After all, the hollow rotating version of Hero’s aeolipile, despite being one of the least useful or sophisticated heat-using devices that even he describes, is mentioned by people all the time. Even earlier, in 1620s Rome, Giovanni Branca depicted a flue-powered slitting mill for rolling hot metal bars, to be powered by the smoke from the blacksmith’s forge:īut that’s not why I was shocked by what I found in de Caus’s book. One English writer in the late 1640s, reporting on an Italian version he’d read about from almost a hundred years earlier, noted how the same device could also be used “for the chiming of bells or other musical devices”, “for the reeling of yarn, the rocking of a cradle, with diverse the like domestic occasions.” He fully understood how it worked, noting that even when there wasn’t an actual fire in the hearth, that if the air outside was colder than within the room then the warm air would rise through the flue to drive the mechanism “as experience shows”. Small turbines were already being applied to chimneys from as early as the fifteenth century, whereby the rising air drove roasting spits. In the same decade, the Spanish military engineer Jerónimo de Ayanz y Beaumont also tried to use the expansionary force of steam to drive water up and out of mines - essentially, an industrial version of what Hero had done with fountains.Īnd then there was the power of the flue. Within just a couple of years, having heard of the demonstration before the French court, and after paying a visit to Bourgeois, the mathematician David Rivault began experimenting on how the same effect might be achieved by heating water in a cannon. In 1605, the French inventor Marin Bourgeois developed an air-powered gun - known as the “wind-gun” - which used air that was pumped and compressed into the barrel. The principle of using heat to expand air or steam was even tried for much heavier-duty tasks. Here’s Giovanni Branca’s 1629 suggestion of using an aeolipile - note its Aeolus face - to crush powders. Taking his idea and running with it, engineers from at least the fifteenth century onwards wrote about directing the aeolipile ’s narrow spout at miniature turbines to turn a roasting spits above a fire - suggested in Italy in Leonardo da Vinci’s notebooks, and in a 1551 Ottoman manuscript by Taqi ad-Din - or to do light industrial work like stamping ores and minerals into powders. He even described a version where water could be forced by steam from one container into another, which would pull on a weight to open some doors. Hero described a version that might make a hollow ball spin, by having the steam issue from bent nozzles. It could even be used to do some light mechanical work. A 1630s English version claimed to make the figure of a dragon hiss. Hero explained how the principle of thermal expansion - of either water or air - could be exploited to spout steam or even wine onto an altar’s fire to make it flare, to make water issue from a fountain, to make miniature dancers rotate and jump up and down, and to push air through bird-shaped automata to make them sing. It could also be put to more sophisticated uses. What did I discover that so shocked me? When researching my last post on the inventors surrounding Prince Henry in the 1610s, and because I’ve been looking into the history of energy at the urging of Apoorv Sinha and others at Carbon Upcycling, I had a read through the published work of one of the inventors, Salomon de Caus.ĭe Caus often features in histories of the steam engine, as someone who in 1615 wrote about and depicted the expansive force of steam - heat up water in a copper vessel with a narrow tube coming out the top, and see how water or steam can be made to rise! He was even briefly known as the “true”, French inventor of the steam engine, because of a nineteenth-century hoax. (For paying subscribers there’s also a special treat at the end - the official reboot of the Invention Quiz - as a reward for your patience.) But I hope this post will be worth the extra wait. And so I had to delve ever deeper to get to the truth, and to reformulate what I knew. Things I thought I knew, and on which I agreed with a lot of other historians, turned out to be ever more questionable. But then, the more I delved into the topic, the more I had to delay writing it up. I had to translate a lot of primary sources from sixteenth-century French, Italian, Dutch, German, and even Latin, so that was already going to cause a delay. Although I haven’t been posting, however, I have been hard at work researching. As regular readers might have noticed, it’s been a long time since my last newsletter - far, far longer than usual.
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