High-tech helps solve mystery of ancient calculator

Results of a high-tech research project being released this week promise finally to unravel much of the remaining mystery of a 2,000-year-old astronomical calculator.

Since its discovery in 1902, the Antikythera Mechanism - with its intricate and baffling system of about 30 geared wheels has been an enigma. Knowledge of its functions has increased as computer-based imaging, analysis and X-ray technologies have evolved. During the last 50 years, researchers have identified various astronomical and calendar functions, including gears that mimic the movement of the sun and moon. But it has taken some of the most advanced technology of the 21st century to decipher the most advanced technology of the first century B.C.

No other artifact this complex has been recovered from the ancient world, though there are numerous written references by Greek, and later by Arab, writers, to different types of geared mechanisms. The level of mechanical sophistication found in the Antikytnera Mechanism would not be seen again until the rise of European clock-making during the Middle Ages.

An international team of researchers will reveal this week the results of the most recent research, carried out over the last year with help from HP Laboratories and X-Tek Systems, a manufacturer of high-resolution, X-ray inspection equipment based in Tring, England. The Antikythera Mechanism Research Project (www.nwdocfinder.com/6258), a joint effort by researchers in Greece and the United Kingdom, hosts a two-day conference starting Nov 30 in Athens.

Team members wouldn't comment on the details, but they are confident they've unraveled many of the remaining puzzles.

"We believe we've found the functions with regard to the sun and moon movements, and to its calendrical function," says Michael Edmunds, a professor in the School of Physics and Astronomy at Cardiff University in Wales, and a specialist in the chemical composition of galaxies. The mechanism caught his interest when he was working in 2000 with a student who chose the device as a research project.

"We believe we [now] understand what the gear trains did," Edmunds says. Other advances include definitive tooth counts, and new details of gears and their assemblies.

In addition, the team more than doubled the number of letters previously found on the device, to more than 2,000, and translated these, says John Seiradakis, a professor with the Department of Physics at Aristolean University in Thessaloniki, Greece.

The mechanism is named after the Greek island of Antikythera, where in 1900 a sponge diver taking shelter from a storm found an ancient shipwreck 200 feet below the Mediterranean's surface. Archeologists removed an array of artifacts, but it wasn't until mid1902 that one of them noticed that embedded in what was thought to be a lump of broken, calcified bronze statuary was a gearwheel.

The lump turned out to be an encrusted, partially destroyed set of bronze gear wheels, dials and plates. About 13 inches high, 7 inches wide and just less than 4 inches deep, the mechanism was held in place by the remains of its original, well-made wooden case, which dried out and crumbled away after being excavated. Greek letters and some inscriptions were visible on the metal plates.

Even then, the complexity of the mechanism was so obvious that some observers speculated that it actually was created during the 1400s, had been lost overboard and landed on the much more ancient wreck. Today, there is no question the mechanism dates from around 65 B.C.

In 1974, a paper by science historian Derek de Solla Price and Greek nuclear physicist Charalampos Karakalos presented new details of the device, based on gamma-ray and X-ray analysis. Price described the mechanism as a calendar computer and famously identified the presence of a differential gear - a set of gears that can move two axles at different speeds.

In the late '90s, another research effort, including 700 X-ray plates digitized for computer-aided analysis, was carried out by Michael Wright, a specialist in the history of mechanicism at the Imperial Museum in London, and the late Alien Bromley of the University of Sydney.

In a paper presented a year ago, "Understanding the Antikythera Mechanism,"Wright faulted some of Price's conclusions. Wright speculated that the mechanism could be an elaborate planetarium, designed to show the movements of the five then-known planets, in addition to the sun and moon, and to predict eclipses.

He also suggested that the mechanism actually was a marriage of at least two separate devices, one being added to the device already in the wooden case. He demonstrated that Price's differential gear was instead an epicyclical gear, in which a central wheel meshes with one or more peripheral gears, which rotate around the center.