Nailing it down

True to the scientific method, Hedges sought to replicate his results and increase his data set. In 2005, between teaching and research obligations, he visited 20 rare-book rooms in libraries on the East Coast. "In one case, I drove to Yale, found what I needed, and drove back in the same day," he says. "That's how dedicated I was to this project." He also acquired a number of prints from Italy, and even some information from the Vatican, with the occasional help of his Italian doctoral student Fabia Battistuzzi for telephone translations. Battistuzzi was happy to assist but confused about the relationship between genetics and rare books, Hedges remembers.

His final data set included 2,674 Renaissance prints, made from both woodblocks and copper plates. And the results were constant and conclusive. In woodblock prints, the number of line breaks increased over time, and in copper-plate prints, the lines became paler, both in a regular clock-like manner.

Hedges' study appeared in the journal Proceedings of the Royal Society A: Mathematical, Physical, and Engineering Sciences in June 2006. Since then, his print clock has garnered plenty of attention from librarians and bibliophiles, including one critic who claimed that Hedges' theory was all wrong, that the lines made from copper plates did not become paler because of random change but because the copper plates were becoming thinner from the compression of the printing process itself. Hedges says that basic physics will tell you this is not the case—just put a copper penny on a train rail and see what happens. "The copper squishes," and the lines get wider. But to prove the point, Hedges took some copper plates, engraved them with a burin, a tool just like the ones that Renaissance artists used, placed the plates between boards, and drove over them with his 6,000-pound Volvo SUV. When the plates did not flatten, he then hit them with a sledgehammer until they did, proving that the lines widened and did not get narrower. He has not heard from any detractors since.

Hedges funds his own research with the print clock, and his passion for this project stems from a lifelong love of old maps. During his undergraduate years at George Mason University, he worked at the U.S. Geological Survey in Reston, Va. He says, "After work I would visit the printing plant, where they would let me have discarded maps containing minor defects, such as a smudge of ink on a beautiful map of Hawaii with all the valleys and waterfalls, and I'd take them home with me." He still has dozens in his attic, added to a collection of old Caribbean maps that he's been collecting seriously for the last decade.

While others in the rare-book world are interested in the print clock, and some are using it, it will take time before those studies are published. Hedges says, "I hope people start using it immediately, but with any new method, you need a lot of evidence and data to convince an entire field. If a half-dozen more studies of copper plates and woodblocks show it to be useful, perhaps then it will become an accepted method.

"Maybe I'll do them all myself in the next 10 years or so."     RPS

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S. Blair Hedges, Ph.D., is professor of biology in the Eberly College of Science; sbh1@psu.edu. His Print Clock website includes both a general overview of the dating process and a pdf version of his technical paper on the subject.

Gigi Marino is editor of Bucknell World and a writer and poet in Lewisburg, Pennsylvania.

Contents copyright The Pennsylvania State University unless otherwise noted. Direct questions about this site to editor@rps.psu.edu.

Most recently updated December 4, 2006.