In search of lost time - the Antikythera mechanism deciphered

The complex mechanism of this ancient astronomical clock has been reconstructed thanks to high-resolution X-ray tomografy analysis. The result, obtained by a British, Greek and American interdisciplinary team unveiled a mechanism even more sophisticated that formerly believed.

When visiting the National Archaeological Museum in Athens, the rusty object inside a display case between the Agamemnon Mask and the Akrotiri frescos might almost go unnoticed.

After more than two thousands years at the bottom of the Aegean Sea, the metallic fragments have been coated by bluish oxides revealing its bronze composition.

However, on closer examination the intricate nature of the mechanism becomes evident.

This is nothing less than the Antikythera mechanism, the oldest mechanical instrument ever discovered, which has led historians to reconsider their views concerning the technological knowledge possessed by the ancient Greeks.

The mechanism was found inside the sunken wreck of a Roman ship in 1901, off the coast of the Antikythera island, halfway between the Peloponnesian peninsula and Crete.

Lying inside a wooden case, it comprises approximately 30 cogs covered in minute Greek inscriptions. In the 1970s Jacques Cousteau located several silver coins at the same site dating the shipwreck to about 80 B.C.

From the 1950s to the 1970s, Derek de Solla Price (1938-1983), Professor of History of Science at Yale University , was the first to systematically study the instrument and correctly postulated that it was a complex astronomical clock.

In a recent issue of Nature, an interdisciplinary research team led by Mike Edmunds of the School of Physics and Astronomy at Cardiff University (UK) published the findings from the reconstruction of the functioning mechanism, obtained by employing a sophisticated High Resolution X-ray Tomography technique.

Their findings revealed that the Antikythera mechanism is 100 years older than previously thought. Furthermore, the researchers have been able to double the number of inscriptions deciphered, thereby discovering something akin to an instruction manual.

The most important result, however, has been the discovery of a new and surprising operational feature of the artifact - a mechanism designed to calculate solar and lunar eclipses - according to Babylonian astronomical knowledge, together with and an ingenious mechanical verification of the irregularities of the Moon’s orbit in keeping with the theory of Hipparchus of Nicea.

Owing to a slight misalignment of the rotation’s fulcrum composed of two superimposed cogs, the Moon’s movement is reproduced in the way it seems to slow down when approaching the Earth and to accelerate when turning away in a cycle that repeats every 9 years.

The Antikythera mechanism is a remarkable archeological artifact from antiquity. And no similar device came into being until the re-invention of the astronomical clock in 14th century Europe. The Antikythera mechanism had, in fact, stolen a very substantial march on history.

It is, however, unlikely that the mechanism was a singular piece appearing without preliminary models and that the mechanism was never subsequently replicated. In all probability it took several generations to develop.

The lack of earlier artifacts of similar complexity is not entirely surprising.

Bronze objects from antiquity are rare as in the Middle Age bronzes were often melted down as a result of the scarcity of alloy metals.

It should be remembered that the majority of Greek statues have survived the ages as Roman marble copies. In the National Archaeological Museum in Athens there are no more than ten bronze statues, all in fact, recovered from shipwrecks.

Moreover, Cicero described a similar mechanism which he attributed to the Greek mathematician Archimedes. After the sacking of Syracuse in 212 B.C. and the death of Archimedes, the Roman General Marcellus removed the mechanism to Rome where Cicero was able to examine it.

The lack of historical continuity in the development of such a sophisticated mechanism is surprising.

As with much of classical knowledge, in all probability, technical advancements passed through to Arabic culture, thereby enhancing its tradition in the construction of astrolabes.

After the Moors invaded Spain in 711 A.C., elements of Moorish scientific knowledge were incorporated into Europe. The first pictorial representation of an astrolabe in European culture dates back to Blanche of Castile’s Psalter of 1223.

Researchers hope that the missing links of this story will be discovered in an unidentified or overlooked artifact buried somewhere in the darkness of a Museum repository or in an Arabic manuscript yet to be examined.

Bibliography

Freeth T. et al., D ecoding the ancient Greek astronomical calculator known as the Antikythera mechanism, Nature, 444, 30 November 2006 , doi:10.1038/nature05357;

Price D. de S., Gears from the Greeks, Trans.Am. Phil. Soc., 64(7), 1-70,1974.

Sitography

National Archaeological Museum of Athens official web site
http://www.culture.gr/2/21/214/21405m/e21405m1.html
Sito ufficiale del Museo Nazionale di Atene

Istitute and Museum History of Science - "Astrolabio"
http://brunelleschi.imss.fi.it/esplora/astrolabio/indice.html

Antikythera - From Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Antikythera
pagina della Wikipedia dedicata al meccanismo di Antikythera

The slide rules - Engineer Giovanni Pastore
http://www.giovannipastore.it/

Derek J. de Solla Price - From Wikipedia, the free encyclopedia
http://en.wikipedia.org/wiki/Derek_J._de_Solla_Price
pagina della Wikipedia dedicata a Derek J. de Solla Price.

Ipparco di Nicea - from Wikipedia(italy), the free encyclopedia
http://it.wikipedia.org/wiki/Ipparco_di_Nicea
pagina della Wikipedia dedicata a Ipparco di Nicea

Cardiff University
www.cardiff.ac.uk