The Antikythera Mechanism

Recently I joined a Scientific Instrument Society study tour to Athens.

We spent five days visiting museums and archeological sites as organised by local SIS members, and feasting on Greek food and wine.

Two highlights had to do with metalwork: a visit to the ancient silver mines of Thorikos, and the Antikythera Mechanism. Thorikos is in the south east of Attica, near Cape Sounion, and the silver from the mines there made Athens prosperous and funded the fleet that defeated the Persians in 480BCE and the building of the Parthenon. We saw only the entrance to a mine [https://www.heritagedaily.com/2016/02/archaeologists-discover-a-network-of-galleries-shafts-and-chambers-at-the-foot-of-the-mycenaean-acropolis-of-thorikos/109654], but more accessible were the remains of ore processing facilities in the hills. The ore (galena or chalcopyrites) was ground into a powder and then washed to separate the heavier metallic component as the lighter dross was washed away. The concentrate was then dried into bricks for transport to areas where there was wood for smelting. The water was cleverly recycled (everything was done by bucket and spade) and the washing and drying areas and channels and large cement-lined (!) water storage cisterns are still in quite good condition.

 

Back in Athens, the National Archeological Museum houses the Antikythera Mechanism, a truly amazing relic from c.100 BCE.  I must have walked right past it on my last visit in 1975, but recent studies have raised its profile and if you hunt a bit, you can now buy an Antikythera Mechanism tee-shirt in the tourist bazaar. It now dominates two rooms of the museum as is fitting for ‘the first computer.’ It happened to be International Museums Day when we visited, so entry was free and the whole museum was crowded.

The relic itself is not very prepossessing, especially compared to the wonderful bronze statuary that came from the same shipwreck, but you can certainly see gearwheels embedded in the three lumps on display. A sort of head-up projected animation of how the pieces fit together enlivens things, or distracts, depending on how you are feeling. Wall panels explain its function as a geocentric planetarium and eclipse calculator.

 A second room displays reconstructions of the device. These have an interesting history of their own and give a much better sense of what it is we are dealing with.  Right from its discovery in 1900 it was realised that it was some sort of astronomical device, but it is only with the use of xray scanning technology in the 1980s by Michael Wright (a SIS member but unfortunately not on the tour) and the late Alan Bromley (from Sydney University) that a real appreciation of its internal layout and its probable capabilities were possible. Bromley made a reconstruction with Sydney clockmaker Frank Percival. I don’t know where that is now. A reconstruction made by Wright was on display, the first one to correctly interpret the arcs on the back as five turn spirals acting as eclipse predictors. Recent high resolution scans have even allowed some of the extensive instructions engraved on its front plate to be deciphered, confirming some speculations on its functions. As well as three earlier and two later reconstructions, this room also had a 3D video of the story of its discovery off the island of Antikythera.This was made by Hublot who make a Antikythera wristwatch and who are sponsoring further dives on the wreck. The video is available in 2D here. Another team has made a three times enlarged model largely of Perspex. We saw one at the Athens Observatory. It was good to see into the mechanism, but too easy to look right through it, so it did not help me too much in understanding how it worked.

 

  In fact one of the best ways to understand the device is to watch ‘Chris’ from Townsville build one on YouTube.https://www.youtube.com/watch?v=ML4tw_UzqZE&t=13s He also addresses questions of what tools were available to its makers.

It was exciting to hear that diving on the wreck is ongoing. It is suspected that the front of the device housed a geocentric planetarium but that part is largely missing. It will be a miracle if the tiny parts can be found, but we can all hope. The diving team do have specially developed metal detectors.

Later we took advantage of the free admission to have a quick look inside the Tower of the Winds that overlooks the Roman Forum (c.50BCE). Adorned with multiple sundials and a windvane, the tower also once contained a water clock of some sort, and looking at the substantial cistern and channels in the floor it is tempting to speculate that it housed some sort of water-driven mechanical clock rather than a simple klepsydra.