The polished and cleaned Antikythera mechanism. Image: imagIN. Shipwrecks have long been sought after for the potential of hidden treasure, but none have been able to compare with the discovery of the Antikythera mechanism.
This day years ago, Stais noticed that within the rock was a gear wheel, which suggested it was not only far more important than the original divers had realised, but may also be one of the most important finds in the history of computer science. The Antikythera mechanism — as it came to be known — was actually a 2,year-old analogue computer, and not a simple astronomical clock as Stais had once thought.
It was only through extensive research and x-ray analysis of the object that it was found to also be capable of carrying out basic math as well as charting everything in the heavens above, and acting as a lunar calendar, detecting the movement of the sun and moon. In terms of design, the ancient computer was a sophisticated and intricate arrangement of 30 bronze gears housed in another case made out of more bronze and wood.
It seems that the information to build such a mechanism was lost through time, perhaps because it was a specialty device or expensive to create. Since inventions like this do not usually come from nothing, though, many researchers think that we may yet find older precursors in an archaeological context some day.
The mechanism tracked the lunar calendar, predicted eclipses, and charted the position and phase of the moon. It also tracked the seasons and ancient festivals like the Olympics. The calendar is based on the time from one full moon to the next, and a special dial allowed the user to also envision the seasons, which would have been useful for agriculture. Since the ancient Babylonians figured out the cycle of eclipses, the inventor of the Antikythera mechanism included two dials that rotate to show both lunar and solar eclipses.
Writing on a bronze panel at the back of the mechanism suggests the inventor left either instructions for how to work it or an explanation of what the user was seeing. The inscription, which is in Koine Greek the most common form of the ancient language , mentions the cycles, dials, and some of the functions of the mechanism. While many of its functions have been figured out, how and where it was used are still unknown.
Scholars think that it could have been employed in a temple or school, but could just as easily have been a fancy curio for a rich family. The use of Koine in the numerous inscriptions places the creation of the mechanism in the Greek world, which was geographically large at the time.
The festival dial mentions the Olympics in central Greece, the Naa in northwest Greece, and the Halieia on the island of Rhodes. A analysis of the inscriptions by classicist Alexander Jones and colleagues suggests the mechanism could keep track of at least 42 different calendar events. The Greeks believed that characteristics of an eclipse were related to good and bad omens.
Because of this belief, by building in predictive eclipse technology, the creator of the mechanism was letting the user divine the future. The mechanism includes hands or pointers for Mercury, Venus, Mars, Jupiter, and Saturn, all of which are easily visible in the sky, as well as a rotating ball that showed the phases of the moon. The parts that work these planetary pointers are gone, but text on the front plate of the mechanism confirms, according to Jones and his team , that the planetary motion was modeled mathematically using numerous complex gears—and that it was highly accurate.
To complement this display of local practical astronomy, a small dial inset in the spiral counted off the years in the four-year cycle that regulated athletic festivals such as the Olympic Games that were honoured across the entire Greek world. Turning from the back to the front face would have taken the spectator from cycles of time to cosmology in motion. The single front dial combined two perspectives on the system of heavenly bodies, showing where the sun, moon, and planets appear to be at any date by means of pointers along a scale representing the zodiac and subdivided into degrees, while at the same time offering a simplified cross-section image of the cosmos as if seen from outside.
The cosmology was geocentric, with the Earth enclosed by a series of nested spherical shells belonging, in order of increasing distance, to the Moon, Mercury, Venus, the Sun, Mars, Jupiter, Saturn, and the stars. On the dial, these seem to have been portrayed as ring-shaped spaces between engraved concentric circles, and the heavenly bodies themselves as little spherical attachments to the pointers, each with a distinguishing material and colour.
The apparent motions of the heavenly bodies through the zodiac vary in speed and in the case of the planets periodically reverse direction. To reproduce the effect of nonuniform motion mechanically required special devices involving a pin attached to a revolving gear while sliding back and forth in the perforation of a slotted arm or gear.
Such a pin-and-slot device for the Moon survives in the largest fragment, but the gearwork for the planets is mostly or entirely lost. Instruments like the Antikythera Mechanism that employed high-end technology and metalworking to visualise the complexities of science were probably rarities in the Greco-Roman world, and most would have had their metal recycled when they stopped working and were no longer wanted.
We are lucky to have this one, saved by an ancient calamity.
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