Arthur C. Clarke (1917-2008), author of 2001: A Space Odyssey, called it “one of the greatest basic mechanical inventions of all time.” (1).You may miss it altogether unless you ask to see “the mechanism.”  Although it’s on the ground floor of the National Archaeological Museum in Athens, Greece, you can easily get caught up in the fascinating displays of pottery, statuary, and (my favorite) medical instruments and completely miss the darkened room in the back dedicated to an ancient astronomical calculator known as the Antikythera mechanism. (2)  Divers retrieved it in 1905 from a two thousand-year-old shipwreck near the island of Antikythera, but the quickest way for an English-speaker to locate it today is to avoid trying to pronounce the name of the island and simply ask museum attendants for the “mechanism.”

Be sure to seek out the darkened room at the back.

Be sure to seek out the darkened room at the back.

Like the museum today, the sunken ship was full of impressive statues and works of art which overshadowed  the relatively small calculating device composed of at least 30 delicately toothed layered wheels. Made of bronze, they were green and corroded, and must have been barely noticeable in the dim light of the ocean floor over 165 feet below the surface.  These fragments, which have been meticulously x-rayed and studied for decades are now suspended in a glass case in a darkened room dedicated to the presentation of this intricate device and the interpretation of its meaning to the public.

The largest fragment in the display case shows layers of gear wheels.

The largest fragment in the display case shows layers of gear wheels.

Critical to understanding its function was the painstaking counting of the teeth in each wheel.  A computer program was devised to analyze number of teeth and the interaction of the wheels in order to reveal the mathematical relationships which were clues to its purpose. Inscribed labels helped too. One ring designates the 365 days of the Egyptian calendar with the months named in Greek. Another has the Greek signs of the Zodiac.  These and other numbers and instructions discovered on the wheels of the device have helped investigators to understand more about its purpose, which encompasses defining the relationships of heavenly bodies–stars, planets, moons, seasons, the timing of eclipses of the sun and moon.

Investigators have devised various models to better understand the mechanism.

Investigators have devised various models to better understand the mechanism.

Far be it from me to try to explain the mechanism itself.  As a historian, I can only point out some much later comparable devices for calculating the movements of heavenly bodies, such as the Strasbourg Astronomical Clock, first built in the 14th century, (http://www.horologica.co.uk/horology/Strasbourg.html)  and Su Sung’s water-powered Astronomical Clock Tower built in China in 1092 (http://afe.easia.columbia.edu/song/tech/experiment.htm). Both of these were much larger than the intricate Antikythera device, but their mechanisms accomplished some of the same purposes, such as calculating eclipses and planetary positions. However, the Greek instrument is neither a clock nor (as once thought) a navigational aid. Rather it is a sophisticated astronomical mechanism which computes the relative orbits of the sun, the moon, the planets, and the stars. And at 2,000 years old, it is much older than any known comparable device.

A continuous film gives the mechanism historical context.

A continuous film gives the mechanism historical context.

The exhibit at the Archaeological Museum in Athens displays the fragments of the Antikythera mechanism in a glass case surrounded by interpretive context. There is an explanatory film that runs on a continuous loop. There is written and diagrammatic commentary. And, perhaps most intriguing, there are several modern reproductions of the mechanism by some of its investigators.  For an adventurous account of discovery, investigation, and analysis, plus a concluding chapter on the significance of astronomy at the time it was made, I recommend Jo Marchant’s Decoding the Heavens. Read it and then go to the museum in Athens and ask to see “the mechanism.” Better yet, bring a friend. I brought 3 of my children and 6 grandchildren. I don’t think any of us will ever forget it.

Detailed charts illustrated the mechanism's layers of complexity.

Detailed charts illustrated the mechanism’s layers of complexity.



1. Jo Marchant, Decoding the Heavens: A 2,000-Year-Old Computer—And the Century-Long Search to Discover Its Secrets. Da Capo Press, 2008. http://www.amazon.com/dp/0306818612/ref=rdr_ext_tmb

The National Archaeological Museum in Athens:    http://www.namuseum.gr/wellcome-en.html

To explore further, try the very thorough article on Wikipedia and its reference list of books, articles, and links.


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