arranged for a 600-pound high-resolution CT scanner to be sent by truck from Belgium, and he made intricately detailed scans of the scrolls. But after months of analyzing the data, Seales was disheartened to find that the ink inside the scrolls, despite the traces of lead, was invisible.
What was worse, the scans showed the layers inside the scrolls to be so carbonized that in many places there was no detectable separation between them. “It was just too complicated for our algorithms,” Seales admits. He played me a video of the CT scan data, showing one of the scrolls in cross-section. The whorls of papyrus glowed white against a dark background, like closely wound strands of silk. “Just take a look at that,” said Seales. “This is when we knew we were doomed for the present time.”
What makes virtual unwrapping such a complex challenge is that, even if you imaged the inside of a rolled-up scroll written in ink that glowed brightly in scans, you would still only see a dizzying mess of tightly packed letters floating in space, like a three-dimensional jigsaw puzzle—but without a final picture to use as a guide. To decipher that jumble of letters, Seales’ key innovation was to develop software to locate and model the surface layer within a wound-up scroll, which analyzes each point in as many as 12,000 cross-sections. Then he looks for density changes that correspond to the ink, and applies filters or other techniques to increase the contrast of the letters as much as possible. The final step is to figuratively “unroll” the image for reading.
Seales spent 2012 and 2013 as a visiting scientist at the Google Cultural Institute in Paris, amping up his algorithms to cope with the complex structures the CT scans had revealed. He got the chance to try his new approach soon afterward, when Pnina Shor, at the Israel Antiquities Authority, or IAA, in Jerusalem, contacted him about a carbonized roll of parchment found in the ancient town of Ein Gedi, on the western shore of the Dead Sea. The scroll was excavated from the remains of a synagogue, which was destroyed by fire in the sixth century A.D. The charred, cigar-shaped lump was far too fragile to open, but Israeli researchers had recently CT-scanned it. Would Seales take a look at the data? Shor handed over a hard drive, and Seales and his colleagues went to work.
In the meantime, Seales was chasing a new idea for reading carbon-based ink: X-ray phase-contrast tomography, a highly sensi- tive form of imaging that can detect subtle density changes in a material—the kind that might result from applying ink to papyrus—by measuring the changing intensity of the beam as it passes through an object. Only a large particle accelerator, though, can produce such a beam. One of the nearest was in Grenoble, in southeastern France. Seales’ initial requests for “beam time” were rejected, but he was subsequently approached by an Italian physicist named Vito Mocella, who had close ties to the facility, and in December 2013 Delattre took Banana Boy and another scroll to Grenoble.
Seales waited eagerly for the promised data, but the files did not arrive. Then, in January 2015, Mocella’s group published the results without him. It was, Seales says, an “excruciatingly frustrating” experience. “I believed we were collaborating, until I realized that the feeling was not mutual.”
News stories around the world reported that Herculaneum scrolls had been deciphered at last. But, in fact, Mocella had claimed to read only letters, and some scholars are cautious about even those, not least because the group did not publish enough information for others to replicate the analysis. Mo-
It was an “excruciatingly frustrating” experience. “I believed we were collaborating, until I realized that the feeling was not mutual.”
cella finally shared his data with Seales and others after publication. After reviewing it, Seales concluded that the findings were a bust. “The dataset did not produce any contrast at the ink,” he told me. Seales thinks the researchers, who were without software to model the surfaces within the scrolls, were seeing “ghosts”—random patterns in the papyrus’ fiber structure that just happen to look like letters. He is now convinced that phase-contrast tomography alone is not sufficient to read the Herculaneum scrolls in any meaningful way. (Mocella insists the letters he saw were real, and he took issue with Seales’ version of the incident. “From my point of view, I and my team are still working with Brent, since we’ve given him, as with other specialists like him, most of the scans,” Mocella said.)
By that point Seales had finished a preliminary analysis of the Ein Gedi scroll, and in July 2015 he and the IAA announced their results. “We absolutely hit a home run,” Seales says.
Unlike the authors of the Herculaneum scrolls, the Hebrew scribes had mixed metals into their ink. Seales’ software correctly mapped the letters to the rolled-up parchment, then virtually unfurled it, revealing all of the surviving text, in perfect sequence, on each of the five wraps of the scroll. There were 35 lines of text in two columns, composed of Hebrew letters just two mil- limeters tall. Israeli researchers identified the text as the first two chapters of the Book of Leviticus, dating to the third or fourth century A.D. It was a hugely significant find for biblical scholars: the oldest extant copy of the Hebrew Bible outside of the Dead Sea Scrolls, and a glimpse into the history of the Bible during a period from which hardly any texts survive.
And it was proof that Seales’ method worked. Following Mocella’s publication, however, the Institut de France refused further access to its Herculaneum scrolls. Which is why Seales turned his attention to Oxford.
THE BODLEIAN LIBRARIES, at Oxford University, possess four Herculaneum scrolls, which arrived in 1810, after they were presented to the Prince of Wales. They are kept deep inside the building, in a location so secret that even David Howell, the Bodleian’s head of heritage science, says he doesn’t know where it is.
Seales wasn’t permitted to see the intact papyri, never mind scan them. But one of the four, known as “P.Herc. 118,” was sent to Naples in 1883, to be unrolled using Piaggio’s machine. It came back as a mosaic of crumbs, which were glued onto tissue paper and mounted behind glass in 12 wood frames. The text appears to be a history of Epicurean philosophy, probably by Philodemus, but it has been particularly challenging for scholars to interpret. A fragment might seem covered with continuous lines of writing, says Obbink, “but really every inch you’re jumping up or down a layer.”
To prove the value of his approach, Seales asked the Bodleian to let him analyze P.Herc. 118. If all went well, he hoped, he might get a shot at scanning the intact scrolls later. “We wouldn’t necessarily have chosen to get involved, except for Brent’s enthusiasm,” says Howell. So in July 2017, the 12 frames were removed from storage and taken to Howell’s third-floor office—something of a coup for Seales, given their invaluable nature. Cheerful and ruddy-faced, Howell has worked in conservation for close to 35 years, and even he felt daunted as the protective glass frames were removed, exposing the fragile papyrus beneath. “These are the most terrifying objects I’ve ever handled,” he says. “If you sneeze, they’d blow away.”
Seales and another colleague scanned these scroll fragments using a hand-held 3-D scanner called an Artec Space Spider. Meanwhile, Howell carried out hyperspectral imaging, which uses hundreds of wavelengths of light. Howell listened to Pink Floyd through noise-canceling headphones to escape the grinding noise of the scanner, he says, plus the knowledge that if anything went wrong, “I might as well pack my bags and go home and not come back.”
After Seales returned to Kentucky, he and his colleagues spent months mapping all of the available 2-D images onto the 3-D template produced by the Artec Space Spider. This past March, they returned to Oxford to present the results on a big screen to a packed conference room. At such a high resolution, the charred papyrus resembled a dark-brown mountain range as seen from above, with lines of text snaking over the ridges and peaks. There was a gasp from the audience as Seales’ student Hannah Hatch rotated the image, then zoomed into creases and peeked over folds, flipping seamlessly between high-resolution photographs, infrared images and even the disegni drawings—all matched up to the 3-D template.
Shortly afterward, James Brusuelas, an Oxford papyrologist working with Seales, revealed several new details visible in the scans, such as the name Pythocles, who was a young follower of Epicurus. More important, Brusuelas was able to decipher the column structure of the text—17 characters per line—which will be crucial for reading the rest of the roll, particularly when trying to join different fragments together. “We have the basic information we need to put Humpty Dumpty back together again,” he said.
The audience buzzed with questions and applause. It was the reaction Seales was hoping for, and a step toward his real goal—gaining access to intact scrolls.
He’d saved his own presentation until last. It wasn’t about P.Herc. 118, but rather one tiny letter: the lunate sigma.
DRIVING SOUTH from the stone archways and quadrangles of Oxford, the road soon cuts through flat green fields reaching to the horizon. On the day I visited, fork-tailed red kites hovered high in the blue July sky. After 15 or so miles a sprawling campus of low gray buildings came into view. At first, it resembled an ordinary industrial park, until I noticed the names of the roads: Fermi, Rutherford, Becquerel, all giants of 19th- and 20th-century physics. Behind a wire fence a huge, silver dome, more than a quarter-mile in circumference, rose from the grass like a giant flying saucer. This was Diamond Light Source, and Seales was waiting inside.
He’d brought a speck of charred papy-
rus from one of the Herculaneum scrolls he studied a decade earlier. The ink on it, he had found, contained a trace of lead. In Grenoble, direct X-ray imaging of the scrolls had not been enough to detect the ink. But when you fire hugely powerful X-rays through lead, the metal emits electromagnetic radiation, or “fluoresces,” at a characteristic frequency. Seales hoped to pick up that signal with a detector placed beside the fragment, which was specially calibrated to capture photons at lead’s characteristic frequency.
It was a long shot. The minuscule fluorescence of the letter would be swamped by radiation from the protective lead lining the room—like looking for a flickering candle from miles away on a rainy night, Seales said, as we stood in the crowded hutch. But after several days of intense work—optimizing the angle of the detector, shielding the main X-ray beam with tungsten “flight tubes”—the team finally got what it was looking for: a grainy, but clearly recognizable, “c.”
“We’ve proven it,” Seales said in triumph as he displayed the legible image to the Oxford audience in March. It is, Seales hopes, the last piece of the puzzle he needs to read the ink inside a Herculaneum scroll.
The results have scholars excitedly re-evaluating what they might now be able to achieve. “I think it’s actually very close to being cracked,” says Obbink, the Oxford papyrologist. He estimates that at least 500 Herculaneum scrolls haven’t been opened. Moreover, excavations at Herculaneum in the 1990s revealed two unexplored layers of the villa, which some scholars believe may contain hundreds or even thousands more scrolls.
Many scholars are convinced that Piso’s great library must have contained a range of literature far wider than what has been documented so far. Obbink says he wouldn’t be surprised to find more Latin literature, or a once-unimaginable treasure of lost poems by Sappho, the revered seventh-century B.C. poet known today only through the briefest of fragments.
Michael Phelps, of the Early Manuscripts Electronic Library, in California, who recently used multispectral imaging to reveal dozens of hidden texts on re-
used parchment at St. Catherine’s Monastery, in Egypt, calls Seales’ methods “revolutionary.” Scholars have long faced a choice between attempting to read concealed texts (and potentially destroying them in the process) or conserving them unread. “Brent Seales’ technology is removing that dilemma,” Phelps says.
Successfully reading Herculaneum scrolls could trigger a new “renaissance of classical antiquity,” says Gregory Heyworth, a medievalist at the University of Rochester in New York. He points out that virtual unwrapping could be applied to countless other texts. In Western Europe alone, he estimates, there are tens of thousands of manuscripts dating from before A.D. 1500—from carbonized scrolls to book covers made from older, glued-together pages—that could benefit from such imaging.
“We’d change the canon,” Heyworth says. “I think the next generation is going to have a very different picture of antiquity.”
SEALES HAS L ATELY BEEN enhancing his technique, by using artificial intelligence to train his software to recognize subtle differences in texture between papyrus and ink. He plans to combine such machine learning and X-ray fluorescence to produce the clearest possible text. In the future, “it’ll all be automated,” he predicts. “Put it in the scanner and it will all just unfurl.”
Seales is still negotiating with curators in Oxford, Naples and Paris for access to intact scrolls. He has surmounted huge technical hurdles, but the complex political challenge of navigating the gatekeepers, winning beam time at particle accelerators and lining up funding can, very occasionally, puncture his optimism. “How does a guy like me make all that stuff happen all at once?” he said in one such moment. He shrugged and looked around him. “It’s more than a computer scientist is really capable of doing.”
Then belief returned to his wide, hazel eyes. “I refuse to accept that it’s not possible,” he said. “At every turn, there has been something that opened up.” Reading a complete intact scroll at last, he went on, would be “like returning home to your family, who have been waiting all along for you to do the thing you started.”
In the 18th century, scrolls were unwrapped at the rate of a centimeter an hour, using a machine designed by Vatican conservator Antonio Piaggio.
Among the many thousands killed by Vesuvius’ eruption was Pliny the Elder, the ancient world’s greatest naturalist, whose death is depicted in an 1813 painting by Pierre Henri de Valenciennes.