Scientist of the Day - Hero of Alexandria

Illustrated title page, The Pneumatics of Hero of Alexandria, transl. for and ed. by Bennet Woodcroft, 1851 (Linda Hall Library)

Hero of Alexandria, an ancient Greek engineer, lived in Alexandria in Roman Egypt, perhaps in the first century BCE, more likely in the first or second centuries CE.  Since we can't even pin down his century, you will not be surprised to learn that we do not know his birthday or death date. But this seems like a good day to talk about him.

We have no doubt that Hero existed, because two of his books have come down to us, a book on mechanical machines, and one on machines powered by heated air and running water. They were recovered from Byzantine manuscripts (written in Greek) in 16th-century Italy and soon translated and printed, again and again.

A singing, rotating bird, powered by water, woodcut, Heronis Alexandrini Spiritalium liber, ed. by Federico Commandino, 1575 (Linda Hall Library)

We will restrict our discussion today to Hero's treatise on water- and air-powered devices, usually called his Pneumatica, although half of his inventions are hydraulic. The devices are most ingenious. One uses running water to make a small carved bird sing and rotate on her perch. Another uses the heat produced by a burning offering to open the doors of a temple and reveal the statue of a god or goddess within.

 A singing bird and a pipe-playing satyr, powered by heated air, woodcut, Heronis Alexandrini Spiritalium liber, ed. by Federico Commandino, 1575 (Linda Hall Library)

As one leafs through the pages, it becomes apparent that Hero's machines are not labor-saving devices, but toys – devices to amuse and delight. This is most apparent with his so-called "steam engine," which is indeed powered by steam, but does no work. It just spins and pleases (sixth image).

Temple doors opened automatically by an offering, woodcut, Gli artificiosi, e curiosi moti spiritali di Herone, transl. by Giovanni Battista Aleotti, 1647 (Linda Hall Library)

A singing bird and a pipe-playing satyr, powered by heated air, woodcut, Gli artificiosi, e curiosi moti spiritali di Herone, transl. by Giovanni Battista Aleotti, 1647 (Linda Hall Library)

I do not believe that any of the Greek manuscripts of the Pneumatica were illustrated, which means Renaissance editors had to come up with their own. Later editors usually adopted the early images, but often changed them in some fashion.  So it is interesting to look at the same machine in different editions.  I show here images from a 1575 edition edited by Federico Commandino (second and third images); a 1647 Italian edition edited by Giovanni Batista Aleotti (fourth and fifth images); and an 1851 English edition by Bennet Woodcroft (first, sixth, and seventh images). The latter was no doubt published to coincide with the opening of the Crystal Palace Exhibition of 1851, where many Victorian inventions were on display.

Steam engine (aeolipile), line drawing, The Pneumatics of Hero of Alexandria, transl. for and ed. by Bennet Woodcroft, 1851. (Linda Hall Library)

We have even more editions of Hero’s Pneumatica in our collections. Commandino’s 1575 edition was republished in Paris and in Amsterdam, and each time the woodblocks were recut. So it would be an interesting project to make a detailed comparison, to see how well each of the images conforms to Hero’s text.

Temple doors opened automatically by an offering, line drawing, The Pneumatics of Hero of Alexandria, transl. for and ed. by Bennet Woodcroft, 1851 (Linda Hall Library)

Naturally there is no original portrait of Hero, but I have not even found a good Renaissance or 17th century rendition. There is one that pops up on Google Image and Wikipedia that some say is from an edition of the Pneumatica, but it is clearly a copy of a copy, and I have not yet run down the source. If anyone can help me out here, and I can find the source, I will add it to this account

William B. Ashworth, Jr., Consultant for the History of Science, Linda Hall Library and Associate Professor emeritus, Department of History, University of Missouri-Kansas City. Comments or corrections are welcome; please direct to ashworthw@umkc.edu.