Antikythera mechanism, c.250-150 BC, reconstruction (metal)

The Antikythera mechanism is an ancient analog computer designed to predict astronomical positions and eclipses for calendrical and astrological purposes, as well as the Olympiads, the cycles of the ancient Olympic Games. Found housed in a 340 mm × 180 mm × 90 mm wooden box, the device is a complex clockwork mechanism composed of at least 30 meshing bronze gears. Its remains were found as 82 separate fragments, of which only seven contain any gears or significant inscriptions. The largest gear (clearly visible in Fragment A) is approximately 140 mm in diameter and originally had 223 teeth. The artifact was recovered in 1900-1901 from the Antikythera shipwreck off the Greek island of Antikythera. Believed to have been designed and constructed by Greek scientists, the instrument has been dated either between 250 and 100 BCE. After the knowledge of this technology was lost at some point in Antiquity, technological artifacts approaching its complexity and workmanship did not appear again in Europe until the development of mechanical astronomical clocks in the fourteenth century.