Credited to Greece. The mechanism was recovered in Greek waters and is Greek in language and design, but where it was built and by whom is unknown, and it is not known how it came to be on the ship. Proposed dates for its construction range from 205 BCE to about 87 BCE.
How it began
The mechanism was among the cargo of a ship that sank off the Greek island of Antikythera around 70 to 60 BCE. It is believed to have been designed and built by Hellenistic scientists, and it has been dated variously to about 87 BCE, to between 150 and 100 BCE, and to 205 BCE. Sponge divers from Symi under Captain Dimitrios Kontos found the wreck in 1900, and the device was raised in 1901. On 17 May 1902 the archaeologist Valerios Stais noticed a gear wheel embedded in one of the corroded lumps.
How it works
The device sat in a wooden-framed case of about 34 by 18 by 9 centimeters and was turned by hand. X-ray scans suggest it had 35 meshing bronze gears, of which 30 survive. The largest is about 13 centimeters across and had 223 teeth. The teeth are small triangles, cut by hand. The gear trains moved pointers that followed the Sun and Moon through the zodiac, predicted eclipses, and reproduced the way the Moon speeds up and slows down along its orbit. Inscriptions covered the case.
Who pushed back
When Stais suggested the object was an astronomical clock, most scholars thought it too complex to belong with the other finds from the wreck. It lay unnoticed for two years while the museum staff pieced together statues. The German philologist Albert Rehm was the first to propose that it was an astronomical calculator. Study then lapsed until Derek de Solla Price of Yale took it up in 1951; he published his findings in 1974.
What lasted
Machines of similar complexity did not appear again until the fourteenth century in western Europe, when astronomical clocks were built. In 2005 a team led by Mike Edmunds of Cardiff University used X-ray tomography and high resolution scanning to see inside the fragments and read faint inscriptions. Further reading of the texts in 2016 revealed numbers tied to the cycles of Venus and Saturn.
Where it stands today
The lump has been separated into 82 fragments, four of which contain gears. All are kept at the National Archaeological Museum in Athens, together with reconstructions and replicas that show how the device may have looked and worked. The basic operation is understood and has been replicated. The main open question is whether, and how, the device displayed the five planets known to the ancient Greeks, since no gearing for such a display survives.
