Study the history of science and technology long enough, and you will discover that – contrary to what popular culture would have you believe – few inventions are the product of a single brilliant mind. Instead, technological progress is the result of incremental discoveries and refinements made by multiple people. But once in a while, a person comes along whose sheer breadth of technical innovation is truly, well, breathtaking: Thomas Edison, Nikola Tesla, John von Neumann, Alan Turing, R. Buckminster Fuller, Charles Kettering, Tony Stark, and Leonardo da Vinci, to name a few. The list of great innovators extends well back into antiquity, but while perhaps the most famous ancient mechanical genius is Archimedes of Syracuse, there is another Greek innovator who was even more prolific: Heron of Alexandria. With a huge body of stunningly creative yet practical innovations ranging from water pumps and fountains to automatic doors, vending machines, automated puppet theatres and even a primitive steam engine, Heron was a mechanical powerhouse whose ideas influenced the development of ancient technology for centuries. This is the story of the forgotten Edison of Ancient Greece.

Surprisingly little is known about the life of Heron – also known as Hero. Even the years during which he lived are debated among historians. Traditionally, he was believed to have lived either around 150 B.C.E or 250 C.E. However, in the early 20th Century a reference was discovered in one of his works to a solar eclipse which took place on March 13, 62 C.E. Thus, today Heron is thought to have lived from approximately 10 to 70 C.E. His origins and background are also unclear, with historians debating whether he was ethnically Greek, a Hellenized Egyptian, or even a Babylonian. Indeed, as ‘Hero’ or ‘Heron’ was a very common name in Ancient Greece, it is difficult to tell whether contemporary records refer to the inventor and mathematician or another citizen of the same name. All that is known for sure is that Heron lived and worked in the Egyptian city of Alexandria and wrote many books on a variety of mathematical and scientific topics – around 15 of which survive to the present day. Given the sheer breadth of these works, it is almost certain that Heron taught at the Museum or “temple of the muses” – home of the legendary Library of Alexandria.

Heron’s known mathematical works include Definitiones, a glossary of geometric terms; Geometria, an introduction to geometry; Geodesia and Liber Geoponicus, two fragmentary works on land surveying; Metrica, a treatise on calculating the area and volume of various shapes; Stereometrica, a two-volume treatise on three-dimensional geometry; and Mensurae, a treatise on measurement tools. In these volumes, Heron collected and systematized various geometric rules and principles from earlier sources such as Archimedes and the Babylonians, including an equation for determining the area of a triangle from the length of its sides – today known as Heron’s Formula.

Heron’s known scientific works, meanwhile, include On the Dioptra, in which he describes a sophisticated surveying instrument very similar to a modern theodolite and methods for using it to determine overland distances; and Catoptrica, a treatise on optics whose principles of light propagation and reflection would only be improved upon 1,000 years by the Arab physicist Ibn Al-Haytham.

But Heron is by far best remembered for his mechanical innovations, as detailed in his remaining five books: Pneumatica, Automata, Mechanica, Cheirobalistra, and Belopoeica – the latter two dealing with catapults and other engines of war. Many of Heron’s inventions were created for use in Egyptian and Greek temples, producing seemingly miraculous special effects designed to enhance the perceived power and influence of the temple priests. One such device was a system for automatically opening and closing the temple doors when a fire was lit on a ceremonial altar. The mechanism consisted of a metal tank full of water hidden under the altar, connected to a siphon hose. This, in turn, drained into a bucket connected to a rope-and-pulley mechanism that operated the doors. When a fire was lit on the altar, the tank would heat up, forcing water out into the bucket, whose increased weight would slowly open the doors. And when, at the end of the ceremony, the fire was extinguished, the condensing and contracting steam inside the tank would create a suction that would draw water back out of the bucket, causing the doors to close. Heron also describes a pneumatic mechanism that automatically blew a trumpet whenever the doors opened. As outlandish as this mechanism may seem, it appears to actually have been implemented in many temples around the ancient world, for in Pneumatica, Heron states that:
“Some instead of water use quicksilver [Mercury] as it is heavier than water and easily disunited by fire.”

Though what exactly Heron meant by “disunited” is unknown, Mercury would indeed have allowed Heron’s door-opening mechanism to be made more compact and efficient, for it is denser and has a greater coefficient of thermal expansion than water. The element was long used in barometers and thermometers for the same reason. Unfortunately, no remains of Heron’s automatic door mechanism have ever been excavated, though given that later Christian and Muslim conquerers were known to have stripped ancient Egyptian and Greek temples of all available metal parts, this is hardly surprising.

Another of Heron’s inventions intended for temple use is a surprisingly modern one: the vending machine. Designed to dispense a small quantity of holy water for ritual ablution, this device consisted of a small water tank with a spout and flapper valve connected to a small balance beam. When a 5-drachma coin was dropped through a slot in the top, it fell onto the balance beam and opened the valve, dispensing the holy water. A moment later the coin slipped off the beam and the valve closed; the accumulated proceeds could then be collected by the priests. Heron appears to have based his design on a similar hygiene device invented by Philo of Byzantium, who lived and worked in Alexandria 300 years before. Philo’s device consisted of a water tank from which protruded a small metal hand holding a ball of pumice stone – commonly used for scrubbing. When a user removed the ball, the hand retracted into the device and water began flowing from the spout. A few moments later, the hand re-emerged holding a fresh stone.

Far more influential among Heron’s many inventions, however, was the Hydraulis, an early form of pipe organ. This consisted of a set of up to 19 vertical pipes derived from panpipes blown by a clever hydraulic mechanism. As the operator pumped a handle, air was forced through a one-way valve into an inverted bowl-shaped chamber submerged in a tank of water. Air from the chamber was drawn off to blow the organ pipes, the weight of the water in the tank maintaining this air at a constant pressure. In this manner, the Hydraulis was able to sustain more consistent notes than a regular bellows-powered organ. The Hydraulis proved extremely popular, seeing widespread use across the ancient Mediterranean world. Indeed, an inscription at Delphi dating from C.E. describes how a musician named Antipatros “covered himself in glory” by playing the Hydraulis for two days straight in a competition. It was reportedly Roman Emperor Nero’s favourite instrument, and was played at all sorts of public events in Rome, from gladiatorial games and theatrical performances to triumphal processions, wedding banquets, and swearing-in ceremonies for public officials. So widely used was the Hydraulica that, unlike most of Heron’s inventions, physical remains have been found – most notably in the ruins of a Roman Clothworker’s Guild hall in Budapest, Hungary, which burned down in the 3rd Century C.E. Intriguingly, Heron later developed a windmill-powered version of the Hydraulica, saving the operator – or his assistant – from having to pump the instrument by hand.

Another of Heron’s hydraulic innovations was what is now known as Heron’s Fountain, which operated without the use of pumps. This consisted of a shallow tray with a spout in the middle from which a stream of water issued. The tray, in turn, was connected by a series of vertical pipes to a pair of sealed chambers. Water flowing from the tray into the first chamber compressed the air inside, which flowed into the second chamber and forced the water inside out the spout in the tray. Despite appearances, this was not a perpetual motion machine, such devices being physically impossible, or so Big Energy would have us believe…. Instead, the water would continue to flow until the first chamber was completely filled, whereupon the whole fountain would stop. Still, the effect must have been mystifying to ancient observers.

Heron also invented a double-action water pump with a rocking handle remarkably similar to modern designs, which was widely used by the notoriously inept and corrupt Roman fire brigades, the Familia Publica. How corrupt, you might ask? Well, when the brigade’s creator, general and statesman Marcus Licinius Crassus, arrived at the site of a fire, he would not begin extinguishing it right away. Instead, he would offer to buy the burning property from the owner. If the owner refused, Crassus would hold his men back and let the building burn, continually lowering his bid until the owner finally relented.

Heron’s genius even extended to the field of theatre, for which he developed a variety of impressive special effects – including carts and set pieces that automatically moved about the stage seemingly of their own volition. These devices were powered by a falling weight system, whose speed was regulated by the flow of sand out of a reservoir – similar to an hourglass. But Heron didn’t stop there; using a sophisticated system of gears, knotted ropes, and other mechanisms, he was able to make these carts stop, start, reverse, and trace circles or figure-eights in a pre-determined sequence. These techniques were the distant ancestors of modern computer programming, which would not be experimented with again until the 18th Century. But even this remarkable achievement was dwarfed by what is perhaps Heron’s most impressive creation: a fully automatic miniature theatre that presented a complete, 10-minute theatrical performance using mechanical puppets. The show, titled Nauplius, told the story of a king whose son is falsely accused of treason by his comrade-in-arms Ajax and stoned to death. King Nauplius then sets about exacting his revenge on Ajax, aided by the goddess Athena. In the first scene, mechanical figures of nymphs were shown repairing Ajax’s ship, accompanied by the realistic sounds of saws and hammers. The doors of the theatre then closed and reopened to reveal the second scene, depicting the launching of the ship. The third scene depicted Ajax’s fleet sailing across the sea, accompanied by leaping dolphins. The sky then turned stormy, causing the ships to draw in their sails. In the fourth scene, King Nauplius was shown holding up a false beacon to draw Ajax’s ships onto the rocks, with Athena looking on approvingly. Finally, the last scene showed the fleet being shipwrecked on the rocks and Ajax struggling in the water. Like all of Heron’s automatons, the entire show was driven by an intricate system of pulleys, gears, and falling weights.

But the invention for which Heron is best remembered is the aeolopile or “wind ball”, a distant ancestor of the modern steam turbine. This comprised a closed metal vessel from which protruded two vertical pipes. Suspended between these pipes was a hollow metal ball with two L-shaped nozzles. When the vessel was filled with water and placed over a fire, the steam produced would flow up the pipes, into the ball, and out the nozzle, spinning the ball about its axis at high speed. Indeed, a replica constructed by classicist Dr. J.G. Landels of Reading University in England spun at an extraordinary 1,500 RMP – likely making it the fastest-rotating object in the world at the time of its construction. Yet while it is tantalizing to speculate that, had history played out differently, the Ancient Greeks could have started the Industrial Revolution nearly two millennia early, in reality Heron’s mechanism was little more than a toy, unsuited to any practical application. Indeed, when constructing his modern replica, Dr. Landels had difficulty finding the optimal tension between the ball and its tubular pivots. Too tight and the ball had difficulty spinning; too loose and excessive steam leaked out through the joint. And even when optimized, the aeolopile had an energy conversion efficiency of only 1%. It would not be until 1577 that Aran Taqu al-Din would find a somewhat practical application for Heron’s mechanism, adapting it to turn a roasting spit over a fire. Still, as far as basic mechanical principles go, the aeolopile was centuries ahead of its time.

Beyond all this, he came up with self-trimming oil lamps, self-filling wine bowls, and even a primitive form of odometer to record the distance travelled by a cart. The list goes on and on and on. In the end, while his name today is perhaps not as readily remembered as the likes of Archimedes or Doctor Emmet Brown, when it came to technology, few in history accomplished more given the tools and scientific understanding of his era than Heron of Alexandria.