Why Heron’s Aeolipile Is One of History’s Greatest Forgotten Machines

Nearly 1,800 years before the start of the Industrial Revolution, an ancient engineer by the name of Heron created the world’s first steam engine.

In 62 A.D., the Roman Empire’s cultural capital of Alexandria, hugging the northern shore of Egypt, was a tide pool of new religions.

Nearly half-a-century after the reign of Caesar Augustus, the Empire was approaching its historical high water mark and new religious influences began to trickle in across its 2.2 million-square-mile expanse. The city quickly sprouted new mystery cults, practiced new forms of worship, and even created whole new gods from the melting pot of Roman, Greek, and Egyptian influences. 

And with so many temples claiming to have divine answers, competition for followers was stiff. To stand out, priests turned to Heron—also known as Mechanikos, meaning “machine man”— to engineer celestial phenomena.

But the Greek wunderkind didn’t rely on the favor of his pantheon of gods to create the impossible, instead he used science and engineering that wouldn’t be seen again for more than a millennium. In these ancient temples, Heron used hydraulic and steam power to create singing birds, bursts of flame, and moving statues in the hopes of inspiring awe—and devotion—into would-be disciples. 

And in the process of manufacturing these man-made miracles, Heron invented something that would change the world—the aeolipile, otherwise known as the world’s first steam engine. 


Heron is a bit of a historical mystery. Researchers believe that he was most likely of Greek origin and lived around 10 – 70 A.D. As a student, he loved to wander the shelves of the library in the University of Alexandria. He was strongly influenced by the works of Ctesibius of Alexandria, another Greek inventor in Ptolemaic Egypt.

As an adult, he wrote works on mathematics and engineering that were filled with ideas centuries ahead of their time. These books included step-by-step diagrams and detailed explanations and were likely meant as lectures or textbooks, evidence that he was almost certainly a teacher at the University of Alexandria.

e invented the world’s first coin-operated machine used to distribute wine in temples, a fire engine, a water organ, and a menagerie of automatons that included singing birds and puppets. He also engineered mechanisms for the theater including an entirely mechanical ten-minute play. Tragically, the majority of his works were destroyed during the destruction of the Library of Alexandria, but a few were preserved thanks to Arabic manuscripts.

Across the seven books that survived the Library’s fire, the ancient inventor explores the concepts of automata, war machines, formulas to calculate area and volume, and theories on the nature of light. But Heron’s most famous work is two books known collectively as Pneumatica, one of the world’s first explorations of steam and hydraulic power, and throughout its pages, Heron uses religious statues and iconography as examples for his mechanical ideas. 

One such statue, “Figure 11: Libation at an Altar Produced by Fire” features the figure of a pitcher-holding woman and a cup-bearing man. Between them sits an altar where a worshipper can light a fire offering and below their feet is a chamber containing wine. Once the worshipper lights the altar, in Heron’s words, “the air within, being rarefied, will descend into the pedestal, and exert pressure on the liquid it contains, which, having no other way of retreat will pass through the tubes [located in the figures] thus the figures will pour a libation and not cease until the fire is extinguished.” 

Later in Pneumatica, Heron adapts this system to make the doors of a temple open. 

But Pneumatica showstopper—the one that would go on to change the world— is the aeolipile. 

Translated literally as the “wind ball,” this device is the world’s first recorded example of a steam engine or reaction steam turbine. “In our terms, Heron’s device is a demonstration of the principle of the rocket, that is, of the principle of reactive force: the sphere spins in reaction to the emission of steam.” explains Paul Keyser, a specialist in ancient engineering, “[But] Heron was too good a mechanical engineer to propose this device as a ‘steam engine’ —the flywheel is too light, the device would spin too fast, and the sphere should be a cylinder for attaching the gearing.”

It consisted of a hollow sphere mounted so that it could turn as steam escaped from two spouts placed at the boiler’s equator. The sphere, filled halfway with water, would begin to spin rapidly once a fire was lit beneath it, creating torque generation derived directly from steam power. 

The practical use for Heron’s aeolipile is unknown but most experts believe it was, along with the other toys and inventions described in Pneumatica, used to entertain and spark wonder in the viewer. Its description does not detail a possible use for it—Heron simply describes how to build one and how it moves. 

New York University’s Harry Kitsikopoulus of New York University recounts in his book Innovation and Technological Diffusion: An Economic History of Early Steam Power a modified version of the aeolipile could have been used to create temple miracles. “A boiler hidden in the hollow figure of an idol would produce steam through a pipe ending in one or two branches through the nose/ or mouth…” writes Kisikopoulus, “the escaping steam giving the impression of a breathing figure, inspiring awe.”

Slowly, Pneumatica spread throughout Europe. Salamon de Caus, a French Huguenot and engineer once credited with the invention of the steam engine, read it while in Italy and in 1571, the German theologian, Malthesius mentioned the aeolipile in one of his sermons. By the 1640s, Pneumatica had gone through five editions in England. The second half of the 16th century marked the rediscovery of steam power, and engineers across Europe began to speculate on its mechanical applications.

Thanks to the widely disseminated translations of Heron’s work, aeolipiles became quite common and people used them for melting glass and metal, blowing fires in houses, and improving the drafts of chimneys. 

Then, in 1689 English inventor Thomas Savery developed the world’s first modern steam engine in the form of a pump to remove water from mines. Using two steam boilers, his device provided a nearly continuous pumping system. However, despite its early success it was soon discovered that Savery’s system only worked in shallow water. In 1711 another English inventor, Thomas Newcomen improved upon Savery’s design by adding a separate condenser with a piston. His system eliminated the need for accumulated steam pressure. 

The Newcomen steam engine went unchallenged for the next 50 years and was used to drain wetlands, supply water to towns, and to power factories and mills. ANOTHER AMAZING FORGOTTEN MACHINEHistory’s Forgotten Machines: The Hulett Unloader

Despite its supremacy, the Newcomen engine was not without its flaws, particularly the fact that it consumed a massive amount of steam. This flaw was remedied in 1769 by Scottish inventor James Watt, who added a separate condenser to the Newcomen model, allowing the steam cylinder to be maintained at a constant temperature. 

Watt’s improvement led to the rapid adoption of steam power across Britain and the U.S., ushering in the Industrial Revolution. Versions of the engine were used in locomotive devices like early cars and trains. By the 1800s steam was powering most factories, breweries, and mills. The technology would lay the foundation for the highly connected world we see today. 

The aeolipile, in both appearance and function, was of course, quite different from the steam-powered machines of the future. Instead, Heron used steam power to mystify and educate—he didn’t know that the ideas embedded in his novel invention would one day change the world.

Source: Popular Mechanics