The Antikythera Mechanism

On Easter Tuesday, 1900, sponge divers from the island of Symi discovered a Roman shipwreck near the coast of the small island of Antikythera. A few months later, the Greek State organized the very first major underwater archaeology expedition, with the sponge divers, assisted by the Greek Royal Navy.

The wreck is dated ca 80 - 60 BCE while much of its rich cargo dates from before the second century BCE; among the superb findings was an object containing gears, dials and inscriptions, also dated
during the second half of this century.
This particular object is now called the “Antikythera Mechanism” and is on display  at the National Archaeological Museum in Athens. Since its discovery, speculation on its use has run from an astronomical device, an astrolabe, planetarium or navigational device, to a combination of various devices.

Over a century of research has now established that it is in fact the oldest known astronomical and calendrical calculating machine. It has been called the “World’s First Computer”. The three main fragments of the Mechanism are on display in the Bronze Collection of the National Archaeological Museum; the remaining 79 smaller fragments are kept in the collection’s store.

It is thought that the Mechanism was probably built during the second half of the 2nd century BCE, as part of the tradition of “Sphairopoiia” (spheremaking), possibly originated by Archimedes. Starting with Apollonios of Perga (3rd - 2nd Century
BCE), Hipparchos of Nicaea (2nd Century BCE) and their contemporaries, astronomical theory had progressed far enough to make it possible to design a mechanism that represented the movement of the “wanderer stars” (the planets) and the variable motion of the Moon (the first anomaly).

Poseidonios of Rhodes had been considered as a possible designer of the Mechanism. Both Hipparchos and Poseidonios were active in Rhodes and this pointed to Rhodes or to the nearby Ionian coasts as the possible birthplace of the Mechanism. Much of the cargo of the Antikythera ship also points to the same region. But the Metonic calendar and the month names point to months that could originate from Corinth itself or from one of its colonies like Tauromenium, founded by Syracusians.

Could a tradition originating with Archimedes have survived, which integrated into sphere making the epicycles or the equants and so permitted the explanation of the variation of the apparent velocity of heavenly bodies?

(Click on the picture to view a detailed map! Pictures taken from: de Price, Derek Solla J. (1974). Gears from the Greeks: The Antikythera Mechanism — A calendar computer from ca. 80 BC. Transactions of the American Philosophical Society, 64 (7):6.)

Turning a crank handle moves all the pointers, simultaneously through gears and axleshat connect them. By selecting a date
on the front 365-day dial (with the possibility of an extra leap day every four years), corresponding information can be read about the astronomical bodies on the other dials. Alternatively, the user can select an astronomical event and then see when the date will occur (or has occurred in the past).

For instance, the user can check the correspondence between the solar and the lunar calendar, the position and phase of the moon, and the eclipses that may occur for any given day of the selected month. But the most remarkable ability of the Antikythera Mechanism is to show the variable motion of the Moon, realized through an extraordinary epicyclic gear train.

(Click on the picture to watch the video!
 The video can be found at: http://www.youtube.com/watch?v=L1CuR29OajI&feature=player_embedded)

From May 1902, in the first publication about the discoveries from the Antikythera wreck, the “strange bronze machine” with a possible astronomical function is mentioned. Subsequent publications referred to the word “astrolabe”, while other opinions prefered a more complex device, such as a planetarium. The debate continued until the 1970s and the first X-rays, when consensus was reached about the nature of the artefact: it is a mechanical calculating device which displays calendars and related astronomical phenomena. But theories about its functions were challenged and the deciphered inscriptions sparse. Consequently, the National Archaeological Museum granted permission for further investigations: in 1990, with linear tomography, and in 2005, with advanced surface imaging and tomography techniques. This last interdisciplinary research is still ongoing.

(Click on the pictures below to watch the videos)

(Video can be found at: www.youtube.com/watch?v=F1LbXSbxEJk
and the Original version at: http://www.nature.com/nature/videoarchive/antikythera/)

(This video can be found at: www.youtube.com/
watch?v=oEpf2Lskpsg&feature=player_embedded)