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The largest part of the Antikythera mechanism

The largest part of the Antikythera mechanism

Shortly before Easter 1900, a Greek sponge diver off the small Aegean island of Antikythera discovered the wreck of an ancient ship filled with artefacts, including bronze and marble statues, dating from 85 to 50 BCE. Among the numerous finds, a small formless lump of corroded bronze and rotted wood lay unregarded at the National Museum in Athens for years. As the wood fragments dried and shrank, the lump split open to reveal the outlines of a series of gear wheels resembling clockwork. Gamma-ray photography allowed the historian of science Derek de Solla Price (1922-1983) to reconstruct the machine’s original appearance.

The gear wheels were proportioned to show the movements of the sun, moon and planets. The gears could be moved backwards and forwards, making the device a calculator that could show the positions of planets in the sky at any required date. It is nothing less than an orrery, a device well known in the Middle Ages. Further research carried out between 2006 and 2010 has enhanced our understanding of the mechanism, revealing its high level of accuracy and enabling most of the text inscribed on its surface to be read.

A reconstruction of the Antikythera mechanism

A reconstruction of the Antikythera mechanism

Although the device is a remarkable achievement, its status should not be exaggerated. We know that the principles of gearing were understood in the Classical world and what is surprising about the Antikythera object is its uniqueness: no similar gearing mechanisms have survived from antiquity. Furthermore, the mechanism is unlikely to have been built for purely scientific purposes, but is more likely to have been part of an astrologer’s toolkit as well as being based around the four-year Olympic cycle. It does not show a Copernican solar system, with the planets revolving around sun, but a Ptolemaic system, with the sun and planets revolving around the earth in complex motions and it has been suggested that it is rooted in Babylonian astrological belief rather than Greek. Calling it a ‘computer’ rather than an ‘orrery’ only serves to make it sound mysterious and out-of-place!

8 Responses to The Antikythera ‘computer’

  • Hannibal says:

    “It is nothing less than an orrery, a device well known in the Middle Ages.” Oh dear! Never send an archaeologist to do an historian’s job! The Antikythera mechanism is not an orrery but rather it is a planetaria. The definition of an orrery is “a mechanical model of the solar system in which the planets can be moved at the correct relative velocities around the sun.” (Collins, Complete and Unabridged. 2003). As you correctly state in the above text the Antikythera mechanism “does not show a Copernican solar system, with the planets revolving around sun, but a Ptolemaic system, with the sun and planets revolving around the earth in complex motions”.

    As for the orrery having been a well known device in the Middle Ages, well, unless it is now common practice for archaeologists to extend the Middle Ages right on through the Renaissance, the Age of Reason and on into the Enlightenment then I fear that you have erred once again! The first written evidence of the existence of heliocentric planetariums which would qualify is, of course, post Copernicus, late C16th onward and the first known example of an orrery was built circa 1704 by George Graham and Thomas Tompion. An early example of such a device was later made for Charles Boyle, 4th Earl of Orrery, a Fellow of the Royal Society and it is from him that the device aquired its name.

    By the way, I do enjoy the website and the archaeology, just not ‘Bad History’ lol.

    Best wishes,

  • Erich von Heineken says:

    When you say, “It is nothing less than an orrey,” but then downplay its existence, as not being a computer, wouldn’t it be better to say, “It is nothing more than an orrey,” (or “planteria”)…?

    If it were an alien device, then I would use that type of phrasing: “It is nothing less than an alien device.”

    I would probably add an exclamation point as well in that situation and maybe a “My dear.”

    My dear woman, it is nothing less than an alien device!

    If Hannibal is correct on all the other counts, then I a complete rewrite is in order. Make the site the best it can be, because we love the site.

  • Hobo says:

    Love the site

    Woulnt it be lovely to have a record of who it might have belonged to. It looks even specialized today and I imagine a pretty penny would be paid for its construction. Who knows what scholar may have gone down with the ship.



  • Angela Conti says:

    This is another one of those situations that makes me feel like we “know” so very little about our past. Here you have a lovely piece of machinery which could tell us so much about the time and people from whence it came, and it took 110 years for scientists, with all of modern technology (I assume) at their disposal, to truly figure it out, mainly because of the severe damage time and the ocean wrought upon it. Who knows what has been lost to time? The evolution of science is like watching sports, ANYTHING could happen at any moment!! It’s so exciting!

  • Robert Firth says:

    The displays of the Antikythera Mechanism are geocentric, but the gearing seems to be heliocentric: the main drive wheel is the sun wheel, and the others depend on it. But it clearly was designed to show the position of the sun, moon and planets, as seen from Earth, at any moment in time.

    Almost all commentators assume that the user dialled in the time, and read off the positions of the heavenly bodies. But if you want to know the latter, why not just look up at the sky? My tentative hypothesis is the converse: the user measured the actual positions of the heavenly bodies, set the Mechanism until it matched, and then read off the time. Why? Because the time told by the heavens is the absolute, true and mathematical time of Newton, and if you know both that and the local (sundial) time, you can compute your longitude.

    Perhaps the makers of the Mechanism anticipated John Harrison’s marine chronometer by 2000 years!

  • marcusloopert says:

    this object is a real computer that show the positions of the planets in the sky

  • Tom says:

    Well, that definition is something that me and my fellow computer scientists continue to squabble over. The Antikythera device would probably best be described as an analog computer,because it uses a physical process to produce a continuously-valued output.

    The modern household computer is:

    A TURING MACHINE (In a very simple overview, that means it works based on if-then cases)
    PROGRAMMABLE (Those if-then cases can be changed)
    DIGITAL (On a higher level of abstraction, it uses those if-then cases to do math, calculating outputs directly instead of modelling them)

    The Antikythera device is none of these, and referring to it as a “computer” implies otherwise. However, it does raise one important point- computers do not, in fact, need to be electrical in nature, and (while very difficult and probably impossible for practical reasons) one could theoretically build a clockwork computer that functions identically to my laptop!


Agree or disagree? Please comment!