Further study of a 2,100 year old gadget found in a ship wreck called an Antikythera (see also here) reveals that the device used mechanical gears to "perform complex astronomical calculations, including the prediction of solar and lunar eclipses and the movement of the planets" and to chart "the four-year cycle of the Olympics and the cycles of other ancient Greek games." The device used "a calendar scheme described by the Greek astronomer Geminos. In this system, months have 30 days with one day omitted every 64th day in order to have the correct average month length over a cycle of 19 years."
According to the researchers "the months correspond to those used in Corinth and suggest that the device may have originated in Syracuse, Sicily, then a Corinthian colony and the residence of Archimedes. Although the Antikythera mechanism was devised several decades after Archimedes’ death, its geographic location suggests a possible link to scientific instruments developed by the Greek scholar."
It was a thousand years ahead of its time.