Antikythera mechanism

Divers recovered the corroded remains of this bronze device from a Roman-era shipwreck off the Greek island of Antikythera in 1901. It is the oldest known scientific calculator, and it is about 2,000 years old. Turn a handle and more than 30 interlocking gears model the heavens: the device could show the positions of the sun, moon and planets, predict eclipses and track the dates of the Olympic Games. That precision changed what historians believed ancient Greek craftsmen could make. It is also the clearest early case of an analogue computer, where the shape of the mechanism itself embodies the mathematics rather than counting in digits.