Google Doodle: The fantastic Antikythera Mechanism

Today’s Google Doodle in most of the world portrays the Antikythera Mechanism, as today is the 115th anniversary of its discovery, at least according to Google.  Wikipedia, however, says it was recovered on August 4, 1901, so figure it out yourself. It wasn’t even studied until 1951, as other artifacts from the wreck were deemed more important:

Whatever the date, this is one of the most splendid devices known from ancient times. Recovered in a wooden box in a sunken Roman shipwreck off Greece, it was in 82 fragments. These reside at the National Archaeological Museum in Athens:

Wikipedia describes its use:

Using modern computer x-raytomography and high resolution surface scanning, a team led by Mike Edmunds and Tony Freeth at Cardiff University peered inside fragments of the crust-encased mechanism and read the faintest inscriptions that once covered the outer casing of the machine. Detailed imaging of the mechanism suggests it dates back to 150-100 BC and had 37 gear wheels enabling it to follow the movements of the moon and the sun through the zodiac, predict eclipses and even recreate the irregular orbit of the moon. The motion, known as the first lunar anomaly, was developed by the astronomer Hipparchus of Rhodes in the 2nd century BC, and he may have been consulted in the machine’s construction, the scientists speculate. Its remains were found as one lump later separated in three main fragments, which are now divided into 82 separate fragments after conservation works. Four of these fragments contain gears, while inscriptions are found on many others. The largest gear is approximately 140 millimetres (5.5 in) in diameter and originally had 224 teeth.

After this was made, we have no record of such complex technology until over 1300 years later–in the astronomical clocks of medieval Europe!

Here’s “Fragment A“, front and back, the most complex piece (captions from Wikipedia):

The main fragment and contains the majority of the known mechanism. Clearly visible on the front is the large b1 gear, and under closer inspection further gears behind said gear (parts of the l, m, c, and d trains are clearly visible as gears to the naked eye). The crank mechanism socket and the side-mounted gear that meshes with b1 is on Fragment A. The back of the fragment contains the rearmost e and k gears for synthesis of the moon anomaly, noticeable also is the pin and slot mechanism of the k train. It is noticed from detailed scans of the fragment that all gears are very closely packed and have sustained damage and displacement due to their years in the sea. The fragment is approximately 30 mm thick at its thickest point.

 

Fragment A also contains divisions of the upper left quarter of the Saros spiral and 14 inscriptions from said spiral. The fragment also contains inscriptions for the Exeligmos dial and visible on the back surface the remnants of the dial face. Finally, this fragment contains some back door inscriptions.

Here are speculative reconstructions, first the front and then the computer-reconstructed back:

The reconstructed front in the Archaeological Museum in Athens:

The back (computer reconstructed):

Here’s an explanatory video featuring Michael Wright who made the replica:

 

And here is the gear scheme as reconstructed by scientists:

Finally, two (of 15) fun facts about the device from Mental Floss (quoted verbatim):

• Since long before the invention of the digital computer you are undoubtedly reading this on, there have been analog computers. These types of computers range from mechanical aids like a slide rule to a device that can predict the tides. The Antikythera mechanism, which was designed to calculate dates and predict astronomical phenomena, has therefore been called the earliest analog computer.

 

• Jones and colleagues’ new interpretation of the mechanism is based on the extant 3400 Greek characters on the device, although thousands more characters are likely missing due to the incomplete nature of the artifact. Most notably, in their thorough linguistic analysis, these scholars discovered that the mechanism refers to eclipses’ color, size, and associated winds. The Greeks believed that characteristics of an eclipse were related to good and bad omens. Because of this belief, by building in predictive eclipse technology, the creator of the mechanism was letting the user divine the future.