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Study Finds Ancient Greek Astronomical Computer Amazingly Sophisticated

An ancient piece of Greek technology recovered from a shipwreck more than 100 years ago is amazing scientists who have analyzed it in detail. Fragments of bronze gearwheels, now green and crumbling from millennia of underwater corrosion, have long been thought to be parts of a 2,100-year-old astronomical calculator. VOA's David McAlary reports that the new examination shows the mechanism to have been far more sophisticated for its time than anyone had thought.

This is what the ancient Greek device probably sounded like. The noise comes from a recent reconstruction based on pieces recovered by sponge divers exploring a 2,100-year-old shipwreck off the Greek island Antikythera in 1901.

Astronomer Mike Edmunds of Cardiff University in Wales is part of the British, Greek, and American team that made the copy and analyzed the original so-called Antikythera Mechanism.

"This is a unique device," said Mike Edmunds. "Nothing like a device of this complication is known for 1,000 years afterwards until you get to the medieval cathedral clocks."

The Greek device contains a complicated arrangement of at least 30 precision, hand-cut bronze gears and three pointing styluses housed inside a wooden case covered with inscriptions. Because the machine is fragmented, its specific functions have been controversial.

Scientists have been trying to copy it ever since its discovery, but Edmunds' team was able to do so after using high resolution X-ray scanning technology to examine the pieces. They were also able to decipher twice as many of the inscriptions as had been read by the late Yale University scholar Derek Price, who studied it decades ago.

Team member Xenophon Moussas, a physicist at the University of Athens, described the device to Nature magazine, which has published the group's paper on it.

"We can count something like 30 gears, which helped astronomers of the second century BC, we believe now, to calculate the positions of the sun, perhaps to work out the time of eclipses of the moon and and possibly of the sun as well," said Xenophon Moussas. "Since we discovered inside the mechanisms very many hidden writings, which are the manual of this ancient computer, we know for sure that many parts of the text refer to the motion of the planets."

In a Nature magazine commentary, Francois Charette of Ludwig-Maximilians University in Munich, says the research shows the Antikythera Mechanism to be the most sophisticated such object yet found from the ancient and medieval periods. He points out that the archaeological record to date shows it was a long time before gearing mechanisms so advanced re-emerged.

The curator of mechanical engineering of the Science Museum of London, Michael Wright, had previously studied the device. He told Nature magazine that much skill went into it.

"I can tell you from having examined the original that the man who made it was a highly skilled mechanic," said Michael Wright. "He knew exactly what he was doing. The other thing I can tell you about it is that the man who designed it certainly knew his astronomy."

The paper on the device shows the Antikythera Mechanism is based on a mathematical model of the moon's motion developed by the astronomer Hipparchus of Rhodes 2,100 years ago. Mike Edmunds at Cardiff University speculates that the ancient Greek scientist even helped design it.

"It's very tempting to think so," he said. "We haven't actually found his sort of fingerprints or actually 'Hipparchus made this' [inscribed] on the mechanism, but whoever did build this was extremely intelligent. It's just beautifully designed. I think that is one of the most surprising things that comes out of this."

Francois Charette at Ludwig-Maximilians University writes that the long interval between the design of the Antikythera Mechanism and the advent of medieval gearing makes it obvious that the technical sophistication available to some parts of the Greco-Roman world was simply not transmitted further. The gear-wheel, he says, had to be re-invented.