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Who built the Antikythera Mechanism?

Nothing else like it was known for centuries. Who was the genius with the means, motive, and opportunity to create Antiquity's most marvellously engineered device?

Originally published in Fortean Times 250.

One of the most astonishing artefacts from the ancient world must surely be the set of calcified bronze fragments known as the Antikythera Mechanism. Recovered from a shipwreck in 1901, it proves that Hellenistic Greeks created the earliest computational instrument to accurately show the positions of heavenly bodies. In a space no larger than a shoebox, the complete device comprised around forty interlinked gearwheels and at least four pointers to indicate the positions of the Sun, Moon, and possibly the five known planets. By turning a crank handle the user could set a position in time and use that to work out when the orbiting bodies would rise and set with incredible accuracy.[1] It also displayed the phases and eclipses of the moon with a tiny rotating sphere. Nothing as mechanically sophisticated was known in Europe for at least another thousand years, yet there is textual evidence for other similar devices existing prior to the one we know.[2]

         A letter from the Antikythera Mechanism Research Project in the July 2008 issue of Nature reports that the Mechanism was not “simply an instrument of abstract science, but exhibited astronomical phenomena in relation to Greek social institutions,” namely the Greek Olympic games. A dial previously thought to be the Callipic cycle, is now found to have four sectors displaying the Olympiad cycle, each sector marking games held at Isthmia, Olympia, Nemea, Pythia, Dodona, and another unknown location. This unexpected finding was made even more surprising by the realisation that the month inscriptions belong to a family of calendars originating in Corinthian colonies of northwestern Greece. With seven of the Mechanism’s months tallying with a Sicilian calendar, where Corinth had a major colony at Syracuse, coupled with Archimedes, who while living at Syracuse wrote of similar mechanisms, the Antikythera team now prefers Sicily or northwestern Greece as the place where the Mechanism was designed to be used, rather than Rhodes as is often suggested.[3]

But even though it is now apparent that the Mechanism was designed for use in the Corinithian colonies, Rhodes should not be dismissed as a place where it could well have been designed and built.

         In the 1st century BCE, Rhodes was still an important intellectual and cultural centre, especially for astronomy. In 147 BCE Hipparchos settles in Rhodes. Building on centuries of work by Babylonian astronomers, this giant of Greek astronomy founds a reliable system for predicting eclipses, and compiles the first comprehensive star catalogue, which in turn leads to his discovery of precessional movement, the way the rotating Earth slowly wobbles like a spinning top. All the foundations needed to design the Mechanism are in his work, and he is a highly plausible candidate for its masterminding.

         While it is entirely possible that Hipparchos is the genius behind the Mechanism, I propose a scenario skipping forward to 95 BCE, when the politician and unrivaled polymath, Posidonius settles in Rhodes and travels widely, including Sicily. Influenced by Hipparchos’ teachings, he calculates the size and distance of the sun and moon. Then, building on what he learned in Sicily from the Archimedes tradition of planetariums, he even constructs an orrery to shows the motions of the known orbiting bodies in what may be a direct reference to the surviving Mechanism.[4] Let us then make a small conjectural leap, supposing that Posidonius – who is interested in astronomy at the right time and place, is a figure of social importance, whose investigations range across all aspects of Nature, visited Sicily, and who even possesses an orrery – is somehow involved in the Mechanism’s creation.

         Who else is on Rhodes then? In 87 BCE the nineteen year-old Geminus is writing his Introduction to the Phenomena, an astronomical primer. Geminus is obscure. However, references to Rhodes in his work suggest he worked there, and if that is so he must have known,and was probably taught by Posidonius. In the year Geminus starts on his primer, Posidonius is forty-three and embarking on an ambassadorship to Rome. Does Geminus, inspired by earlier gearwheel technology and captivated by the actual orrery of Posidonius, conceive of an even finer mechanism as the ultimate expression of Greek astronomy? Or does Posidonius, requiring a new and better orrery to impress his new Roman masters, recruit Geminus to help him? They are almost the Steve Jobs and Steve Wozniaks of their day: building on cutting-edge advances to construct the most complex and elegant calculating instrument ever. There is also a talented craftsman fashioning the bronze, someone from the Sicilian mechanical tradition perhaps? There is conjecture that the Mechanism contains parts from an earlier device, so that it was an ‘upgrade’, maybe from the other one in Posidonius’ ownership. Bronze is scarce and precious, so the metal for these mechanisms might have come from fragments of the Colossus of Rhodes, at that time lying scattered around the harbour following an earthquake two centuries earlier. It is fine to imagine the material of one world wonder being recycled into the basis for another, entirely different, marvel.

         Combining knowledge and techniques from Rhodes and Sicily, the Antikythera Mechanism is designed, built, refined. It is too small to display publicly, so is it designed be taken to Athens and other centers of learning where it can be appreciated and consulted by intellectual insiders and select groups? Perhaps only a few people even knew of its undertaking, yet the Olympiad function indicates a wide social application so, once finished, the mechanism was probably widely known.

         In my scenario of Mechanism intrigue, the year 79 BCE is critical in it’s brief working life, for it is then that the great Roman intellectual and statesman, Cicero, embarks on his Aegean tour. First he visits the Academy at Athens to consolidate his Stoicism, then the Oracle at Delphi where he is initiated into the Eleusinian mysteries, thence to Rhodes where he meets his friend Posidonius. With the Mechanism by now completed it is inconceivable that Cicero, who writes of Posidonius’ orrery, is not made aware of its existence. With his learned optimism, Cicero recognises how the Mechanism could have far greater influence in Rome. Solar eclipses are reputed to have occurred at the birth of Romulus and at the founding of Rome, and the eclipse event is deeply fixed in the common Roman mind (and indeed across the entire ancient world) as a capricious act by gods and demons, often a bad sign. Cicero approved of education, for narrowing the gulf that existed between the educated elites and the masses. He was wryly disparaging of superstition and divination, but was savvy enough to concede the importance of mysticism to the State and to the masses (and was duly made Augur in 53 BCE) [5] Maybe he argued that the Antikythera Mechanism could be used to teach Romans not to fear the gods, thus empowering them for the general good. If, the cause of those fears can be predicted, he might have argued, those fears can be banished. But Posidonius, understandably proud of his achievement, will not permit Cicero to take it when he returns to Rome in 77 BCE and Cicero is unwilling – or not yet in a position – to coerce his elder mentor, and leaves empty-handed.

         Scholars suppose that the ship carrying the Mechanism was on its way back to Rome with a cargo of seized booty. The ship’s loss off the coast of Antikythera island is thought to be between 85 and 59 BCE.[6] Between those years Pompey, the dazzling Roman military leader, rises in political eminence along with Cicero. In 77 BCE Cicero, now an administrator on Sicily, discovers the tomb of Archimedes, a sure reminder of these wonderful mechanisms. In the same year that Cicero is elected Consul, 63 BCE, Pompey (also a Consul) is being taught by Posidonius, my candidate as the force behind the Mechanism. Taking the later date for the ship’s loss, then, imagine Cicero, with Pompey’s backing, persuading Posidonius to allow a ship to bring the Mechanism back to Rome where they could display it in their educational institutes, maybe even reproduce it for wider appreciation. Posidonius was trusting (or wary) enough of the Romans to allow them to ‘borrow’ it for a while. Happily for us, the plan was enacted but failed.

            We might want to thank the Romans for coveting the Antikythera Mechanism, for if it had not been transported on a ship destined to sink, preserving its cargo at the bottom of the sea for two thousand years, then it almost certainly would have been lost forever.

Nothing as mechanically sophisticated was known in Europe for at least another thousand years, yet there is textual evidence for other similar devices existing prior to the one we know.

antikythera mechanism

Posidonius (c.135 BC – c.51 BC)

Perhaps only a few people even knew of its undertaking.


Cicero (3 January 106 BC – 7 December 43 BC)

anithythera, mechanism, xray

Antikythera mechanism x-ray



1. Many of the details and background information was provided by Professor John Seiradakis and his team during a talk at the Astrophysics Department of Oxford University on January 14th, 2008.

2. Archimedes wrote about such devices in a lost manuscript called On Sphere Making. Two were taken to Rome in 212 BCE, alas now lost.

3. Freeth, Jones, Steele, Bitsakis, Calendars with Olympiad display and eclipse prediction on the Antikythera Mechanism, Nature Vol 454, July 2008.

4. Cicero writes of it in On The Nature of the Gods


5. Cicero discusses all kinds of divinatory practices with some dry humour in the two books of On Divination (

6. Victor Kean, The Ancient Greek Computer From Rhodes (ISBN 9602262273) places the date at 5th May 59 BCE based on the final position of the dials.

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