The inventions of Heron of Alexandria of the 2nd century AD are well-known, and namely, the steam-powered turbine called the aeolipile - has been used to suggest the possibility of an earlier industrial revolution than what occurred in reality - yet it seems there is a distinct possibility of the precursor to da Vinci's steam-powered cannon (the Architonnerre) having been invented by Archimedes (as da Vinci himself asserted), thus pushing the possibility of using steam for power to the 3rd century BC - not to mention the fact the aeolipile has been described by Vitruvius in De Architectura about a hundred years earlier than when Heron of Alexandria himself flourished.
Yet during my reading, I have stumbled upon the interpretation of an early experiment with flight performed by Archytas, a dear friend of Plato and a fascinating person in his own right, being powered by steam, based on the following passage:
"But that which Archytas the Pythagorean is said to have devised and accomplished ought to seem no less marvellous, but yet not wholly absurd. For not only many eminent Greeks, but also the philosopher Favorinus, a most diligent searcher of ancient records, have stated most positively that Archytas made a wooden model of a dove with such mechanical ingenuity and art that it flew; so nicely balanced was it, you see, with weights and moved by a current of air enclosed and hidden within it."
- Aulus Gellius, "Attic Nights", Book X, 12.9
How likely is it that this small device really used steam at all? Is the modern conjecture of a steam-powered bird model too daring a historical thesis? Are there any more possible uses of steam predating Heron of Alexandria, or even possibly Archytas at the break of the 5th and 4th century BC?
As I have written here before, there are many problems with Hero's Engine possibly powering an industrial revolution. Like turbines and rockets, it's a reaction engine: the weight times acceleration of the steam coming out of the nozzles on the rotor is going to be equaled by the weight times acceleration of the rotor whirling in reaction in the opposite direction. Because water vapor is very light and the rotor ( plus whatever it's pulling) is much heavier, a lot of steam has to come out of the nozzles to get much of a reaction and do much work. That means the steam is going to have to be under considerable pressure and will be pretty hot, and all that requires a pressure vessel, AKA boiler , that's strong , and rotating seals with the bearings that can spin pretty fast. And that's a lot to ask the pre-industrial craftspeople to do. Not perhaps on a small scale-the Antikythera Device shows that the Greeks could make something reasonably precise if it was a small. But not something big enough to do real work . Even when the first steam engines begin to be used in the 18th c., they functioned at quite low pressures because high-pressures and precise tolerances on a large scale were very, very difficult. James Watt famously bragged about having a mechanic who could file a steam piston to within a worn farthing's thickness of a steam cylinder- let's call that 1 millimeter- and the cylinder was likely around 1 meter. The gap was filled with packing made of well-greased old rope fibers.
A very small Hero's Engine seems like it might have been made. A lot of Hero's described devices were to do magic tricks, and it's possible to imagine a little engine the size of a teapot could be fired up and run for a half minute to just reel in a string and pull open a door. But it would have been a very lucky team of craftsmen who could have managed to create anything with a horsepower, big enough do real work- and it would have been incredibly hard for them to make them over and over again for an industrial revolution. And the penalty, the human cost, for building a defective boiler that's running a hundred pounds of pressure per square inch is extreme. Boiler explosions can not only kill but demolish buildings.
Now , what Archytas is supposed to have made is also obviously rather small. Like Hero's Engine, that makes it much more possible for the Greeks to have built it. However, for it to be run by steam gives it two other problems. First, there has to be something that can boil water and contain the steam- that's all going to have to be made of a metal, like bronze. That metal will add a lot of weight. And weight, of course, is something you really don't want on a little model airplane. Second, a small steam engine has a greater ratio of surface area to volume than a big steam engine, which means it cools off much faster. Heat engines need heat- if that engine cools, the steam turns to water or at least loses pressure and doesn't work anymore. It would not be possible to just load up a little reservoir with steam. So, along with the engine there'd have to be a heat source of some sort to keep it steaming, an oil burner or something, powering that flammable little wooden model of a dove...think about that for just a moment and it starts to seem a bit crazy.
But that mention of enclosed air is intriguing. Because a good while before people were making working steam engines, they had figured out how to make air pumps. Those are much simpler. The earliest existing air rifle is from 1580, and in the 17th c. they were used for hunting. The small air reservoirs in them would hold typically around 700 pounds per square inch. It would be impossible to say it could have been done, but it is at least possible to imagine some sort of little air reservoir with a simple nozzle, inside a very light wooden bird , that could be pumped up, uncapped, and provide enough of a boost for a few seconds to make the thing fly across the room.