Tuesday, December 14, 2010

Ancient Mechanical Computing: the Antikythera Mechanism

Name of Model: Antikythera Mechanism
Created by: Andrew Carol (also on MOCPages)
Found at: http://acarol.woz.org/antikythera_mechanism.html
Details: You may remember having seen this builder's difference engine some years back, but he now has another viral hit and fantastic mechanical computing model working its way across "teh intarwebs". This time he has taken on reproducing the Antikythera Mechanism, an ancient device that predicts eclipses. Discovered off the coast of Antikythera over a hundred years ago, the mechanism appears to have accurately calculated the locations of planets, the moon, and the sun - all based on a date input provided by a hand crank. For more information on the original machine, see the research website and this article in Nature.

Since the original mechanism was rather damaged when it was found, replicating the original gearing exactly wasn't really an option (nevermind the limitations in how many sizes of gears LEGO actually makes...) - so this machine is as close as possible to the original math, but features different actual gearing. More specifically, rather than very precise bronze gears, the exact ratios needed to get the calculations right are handled by differentials. Normally, when you see differentials used in a mechanical computer, they're being used to average two input speeds. That's not the case here. You'll need to look at the original webpage to fully understand exactly what was done here instead, and how that enabled the more advanced gear ratios necessary here. If tomorrow's LMOTD is late, it's probably because I'm still studying the details of this one.

The video featured above is the The Antikythera Mechanism in Lego from Small Mammal on Vimeo. The video's producer has a behind the scenes post up on his blog. For once - a professional video treatment for a worthy model! If only more of us could have our LEGO creations documented in that way...

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