Science: Beaming in on the Past

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The world of academia has been astir lately with revelations about historic books and documents. Subscribers receiving their copy of the quarterly Papers of the Bibliographical Society of America found it devoted largely to analyses of paper and ink used in the Gutenberg Bible; the research shed new light on the production techniques used in Johann Gutenberg's print- shop. In Ann Arbor, Mich., UMI Research Press was shipping copies of The Calov Bible of J.S. Bach, which reveals that markings on the pages of the Bible owned by Bach were made by the great composer. And in Washington, the journal Analytical Chemistry was reviewing for publication a report suggesting that the Vinland map, a purportedly pre-Columbian world map once denounced as a counterfeit, may not be fraudulent after all.

These and other new insights into historic works were all gained with the help of an aging machine located in a bunker-like structure on the campus of the University of California at Davis. It is a refurbished cyclotron, an early model particle accelerator that is able to crank a circulating beam of protons up to velocities as high as one-third the speed of light. By focusing the penetrating but low-intensity beam on the documents and then analyzing the spray of the X rays emitted when the protons collide with atoms in the target, Historian Richard Schwab and Physicist Thomas Cahill can determine in remarkable detail the chemical composition of both ink and paper, without damaging either. That composition, they have shown, holds the key to many bibliographic mysteries.

By far the most dazzling success enjoyed to date by Schwab, Cahill and their colleagues is the resolution of a controversy involving the first book printed with movable metallic type. Most experts have awarded that honor to Gutenberg's two-volume, 1,282-page Bible, printed some-time between 1450 and 1455 with 42 lines of type a page. But doubts remained because of two cruder works of the mid-1400s: a rare 36-line Bible and a scrap of paper known as the Sibyllenbuch fragment, also printed in 36-line type. The question that has nagged scholars for years is whether these works were produced by Gutenberg or by someone known only as the 36-line printer.

Borrowing two of the world's 49 remaining volumes of the Gutenberg Bible, leaves from the 36-line Bible and the Sibyllenbuch fragment, the Davis team exposed them, one at a time, to the proton beam. The results of those tests, begun in 1982, are still being evaluated, but most of the doubts about Gutenberg's role have vanished. The Davis tests established that instead of carbon-based ink, the German printer employed a slurry of copper and lead for his famous Bible. Printed characters in both of the 36-line works, the X-ray patterns showed, consisted of an almost identical mixture. The conclusion: Gutenberg printed all the works, and the 36-liners were his earlier attempts to perfect the art of printing.

"It explains a lot," says Cahill. "People couldn't understand how the Gutenberg Bible could turn out so perfectly if it was really his first book. It now seems he had practice beforehand."