Antikythera mechanism
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The Antikythera mechanism is an ancient artifact believed to be an early clockwork mechanism. It was discovered in a shipwreck off the Greek island of Antikythera, between Kythera and Crete, and has been dated to about 87 BC.
The wreck was discovered in 1900 at a depth of about 43 m (140 ft), and many statues and other works were retrieved from it by sponge divers. On May 17, 1902, archaeologist Spyridon Stais noticed that one of the pieces of rock had a gear wheel embedded in it.
The mechanism is one of the oldest surviving geared mechanisms, made from bronze in a wooden frame, and has puzzled and intrigued historians of science and technology since its discovery. The most commonly accepted theory of its function is that it was an analog computer designed to model the movements of heavenly objects. Recent working reconstructions of the device support this analysis. The device is all the more impressive for its use of a differential gear, which was previously believed to have been invented in the 16th century and the level of miniaturization and complexity of its parts, comparable to a clock made in the 18th century.
The original mechanism is displayed in the Bronze collection of the National Archaeological Museum in Athens, accompanied by a replica. Another replica is on display at the American Computer Museum in Bozeman, Montana.
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Reconstructions
Bromley
A partial reconstruction was built by Australian computer scientist Allan George Bromley (1947–2002) of the University of Sydney and Sydney clockmaker Frank Percival. This project led Bromley to review Price's X-ray analysis and to make new, more accurate X-ray images that were studied by Bromley's student, Bernard Gardner, in 1993.
Gleave
Later, a British orrery maker named John Gleave constructed a working replica of the mechanism. According to his reconstruction, the front dial shows the annual progress of the sun and moon through the zodiac against the Egyptian calendar. The upper rear dial displays a four-year period and has associated dials showing the Metonic cycle of 235 synodic months, which approximately equals 19 solar years. The lower rear dial plots the cycle of a single synodic month, with a secondary dial showing the lunar year of 12 synodic months.
Wright
Another reconstruction was made in 2002 by Michael Wright, mechanical engineering curator for The Science Museum in London, working with Allan Bromley. He analyzed the mechanism using linear tomography, which can create images of a narrow focal plane and thus visualized the gears in great detail. In Wright's reconstruction, the device not only models the motions of the sun and moon, but those of every celestial body known to the Ancient Greeks: Mercury, Venus, Mars, Jupiter, and Saturn.
This new reconstruction gives credence to ancient mentions of such devices. Cicero, writing in the first century BC, mentions an instrument "recently constructed by our friend Poseidonius, which at each revolution reproduces the same motions of the sun, the moon and the five planets." Such devices are mentioned elsewhere as well. It also adds support to the idea that there was an ancient Greek tradition of complex mechanical technology which was transmitted via the Arab world, where similar, but simpler, devices are found later, and could have yielded to or integrated with European clockmaking and ancient cranes. Some scientists believe that not only was the device used to track celestial bodies, but to calculate their positions for events or births.
Ongoing imaging research
The Antikythera mechanism is now being studied by The Antikythera Mechanism Research Project, a joint programme between Cardiff University, the National and Kapodistrian University of Athens, the Aristotle University of Thessaloniki, the National Archaeological Museum of Athens, X-Tek Systems UK and Hewlett-Packard USA, funded by the Leverhulme Trust and the Cultural Foundation of the National Bank of Greece.
The Hewlett-Packard research team studies the Mechanism with its "PTM Dome" digital imaging system, and X-tek X-ray are using 400kV microfocus computerised tomography.
See also
- Armillary sphere
- Astrario by Giovanni De' Dondi
- Astrolabe
- Astronomical clock
- Orrery, a free-standing solar system model
- Planetarium
- Prague Orloj
- Torquetum
External links and references
- American Mathematical Society's The Antikythera Mechanism I and The Antikythera Mechanism II (Java Animation by Bill Casselman)
- Fortunat F. Mueller-Maerki's Geartrain diagram
- Manos Roumeliotis's Antikythera Mechanism MOV files
- Rupert Russell's The Antikythera Mechanism
- Price, Derek J. de Solla, "An Ancient Greek Computer". Scientific American, June 1959. p. 60–67.
- Rice, Rob S., "The Antikythera Mechanism: Physical and Intellectual Salvage from the 1st Century B.C.". USNA Eleventh Naval History Symposium.
- The Economist, "The Antikythera mechanism: The clockwork computer". September 19, 2002.
- Rice, Rob S., "Gears, Galleys, and Geography The Antikythera Mechanism's Implications". Text of the 1993 APA Abstract.
- Lienhard, John H., Antikythera Mechanism. "The Engines of Our Ingenuity". KUHF-FM, Houston.
- Wright, M T. "A Planetarium Display for the Antikythera mechanism". Horological Journal, 144 No. 5, 169–173, May 2002.
- Derek De Solla Price. Gears from the Greeks: The Antikythera Mechanism—A Calendar Computer from ca. 80 B.C.. Science History Publications, New York, 1975, ISBN 0871696479; originally published in Transaction of The American Philosophical Society, New Series, Volume 64, Part 7, 1974.
- Russo, Lucio, "The Forgotten Revolution : How Science Was Born in 300 BC and Why it Had to Be Reborn". Springer , 2004, ISBN 3540203966.
