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.

Automatic doors, a 2,000-year-old invention

Several years ago, I happened to visit the plantation of former President Thomas Jefferson in Monticello, Virginia, USA. His estate which was completed in 1809 boosted on having a set of automatic doors inside the parlor. I found this a fascinating feature since I assumed this kind of automation was only born in the second half of the 20^th century. Well, I was wrong. 

Hero, a Greek engineer and mathematician from the 1^st century AD is the oldest known - or documented - inventor of the automatic door. The working principle is simple and must have amazed those who witnessed how the temple doors would open ‘spontaneously’ after the prayers of the priest.

We keep forgetting the huge amount of knowledge that was circulating in antiquity. Most of the great minds performed in many fields. They were philosophers, astronomers, mathematicians, architects, engineers, geographers, poets, etc. (see: Greek philosophers Alexander knew).

What a wondrous world!

A steam engine in antiquity?

We tend to think that inventions belong to our modern world, but deep down, we know that is not true. The wheel was one of the oldest inventions – somebody had to come up with the idea! 

The main problem may simply be that many inventions were not documented, and, if they were, the documents did not survive. They certainly were not patented. 

This being said, a special case is to be made for Hero of Alexandria (c. 10 – 70 AD), who was a mathematician and an engineer.  

Hero created the first steam engine ever, the Aeolipile, meaning “wind ball”. The concept was rather simple. He used a sealed caldron filled with water, which he placed over a fire. As the water boiled, steam rose through a pipe to fill the hollow sphere above. This sphere was equipped with two bent outlet tubes, and when the steam escaped through the tubes, the sphere started to spin. 

For Hero, this was only one of his inventions that he considered a toy or gimmick – a piece of conversation, who knows! 

Imagine what would have happened to our world if Hero or any of his contemporary inventors had sought a way to turn the Aeolipile into something useful. The industrial revolution started in the 18^th century when James Watt presented his steam engine. 

We lost 2000 precious years of evolution! Are there more examples of such lost chances?

Alexandria, the first Renaissance

The term Hellenism is often interchanged with Greek, especially in art. Classical Greek art almost unnoticeably merged with Hellenistic art, and we owe it all to Alexander. In the wake of his conquests, Greek culture and language spread all over the ancient world, from Greece to India. Thanks to the common use of the Greek language, trade developed as merchants were always looking for business opportunities. Talking to buyers and sellers in the same language was a considerable asset. 

After the wars among Alexander’s successors were settled, peace returned in one form or another. Traffic and exchanges between East and West soon blossomed to reach a level never achieved before. 

Greek knowledge and culture were mixed and blended with the learning of Egypt, Mesopotamia, Central Asia, and India. In this context, Alexandria became the new center of the ancient world. 

It was in Alexandria that the first Library was created. In today’s words, this could be compared to a university. Ptolemy I Soter initially founded a Museum inside the Temple of the Muses (hence the name Museum), where all art and sciences were brought together. 

It seems that the Library was, in fact, an extension of the temple built by Ptolemy II Philadelphus, his son. Like every other building in Alexandria, we only have a slight idea of what it looked like, as, to this day, very few remains have been unearthed. An outstanding effort to visualize the great Library was made by Kevin Kok, Senior Level Artist at Ubisoft Montreal, to recreate the complex as it would or could have been (see: The Library of Alexandria). In time, the terms Museum and Library were used interchangeably. 

The Library of Alexandria certainly met Alexander’s own desire to create a research center where knowledge from East and West would be collected to be shared by all. The very concept existed already in the Academy and the Lyceum of Athens, but at Alexander’s death in 323 BC, the ancient world had grown into another dimension. We must credit Ptolemy for understanding Alexander’s vision and executing his ambition. 

Eventually, great scientists flocked to Alexandria, exchanging and discussing their understanding and perception of the world. Much research was done at the Museum, which held an astronomical observatory and rooms for anatomical dissections, and where all sorts of experiments were carried out. The site also included botanical and zoological gardens. How modern is that! 

It is generally accepted that Dimitrios of Phaleron was responsible for the organization. With the budget made available by Ptolemy II, he collected all the books he could, including the works of Aristotle and Theophrastus. Ptolemy III continued this trend, and the Library could boast of having half a million parchment rolls. Among them were all the great Greek works from Homer onward! 

After the death of Dimitrios, Zenodotus of Ephesus took over, assisted by Callimachus of Cyrene. This Callimachus is credited with being the first to classify 120,000 works of prose and poetry, sorting them by author and subject. Eratosthenes of Cyrene was appointed around 235 BC as the new head of the Library. He concentrated on mathematics, astronomy, and geography. We’ll remember Eratosthenes’ contribution to calculating the planet Earth's size after Pythagoras had declared that the Earth was a sphere (see: Alexander missed Eratosthenes by less than a century). 

Great scientists widely contributed to the Library. Euclid wrote his Elements of Geometry, which is still used today, and also a book on astronomy and one on perspective, the Optica. Archimedes, a native of Syracuse, probably studied in Alexandria. He is best known for his theory of calculating the volume, which he discovered while bathing. He was so excited about his discovery that he ran out of his house, stark naked, shouting, “Eureka!” - I found it! (see: Archimedes, the most illustrious citizen of Syracuse). The greatest astronomer of antiquity was Hipparchus of Nicaea, who made great use of the Library of Alexandria.  Besides being a geographer and a mathematician, he was also the inventor of trigonometry, and most famous for discovering the precession of the equinoxes in the late 2^nd century BC. 

Lesser known but equally important is Ctesibius of Alexandria, the inventor of toys and devices using air under pressure, i.e., pneumatics. He created automatons such as a water clock, a fire engine, and even a singing statue. He also invented the first keyboard-wind instrument, the hydraulis, a recreation of which is exhibited in the Museum of Dion, Greece (see: Close encounter with an ancient Water-Organ). 

By 62 AD, Hero of Alexandria even invented the first steam engine! Imagine our world if this invention had not been lost. 

The list of scientists, astronomers, mathematicians, physicians, and inventors seems endless. All their knowledge was born in Alexandria, from where it spread over the entire ancient world for more than three hundred years! The famous Lighthouse of Alexandria, the Pharos, was one of the Seven Wonders of the World, shining its light over a great distance thanks to an intricate system of mirrors. How it actually worked remains obscure. It was probably damaged by the catastrophic earthquake that hit the entire coast of North Africa in 365 AD. Repairs never resuscitated this unique structure. 

Alexandria was also the center where Medical Science was born under Herophilus. He was the first scientist to systematically perform dissections of dead people, often in public, to explain his actions to those interested in these matters. His books are lost but were frequently quoted in the 2nd century AD by the physician Claudius Galenus, better known as Galen of Pergamon (see: Hello? Dr. Galen?) 

Other Libraries were known from antiquity (see: Libraries in antiquity, a short overview), but none surpassed the one in Alexandria. 

After centuries of glory, this great Library succumbed to earthquakes and repeated fires. The lack of funds to sponsor and maintain the premises was another reason for its degradation. Eventually, the knowledge was transferred to Antioch, and with the Arab conquest to Baghdad. We owe very much to Caliph Al-Mansur (754-775 AD), who had a vivid interest in Greek science. He ordered the Greek documents to be translated into Arabic. Over the centuries, these translations traveled back west to become available in Latin. In fact, Al-Mansur saved ancient Greek literature and science for us to enjoy today. This entire process is developed in detail by John Freely in his book Aladdin’s Lamp. How Greek science came to Europe through the Islamic World.