BoingBoing reader Rafael says,
This is a link to an article written for the American Mathematical Society’s website back in April 2000 on the function of the Antikythera Mechanism (the world’s oldest example of a mechanism with gears dating from 87 B.C.). The discovery of the mechanism surprised scholars because it was not believed that ancient Greeks possessed such technology. The article goes into a lot of detail and has working Java applets!
Link to part one, Link to part two.