Books: Decoding the Heavens

AMONG the priceless marble figures and decorated pots of Athens' National Archeological Museum stands a small object far less eye-catching but a great deal more mysterious. Jacques Cousteau and Arthur C Clarke were fascinated by it, and the physicist Richard Feynman made a point of seeing it when he visited the museum in 1980, to the bemusement of a curator who couldn't understand what was so interesting about a small lump of green corroded bronze. Yet according to Jo Marchant, this 2,000-year-old artefact was the world's first computer.

The 'Antikythera mechanism' takes its name from the Greek island in whose waters it was found by sponge divers in 1901. They had chanced upon the wreck of what was probably a Roman ship filled with booty from Rhodes, and what caught the divers' attention were the numerous statues that had made up a large part of the ship's cargo. In an age when archaeology was more about treasure hunting than science, they lifted whatever they could, leaving no record of where exactly the bits had all come from. Among the artefacts was the innocuous-looking mechanism, whose pieces ended up in a box in the basement of the Athens museum, while the statues were proudly put on display. It would be decades before the machine's significance became apparent.

Marchant's book gets off to a similarly slow start, with a history of Greek sponge diving that sets a pattern for what follows. As a writer for New Scientist and a trained biologist, she is on top of the technicalities of the story, but the amplifications and digressions are too plentiful. Most readers of this book will either know already how carbon dating works, or else won't want to be told in too much detail. What they want to know is how the world's first computer worked, and whether it fell out of a space ship.

That was the view of Erich von Dniken, who in his 1968 bestseller Chariots Of The Gods? proclaimed that the device was beyond anything the ancient Greeks could have made. He did not explain, though, why the aliens inscribed it with Greek words and symbols that fix its date of manufacture to about 100BC. Yet it did have something to do with space.

As Marchant explains, the fragmentary remains were enough to show an astronomical connection, possibly as an aid to navigation or calendar-keeping. But for classical historians of the early 20th century, it was an oddity that didn't fit in with existing knowledge, so they largely ignored it. This is Marchant's most telling point: when scholars have a choice between rewriting their books or dismissing evidence, they are more likely to choose the latter. It was left to a few amateur enthusiasts to try to solve the mystery.

The wreck itself attracted Arthur C Clarke, a keen diver, and subsequently Cousteau, who visited it on his ship Calypso but failed to find anything new. The real progress was made by mathematicians and engineers who took up the challenge of the mechanism's fused and broken gears.

Marchant's narrative takes on a human-interest angle as these scientists' stories unfold, given the obsession they shared and the rivalries that grew up between some of them. It would make a wonderful TV documentary, if only they were all still alive and able to be interviewed. Instead the book feels like a documentary without pictures, which is particularly unfortunate in the case of the mechanism. There are some photographs and diagrams, but not enough, making it hard while reading to keep a clear image of the object at the centre of the story.

Despite these reservations, this is an informative and thoroughly researched book that avoids sensationalising the subject. Work on the mechanism continues: X-rays show it contains a collection of cogs whose numbers of teeth enable researchers to speculate what they were meant to calculate. It seems the device may have had a rotating Moon set into its face, and by turning a dial you could see the phase and position for any day, as well as knowing when the next eclipse was due. Whoever made it had a phenomenal mind, but their identity will probably never be known. The machine may not be much to look at now, but as a monument to ancient ingenuity it surely rivals the Parthenon.