Fragmentary Knowledge.

In October, 2005, a truck pulled up outside the National Archeological Museum in Athens, and workers began unloading an eight-ton X-ray machine that its designer, X-Tek Systems of Great Britain, had dubbed the Bladerunner. Standing just inside the National Museum's basement was Tony Freeth, a sixty-year-old British mathematician and filmmaker, watching as workers in white T-shirts wrestled the Range Rover-size machine through the door and up the ramp into the museum. Freeth was a member of the Antikythera Mechanism Research Project--a multidisciplinary investigation into some fragments of an ancient mechanical device that were found at the turn of the last century after two thousand years in the Aegean Sea, and have long been one of the great mysteries of science.

Freeth, a tall, taciturn man with a deep, rumbling voice, had been a mathematician at Bristol University, taking a Ph.D. in set theory, a branch of mathematical logic. He had drifted away from the academy, however, and spent most of his career making films, many of them with scientific themes. The Antikythera Mechanism, which he had first heard about some five years earlier, had rekindled his undergraduate love of math and logic and problem-solving, and he had all but abandoned his film career in the course of investigating it. He was the latest in a long line of men who have made solving the mystery of the Mechanism their life's work. Another British researcher, Michael Wright, who has studied the Mechanism for more than twenty years, was coincidentally due to arrive in Athens before the Bladerunner had finished its work. But Wright wasn't part of the research project, and his arrival was anticipated with some trepidation.

It had been Freeth's idea to contact X-Tek in the hope of finding a high-resolution, three-dimensional X-ray technology to see inside the fragments of the Mechanism. As it happened, the company was working on a prototype of a CAT-scan machine that would use computer tomography to make 3-D X-rays of the blades inside airplane turbines, for safety inspections. Roger Hadland, X-Tek's owner and chief engineer, was interested in Freeth's proposal, and he and his staff developed new technology for the project.

After the lead-lined machine was installed inside the museum, technicians spent another day attaching the peripheral equipment. At last, everything was ready. The first piece to be examined, Fragment D, was placed on the Bladerunner's turntable. It was only about an inch and a half around--much smaller than Fragment A, the largest piece, which measures about six and a half inches across--and it looked like just a small greenish rock, or possibly a lump of coral. It was heavily corroded and calcified--the parts of the Mechanism almost indistinguishable from the petrified sea slime that surrounded them. Conservationists couldn't clean off any more of the corroded material without damaging the artifact, and it was hoped that the latest in modern technology would reveal the ancient technology inside.

The Bladerunner began to whirr. As the turntable rotated, an electron gun fired at a tungsten target, which emitted an X-ray beam that passed through the fragment, so that an image was recorded every time the turntable moved a tenth of a degree. A complete three-hundred-and-sixty-degree rotation, resulting in three thousand images or so, required about an hour. Then the computer required another hour to assemble all the images into a 3-D representation of what the fragment looked like on the inside.

As Freeth waited impatiently for the first images to appear on the Bladerunner's monitor, he was trying not to hope for too much, and to place his trust in the skills of the group of academics and technicians who were there with him. Among them, waiting with equal anticipation, were John Seiradakis, a professor of astronomy at the Aristotle University of Thessaloniki; Xenophon Moussas, the director of the Astrophysics Laboratory at the University of Athens; and Yanis Bitsakis, a Ph.D. student in physics. (Mike Edmunds, an astrophysicist at Cardiff University, who was the academic leader of the research project, remained in Wales.) "I was just focussed on my relief that this was happening at all, with all the delays of the past four years," Freeth told me. "Honestly, there were times when I thought it would never happen."

One day in the spring of 1900, a party of Greek sponge divers returning from North Africa was forced by a storm to take shelter in the lee of the small island of Antikythera, which lies between Crete and Kythera. After the storm passed, one of the divers, Elias Stadiatis, put on a weighted suit and an airtight helmet that was connected by an air hose to a compressor on the boat, and went looking for giant clams, with which to make a feast that evening.