left hand, however, holds a curious contraption, something that looks a bit like a plumber’s helper but is in fact one of history’s most important leaps of mechanical imagination: the world’s first steam-driven piston. The hand holding it belongs to its inventor, Denis Papin, whose ingenuity was critical to the creation of a steam-powered world, and whose life illustrates, as well as anyone’s, the challenges of the inventive life.

The son of a government official in the city of Blois, Papin, a Huguenot (like many in the city, which had long been a haven for French Calvinists), was trained as a physician at the University of Angers and possibly even practiced as one for a few years, though his later comments suggest he much preferred physics. In 1671, he got the chance1 to act on that preference when he met the Dutch mathematician and physicist Christiaan Huygens, a founding member of the Académie des Sciences (inaugurated in 1666 as the French equivalent of the Royal Society), who was at Versailles repairing a balky windmill used to power the palace’s fountains. The following year, Huygens, who had been impressed with Papin’s mechanical insights, offered him a job as his secretary, and Papin gave up the healing arts for good, migrating to Paris to work at the Royal Library.

Huygens was another in a seemingly unending line of seventeenth-century scientists fascinated by vacuum and atmospheric pressure, and Papin’s time with him was evidently both satisfying and productive. The two worked on a number of air pump experiments, and jointly published five papers in the Philosophical Transactions of the Académie Royale in 1675, though histories differ on whether they worked together on Huygens’s gunpowder-driven piston, a promising but slightly hazardous technology.

During Papin’s stay in Paris, life in France was becoming more than slightly hazardous for the nation’s Huguenots, the beginning of a process that would end in the revocation of the Edict of Nantes and the return of official persecution, in 1685. By then, Papin had accurately read the writing on the wall, and, seeing no future for him in his birth nation, crossed to England in the fall of 1675. He was armed with a letter of introduction from Huygens to Robert Boyle, who was in need of a collaborator to replace Hooke, whose own researches were by then being financed by his employers at Gresham College and the Royal Society. The two evidently hit it off, and Papin joined Boyle as his secretary, though a better term would have been “experimental assistant.”

While Papin was no Hooke (this is scarcely an insult: by 1675, Hooke had explained the twinkling of stars, described the earth’s elliptical orbit, rebuilt the fire-destroyed Royal College of Physicians, disputed with Sir Isaac Newton over the discovery of the diffraction of light, and invented the anemometer, and he still had twenty productive years in front of him), he did excel at both experimental design and mechanical gadgetry. Most famously, in 1681 he invented a steam digester, or “machine for softening bones” as he described it, which was essentially a pressure cooker designed to clean bones rapidly for medical study.

The subsequent pattern of Papin’s life would be familiar to any contemporary academic in search of a tenure-track position. In 1679, before the steam digester made him briefly famous, Papin was hired by his predecessor, Robert Hooke, as a secretary at the Royal Society at an annual salary of £20; he left there in 1681 for a new job as “director of experiments” at the Accademia Publicca di Scienze in Venice, yet another Royal Society imitator. After the Accademia failed, Papin returned to England, and Hooke, for three more years, this time as “Temporary Curator of Experiments” at the Royal Society, leaving that to become professor of mathematics at the University of Marburg.

Papin’s contributions might have had an even larger impact had he enjoyed, like Boyle, the income from lands acquired by the Earl of Cork. And they are not small even so. In the 1686 issue of Philosophical Transactions,2 Papin describes (though evidently did not actually construct) an early air gun, probably a direct outgrowth of his gunpowder-piston experiments with his onetime mentor, Huygens. His digester featured a brilliantly innovative safety valve: When the pressure inside the chamber of Papin’s invention grew high enough, it would overcome the weight of a hinged and weighted stopper and open a path to the outside, but when the pressure subsided, the stopper’s weight would cause it to sink back to its normal position.

Most significantly for the evolution of the steam engine, in 1690 he published, in the Acta Eruditorum of Leipzig, a design of a true atmospheric engine: one that used the vacuum created by steam condensation to let atmospheric pressure drive a piston—the same one carried by his statue at the Louvre. Papin’s great insight was recognizing that the weight of the atmosphere on the top of an open cylinder, which is apparent only when a vacuum is created at the cylinder’s bottom, could also drive something mechanical within the cylinder. He wrote, “Since it is a property of water3that a small quantity of it turned into vapour by heat has an elastic force like that of air, but upon cold supervening is again resolved in water, so that no trace of the said elastic force remains, I conclude that machines could be constructed wherein water, by the help of no very intense heat, and at little cost, could produce that perfect vacuum which could by no means be obtained by gunpowder.”

By 1707, he was corresponding with Gottfried Wilhelm Leibniz, the German mathematician, engineer, and philosopher,* about the possibilities of an engine driven by steam pressure, all while trying to keep his head above water as a poorly paid councillor to Charles-August, Landgrave of Hesse-Kassel, a German principality located on the Prussian border. Keeping the landgrave interested proved a challenge all its own: Papin built him a centrifugal pump (evidently to water the landgrave’s gardens) and a furnace air blower that became known as the “Hessian bellows.” He even tried to design a hydraulic perpetual motion machine based on the belief that pressure from one large cylinder would provide a never-ending source of pressure on a smaller cylinder. By the time he built a demonstration submarine4 for his patron, however, the landgrave had already lost interest in it, and in Papin, who returned to England for the final time, spending his last years in unsuccessful attempts to promote a pension from the Royal Society and dying in poverty in 1712.

Papin was by all accounts a difficult man who lived a difficult life, and it is impossible to tell which was cause and which effect. He spent virtually all his adult years as a refugee, partly because of his religion—the late seventeenth century was no time to be a French Protestant—but even more because he was enormously rich in talents for which no market yet existed. He was an industrial scientist before there was an industry to employ him, which made him, in consequence, completely dependent on patronage. His correspondence is evenly divided between generous sharing of his scientific discoveries and pleas for pensions, the latter wearing out his welcome in half a dozen countries. Papin’s career, even more than Hooke’s, illustrates the challenges faced by the most talented scientists if they lacked an independent source of income. The archetype—innovative talent supported either by patronage (governmental or aristocratic) or by inheritance—was as old as humanity and still quite sturdy.

Before he became an object lesson in the difficulties of making a living as a seventeenth-century inventor, however, Papin made one final connection on the route to engine 42B, and to Rocket. In 1705, Leibniz, then a courtier in the north German city of Hanover, received a sketch of a new machine for using steam to raise water, which he immediately sent to Papin in Hesse. The sketch had come from London.

THE TALLEST SKYSCRAPER IN the City of London, known variously as Tower 42 and NatWest Tower, occupies a site in Bishopsgate that was the former home of what was once London’s only university: Gresham College, founded by a bequest from the will of Sir Thomas Gresham as a sort of scholarly Shangri-La, a college with neither students nor degrees. Instead, it houses scholars who offer lectures to any member of the public who cares to attend, and has been doing so ever since 1597. When Christopher Wren was tapped, in 1660, for the first lecture to what was to become the Royal Society, he was the Gresham Professor of Astronomy, and consequently that was where the lecture was given. The Royal Society called Gresham home for the next forty years, except for a brief period when fire and plague chased them out of London altogether.

Thus it was at Gresham College on June 14, 1699, that the Royal Society assembled for a demonstration of what was described as “a new Invention for Raiseing of Water and occasioning Motion to all Sorts of Mill Work by the Impellent Force of Fire which will be of great use and Advantage for Drayning Mines”—in plain English, a steam engine. Its inventor was a military engineer named Thomas Savery.

The need for “drayning mines” was a relatively recent phenomenon, a direct consequence of the replacement of charcoal by pitcoal as the preferred fuel for space heating and for smelting metal. The preference was due less to the superiority of the mineral over wood, than to the fact that the raw material for charcoal was disappearing far faster than it could ever be produced. However, the deeper one digs for pitcoal, the greater the chance of finding water that needs “drayning,” either by digging drainage tunnels, or adits—expensive, and only practical where the topography permits—or building pumps. The most powerful pumps in use in seventeenth-century England were operated by waterwheels, but nothing obliged rivers and streams to be convenient to mines; finding an alternative machine that could overcome water’s tendency to seek the lowest level of any excavation meant that vacuum was no longer a purely philosophical concept.

Savery was not the first to realize that, just as turning water into steam created pressure, converting it back into water produced the opposite: a vacuum. By the middle of the seventeenth century, large numbers of people started to sense the enormous potential of a steam-created vacuum for pulling wealth out of the ground in the form not only of coal but also of copper, tin, and silver. Some of the attempts were made by Italians: in 1606, a Neapolitan engineer named Giambattista della Porta designed a machine to pump water out of a closed container using steam; some by Frenchmen: in 1609 or 1610, Salomon de Caus, an ambitious gardener who specialized in designing fountains, traveled from Dieppe to England, where he built a number of steam-driven toys at one of the residences of the Prince of Wales. And some were Englishmen, like the now forgotten David Ramsay, who supposedly invented, in 1631, a device “to Raise Water from Lowe Pitts by Fire,”5 or the Marquess of Worcester, whose “water-forcing engine” dates from 1663.

The inability of della Porta, de Caus, and others to produce a working steam pump was, in some sense, as valuable as success might have been, since they failed publicly enough that others were able to learn from their failures. Thomas Savery was one of them, and it is worth noting that his own experiments were financed not by a wealthy aristocrat, but by a national government.

This is a poorly understood aspect of the Industrial Revolution. It doesn’t fit very well with either a heroic entrepreneurial history in which visionary innovators, usually working alone, develop the ideas, machines, and institutions of progress, or a deterministic one, in which technological progress is a function of predictable natural laws. The messy truth turns out to be that the innovative culture that blossomed in eighteenth-century Britain depended both on individuals looking out for their own interests, and on recognizing a national interest in innovation. When Savery started investigating the “impellent force of fire,” he was almost certainly working on his own behalf. But he did so at an English government facility: the Royal Office of Ordnance, which supported a large number of workshops and factories around London, and whose sole purpose was improving the technology of war. And so they did; though the cannon of the era were still mostly manufactured by private contractors located in the Weald, an ironworking center forty miles south of London, the Office of Ordnance tested them, and, more significantly for an engineer like Savery, “was responsible for the design and fabrication6 of various military engines … cranes, devices for mechanically hurling projectiles, gun carriages … and pontoon bridges for spanning streams.” Sometime around 1639, the original Lambeth works of the Office of Ordnance had been expanded to include part of an ancient estate known variously as Fauxhall or Vauxhall, and made “a place of resort for artists, mechanics,7 &c [where] experiments and trials of profitable inventions should be carried on”—a sort of seventeenth-century equivalent of the U.S. Department of Defense Advanced Research Projects Agency, or DARPA, whose self-described mission is “to prevent technological surprise to the U.S. [and] to create technological surprise to our enemies.”*

As with DARPA—which is where, among other things, the predecessor of the Internet was invented—engineers at Vauxhall produced technological surprises for the civilian world as well as the military. British monarchs, after all, had interests in mining as well as conquest, so it is no coincidence that one of Savery’s predecessors at Vauxhall, Samuel Moreland (or Morland), an engineer in the employ of Charles II, made some sort of fire-driven water pump, “a new invention for raising any quantity of water to any height by the help of fire alone,” in 1675. Moreland left behind not only his notes about the pump (since vanished) but something far more useful: a calculation of the volume of steam—about two thousand times that of water.

Moreland’s calculation was not only the most precise estimate for more than a century; it was also critical for building any sort of working steam engine. Knowing that steam, once condensed back into water in a sealed container, leaves behind a vacuum that takes up two thousand times the cubic area of the condensed liquid is very nearly as important as knowing the temperature at which water boils—perhaps more so, since the first working steam engines were built decades before the first accurate thermometers.

Thus, when Savery made the first demonstration of his pumping machine “at a potter’s house in Lambeth,”8 two years before he did so with an identical machine at Gresham, he owed a large debt to his employers at the Royal Office of Ordnance. That machine consisted of a tall cylinder filled with water and connected to a boiler, in which Savery produced steam, which he then introduced into the cylinder at a pressure estimated to be about 120 pounds per square inch. The pressure pushed the water out one end of the cylinder, leaving steam behind; when the steam-filled cylinders were sprayed with cold water, the resulting vacuum pulled water from a chamber below, creating a pumping action.

Fig. 1: Thomas Savery’s pumping machine, as seen in a lithograph from his 1702 book The Miner’s Friend. The image on the right shows the components: When the canister sprayed cold water on the steam filled cylinder, the resulting vacuum pulled the water up. On the left is the machine at work, two-thirds of the way down a mine shaft, since the vacuum could pull the water only a bit more than twenty feet. Science Museum / Science & Society Picture Library

Savery’s machine was a long way from perfect. The use of water as its “piston” meant that the engine couldn’t pump anything else. Unlike Papin’s digester, it lacked any sort of safety valve. Using it even in its (slightly) improved version would have required an operator to open the steam cock and the cold water valve at least four times a minute; to refill the boiler at least once a minute;9 and to stoke the fire under it as needed. The cylinder was soldered together, and the solder had a melting temperature dangerously close to the temperature of the steam at high pressure, which could exceed 350°F/175°C. Worst of all, while the high-pressure steam could, in theory, push the water several hundred feet upward, the machine depended on suction for the first leg of the journey. Any working Savery pump needed to be built not at the top of a mine shaft, but no more than twenty-five feet from the bottom.

The reason for this limit, which had been well known to Galileo, Torricelli, and Papin, was atmosphere. At sea level, the maximum height that water can be lifted inside a tube under perfect conditions is about thirty-four feet, or just a little more than ten meters, calculated by dividing atmospheric pressure at sea level (14.7 pounds per square inch) by the weight of a cubic inch of water, or 0.0361 lbs. At this point, the water inside exerts a pressure equal to the weight of the atmosphere pushing down on the water’s surface. Since this represents a theoretical limit, requiring a perfect vacuum, the practical limit is even lower, usually assumed to be around twenty-five feet, as anyone who has tried to use a suction pump to draw water to the top of a three-story building has learned. This was a fairly serious problem for draining mines that were already more than one hundred feet underground.

Nonetheless, Savery’s machine was a revelation. And not merely to the “gentlemen, free and unconfin’d” of the Royal Society, who reported, with characteristic understatement, “Mr. Savery … entertained the Royal Society10 with shewing a small model of his engine for raising water by the help of fire, which he set to work before them, the experiment succeeded according to expectation, and to their satisfaction,” but to King William III in a private showing at Hampton Court. More modestly, but far more importantly, it also inspired a Devonshire ironmonger and blacksmith named Thomas Newcomen.

FOR CENTURIES, THE LANDED gentry who held the lands around Dudley Castle in the West Midlands of England prospered in direct proportion to the value of the minerals extracted from those lands. Indeed, that prosperity often took precedence over maintaining the land, and by the mid-1660s, the current Baron Dudley had heavily mortgaged the lands—so heavily, in fact, that he was forced to marry his daughter to someone wealthy enough to pull the family out of debt. The priority of succeeding barons was, as a result, the revitalization of the Dudley real estate, the most valuable pieces of which were the Conygree coal mines, lying one mile east of Dudley Castle.

The Conygree mines, like all excavations, were only workable when dry, or at least free of standing water. This, of course, is why Savery called his pump the “Miner’s Friend” in an eponymous 1702 book. The book, and the invention, demonstrated how Torricelli’s (and von Guericke’s) vacuum could be economically created using the two-thousandfold difference in volume between water in its liquid and gaseous state, and showed how such a vacuum could pull water out of any mine.

So long as the pump could be built no more than twenty-five feet from the mine’s floor.

After two hundred years of excavating, however, the mines at Conygree were more than six times deeper than the working distance of a vacuum pump, which meant a Savery-style engine would need to be built (and operated) more than one hundred and twenty-five feet below ground level. What they needed was an entirely new machine. Even more, they needed an act of genius, and this time the word, so frequently devalued by overuse, is appropriate. One historian of science calls the machine that made history near Dudley Castle in 1712 “one of the great original synthetic inventions11 of all time.”

The synthesis in question tied together two intellectual threads whose history dates from Heron’s first-century Alexandria. The first was man-made vacuum: the concept that was studied by Torricelli and pursued by Giambattista della Porta and Salomon de Caus, and that reached its culmination in Savery’s “new Invention for Raiseing of Water.” The other was the realization that a functional piston could be driven by atmospheric pressure, which was investigated by Huygens and described, though not built, by Papin in 1690. The 1712 engine of Thomas Newcomen,12probably the first working engine built by this enigmatic man, was certainly the first to connect the two threads; and if any single invention can be said to have inaugurated the steam revolution, this was it.

Much more is known about the machine than its inventor. He was born in 1664 in Dartmouth, to a family that may have been in the shipbuilding trade. In his teens he was in all likelihood apprenticed to an ironmonger—part smith, part hardware salesman—since he was practicing the trade as a journeyman by the age of twenty-one, but his name doesn’t appear in records of indentured freemen, likely because his family was Baptist in a land that recognized only the Church of England.

Newcomen’s religion had consequences greater than absence from a local census. Dissenters, including Baptists, Presbyterians, and others, were, as a class, excluded from universities after 1660, and either apprenticed, or learned their science from dissenting academies.

Bad luck for the universities, good luck for the nation. Only decades after a tidal wave of scientific knowledge started washing over Britain—the first English translation of Galileo’s Dialogue Concerning Two New Sciences was published in the 1660s, nearly seventy years before an English edition of the Principia of Isaac Newton (Latin edition, 1687)—some of the nation’s most ambitious and practical young were excluded from Oxford and Cambridge. At the same time that he chartered the world’s first scientific society, Charles II had created an entire generation of dissenting intellectuals uncontrolled by his kingdom’s ever more technophobic universities. Some attended so-called dissenting academies, which mimicked an Oxbridge classical education with notably less arrogance about the teaching of science and modern languages. Many more learned their science in the most practical way: as apprentices to artisans who were more likely to be literate than ever before in history.

Newcomen may have been unable to translate Horace, but that did not mean he was, in any important sense, uneducated. He could perform calculations rapidly, knew a fair bit of geometry, could calculate the strength and velocity of moving parts, could draw clearly, and—obviously—could read all that was available on subjects that interested him.

With books to read, and tools to practice his trade, Newcomen might still have lacked sufficient resources to travel all the way to Conygree but for one more unanticipated consequence of the Restoration: a package of laws that prohibited pastors who refused to conform to their dictates—using the Book of Common Prayer, for example—from teaching or preaching anywhere within five miles of their former “livings.” As a result, Dartmouth’s Baptists hired as their pastor the Reverend John Flavel, a well-known Presbyterian who not only led secret community services (another law forbade religious gatherings of more than five people) but organized secret community banks as a method of pooling their resources. One of them funded Newcomen’s first experiments.

This is worth underlining. The significance of the Dartmouth “bank” in the history of steam power is real, but modest. However, it is also a reminder of what we might call the British advantage in the development of the Industrial Revolution. Compare, for example, the experience of being a Baptist in Restoration England with that of being any sort of Protestant in seventeenth-century France. Newcomen may have been invisible to his local census, but at least he was not, like Papin, exiled from his country.

Thus, between 1700 and 1705, while Papin was wandering across central Europe trying to secure a pension, Newcomen, and his partner, John Calley (sometimes Cawley), a glazier (sometimes a plumber),13 set up a workshop in Newcomen’s basement, financed by Flavel’s bank, and started experimenting. During the next decade, more or less, most of their time was spent on trying to improve one or the other of the two seemingly independent threads of steam engine development: Savery’s vacuum, and Papin’s piston.

Frustratingly, we know little of just how and when the knowledge of the two came to Newcomen. Relatively detailed descriptions of Savery’s “Miner’s Friend” were, of course, available to anyone who could read once it appeared in the Royal Society’s Philosophical Transactions in 1699, and certainly after the onetime military engineer published his book cum sales brochure in 1702. Intriguingly, Savery was then living in Modbury, only fifteen miles from Newcomen’s Dartmouth home, and we know that he was regularly hiring artisans to build models and parts for his engines. Given Newcomen’s reputation as an ironmonger and wheelwright, it isn’t a huge leap to imagine some contact between the two.

Details about Papin’s piston-driven engine weren’t quite as public, but they were scarcely secret. Newcomen maintained active correspondences with a number of contemporaries, none more important than that with Robert Hooke, one of the most wide-ranging intelligences of the entire century. Hooke corresponded not only with Newcomen but with Papin as well, and he very likely kept the former apprised of the latter’s progress.14 At some point before his death in 1703, Hooke even talked Newcomen out of Papin’s idea of driving the pump’s pistons by air pressure, urging him instead to pursue the idea of creating a vacuum under the piston, writing “could he [Papin] make a speedy vacuum15 under your piston, your work is done….”

Well, not quite done. Newcomen’s real conceptual breakthrough came when he finally combined the strongest features of the two different approaches—or, at least, discarded their weaknesses. His brilliant synthesis lay in forgoing Savery’s dependence on vacuum to raise water, and Papin’s use of a piston operated by expanding steam. And in adding one critical element: the beam.

The most conspicuous mechanical element in Newcomen’s 1712 engine—for that matter, the most conspicuous element in virtually every steam engine for the next century and a half, including the Crofton pump station’s engine 42B—was its horizontal working beam. It looks a bit like an unbalanced seesaw, with the underside of one end attached to a piston and the other to a pump rod holding a bucket, which made the pump end much heavier. When at rest, therefore, the beam angled down toward the bucket at the bottom of the mine shaft, which forced the piston, inside a cylinder filled only with air, up to its highest point. Since the bucket on the end of the pump rod could be hundreds of feet below the guts of the engine, the critical problem with Savery’s engine—the need to place it near the bottom of the mine shaft—was solved. In fact, the only limitation on the depth at which it could work was the weight of the cable holding the bucket, which was relatively insignificant.

Newcomen’s first brilliant innovation—to lift water by seesawing a horizontal beam—was entirely dependent on his feel for the machine’s geometry; the beam, however, didn’t do anything about the need to renew the cycle of vacuum in a “speedy” manner, as advised by Hooke. This was critical for a working machine, which had to do more than impress German princelings or even the Royal Society; it had to return to room temperature after being heated well past the boiling temperature of water, and it had to so a dozen times a minute.

Savery’s method for producing condensation—spraying cold water on the outside of the cylinder—was simply too slow. Calley and Newcomen had designed a lead envelope to surround the cylinder, into which cold water could be poured, which improved the speed for heating and cooling the cylinder, but not a lot. Enter luck: The cylinder was essentially a flat piece of tin wrapped into a cylinder shape, its ends held together with a strip of solder. At one point, the solder was imperfectly applied, and the heat of steam in the cylinder melted it, opening a hole. When Newcomen poured cold water into the lead envelope wrapped around the cylinder, a stream of it found the hole, rushed through it, and condensed the steam immediately, with powerful results. For purposes of the experiment,16 Newcomen had attached a weight to the end of the beam to represent the weight of water; when the steam condensed, it pulled the beam down so violently that it broke the chain, the bottom of the cylinder, and even the lid of the boiler underneath.

Newcomen and Calley had, in broad strokes, the design for a working engine. They had enjoyed some luck, though it was anything but dumb luck. This didn’t seem to convince the self-named experimental philosopher J. T. Desaguliers, a Huguenot refugee like Papin, who became one of Isaac Newton’s assistants and (later) a priest in the Church of England. Desaguliers wrote, just before his death in 1744, that the two men had made their engine work, but “not being either philosophers17 to understand the reason, or mathematicians enough to calculate the powers and to proportion the parts, very luckily by accident found what they sought for.”

Fig. 2: The engine that Thomas Newcomen and John Calley erected at Dudley Castle in 1712, as seen in a 1719 engraving, used its vacuum to drive not water, but a piston attached to a beam. Science Museum / Science & Society Picture Library

The notion of Newcomen’s scientific ignorance persists to this day. One of its expressions is the legend that the original engine was made to cycle automatically by the insight of a boy named Humphrey Potter, who built a mazelike network of catches and strings from the plug rod to open the valves and close them. It is almost as if a Dartmouth ironmonger simply had to have an inordinate amount of luck to succeed where so many had failed.

The discovery of the power of injected water was luck; understanding and exploiting it was anything but. Newcomen and Calley replaced18 the accidental hole in the cylinder with an injection valve, and, ingeniously, attached it to the piston itself. When the piston reached the bottom of the cylinder, it automatically closed the injection valve and opened another valve, permitting the water to flow out.

Indeed, the valves, one between the boiler and the piston, and the self-acting valve, with a flap that closed once the condensed water was let out of the bottom of the cylinder, demanded quite as much ingenuity as the horizontal beam itself. All of the discoveries since Torricelli had underlined the potential power of vacuum combined with atmospheric pressure, but the power remained potential so long as the vacuum was unstable; losing the vacuum in the middle of a cycle was functionally equivalent to getting off one end of the seesaw while the other kid is still up in the air. Maintaining it, which meant in practice keeping any air out of the cylinder, was therefore critical, and to do so Newcomen invented what he called a “Snifting Clark” (so called because, in the words of a contemporary observer, “the Air makes a Noise19 every time it blows thro’ it like a Man snifting with a Cold”), a valve carefully designed—not too heavy, not too light—to blow the air out of the chamber without letting any steam escape. Another vacuum preserver, probably the simplest, was the layer of water Newcomen added at the top of the piston, which served to seal the chamber from any air, which would compromise the vacuum.

Newcomen spent ten years experimenting with solutions to the problem of maintaining a regular and stable motion in his engine. None of his solutions was more innovative than his so-called plug rod. Since the machine depended on regular injections of water to condense the steam, it required an equally regular water supply. In Newcomen’s machine, this water was held in an overhead tank; gravity could be relied upon to move water from the tank into the cylinder, but to feed the tank itself, another pump was necessary. Newcomen suspended the plug rod from the horizontal beam itself; this rod, in turn, operated the cylinder valves, thus connecting the flow of water from one chamber into another. As water was pumped into the overhead tank, it also lifted the plug rod and thereby opened the valves of the cylinder, giving the beam a continuous (though jerky) motion. The ingenious F-shaped lever that opened the catch and operated the injection valve may have been a primitive design, but when the University of Manchester Institute of Science and Technology built a scale model of the original 1712 engine in 1968, “the valve still functioned perfectly,20 and was another amazing case of Newcomen arriving at the correct answer.”

Even more elegantly, the onetime ironmonger designed a Y-shaped lever to control the steam entering the engine itself. The lever stayed balanced on the trunk of the “Y” until the piston reached the bottom of its stroke, where an attached peg pushed one of the arms, overbalancing and opening the steam valve, simultaneously destroying the vacuum and pushing the air out through the snifting valve. As the piston rose, the valve stayed open until the top of the stroke, when another peg pushed the other arm, shutting the valve during the complete working stroke.

Newcomen’s valves aren’t just expressions of how well he had trained his mind during his years of experimentation. They also tell of the years he spent21 “educating” his hands at the blacksmith’s anvil, the mechanic’s lathe, and the carpenter’s bench.

This insight is hugely important for understanding not only invention generally, but the era of sustainable invention that Thomas Newcomen inaugurated. Consider, for example, a single element of the Newcomen design: the Y-valve. It was utterly essential to the stable functioning of the engine, but to do its job, it needed to be precise both as to shape and to weight; it would only work if it rocked back and forth on its base as the piston rose, which meant that it needed to be balanced with exactly the same mass on each “arm” of the Y.

Now imagine producing such a fitting22 when the only tools available were a hammer, a chisel, and a file, and perhaps a set of calipers for measurement; no lathes (at least, no lathes that could work metal), no drills, and certainly no powered tools, all of which were decades in the future. The only way to “machine” such a valve was by hand, and the hands in question had to be as sensitive, and as precise, as those of a violinist. Newcomen could perhaps imagine the shape of his valves by eye, but he needed to feel their weight, and their texture, with his hands.

For centuries, certainly ever since Immanuel Kant called the hand “the window on the mind,” philosophers have been pondering the very complex way in which the human hand is related to the human mind. Modern neuroscience and evolutionary biology have confirmed the existence of what the Scottish physician and theologian Charles Bell called “the intelligent hand.” Stephen Pinker of Harvard even argues that early humans’ intelligence increased “partly because they were equipped23 with levers of influence on the world, namely the grippers found at the end of their two arms.” We now know that the literally incredible amount of sensitivity and articulation of the human hand, which has increased at roughly the same pace as has the complexity of the human brain, is not merely a product of the pressures of natural selection, but an initiator of it: The hand has led the brain to evolve24 just as much as the brain has led the hand. The hands of a pianist, or a painter, or a sushi chef, or even, as with Thomas Newcomen, hands that could use a hammer to shape soft iron, are truly, in any functional sense, “intelligent.”

This sort of tactile intelligence was not emphasized in A. P. Usher’s theory of invention, the components of which he filtered through the early twentieth-century school of psychology known as Gestalt theory,* which was preeminently a theory of visual behavior. The most important precepts of Gestalt theory (to Usher, anyway, who was utterly taken with their explanatory power) are that the patterns we perceive visually appear all at once, rather than by examining components one at a time, and that a principle of parsimony organizes visual perceptions into their simplest form. Or forms; one of the most famous Gestalt images is the one that can look like either a goblet or two facing profiles. Usher’s enthusiasm for Gestalt psychology explains why, despite his unshakable belief in the inventive talents of ordinary individuals, he devotes an entire chapter of his magnum opus to perhaps the most extraordinary individual in the history of invention: Leonardo da Vinci.

Certainly, Leonardo would deserve a large place in any book on the history of mechanical invention, not only because of his fanciful helicopters and submarines, but for his very real screw cutting engine, needle making machine, centrifugal pumps, and hundreds more. And Usher found Leonardo an extraordinarily useful symbol in marking the transition in mechanics from pure intuition to the application of science and mathematics.

But the real fascination for Usher was Leonardo’s straddling of two worlds of creativity, the artistic and the inventive. No one, before or since, more clearly demonstrated the importance to invention of what we might call “spatial intelligence”; Leonardo was not an abstract thinker of any great achievement, nor were his mathematical skills, which he taught himself late in life, remarkable. His perceptual skills, on the other hand, developed primarily for his painting, were extraordinary; but they were so extraordinary that Usher could write, “It is only with Leonardo25 that the process of invention is lifted decisively into the field of the imagination….”

Seen in this light, Usher’s attention to Leonardo makes perfect sense. What the great artist-inventor “saw,” in Gestalt terms, was determined as much by what was inside his head as by what was in front of his eyes. Leonardo’s gifts, his education, and his history constrained his perceptions, but also gave them direction. Any inventor’s moments of insight, certainly including Newcomen’s and supremely Leonardo’s, are primarily visual; as a modern scholar puts it, “Pyramids, cathedrals, and rockets26 exist not because of geometry, theory of structures, or thermodynamics, but because they were first a picture—literally a vision—in the minds of those who built them … technology has a significant intellectual component that is both nonscientific and nonliterary.”

There is, however, something missing from Usher’s pure Gestalt explanation of the process of invention. For while it seems reasonable to suppose that most insights are visual, the equally creative process of critical revision is almost overwhelmingly tactile. Leonardo’s hands—holding a brush or a pen, or building a model—were as important as his eyes.

This had obviously been true for a thousand generations of craftsmen and artists, including Praxiteles, Mozart, and, once again, Leonardo. But with the beginning of the eighteenth century, the implications changed, and the reason was an unprecedented enthusiasm for scale models.

The eighteenth century’s need for mechanical models that could be enlarged by orders of magnitude while still performing as they did in their miniaturized form has no precedent in history. Before then, except for the work of a few outliers like Leonardo, mechanical objects that were built by “intelligent hands” were usually as large as they were ever going to get; only with the advent of scale modeling, frequently performed in stages during which a device could grow from the size of a suitcase to that of a house in several steps, were those hands employed in improving mechanisms bigger than toys, or, as was the case with Hooke and Boyle, scientific apparatuses. Thereafter, the critical revisions that Usher described were going to be performed by, and improved by, the hands of trained artisans. The intelligent hands of Thomas Newcomen made him eighteenth-century England’s first important craftsman-inventor. He would not be the last.

This was because Usherian critical revision is a social process, in which the insight of one inventor is revised and reinforced by others. The inventor, in Usher’s words, “lives in the company of a great company of men, both dead and living.”27 By the beginning of the eighteenth century, a literate artisan class, trained in practical mathematics and engineering, was exhibiting a never-before-seen passion for revising and reinforcing one another’s inventions. The size of that “great company of men” and therefore the potential for cross-fertilization—for critical revision—had exploded.

SO IT WAS THAT while only Thomas Newcomen and John Calley arrived at the Conygree mine a mile east of Dudley Castle that day in 1712, a “great company of men” from different times and places accompanied them, observed the construction of the sturdy machine on site, and (metaphorically) applauded when the boiler was fired up, the steam was injected into the cylinder, and the beam rocked on its pivot for the first time. Every stroke of Newcomen and Calley’s engine lifted ten gallons of water out of a 50-meter-deep mine, and did so at a rate of twelve strokes per minute. “During the up-stroke,28 the water was drawn up into the pump cylinder as the bucket [at the end of the connecting rod] was being raised. Valves in the bottom of the bucket opened on the down-stroke to let the water pass through to the upper side … and was then lifted on the next up-stroke.”

The inventive power is inherent in the idea that a column of air has weight in the same way as does a column of bricks, and that if some “bricks” of air are removed from the bottom of the column, the top will move downward. Newcomen’s cylinder removed the bricks by condensing steam into water, under the watchful, if figurative, eyes of Galileo, Torricelli, Boyle and Hooke, Denis Papin, Heron of Alexandria, Otto von Guericke, and a thousand others. What was on display was, even by their elevated standards, genius.

Yet there is an even more important way in which the engine on display at Conygree in 1712 was a work of genius. In its original Latinate meaning, the word is defined as the guardian spirit of a particular household, or tribe: a gens; and the genius responsible for the machine at Conygree was, indeed, from a very particular tribe. In Newcomen’s case, he was the first (or very nearly) and clearly the most important member of a tribe of a very particular, and historically original, type: the English artisan-engineer-entrepreneur. His great invention was not merely an ingenious toy but a profitable one, whose great virtue was not only its productivity but its simplicity and ruggedness. Like another century’s AK-47 assault rifle, it survived the ministrations of even the most technically inept users. It was forgiving, requiring no real precision in alignment, and could be built (except for the cylinder) by local craftsmen using local materials. It truly deserves its description, given by Abbott Payson Usher himself, as “the greatest single act of synthesis29 in the history of the steam engine, and must be regarded as one of the primary or strategic inventions” of all time.

Unfortunately for Newcomen, one of the “company of great men” present at Conygree in spirit had a legal interest in the proceedings. Thomas Savery would live only three years after Newcomen’s demonstration, but his patent survived. What this meant for Thomas Newcomen was that in order to exploit his invention—and he clearly wanted to: in a 1722 lawsuit, he described himself from the beginning as “designing to turn his engines30 or part of them into cash”—he was compelled to make his peace with Savery, or rather, Savery’s heirs. There was little question that the 1712 engine represented an enormous advance over the 1698 “Miner’s Friend”; the Savery engine had found only a few customers, and of those he had installed, most, including the engine used by the York Buildings Company to pump water to its London customers and the one used to drain the Broad Waters pool in Staffordshire, showed a disconcerting tendency to blow up. But Savery still owned an exclusive on the concept, and (because of a special Act of Parliament) would continue to do so until 1733. This was eighteen years after Savery’s death, but his exclusive rights survived. And so, therefore, did a method for earning money from those rights; at Savery’s death in 1715, his partners created a company named “The Proprietors of the invention for raising water by fire.” According to an adviser to one of those Proprietors, the lawyer Sir Thomas Pengelley, Savery “divided the profit to arise31 by his invention into 60 shares … after his death, his executors sold the rest. One Mr. Newcomen having made considerable improvements to the said invention, the Proprietors in 1716 came to an agreement amongst themselves and with the said Newcomen and by indenture in pursuance of articles made between Savery and Newcomen, they agreed to add 20 shares to the 60 which were to be had by Newcomen in full of his improvement and of the said agreement.”

THOUGH NEWCOMEN’S TAKE32 FROM the sale of the engines was “only” one-quarter—twenty shares out of eighty—they were enough to guarantee his prosperity, since the new company charged up to £300 a year just to license the machine; one coal miner paid the Proprietors £200 plus half his yearly profits—and that was in addition to paying for building the engine itself. The year the company was founded, an article appeared in the London Gazette with the following teaser:

Whereas the invention for raising water33 by the impellent force of fire, authorized by Parliament, is lately brought to the greatest perfection, and all sorts of mines, &c., may be thereby drained and water raised to any height with more ease and less charge than by the other methods hitherto used … these are therefore to give notice that if any person shall be desirous to treat with the proprietors for such engines [i.e. Newcomen and Calley; all the examples given in the article are of their installed engines] attendance will be given for that purpose every Wednesday at the Sword Blade Coffee House in Birchin Lane, London.

Within three years, more than a hundred Newcomen-style engines were pumping away in various parts of England, all of them helping the onetime ironmonger and Baptist lay preacher to “turn his engines into cash.” He owed his success in doing so to predecessors making discoveries as far away as Tuscany and as close as Oxford; but the most important occurred only about three miles west of Birchin Lane, on the banks of the Thames, in sight of Westminster Abbey.

* It is impossible to do justice to Leibniz with anything less than a full biography. He was simultaneously one of the greatest mathematicians and philosophers of the eighteenth century, with a list of achievements ranging from the calculus (the notation we use today is his, not Isaac Newton’s) and binary logic to metaphysics, philology, and both basic and highly speculative physics.

* Even more famous, and earlier, was the arsenal of the Republic of Venice, founded in 1104, which covered sixty acres and employed more than a thousand artisans, and which inspired even Galileo, who opened the Dialogue Concerning Two New Sciences by complimenting the Venetians whose “famous arsenal suggests to the studious mind a large field for investigation, especially that part of the work which involves mechanics, for in this department all types of instruments and machines are constantly being constructed by many artisans.”

* Gestalt, for those preparing for a midterm on the history of cognitive science, was an attempt to explain, or at least describe, the way in which the mind integrates perception with cognition, developed by Germans Max Wertheimer, Wolfgang Kohler, and Kurt Koffka, who were in turn strongly influenced by the work of the Austrian physicist Ernst Mach, who will crop up again in chapter 8.

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