Unravelling an old mystery
Scientists use X-rays to read charred scrolls
TALK about reading between the lines. Scientists using X-rays say they can, for the first time, read words inside the charred, rolled-up scrolls that survived the catastrophic eruption of Mount Vesuvius nearly two millenniums ago.
The findings, described in the journal Nature Communications, give hope to researchers who until now have been unable to read these delicate scrolls without serious risk of destroying them.
The scrolls come from a library in Herculaneum, one of several Roman towns that, along with Pompeii, were destroyed when Mount Vesuvius erupted in AD 79. This library, a small room in a large villa, held hundreds of handwritten papyrus scrolls that had been carbonized from a furnace-like blast of 320 C gas produced by the volcano.
“This rich book collection, consisting principally of Epicurean philosophical texts, is a unique cultural treasure, as it is the only ancient library to survive together with its books,” the study’s authors wrote.
Researchers have tried every way to read these rare and valuable scrolls, which could open a singular window into a lost literary past. The problem is, they are so delicate it’s nearly impossible to unroll them without harming them. That hasn’t kept other researchers from trying, however — sometimes successfully, and sometimes not.
This is where a technique such as X-ray computed tomography, which could penetrate the rolled scrolls, would come in handy. The problem is, the ancient writers used ink made of carbon pulled from smoke residue. Because the papyrus had been carbonized from the blazing heat, both paper and ink are made of roughly the same stuff. Because the soot-based ink and baked paper have about the same density, until now it’s been practically impossible to tell ink and paper apart.
But a team led by Vito Mocella of the Institute for Microelectronics and Microsystems in Naples, Italy, realized they could use a different technique called X-ray phase-contrast tomography. Unlike the standard X-ray CT scans, X-ray phase-contrast tomography examines phase shifts in the X-ray light as it passes through different structures.
Using the technique, the scientists were able to make out a few words and letters from two scrolls, one of them still rolled.
Reading these scrolls is difficult; computer reconstructions of the rolled scroll reveal the paper inside has been thoroughly warped, and some of the letters on the paper are probably distorted almost beyond recognition.
Nonetheless, the researchers were able to read a number of words and letters, which were about two to three millimetres in size. On an unrolled fragment of a scroll called PHerc. Paris. 1, they were able to make up the words for “would fall” and “would say.” In the twisted, distorted layers of the rolled-up papyrus called PHerc. Paris. 4, they could pick out individual letters: alpha, nu, eta, epsilon and others.
The letters in PHerc. Paris. 4 are written in a distinctive style with certain decorative flourishes that seemed very similar to a scroll called PHerc. 1471, which holds a text written by the Epicurean philosopher Philodemus. The researchers think they were written in the second quarter of the first century BC.
If they’re right, “then the papyrus is quite likely to contain a text by Philodemus,” the authors wrote. “Thus, this study, without compromising the physical integrity of the roll, has not merely discovered traces of ink inside it, but has also helped identify with a certain likelihood the style of handwriting used in the text, along with its author.”
Ultimately, the researchers wrote, this work was a proof of concept to give other researchers a safe and reliable way to explore ancient philosophical works that were until now off-limits to them.
RIGHT: Visitors at the library examine one of the scrolls damaged by the eruption of Mount Vesuvius.
ABOVE: David Blank, a classics professor at the University of California, examines an ancient papyrus scroll at the National Library of Naples.