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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 [[Greece|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 40 m (140 ft), and many statues and other works were retrieved from it by [[sponge]] divers. On [[May 17]], [[1902]], [[archaeology|archaeologist]] Spyridon Stais noticed that one of the pieces of rock had a gear wheel embedded in it.
The mechanism is the oldest known surviving [[gear]]ed mechanism, 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 track 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]].
[[Derek J. de Solla Price]], a science historian at [[Yale University]], published an article on the mechanism in ''[[Scientific American]]'' in June [[1959]] while the device was still only partially inspected. In [[1973]] or [[1974]], he published an analysis based on [[gamma ray]] imaging by Greek archaeologists. He claimed that the device had been built by a Greek [[astronomer]], [[Geminus]] of [[Rhodes]]. His conclusion was not accepted by experts at the time, who believed that the ancient Greeks had the theoretical knowledge but not the necessary practical skills.
A partial reconstruction was built by [[Australia]]n 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]].
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_month|synodic months]], which equals 19 solar [[year]]s. The lower rear dial plots the cycle of a single synodic month, with a secondary dial showing the lunar year of 12 synodic months.
[[Image:Meccanismo_di_Antikytera.jpg|frame|]]
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|sun]] and [[Moon|moon]], but those of every celestial body known to the Ancient Greeks: [[Mercury (planet)|Mercury]], [[Venus (planet)|Venus]], [[Mars]], [[Jupiter (planet)|Jupiter]], and [[Saturn (planet)|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 could have yielded to or integrated with European [[Clockmaker|clockmaking]] and [[Crane_(machine)#Ancient_cranes|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.
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]].
The Antikythera mechanism, not described in any surviving source, shows that our knowledge of ancient technology is incomplete. In [[1996]], the Italian [[physicist]] Lucio Russo (professor at Università di Roma "[[Tor Vergata]]") published an essay putting new light on the issue. The essay has been translated and published in English in [[2004]] under the title "The Forgotten Revolution: How Science Was Born in 300 BC and Why it Had to Be Reborn".
==See also==
*[[Armillary sphere]]
*[[Astrario]] by [[Giovanni De' Dondi]]
*[[Astrolabe]]
*[[Astronomical clock]]
*[[Orrery]]
*[[Planetarium]]
*[[Prague Orloj]]
*[[Torquetum]]
==External links and references==
* American Mathematical Society's [http://www.math.sunysb.edu/~tony/whatsnew/column/antikytheraI-0400/kyth1.html The Antikythera Mechanism I] and [http://www.math.sunysb.edu/~tony/whatsnew/column/antikytheraII-0500/diff1.html The Antikythera Mechanism II] ([http://www.math.sunysb.edu/~tony/whatsnew/column/antikytheraI-0400/kyth5.html Java Animation] by Bill Casselman)
* Fortunat F. Mueller-Maerki's [http://www.horology.com/htu-anti.html Geartrain diagram]
* Manos Roumeliotis's [http://etl.uom.gr/mr/Antikythera/anti.html Antikythera Mechanism MOV files]
* Rupert Russell's [http://www.giant.net.au/users/rupert/kythera/kythera.htm The Antikythera Mechanism]
* Price, Derek J. de Solla, "[http://www.giant.net.au/users/rupert/kythera/kythera3.htm An Ancient Greek Computer]". ''Scientific American'', June 1959. p. 60–67.
* Rice, Rob S., "[http://ccat.sas.upenn.edu/rrice/usna_pap.html The Antikythera Mechanism]: Physical and Intellectual Salvage from the 1st Century B.C.". USNA Eleventh Naval History Symposium.
* The Economist, "[http://www.economist.com/displaystory.cfm?story_id=1337165 The Antikythera mechanism]: The clockwork computer". [[September 19]], [[2002]].
* Rice, Rob S., "Gears, Galleys, and Geography [http://ccat.sas.upenn.edu/rrice/apagadgt.html The Antikythera Mechanism's Implications]". Text of the 1993 APA Abstract.
* Lienhard, John H., ''[http://www.uh.edu/engines/epi1031.htm 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.
[[Category:Ancient Greece]]
[[Category:Archaeoastronomy]]
[[Category:Protoengineering]]
[[cs:Mechanismus z Antikythery]]
[[de:Mechanismus von Antikythera]]
[[el:Μηχανισμός των Αντικυθήρων]]
[[es:Mecanismo de Antiquitera]]
[[fr:Machine d'Anticythère]]
[[it:Meccanismo di Antikytera]]
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