Tech & Science

X-Rays Reveal the Secrets of Egyptian Scrolls

01_29_Papyrus_01
01/29/16
In the Magazine
A Papyrus scroll from Herculaneum, which was carbonized in the eruption of Mt. Vesuvius, undergoes part of the CT scan process to help decipher the writing contained within the scrolls, in an image from the University of Kentucky's Center for Visualization and Virtual Environments taken in 2009. Dr. Brent Seales, a pioneer in ancient document scanning techniques, was able to recover a legible portion of the scroll, compiled from 10,000 separate CT slices; researchers in Germany hope to use similar techniques to reveal the content of the Elephantine scrolls currently in the collection of the Egyptian Museum in Berlin. Dr. Brent Seales/University of Kentucky

“Usually, in this area, no visitor gets in,” Verena Lepper tells me on a gray Friday morning in Berlin. She gently closed a set of double doors behind us, careful not to create any vibrations in the walls. We were standing in a room that was white from floor to ceiling, without a single scuff. It felt more like an airlock on a spaceship than a vestibule in the city’s Archaeological Center, completed just four years ago. There, I would sign my third guestbook of the day.

The procedure was not just a German reflex for meticulous record-keeping but also a security policy: Inside was the nation’s largest collection of papyri, among the four largest in the world, two floors crammed with scrolls that were pressed between glass and tucked away in metal drawers. Although academics hesitate to put a price tag on research material they consider priceless, any one of these scraps of paper would sell for thousands of dollars on the antiquities market.

Among the manuscripts was a section of The Ahiqar, a proverb-loaded narrative about a betrayed chancellor of the Assyrian King Sennacherib. The 2,500-year-old text was written in Aramaic, the language Jesus spoke, and one of the 15 that Lepper, a curator at the Egyptian Museum and Papyrus Collection in Berlin, knows herself. “Literary studies people claim this is the first novel ever to be written,” she says. But for Lepper what is most interesting about this first copy of The Ahiqar is where it came from: Elephantine Island, a narrow patch of land less than a square mile large in the middle of the Nile River, opposite Aswan in southern Egypt.

The hundreds of documents that have turned up at Elephantine include 10 different languages and range four continuous millennia, from Egypt’s Old Kingdom around 2500 B.C. to the Middle Ages. “I’m not aware of any other place in the world where you have 4,000 years covered by textural resources from one single place,” Lepper says. And yet most of the texts from the island haven’t been studied or published—and many haven’t even been unfurled because they're so delicate.

To make a paper-like sheet of papyrus, thin strips of the pith from inside the stems of reedy papyrus plants were sliced and arranged in overlapping, perpendicular layers. No glue was necessary; the plant’s natural stickiness fused the fibers together. Like all organic material, papyrus tends to rot when exposed to oxygen and moisture, but when it’s buried in dry climates like Egypt’s, it has a better chance of survival.

Still, the scrolls archaeologists find aren’t always in great shape. Some from Elephantine are still intricately folded with layers that might be brittle or stuck together—scholars of the past would pry them open anyway, at risk of destroying the fragile documents. But thanks to advanced imaging technology—and a $1.6 million grant from the European Research Council—Lepper will be able to read papyrus scrolls from the island that have never been unrolled. Over the next five years, she’ll be working with physicists and mathematicians to extract hidden words, letter by letter, with high-energy beams.

Located at the first cataract of the Nile, Elephantine was strategically important and marked the southern border of Egypt throughout much of ancient history. Pharaohs fortified the island and filled it with soldiers. The outpost became an economic hub too, where goods like Nubian gold, ivory, exotic animals and ostrich feathers flowed to the rest of Egypt. Typically teeming with mercenaries and traders, Elephantine was surprisingly diverse for its size. Polytheistic Egyptian worshippers likely walked to the temple of the ram-headed god Khnum alongside Aramaic Jewish soldiers going to their own temple next door. Texts from the island reveal examples of Coptic Christians converting to Islam and Egyptians converting to Judaism.

“You have all these kinds of first hints of what might be called a multicultural and multireligious society,” Lepper says.

Elephantine eventually outgrew its digs; settlers spilled over to Syene (now Aswan) on the eastern bank of the Nile, and as this city grew Elephantine waned in importance. The ruins of Elephantine were not necessarily forgotten. (The island’s ancient Nilometer—a device used to measure the flooding of the Nile—was used until the 1800s.) But without sprawling monuments and gold treasures, early archaeologists bypassed Elephantine, says Johanna Sigl of the German Archaeological Institute in Cairo. Then, in the late 19th century, farmers collecting the island’s ancient mud bricks for fertilizer found troves of papyri.

In the conservation workshop of the Archaeological Center, papyrus conservator Tzulia Siopi motioned to a dull gray metal container slightly longer than a shoe box. On the outside, in white paint, it was labeled “Elephantine” and dated November 12-16, 1907—when German archaeologist Otto Rubensohn and papyrologist Friedrich Zucker filled this box for the Berlin Royal Museums. Siopi propped open the lid to reveal an assortment of ancient confetti. With a pair of surgical tweezers, she lifted layers of crumpled brown tissue paper, packed with hundreds of papyrus fragments, many barely the size of a fingernail. They were scribbled with text in dead languages like Demotic and Hieratic. The box hadn’t been touched in a century. There were still tiny feathers and sand that had blown in from the excavation site. Fifty of these straight-from-the-field metal boxes have languished in storage in Berlin.

01_29_Papyrus_02 Boats sail on the Nile river near Elephantine Island in Aswan, Egypt on May 27, 2014. De Agostini/Getty

To extract the words from fragile scraps like these, conservators have an ever-expanding toolkit. They can use multispectral imaging, where a text is photographed in different wavelengths of light—sometimes ultraviolet and infrared light, which are invisible to the human eye. Because the paper and the ink have different chemical properties, they might reflect certain wavelengths of light in different ways, which could reveal previously unseen scribbles. That’s how researchers discovered two previously unknown treatises by the ancient Greek scientist Archimedes on pages that had been overwritten and reused in a 13th-century prayer book.

Then there’s X-ray imaging, borrowed from the medical sciences. Brent Seales, head of the computer science department at the University of Kentucky and a pioneer of digital reconstruction, likens the papyrus scroll to the body of a person going to the doctor for an X-ray: The ink letters are the bones, and the paper surfaces are the soft tissue. When X-rays are blasted at a manuscript, the denser ink leaves a shadow, and if researchers are lucky these shadows will appear in the shape of legible text.

For looking inside folded texts, researchers have another method inspired by doctors: computed tomography. CT scans take X-ray slices of a papyrus chunk, and these images are stacked together to visualize where the ink blobs lie inside of the scroll. Then a separate challenge looms: reconstructing the way the papyrus was folded, which makes digitally unraveling a text like solving an ancient Rubik’s Cube. Each surface of the crumpled scroll must be distinguished and then aligned to form a coherent, readable sheet of text. The sheer amount of data to be processed in this phase of such a project can be staggering. Last year, Seales helped a group of Israeli researchers successfully unravel the Ein Gedi scroll to reveal text from the biblical book of Leviticus. The software he designed had to sort through 10,000 CT slices to make sense of a scroll section just 3 inches long.

These methods all rely on the imaging machines being able to differentiate between ink and paper. Unfortunately, the ink used in antiquity was often carbon-based charcoal—and the difference in X-ray absorption between the pure carbon of the ink and largely carbon organic papyrus is so minor that the contrast between the two is often undetectable. Some scientists have been trying to combat this problem by searching for alternative methods. Seales recently worked with a group of French and Italian researchers to examine rolled up and charred papyri that were buried inside a luxury villa’s library at Herculaneum during the A.D. 79 eruption of Mount Vesuvius. The impossibly delicate scrolls had frustrated antiquarians since the 18th century. But the scientists used a more sensitive variation of CT scanning, called X-ray phase-contrast tomography, which proved refined enough to reveal a few previously hidden sequences of Greek letters. Their initial results made headlines after they were published in January 2015 in the journal Nature Communications.

Still in the early stages of the project, Lepper and physicist Heinz-Eberhard Mahnke are creating mock-ups of folded papyrus scrolls to test how they might approach the texts from Elephantine. They’re also looking for a specialist with math and computer science skills to help develop algorithms that might be able to automatically pick out letters and help piece together fragments of papyrus surfaces.

The ancient texts preserved at Elephantine range from literary works like The Ahiqar to marriage contracts, divorce documents, lists of donors to the Jewish temple, everyday letters and ancient beer receipts. What survived is mostly a matter of luck. And yet Lepper hopes to make sense of this 4,000-year written record by focusing on a few themes: She’s looking for texts that shed light on the role of women, and she wants to understand how Elephantine managed such a diverse population in such a small geographic area.

By 2020, Lepper wants to create an online database that brings together not only the texts she can virtually unroll but also each of the thousands of written scraps from the island, which today are spread across 60 institutions around the world. It’s her hope that dumping all the data online will help future researchers draw their own connections. “It’s been my dream to bring all of these pieces together and try to let them speak,” she says.