Calendars with Olympiad display and eclipse prediction on the Antikythera Mechanism

Abstract

Previous research on the Antikythera Mechanism established a highly complex ancient Greek geared mechanism with front and back output dials. The upper back dial is a 19-year calendar, based on the Metonic cycle, arranged as a five-turn spiral. The lower back dial is a Saros eclipse-prediction dial, arranged as a four-turn spiral of 223 lunar months, with glyphs indicating eclipse predictions. Here we add surprising findings concerning these back dials. Though no month names on the Metonic calendar were previously known, we have now identified all 12 months, which are unexpectedly of Corinthian origin. The Corinthian colonies of northwestern Greece or Syracuse in Sicily are leading contenders-the latter suggesting a heritage going back to Archimedes. Calendars with excluded days to regulate month lengths, described in a first century bc source, have hitherto been dismissed as implausible. We demonstrate their existence in the Antikythera calendar, and in the process establish why the Metonic dial has five turns. The upper subsidiary dial is not a 76-year Callippic dial as previously thought, but follows the four-year cycle of the Olympiad and its associated Panhellenic Games. Newly identified index letters in each glyph on the Saros dial show that a previous reconstruction needs modification. We explore models for generating the unusual glyph distribution, and show how the eclipse times appear to be contradictory. We explain the four turns of the Saros dial in terms of the full moon cycle and the Exeligmos dial as indicating a necessary correction to the predicted eclipse times. The new results on the Metonic calendar, Olympiad dial and eclipse prediction link the cycles of human institutions with the celestial cycles embedded in the Mechanism's gearwork.

Ancient astronomy: Mechanical inspiration

“…But the month names on the device are most closely related to those used in colonies established by the city-state of corinth in northwest Greece and sicily 4 . And a four-year dial on the device displays the timing of the olympics and various other games -including 'naa', a small athletic event of interest only near dodona in northwestern Greece.…”

The Antikythera Mechanism: The oldest mechanical universe in its scientific milieu

“…Theophanidis, J., 2006) and that gives the position of some planets and, Price (1956Price ( , 1974, together with H. Karakalos perform radiographs and reconstruct a model. More interesting results came from tomographies by Bromley, Wright and Mangkou (Bromley 1986(Bromley , 1990aWright et al 1995;Wright 2002Wright , 2003Wright , 2005aWright ,b,c, 2006a and more recently by Freeth et al (2006Freeth et al ( , 2008 with a more accurate computer tomography advance even further our understanding of the Mechanism, and that read several parts of the manual of the instrument written in the almost every available surface of the mechanism, hidden in the rust in it since it sunk in the sea during the second century BCE. See Marchant (2009) andFreeth (2009) for an account of the story.…”

The gears of the Antikythera Mechanism: an educational pathfinder to the solar system

“…The fragments were part of the cargo of a large shipwreck of the 1st century BCE that was full of treasures been transported from Greece to Rome. This intriguing and mysterious device has perplexed many scientists who have been studying it through today (Moussas 1991;Freeth et al 2006Freeth et al , 2008Wright 2007). The research studies of the Mechanism continually unveil extraordinary information about the ancient Greek science and technology, some of which are unknown and very surprising.…”

“…One dial is on the "front" and the rest of the dials on the "back" side of the Mechanism. The pointers are driven by gears that rotate by a single input shaft (Freeth et al 2006(Freeth et al , 2008Price 1959Price , 1974Theofanidis 1934). The device was originally housed in a wooden case, with its manual…”