X-ray Brings Archimedes’ Hidden Treatises to Light

Scientists are using the powerful X-ray light emitted by the synchrotron at the Stanford Linear Accelerator Center to read hidden text on a 1,000-year-old copy of the Archimedes palimpsest, a mathematical and engineering text written by the Italian philosopher in the 3rd century BC.

The palimpsest is the only known source for two treatises written by Archimedes, who is perhaps best known for supposedly running naked through the streets of Syracuse shouting “Eureka!” after discovering the principle of water displacement in his bathtub.

In the 10th century, a scribe copied some of Archimedes’ writings onto a goatskin parchment. Two centuries later, with parchment in short supply, the ink was erased with a weak acid -- possibly lemon juice -- and scraped off with a pumice stone so that the parchment could be used for a prayer book.

The damage was compounded in the 20th century when forgers painted Byzantine religious images on four pages to increase the value of the prayer book.

Much of the 174-page palimpsest can be deciphered by conventional techniques using visible or ultraviolet light, but several pages, including those under the paintings, have proved more difficult.

Physicist Uwe Bergmann of Stanford had a eureka moment in 2003 when he read an article about the palimpsest that noted the inks contained iron. “I immediately thought we should be able to read the parchment with X-rays,” Bergman said. “That’s what we do ... we measure iron in proteins, extremely low concentrations of iron.”

Last week, the team used the synchrotron to scan three pages of the document, on loan from the Walters Art Museum in Baltimore. A very narrow beam of X-rays was swept repeatedly across the page, triggering fluorescence in the iron molecules.

The hidden text on two of the pages deals with floating bodies and the equilibrium of planes. On the third page is a previously unknown introduction to Archimedes’ Method of Mechanical Theorems.

The team plans to transcribe the text digitally and place it on an interactive DVD.