Thread by @antonhowes

Who invented the steam engine?

The usual answer focuses on British inventors like Thomas Newcomen, or Thomas Savery. They were both active in the late 17thC.

But there's also a much earlier, Spanish claimant... (Thread)

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The claimant is Jerónimo de Ayanz y Beaumont, an aristocrat and military engineer from Navarre.

He managed the Spanish royal mines, and in the late 16thC invented a host of devices, from diving equipment and mine ventilation systems, to improved mills, pumps, and furnaces.

And since a biography of Ayanz was published in 2010, he's become increasingly well-known in Spain for his invention of a steam engine - almost a century before Thomas Savery.

But did he really beat Savery to it? Well, it depends on what you mean by "steam engine".

In 1606, Ayanz obtained a 20-year patent from the king of Spain for the use of over 50 different inventions, including two steam-related devices.

One of these was intended to remove deadly gases from mines (which had killed one of his friends, and almost killed him too).

Ayanz's solution was a steam injector (pictured). Pressurised steam was funnelled up a narrowing tube, to enter an air pipe at an angle. The steam created a powerful sucking effect behind it, thus rapidly drawing deadly gases out of the mine via the air pipe.

But it's his other steam device that is often described as a steam engine. And like Savery's and Newcomen's inventions about a century later, he designed it to pump water out of mines.

Ayanz seems to have even tried to build one in c.1608-11 at the silver mines of Guadalcanal.

But did Ayanz anticipate Savery? That's where things get interesting. His biographer, the historian/engineer Nicolás García Tapia, after all described their inventions as "very similar".

And in some respects they are. Take a look at them side by side. Ayanz left, Savery right.

They both involved piping steam from a boiler into tanks filled with mine water, to force the water inside them up a narrow pipe to the surface - what we might call a pushing effect. (Diagrams by Tapia btw - this shows the principle as used by Ayanz's engine).

Both Ayanz's and Savery's engines also involved alternating tanks. So while one tank refilled with mine water, the steam pushed water out the other. (Pictured is how that looked in Ayanz's engine.)

But that's where the similarity ends.

You see, Savery's engine (and Newcomen's, for that matter) did something that Ayanz's or Hero's or anyone else's before the mid-17thC did not. No, *could* not.

Because Savery and Newcomen exploited the remarkable discovery that the air had a weight.

The main force in their engines was applied, not by the steam itself doing the pushing, but by the steam within a tank being doused in cold water, causing it to rapidly condense.

The resulting partial vacuum meant that it was the weight of the air that did the real lifting work.

Savery's and Newcomen's engines used steam's condensation to create a sort of "pulling", or sucking effect.

(Or rather, that's what it seems like. In fact, the atmospheric pressure - the weight of the air - pushes the water to fill the vacuum caused by the steam's condensation).

For Newcomen's engine, this pulling effect happened under a piston, with the piston driving a beam up and down, which in turn worked a pump all the way down the mine.

In the illustration, the man is opening a valve to squirt the cold water under the piston to condense the steam.

Savery's engine, however, was supposed to be down inside the mine. Instead of using a piston, the condensation of steam in a tank was used to suck up the mine water itself. Only then, like in Ayanz's engine, was steam admitted into the tank to push that water up out of the mine.

Thus, Savery exploited both the pushing *and* pulling power of steam, with one of the tanks admitting steam while the other was being condensed. Ayanz's machine, on the other hand, only exploited the pushing.

It's a crucial difference.

The tanks in Ayanz's machine only received water by being below the level of the mine water that was being drained. Savery's, by using that sucking effect, could be up to about 8m above it.

Ayanz did not even consider the possibility of exploiting atmospheric pressure.

And nor could he have, for he was tinkering with steam decades before atmospheric pressure was sufficiently understood.

It's actually a great and very clear case of how the lack of science limited the technological possibilities.

Ultimately, it was Newcomen's atmospheric engine that achieved the major breakthrough - he applied the science of vacuums in a much more elegant and practical way than Savery did.

But at least, unlike Ayanz, Savery was on the right track.

So Jerónimo de Ayanz may well have invented a steam engine. And it was in many ways ingenious.

But he did not - could not - invent the atmospheric engine that changed the modern world.

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