The Antikythera mechanism The Antikythera mechanism is the earliest known geared mechanism. Scholars estimate that it was created sometime between the late 2nd century and 1st century BC. Its design was informed by ancient Greek theories of astronomy and mathematics developed during the 2nd century BC. The mechanism is essentially a hand-powered orrery. It was used as a calendar and also to predict astronomical positions and eclipses for practical and astrological purposes, sometimes decades in advance. Detailed imaging of the mechanism suggests that it had thirty or so gear wheels with neat triangular teeth, as well as a ring divided into degrees (reminiscent of a protractor), enabling it to follow the movements of the moon and the sun through the zodiac. It could also predict eclipses and model the irregular orbit of the moon. Radiographic (x-ray) imaging has also revealed remnants of wood, indicating that the device was housed in a wooden case. The mechanism was discovered in 1901 in a Roman-era sea vessel wreck just off the coast of the Greek island of Antikythera. Scholars could make little sense of the hunks of corroded bronze until radiographic imaging, conducted in the 1970s and 1990s, revealed that the device was capable of replicating and tracking the motions of the heavens. Read more about the Antikythera mechanism in the Clocktime article The first timekeepers: Telling time before the pendulum clocks. Further reading Allen, M. 27 May 2007. ‘Were there others? The Antikythera Mechanism Research Project’, http://www.antikythera-mechanism.gr/. Freeth, T., D. Higgon, A, Dacanalis, L. MacDonald, M. Georgakopoulou and A. Wojcik. 12 March 2021. ‘A model of the cosmos in the ancient Greek Antikythera mechanism’ in Nature: Scientific Reports 11: Article number 5821. Iversen, P. A. 2017. ‘The calendar on the Antikythera mechanism and the Corinthian family of calendar’ in Hesperia 86(1): 129–203. Marchant, J. February 2015. ‘Decoding the Antiythera mechanism, the first computer: Hidden inscriptions offer new clues to the origins of a mysterious astronomical mechanism’ in Smithsonian Magazine. Image credit Antikythera mechanism, artwork. C017/7188, Jose Antonio Peñas / Science Photo Library