At the western entrance to the Aegean Sea, midway between the islands of Crete and Kythera, rises little Antikythera. It was off that island in 1900 that a sponge diver found, on the bottom, the wreck of an ancient ship loaded with statues, amphorae, and other objects.
This wreck was the first great underwater find of modern archaeology. It yielded not only a rich hoard of art treasures but an astonishingly sophisticated scientific instrument. But while the statues and pottery were recognized at once as the work of Greek artisans around the time of Christ, the bronze instrument, encrusted with calcareous deposits, lay ignored.
As it gradually dried, the ancient wood casing and internal parts cracked and split into four flat fragments, the inner sides of which revealed parts of geared wheels together with some barely legible inscriptions. As cleaning exposed more gears and inscriptions, scholars affirmed that the device was a navigational tool, an astrolabe, used to determine the altitude of the sun and other celestial bodies. This identification was remarkable enough, considering that only simple implements had previously turned up from the Hellenistic period.
There speculation about the artifact stood until 1951, when Professor Derek de Solla Price of Yale University began what would become the definitive study of the Antikythera Mechanism, as it had come to be called.
Attempting to re-create the device, Price and his Greek co-workers used x-rays and gamma-rays to probe the internal structure. The mechanism, he discovered, contained layer upon layer of variously sized gears. After long calculations of possible gear ratios, Price arrived at an astonishing conclusion: Some ancient Greek inventor had designed a mechanism that mimicked the actual movements of the sun, moon, and planets, past, present, and future. The Antikythera Mechanism was a 2,000-year-old ANALOG COMPUTER.
As hypothetically reconstructed by Price, the original mechanism consisted of a rectangular box about twelve by six by three inches, with the bronze machinery contained by wooden sides. The front and back were covered by bronze doors on which the inventor had inscribed detailed instructions. Three dials displayed the device's readout. The first contained two concentric bands, one showing the signs of the zodiac, a sixteen-degree-wide belt straddling the apparent path of the sun, and the other the names of the Greek months. A pointer revealed the position of the sun in the zodiac for every day of the year. A second dial displayed an eighteen-year cycle of solar eclipses, while a third kept track of the different phases of the moon.
Inside the box, some thirty-nine bronze gears were meshed on parallel planes and set in motion by a handle that needed to be turned once a day. These were linked through a kind of toothed turntable that acted as a differential gear train, permitting two shafts to rotate at different speeds. Operating on the same principle that allows the traction wheels on modern automobiles to turn at different rates on curves, the differential gear had long been assumed to be an invention of the seventeenth century.
Fascinated by Price's hypothesis, physicist Allan Bromley, a professor at the University of Sydney, enlisted the help of clockmaker Frank Percival to construct a working modern of the Antikythera Mechanism. Using techniques that would have been available to the ancient Greeks, in 1987 the pair assembled a functional replica that largely verified a majority of Price's theories.
Still, the identity of the machines original creator is lost in time. Some scholars believe that the Antikythera Mechanism originated on the island of Rhodes, where cultural conditions two thousand years ago might have been right for the emergence of the necessary skills. There, without any fanfare, a consummate mechanical artisan who had a strong knowledge of the heavens somehow fashioned the ancient computer of Antikythera, the device that Price called one of "the greatest basis mechanical inventions of all time."
Rising from its water grave after two millennia, the mechanism belied the prevailing view that ancient Greece was a land of brilliant theoreticians who, pampered by slaves, disdained the physical. Our ancestors, it seems had mechanical genius after all...