The geared calculator was found over a century ago, in 1900, but only recently have the techniques existed to penetrate fully the fragments of metal and undersea accretions to see what is embedded within.
A Cardiff University team led by Mike Edmunds and Tony Freeth, in partnership with the National Archaeological Museum of Athens and universities in Athens and Thessaloniki, have used X-ray tomography and high resolution surface scanning to study and reconstruct the mechanism itself, and to read the 2,000 character ancient Greek inscription on its dials and the remnants of its case.
This reveals that the mechanism, which is comparable in complexity to an 18th century orrery, was used to predict the positions of the sun, the moon, the phases of the moon and possibly planetary motions. Spiral scales with sliding pointers were used to plot the 19 year calendar cycle, after which the sun, moon and earth return to the same relative position, as well as the Saros cycle of solar and lunar eclipses.
‘This device is extraordinary’, said Professor Edmunds: ‘The design is beautiful, the astronomy is exactly right for its age – it was probably made around 100 BC. The way the mechanics are designed just makes your jaw drop. Whoever has done this, has done it extremely carefully.’ The researchers are now hoping to create a computer model of how the machine worked, and, in time, a full working replica. It is still uncertain how widespread this technology was: some researchers believe it was unique, and was part of a treasure looted from Rhodes that was en route to Rome. It is more likely that there was a long tradition of building such devices in ancient Greece. •
This article is an extract from the full article published in World Archaeology Issue 30. Click here to subscribe