X-ray, scrolls, Herculaneum

Exciting X-Ray Technique To Help Decipher Ancient Scrolls

A new use of X-rays may help to decipher the contents of ancient scrolls discovered in the ruins of Herculaneum, a Roman town that was destroyed in 79 A.D. by the eruption of Mount Vesuvius. Papyrus scrolls found in the remains of a Herculaneum villa may become readable using X-ray techniques without unrolling them.

Herculaneum was one of two towns destroyed in 79 A.D. by Mount Vesuvius. It was destroyed by superheated gases and ash, preserving the papyrus documents in a villa likely owned by the family of Lucius Calpurnius Piso Caesoninus, Julius Caesar’s father-in-law. Little is known of the nature of the scrolls, but scholars hope that they might be able to recover lost Greek and Latin works from this collection.

During excavations in Herculaneum in 1752 and 1754, a collection of carbonized scrolls were found in the villa. The site became known as the Villa of the Papyri, and the rolled-up scrolls were referred to as the Herculaneum scrolls, or papyri. Some attempts were made to unroll the scrolls, but their fragility led researchers to abandon the effort in hopes that new methods might be available in the future to reveal the scroll’s contents.

This left around 300 scrolls unexamined with a number of fragments, some left over from earlier attempts to unroll them. Infrared photography yielded some success but also caused additional damage. CT scans provided no information on the scroll’s contents.

There is now new optimism that the scrolls’ contents may become readable using a method called X-ray phase-contrast tomography. Normal X-rays make straightforward images based on the amount of light that passes through an object. X-ray phase-contrast tomography uses the change in the phase of X-rays as they pass through different materials and thicknesses in an object to produce a 3D image of the contents of an object, in this case a brittle, rolled-up scroll. The phase difference is caused by the slight change in the speed of the X-rays as they pass through the minute variations in structure the scroll. The 3D image of a letter appears as though it is floating within the rolled up volume of the scroll.

The idea to use X-ray phase-contrast tomography for examining these scrolls was conceived by physicist Dr. Vito Mocella of the National Research Council’s Institute for Microelectronics and Microsystems (CNR-IMM) in Naples, Italy. He told the BBC News, “I was in Grenoble for a collaboration, and they explained to me some new developments using phase contrast for science, for palaeontology [sic]…. They sounded like exotic applications.”

Dr. Mocella had a different idea. When he and his colleagues placed a scroll in synchrotron, the surface texture of the papyrus revealed the hidden text. Dr. Mocella said, “What we see is that the ink, which was essentially carbon based, is not very different from the carbonised [sic] papyrus.”

When the ink was placed on the papyrus, it did not penetrate the papyrus but rather sat on top of the scroll. “So the letters are there in relief,” he said, “because the ink is still on the top.”

The work is detailed and painstaking because the technique is new, and the scrolls are twisted and deformed due to their exposure to the effects of the volcanic eruption. Additionally, the papyrus itself has fiber structure that is not much different from the thickness of the letters. These fibers can mimic pen strokes and make characters difficult to make out.

Still, the technique holds promise that the contents of the scrolls maybe revealed as the procedure is further refined. The result may be the revelation of lost works and possibly new discoveries from the ancient world.

[Image Credit: AP/Emmanuel Brun]