Inventions by Hero of Alexandria

The best-known works by Hero of Alexandria are his Pneumatica and Mechanica in which he described how “Automata” actually works. “Automata” is a Greek word meaning as much as “self-moving”, “self-acting” or “self-willed” which is familiar in our modern world. It may be debated whether the inventions were truly his or if he collected them from other sources available at the Library of Alexandria.  

[Reconstruction inside of Alexandria's Library]

Hero lived in the 1^st century BC, and his Pneumatica was widely read far into the Middle Ages. More than 100 manuscripts have survived, illustrating how ancient texts can live a long life. The earliest surviving copy is kept in the Bibliotheca Marciana in Venice, Italy, and dates from the 13^th century, i.e., 1400 years after it was initially written! 

The inventor’s Mechanica has survived thanks to one single Arabic translation made between 862 and 866 AD, preserved at the Library of Leiden University, the Netherlands. 

His most striking invention, in my eyes, is his steam engine, which I already developed in a separate post, A steam engine in antiquity. 

Another of his inventions is a coin-operated dispenser for Holy Water in Egyptian temples. Worshippers who visited the temple needed this water for their ritual washing. Dropping a coin into the slot of the dispenser would set a chain reaction into motion. The weight of the coin would tilt a metal lever which would open a valve through which the water flowed into the cup held by the worshiper. As the coin slipped off the lever, the valve was closed. This invention eventually led to the modern vending machine. 

Hero took his ingenuity one step further when he conceived a series of mechanisms for the Greek theater. He orchestrated a mechanical puppet show using a system of ropes, knots, and simple machines operated by a rotating cylindrical cogwheel. To add the sound of thunder, he used metal balls released at timed intervals onto a hidden drum. 

Another marvel Hero described in detail is the automatic temple door opener (see: Automatic doors, a 2,000-year-old invention), another way for the priests to collect money. 

He also invented the first wind-powered organ using a small wind wheel, probably not unlike the windmills used by the early modern colonists in Australia and the American Far West. The wind wheel powered a piston and forced air through the organ pipes creating sounds resembling a flute.

This mechanism includes the ‘hydraulis,’ which first appeared in Alexandria also, said to have been built by Ctesibius. It was operated by compressed air channeled through a container of water to equalize the pressure. A row of pipes of different lengths produced the sound. More control was acquired with the keyboard-wind instrument as replicated at the Museum of Dion, Greece (see: Close encounter with an ancient Water-Organ). 

I’d like to pick out one more of Hero's inventions from a list that may have counted up to 80, the syringe. The device is much larger than the one we know today since its purpose was entirely different. It was used to control the delivery of air or fluid with precision. Yet the principle of the antique version is the same: the plunger forced the liquid or air out in a controllable quantity. Something to remember next time we get an injection!

We will never know if the concept of creating a center of knowledge in Alexandria was Alexander’s idea or a later addition by Ptolemy. In my opinion, the concept was too vast for Ptolemy while it would perfectly fit Alexander’s thrive to melt East and West together as initiated at the Susa Wedding. 

We cannot imagine the impact of the Museum of Alexandria and its Library on the world’s history. Philosophers, mathematicians, botanists, writers, poets, historians, physicists, anatomists, astrologists, investors, and engineers from all over the then-known world would mingle and exchange their scholarship and wisdom. No other city in the world has ever reunited so many bright minds, not even in the Renaissance. Today’s digital world is the first to come close to attaining this level of universality.