The Antikythera Mechanism
A paper on the Mechanism appears in tomorrow’s Nature. In brief what it is these days is a rather unimpressive looking lump of heavily corroded metal. I have a photo of it somewhere, but it’s a very bad blurry photo which doesn’t do justice to its lumpy unimpressiveness. Fortunately Wikipedia has this much better photo.
The Antikythera Mechanism in the National Museum, Athens. Photo from Wikipedia.
The reason why it’s news is that there’s been a lot of painstaking work to try and see beyond the corrosion, and its proven spectacularly successful. The mechanism has been examined using X-ray tomography, which is where X-rays are used to build up a cross-section of a subject slice by slice without physically pulling the subject apart. The results are confirming that Greek technology could be staggeringly sophisticated.
The mechanism was found in the early 1900s. It was found when some sailors sheltered from a storm off the island of Antikythera. They went sponge diving, but one of the divers returned to the ship and told the captain of the corpses he’d found on the sea bed. The other divers went to confirm his story and found the wreck of a Roman vessel which sunk in the first century BC. The corpses were bronze and marble statues, some of which can be found in the National Museum of Greece today. Along with these finds were recovered some cogs congealed by rust into lumps.
The problem is what would cogs be needed for? The device was throughly investigated by Derek de Solla Price and his conclusion was startling. The device may have looked like clockwork, but it was no clock. Instead he argued it was an analogue computer, used for calculating the position of the sun, moon and planets against the celestial sphere.
The letter in Nature for Nov 30 2006, announces the findings of the X-ray team and appears to confirm this astronomical hypothesis. The X-rays have enabled more of the mechanism to be read, an inscription on the back door appears to include astronomical periods, including the Saros cycle of 223 synodic months, a synodic month being the period from one new moon to the next. The inscription on the front door is fragmentary but with lines like “brings towards the Sun up to — and conjunction” it would take a powerful imagination to conclude it wasn’t some form of calculation device.
As a piece of interdisciplinary work it’s all really impressive. The recording of the inscriptions should be more than enough to give epigraphists to argue over, and a full publication of that will follow. There will also be a data-set online at www.antikythera-mechanism.gr, which at the time of writing is inaccessible, presumably due to the quantity of traffic its getting. The conclusions drawn from the inscriptions and imaging of the gears also appears to be eminently reasonable. There is a danger, when you know what the right astronomical answer is, that you interpret the historical data to fit the answer. So far I haven’t seen that here. Gaps in the inscription are there, and questionable readings where the glyphs may say one thing or possibly another are professionally acknowledged. The skill of the work is hard to underestimate. It’s not simply a 2000 year old jigsaw. It’s like putting together a 2000 year old jigsaw where are the pieces that haven’t been chewed by the dog of time are missing, and no picture on the box to say how the thing should look.
It does open up some more questions. One is if the Greeks were capable of producing such sophisticated items then why wasn’t there a scientific revolution earlier? It’s like Greek history now has its own Needham question. Another reasonable question is why did these devices disappear so completely from the archaeological record? In his news item François Charette argues that just as Greek astronomy was preserved by the Arabs, so too was Greek technology in the form of Astrolabes.
This is a story where potentially the discoveries are as exciting as the scientists say they are. However as Rob Rice noted:
It is neither facile nor uninstructive to remark that the
Antikythera mechanism dropped and sank–twice. The first time was around 76 B.C., when the intricate astronomical computer was lost with the rest of a treasure-ship’s cargo. The second time came after Derek de Solla Price analyzed and published its construction and nature decades after its recovery. Since his Gears from the Greeks in 1975, little attention has been paid to our most exciting relic of advanced ancient technology.
Hopefully the new evidence this team has uncovered will help this project avoid the same fate.
The project’s website
In search of lost time by Jo Marchant at Nature (free access), an excellent write up of why this is so interesting.
X-tek’s page on their work for the project.
The Wikipedia entry for the Antikythera Mechanism.
The press release.