Antikythera Mechanism

Recovered from a Roman-era shipwreck off Antikythera in 1901, the mechanism is a geared bronze calculating device of at least thirty interlocking wheels. Microfocus X-ray computed tomography and surface imaging carried out from 2005 onward read the inscriptions and resolved the gear trains. It models the solar and lunar calendars, predicts eclipses using the Saros cycle, tracks the four-year athletic-games cycle, and reproduces the moon's variable speed using a pin-and-slot epicyclic arrangement.

That last feature matters: it is a mechanical implementation of a known astronomical irregularity. Someone translated a theory into gearing.

A device this refined is not a first attempt. It implies a workshop tradition, prior prototypes, trained artisans, and customers. Almost none of that survives. Cicero mentions geared planetary devices attributed to Archimedes and Posidonius, which corroborates the tradition textually, but the material record is a single corroded lump.

Bronze is the likeliest reason. It is valuable, it is recyclable, and objects like this survive only when they are lost somewhere nobody can retrieve them — which is to say, by shipwreck.

The exact planetary display on the front face, the precise calibration date, and the workshop's location are all reconstructions with competing versions. These are technical disagreements between researchers working from the same CT data, not challenges to the device's authenticity or function.