Infrared Illuminates Ancient Scrolls

Despite the thriving trade in manuscripts that occurred throughout the Greek and Roman empires, many plays, poems, and philosophical musings by writers such as Aeschylus, Euripides, Aristophanes, and Sophocles have been lost. Now, a collaboration between Oxford University and Brigham Young University (BYU) in Provo, Utah, is revolutionizing paleography by rescuing words and images from charred and battered fragments of ancient scrolls.

Paleologists have been experimenting since the 1930s with IR photographs to decipher old paintings and texts. But success with manuscripts was elusive until 1994, when Greg Bearman, a physicist at NASA’s Jet Propulsion Laboratory and an amateur history buff, hit upon the idea of using a space satellite technique called multispectral imaging. Bearman used MSI, in which photographs are taken at different wavelengths, on a badly degraded fragment of the Dead Sea Scrolls. The nearly invisible text showed up clearly at a wavelength of 900 nm. “We were surprised at how easy it was when we got the results,” says Bearman.

After hearing of Bearman’s research, BYU’s Institute for the Study and Preservation of Ancient Religious Texts commissioned Gene Ware, a professor of engineering who was already building a multispectral imager to study ancient murals, to try MSI on some burnt 6th-century-AD scrolls in Jordan. “The new multispectral system was able to record the carbonized scrolls very effectively,” says Ware.

Over the past seven years, BYU has been building an interdisciplinary team, including Ware, classicist Roger Macfarlane, and computer scientist Steven Booras, to develop an MSI technique specifically for papyrus. It works by placing an automated rotating wheel with 10 to 15 filters in front of a digital camera. Longer wavelengths in the IR often increase contrast because most carbon-based inks remain dark while papyrus, animal hide, bark, and the like tend to become lighter. Focusing and shooting each photograph takes about a minute, with exposure times between 50 and 1000 milliseconds. “The real power of MSI comes from post-processing … where some really exciting results are often obtained by combining images at different wavelengths,” says Ware.

The process typically works well on darkened, charred, or stained surfaces. It may not be as successful on washed-out surfaces or those coated with mud, clay, or silt. More than one filter is often needed to uncover the hidden text, because spectral characteristics may change across a document.

Four years ago, after working with the BYU team on damaged scrolls from Herculaneum, a small town caught up in the eruption of Mt. Vesuvius in AD 79, Oxford’s Dirk Obbink asked the team to apply its technique to the Oxyrhynchus papyri, a collection of 400 000 fragments (3rd century BC through 7th century AD) excavated in Egypt 100 years ago from an ancient trash dump. Only 5000 of the fragments have been published; the rest are currently unreadable, and all the fragments are exceedingly fragile.

“It would take roughly 450 years to complete the multispectral imaging of the collection,” says Obbink. But that’s just half the story. Once the text is legible, the computer-aided process of identifying the author and checking for matching fragments begins.

During a visit to Oxford to test improved equipment this past April, Ware and Obbink uncovered parts of a long-lost tragedy—Epigonoi (The Progeny) by Sophocles—and writings by Euripides, Hesiod, and Lucian. The most significant find, says Obbink, is a 30-line passage from Elegies by the 7th-century-BC poet Archilochos. Oxford University Press will publish these newest discoveries next month. Says Ware, “There is no question that the ability to image deteriorated papyri and carbonized scrolls has significantly added to our knowledge of the ancients.”