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Age of Invention: Why wasn't the Steam Engine Invented Earlier? Part II
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As I noted in Part I of Why wasn’t the Steam Engine Invented Earlier? the general idea of using heat and steam for mechanical work had a long and continuous history back to ancient times. But when we talk of the breakthrough “steam engine” in the eighteenth-century sense, we don’t mean a machine that exploits steam’s expansive, or pushing force. We actually mean a machine that does the exact opposite, exploiting the apparent sucking power that occurs when hot steam is rapidly condensed with a spray of cold water. It’s the relative weight of the atmosphere, compared to the sudden vacuum from condensing steam, that does all the work.
This exploitation of atmospheric pressure is supposed to have stemmed from Evangelista Torricelli’s 1640s demonstration both that vacuums are possible and that the atmosphere has a weight, eventually leading to water-raising engines invented in the 1690s by Thomas Savery, which exploited atmospheric pressure by condensing steam (as well as then using the expansive force of steam to push the water even higher).
As I mentioned in Part I, however, a machine very similar to Savery’s and operating on an identical principles appears to have been designed decades before any of Torricelli’s experiments in the 1640s. As this post shows, the mechanical exploitation of condensation — and thus of atmospheric pressure — has a much, much older history extending back to ancient times, along the way involving alchemists, debates on the origins of the winds, and perpetual motion machines that really worked (trust me, you’ll see). Given the length of that history, and the prominence of the technologies and debates along the way, it’s all the more surprising that Savery’s engine did not appear much sooner.
Let’s get stuck in.
Ancient Condensation Engines
As I explained in Part I, the spark for my investigation was noticing that one Salomon de Caus, as early as 1615, had very probably made what amounts to a solar-powered version of Savery’s engine. By concentrating the sun’s rays on trapped air above the water in copper vessels, the resulting expansion of the trapped air and steam drove the water up a pipe to make a fountain flow. Most crucially of all, however, when the vessels cooled again they sucked water up and into them from a cistern below — a principle that de Caus also applied to having statues make music when the sun shone, and which he hinted may be useful for other things too.1
Noticing this machine was a big shock to me, but de Caus’s invention was not even that original. It was actually an improvement of another, almost entirely ignored device described by Hero of Alexandria as early as the 1st Century, and which Hero in turn derived from one Philo of Byzantium who wrote in the 3rd Century BC.
Philo’s original device was very simple: a hollow leaden sphere with a bent tube rising out of it and into some water at the bottom of a jug. As the sun heated the sphere, the expanding air was pushed up the tube and into the jug’s water, escaping by bubbling out of the water. And crucially, when the sphere was removed from the sun and allowed to cool, the water was then drawn up the tube and into the sphere — Philo, about 1,900 years before Savery, had already encapsulated in a simple model the power of condensation, or at least air contraction through cooling, to raise water.2
Philo’s device was simple, but the principles it illustrated do appear to have been applied. Hero’s work, for example, includes a libas, or “dripper” fountain. In this alternative version of Philo’s apparatus, Hero connected the jug and sphere by two other pipes to a cistern underneath, as well as starting with some water already in the sphere. The jug now acted more like a funnel, into which the original bent tube now dripped its water like a fountain when the sun shone on the sphere. When cooled, however, the sphere replenished itself from the cistern underneath.3 It was almost exactly like de Caus’s version, which merely improved the strength of the fountain when it was heated, seemingly by replacing the lead with more heat-conductive copper and by using glass convex lenses to concentrate the sun’s rays.
Hero’s solar-powered dripping fountain doesn’t sound all that impressive, but both Philo and Hero appreciated the wider potential of its underlying principles.
Philo, for example, noted that it might make use of alternative heat sources: he described how his apparatus would work whether pouring hot water over the sphere, or by heating it over a fire. Once it cooled, it would always draw the water up.4
Hero even suggested a mechanical use for the effect. By setting a fire on a hollow, airtight altar, the heated air within would flow down a tube into a sphere full of water, which in turn would be pushed up another tube into a hanging bucket. The bucket, when sufficiently heavy with water, would then pull on a rope to open some temple doors. Crucially, when the fire was extinguished, Hero noted that the cooling of the air in the altar would draw the water back into the sphere again, lighten the bucket, and so allow the doors to be closed by a counterweight.5 Although the condensing or cooling phase was really just for resetting the device, the fundamental ideas behind a Savery engine were already there: it raised water, used a fuel, and exploited contraction through cooling. It even did some light mechanical work.
Unfortunately, we don’t know how else the water-raising power of cooling or condensation may have been applied in the ancient world. But over the course of the Middles Ages the works of Philo and Hero were often painstakingly copied out into manuscripts and translated. A handful of scholars with access to the manuscripts and able to read Greek, Arabic or Latin, were thus occasionally exposed to Philo’s and Hero’s ideas. They may even, as we shall see, have been regularly put into practice.
When I discussed my research-in-progress with the folks at Carbon Upcycling, the very good point was raised that perhaps something might have changed, thanks to printing, or more open publishing, to make the water-raising power of condensation more commonly known. Hero’s work on pneumatics was first printed in full in Latin at Urbino in 1575, and was translated into Italian and printed at Bologna in 1589. So these might plausibly be treated as points from which the timer ought to have started ticking for when atmospheric engines should have been developed further.
Ye the crucial ideas involving condensation had already, decades earlier, widely appeared in print. And they were at the centre of some major scientific debates.
The Source of the Wind
In 1558 a young Neapolitan named Giovanni Battista della Porta, just twenty-three years old, published a grab bag of various “secrets of nature” that he had been collecting since he was fifteen. This work, Magiae Naturalis, or Natural Magic, was an instant hit, within just a decade going through multiple Latin editions and being translated into Italian, French, and Dutch.
Amongst the tricks was one that della Porta seemingly derived from reading Hero’s manuscript — he cites him in the same paragraph — of how “an inverted vessel in water will draw it up”.6 It was extremely simple, and can easily be tried at home: take a long-necked glass flask, the clearer the better, and heat it. Then place the vessel mouth first in a basin of water, so that the heated air inside bubbles out through the water and escapes. Once it cools, the water is drawn up into the glass. Natural magic!
From this point on, we start to get a few hints of further development. Della Porta returned to his book over thirty years later in 1589 to expand, revise, and re-organise it. To the list of tricks he added one of how “by heat alone to make water rise”. It used exactly the same process, but this time instead of a glass flask he placed a closed vessel of brass on top of a tower, with a pipe connecting it to water below. The sun heated the vessel to drive out the air, bubbling out of the pipe. As it cooled again, to prevent a vacuum, della Porta explained that it would cause the water to rise up the pipe.7
Could he have put this into practice? It’s unclear. But in another section discussing some of Hero’s fountain designs, della Porta mentions making a fountain in Venice “that let in light, and when the air was extenuated, so long as the light lasted the fountain issued forth water, which was of little labour and of much admiration.”8 It sounds tantalisingly like della Porta had by 1589 actually made a more effective version of Hero’s solar-powered dripper, like the fountain design de Caus would publish almost thirty years later.
Apart from the applications, however, the inverted flask experiment was mainly of interest to della Porta and his contemporaries for what it told them about nature. When he first mentioned it in 1558, it was not just as a neat trick. He also described it as a demonstration of the origins of the wind. Aristotle’s theory, which had become the common one by the sixteenth century, was that the rays of the sun, beating upon the earth, drew forth dry exhalations of air. In much the same way, heating the flask with the sun would push the air out of it to bubble through the water and escape.
But very quickly, others noticed that the second part of the experiment — the fun bit, with the rising water — might actually suggest that Aristotle was wrong. Once the remaining air in the flask cooled again, the water rose, suggesting that this air within was both expanding when hot and contracting when cool. And what if the air within the flask was the same matter as the air in general? If one could do these wonderful things by heating and cooling air using the model, might not the air in the atmosphere act exactly the same way?
So thought Giovanni Battista Benedetti, a Turin-based mathematician, in 1585. Attacking Aristotle’s explanation, Benedetti argued instead that the winds were caused by changes in the weight of the atmospheric air. As it got hotter or colder thanks to the presence or absence of the sun’s rays, the air thus expanded or contracted, becoming agitated or quietening down. The sun, he said, provided nothing but the heat. Its rays did not draw anything forth from the bowels of the earth. Benedetti thus repurposed the inverted flask experiment as a microcosm, its small piece of remaining trapped air being analogous to the atmosphere as a whole.9
Unleashing the Microcosm
Although Benedetti’s microcosm wasn’t an experimental proof, using the inverted flask experiment in this way was to become an extraordinarily popular and powerful idea. With it, inventors would perform miracles, chief among them the Dutch engraver and alchemist Cornelis Drebbel.10 Drebbel is not a widely recognised name today, and in the nineteenth century gained a reputation as something of a charlatan because his inventive achievements sounded so unlikely. But he was actually one of the most influential scientific writers of the early seventeenth century, and Europe’s most famous inventor. In a way he was like the Leonardo da Vinci of his age, but better — he actually put his most incredible designs into practice.
Drebbel’s most famous invention was based on a version of the inverted flask microcosm. Indeed, he made it the centrepiece of his entire scientific worldview — not just treating it as a model, but developing it into the model of all Creation. In the microcosm lay the secrets to the weather, to the transmutation of the elements, and the source of all motion in the universe, including the source of life itself.
To understand how, we need to appreciate the way Drebbel and his contemporaries saw the world. Following Aristotle, most people believed the world to be a closed system contained within a sphere. The Earth, at the centre, was thus like the yoke of an egg, with its oceans and atmosphere held like a thin layer of egg white around it, and with a mysterious aether making up the space between the atmosphere and the stars, which sat firmly fixed to the inside of the egg’s shell — the firmament. Beyond that, only God knew. Even Copernicus, when he placed the sun at the centre instead of the Earth, still believed that all Creation was contained within the firmament.
The belief came with a few key implications. One of these was that vacuums were literally impossible, as the closed system was totally full of matter and could not accommodate an empty space. Within a universe that was already completely full, the creation of a totally empty space within it would force the heavens themselves to move in order to accommodate it — something only God could do. The firmament was not an egg that any mere mortal could crack. Many believed, of course, that matter actually had a bit of leeway or flexibility to contract and expand. Air could be compressed or rarefied. But the moment a person did something that threatened to create a vacuum with no matter whatsoever, then the universe would immediately supply matter from the closest convenient source in order to prevent the gap from occurring. It was thus Creation’s abhorrence of a vacuum that was exploited to make a pump raise water, or to explain why water would rise up the inverted flask as it cooled.
The other implication of a full universe, however, was that it suggested the possibility of perpetual motion. Creation itself was a closed system, much like any device or machine — one set going by God when the universe began, but which continued to be in constant motion, with winds, tides, storms, planets, a rotating firmament (or Earth, if you believed Copernicus), and especially life. If the macrocosm of the universe itself was in constant motion, might not a microcosm of it also be made to reflect that same motion, to act in the same ways as the whole? This was the ambition of Cornelis Drebbel: not to create perpetual motion of his own — that was something only God could do — but to harness the existing perpetual motion of the universe, in miniature.
Drebbel supposed that God, when creating the universe, first separated out the elements of fire — let there be light! — followed by air, then water, then earth. The elements were not conceived of as being fundamental substances like they are today. They were thought of more like what we now call matter’s states: what was meant by earth, water, and air was really more like solid, liquid, and gas. To evaporate water into steam was thus to perform an elemental transmutation. Drebbel spoke of it in terms of using fire to turn water into air. Indeed, fire had a special place in Drebbel’s thought. It was not just the first state, but somewhat similar to our modern concept of energy. Drebbel believed that the potential for fire was there in all matter (else it would not burn), and that fire was needed for all transmutations, all light, and all motion, including life: “it gives all things life and without it all things are dead”.
From this, Drebbel also derived a theory of the weather that was very similar to Benedetti’s. It was the sun — fire — that gave the initial motion to the atmosphere, causing the air to heat and to rise, with that movement of the air causing winds, and with the heat likewise evaporating water into the air. When the sun had passed, however, or when these hot winds came into contact with colder air, the air would cool and become heavier, and the water would condense into clouds and then rain. Just like in the inverted flask experiment, he noted, the cooling “pulls back in again all the wind which through the heat had gone out.” It was a remarkably modern-sounding explanation (though Drebbel seems to have also thought that the same principles of heating and cooling of the oceans also accounted for the movement of the tides).
Drebbel may have come into contact with the inverted flask via della Porta, but I suspect not. Instead of the simple glass flask, Drebbel’s version much more closely resembled that of Philo of Byzantium with its sphere and bent pipe passing into the water of a jug. Indeed, Drebbel’s version used an alchemist’s glass retort with a long, narrowing spout — it was strikingly similar to the aeolipile, or philosopher’s bellows, which I mentioned in Part I was used throughout the middle ages by alchemists to issue high-pressure steam at a lamp’s flame, producing a sort of blow-torch effect with which to melt metal or glass.11
Drebbel, as a practising alchemist obsessed with fire, would have been very familiar with the philosopher’s bellows. But quite apart from its use of the expansive force of steam, the tricky thing was how to fill it with water in the first place. As a later French author put it, “there is a finesse in filling these aeolipiles with water through such a small hole, and one must be a Philosopher to find it out.”12 The knack to it, documented as early as 1594, and which I strongly suspect was known and practised by at least a few aeolipile-users throughout the middle ages, was to heat the vessel when empty and then plunge it into cold water so that it would “suck some of the water into it” as it cooled.13 It could be heated up and then cooled again and again to suck in even more. In other words, the clever method of filling the narrow-spouted aeolipile was to make use of the sucking power of condensation, exactly as described by della Porta in the 1550s and by Philo almost two thousand years earlier. Thanks to the continuous use of the aeolipile by alchemists, the raising of water through condensation may have continued to be put into practice since ancient times, and before the spread of print.
Regardless of whether Drebbel got the idea from della Porta’s books or from the traditions of alchemists, however, he took it significantly further. For a start, he noticed the fact that once the water was sucked into the cooling glass retort, the level of water in it would continue to rise and fall, even when it wasn’t being heated or cooled on purpose — movements that were the result of natural changes to atmospheric pressure and temperature. Now, in a sense, Philo had already exploited this, his original model having relied on the alternating presence or absence of the sun’s heat. But Drebbel realised its potential. It was not just an inanimate machine. It seemed instead to be a living microcosm, tapping and displaying the elemental transmutations and perpetual motion of the universe itself.
That recurring, perpetual motion could be applied to plenty of uses. In 1598 Drebbel obtained a Dutch patent for a perpetual clock, and a few years later was writing to king James I of England offering to construct for him a comprehensive and perpetually moving model of the entire cosmos. He made good on the offer. Displayed at Eltham Palace from c.1606, Drebbel’s perpetual motion machine became the wonder of all Europe.
The Eltham Wonder
Drebbel was cagey about revealing the machine’s details. His career as an inventor relied on making his specific skills and knowledge seem indispensable. But we have sufficient hints from his own writings and plenty of drawings and descriptions by visitors, his friends, and his relatives, to have a pretty good general idea of how it worked. A sphere in the centre moved to show the time, day, months, and years, along with the signs of the zodiac, and various other movements of the heavens. Blue-tinted liquid in a ring of glass around it appeared to move and up and down in keeping with the ebb and flow of the tides. Another little sphere above it rotated to indicate the phases of the moon. (To accompany it, Drebbel also designed instruments that would automatically sound at certain times.)
How the “tide” ebbed and flowed was most likely because it was a version of the inverted water flask, all contained within a glass tube shaped like a broken circle. With air trapped in the closed end, and with the other end open to the atmosphere, the level of the tinted liquid — possibly water, though it’s unclear — would rise and fall in response to small changes in temperature and atmospheric pressure, particularly between the relative cold of night and the heat of day. So long as the liquid in it did not all evaporate out of the open end (if it was water, it was probably occasionally topped up), it would continue to rise and fall, day after day, for months and even years.14
As for the perpetual movement of the dials and spheres, the clues are contained in the published work of one of Drebbel’s colleagues at the court of James I: none other than the person who started off my entire investigation, the French engineer Salomon de Caus. Listed immediately before de Caus’s solar-powered atmospheric fountain is a description of a “machine that moves of itself”, which operated on nearly identical principles. De Caus thought it blasphemous and vain to call its motion perpetual, as only God was truly without beginning or end, but he nonetheless described a variant of the inverted flask where the rise and fall of the level of water thanks to changes in temperature would also raise or drop a weight attached to a pulley, which in turn could be connected to a dial or clock.15
De Caus’s version is very simple. His dial straightforwardly indicates the level of the water. Drebbel’s device, however, managed to run a whole series of dials and indicators that needed to move regularly and continuously. Drebbel hinted in his initial letter to James I that he could apply perpetual motion to any kind of timekeeping device, whether it was driven by falling weights, by water, or by springs. He must have had the rising or falling weight essentially rewind his device, like a rudimentary version of how a wrist-watch today can be made to automatically wind itself by simply moving one’s arm. Indeed, an eye-witness described how the clock-hand would suddenly correct itself, jumping forward by two hours when the sun reappeared from behind some clouds. Clocks at the time were not yet regulated by pendulums or spring-balances — those would later be developed by Christiaan Huygens, the son of one of Drebbel’s biggest fans — so re-winding may well have directly increased the speed of the driving mechanism, causing the dial to lurch forward.
All in all, Drebbel’s perpetual motion was an astonishing device. It secured his fame as a natural philosopher and inventor, and it prompted people all over Europe to try to copy and improve on it themselves. As we shall see in Part III, in the early seventeenth century the fundamental principles for a steam engine were not just some obscure line of investigation. With the debate on the origin of the winds attracting more controversy, and with still more wonders issuing from Drebbel’s workshop, the inverted flask experiment and the water-raising powers of perpetual motion in fact took centre-stage.
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Salomon de Caus, Les raisons des forces mouvantes (Jan Morton, 1615), pp.19-21
A couple of readers have pointed out that Philo’s machine seems to use just air contraction, rather than condensation. That’s potentially true, and I have thus edited this line to clarify. Although the initial phase uses just air, any repetition could have involved water vapour condensing too, when heated with water already in the sphere. Philo does mention using fire, so he may have done something very similar to Drebbel. I have also edited because of the modern use of the term condensation, though in the parlance of the time (both ancient and early modern), they tended to frame all expansions and contractions as a simple matter of “dense vs rare”. So although condensation now has a very specific meaning for an actual state change from gas to liquid, at the time they tended not to talk of steam as something distinct, but often referred to it as air. Condensation and contraction were thus effectively synonymous. We’ll explore an appreciation of the important difference in Part III. For a description of Philo’s machine, see Allen G. Debus, ‘Key to Two Worlds: Robert Fludd’s Weather-glass’, Annali dell’Istituto e Museo di storia della scienza di Firenze 7, no. 2 (1 January 1982), pp.118-120
Hero of Alexandria, The Pneumatics of Hero of Alexandria from the Original Greek, ed. Bennet Woodcroft (Taylor, Walton and Maberly, 1851), p.69; Hero of Alexandria, Heronis Alexandrini Spiritalium liber. A Federico Commandino Vrbinate, ex Graeco, nuper in Latinum conversus, trans. Federico Commandino (Urbino, 1575), pp.49-51
Morris R. Cohen and I. E. Drabkin, A Source Book in Greek Science (Harvard University Press, 1958), pp.255-56
Heronis Alexandrini Spiritalium liber, pp.42-3
Giovanni Battista della Porta, Magiae naturalis, siue De miraculis rerum naturalium libri 4 (1558), p.70, under the heading “Vas inuersum aquam hauriet”
Arianna Borrelli, ‘Giovan Battista Della Porta’s Construction of Pneumatic Phenomena and His Use of Recipes as Heuristic Tools’, Centaurus 62, no. 3 (2020), p.418
Giovanni Battista della Porta, Magiae Naturalis libri XX (Horatio Salviano, 1589), p.291. In the 1658 English translation of this edition, p.393.
Arianna Borrelli, ‘The Weatherglass And Its Observers In The Early Seventeenth Century’, in Philosophies of Technology: Francis Bacon and His Contemporaries, ed. Claus Zittel et al. (BRILL, 2008), pp.67–130.
For the following sections on Drebbel I have mainly relied on the excellent work of Vera Keller, particularly ‘Cornelis Drebbel (1572–1633): Fame and the Making of Modernity’ (Ph.D., Princeton University, 2008), which also contains full translations into English of Drebbel’s writings. Quotations are taken from there. See also Keller’s ‘Drebbel’s Living Instruments, Hartmann’s Microcosm, and Libavius’s Thelesmos: Epistemic Machines before Descartes’, History of Science 48, no. 1 (March 2010), pp. 39–74.
I got a few questions about this after the last post, as it seems infeasible that it could create such a high heat. From what I can tell based on the sources, it was essential that there be a gap between the spout and the flame, such that it may have been the hot air in front of the steam rather than the steam itself that created this effect.
H. van Etten [Jean Leurechon], Récréation mathématique (Jean Appier Hanzelet, 1624), p.75. I used the 1626 edition, but they are seemingly identical, including the pagination. My own translation. The 1633 English translation, Mathematicall recreations, translates the word “finesse” as “cunning and subtlety”.
Hugh Plat, The jewell house of art and nature conteining diuers rare and profitable inuentions (Peter Short, 1594), p.25
For full notes on modern attempts at reconstruction, see Dr James M Bradburne, ‘Going through the Motions: Some Further Considerations about the Perpetuum Mobile of Cornelis Drebbel, Based on a Manuscript Discovered by Dr Alexander Marr’, 2006.
de Caus, pp.18-19