The Temporary Exhibition of the Mechanism and the Antikythera shipwreck...>>

The function of the Antikythera Mechanism

Most of metal parts of the original Mechanism seem to have been cut from sheets of low-tin bronze. The complex assembly of gear wheels resulted in the output of three main dials, one at the front and two at the back. The front dial had two concentric scales, one fixed ring with the names of the signs of the zodiac and one movable with the months of the Egyptian calendar (365 days). A pointer, probably topped with small gold sphere, used to show the motion and the position of the Sun, while another one with probably a silver sphere at the end, showed the motion and the position of the Moon. The existence of a third pointer is almost sured and represented the risings and settings of the five known planets throughout the year. On the top and the bottom of this main dial were inscriptions known as a parapegma, which is an astral calendar tracing the rising and setting of stars and constellations in the annual cycle.

Key numbers inscribed on two fragments (fragment 19 and E), for example the numbers ΙΘ (19), ΟC (76), ΣΚΓ (223) and ΣΛΕ (235) corresponding to astronomical cycles, which deal with the phases of the Moon, that is the Metonic, Callippic, and Saros Cycles. On the back side of the Mechanism there were two dials. The upper back dial is arranged as a five-turn spiral, divided in 235 parts, corresponding to 235 lunar months, that is 19 years, the Metonic Cycle. The restoration of a subsidiary display of the 76-year cycle, the Callippic Cycle, is a conjecture, based on the fragmentary inscription mentioned above. The Callippic Cycle improved the Metonic Cycle. The subsidiary Olympic dial, which is shown inside the Metonic dial, was a four-year dial predicting the dates of the Pan-Hellenic games. The lower back dial consists of a four-turn spiral, divided on 223 parts, corresponding to 223 lunar months, illustrating the Saros cycle, an 18-year calendar, which predicts the solar and lunar eclipses. Inside the Saros dial there is a smaller subsidiary dial, the Exeligmos dial. This is a 54-year triple Saros dial, which predicts the eclipses with absolute accuracy.

The turning of a handle through the side of the Mechanism moved all pointers simultaneously by means of gears and axles connecting them. By selecting a specific day on the front dial with the calendar and the desired year and month on the upper back dial, the rest of the pointers supplied all the corresponding information. Conversely, by setting the pointer on an astronomical event, its date in the future or in the past was furnished.

The Antikythera Mechanism is the most precious piece of ancient technology to have survived. It demonstrates the philosophical and geocentric approach of most ancient Greek thinkers towards the world and its structure according to which mathematics and physics were the means for deciphering the universe.

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Contributions, R. Proskynitopoulou, Ε. Magou, Μ. Zapheiropoulou, in: Ν. Kaltsas - Ε. Vlachogianni - P. Bouyia (eds), The Antikythera Shipwreck. The Ship - The Treasures - The Mechanism, Exhibition Catalogue, National Archaeological Museum, April 2012-April 2013, Athens 2012.

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Position in the museum