Herculaneum Scrolls Could Be Read Through Lead X-Ray Scans

When Vesuvius erupted almost 2,000 years ago, it ravaged the neighbouring Roman city of Herculaneum with searing gas, ash and earthquakes. These forces choked its streets, brought down masonry and even transformed one man’s brain into glass.

Although much of the city was ruined and its inhabitants were vaporised, ash that enveloped the site preserved its library of obscure knowledge for future generations.

Excavations backed by the Bourbon kings of nearby Naples in 1752 CE uncovered a collection now comprising more than 1,800 papyrus scrolls, all of which remain rolled up.

Herculaneum scrolls: antiquity’s surviving library

The scrolls are the only known intact library to survive from antiquity.

That is true only in a sense, however, because they have been extensively carbonised: burned to a crisp and reduced to fragile charcoal.

Yet this may not prevent them from being read. A new study has shown that lead contained in the Herculaneum writings can make them particularly legible without unrolling them, as demonstrated by the multi-million-dollar Vesuvius Challenge.

Anyone who has had an X-ray may recall putting on an unwieldy lead apron.

The same underlying principle applies to these texts. Lead within the scrolls’ letters can absorb X-rays up to 25 times more effectively than the atomically lighter, charred papyrus, creating a visible contrast between the writing and its material.

Recreating and scanning ancient texts

For a potentially groundbreaking study published in PLOS One, researchers including scientists from the University of California, Berkeley, and the National Institute of Standards and Technology (NIST) used fire to investigate fire.

Supported financially by first author Douglas Seiler - a Berkeley SETI affiliate working on the Panoseti project, which searches for alien laser signals - the researchers, along with their relatives and friends, created their own Herculaneum-style scrolls.

Using historically appropriate materials and methods, they wrote quotations from Star Wars, The Outer Limits and the Bible across sizeable sections of scrolls. Their materials included Egyptian papyrus, Japanese lampblack ink, ink enriched with lead and a reed stylus.

Seiler then burned the scrolls in his home laboratory to replicate the characteristics of the genuine artefacts - making millennia-old scrolls in a personal burning laboratory is quite the flex, incidentally.

"The value in this project is practically unquantifiable," says Leah Packard-Grams, an archaeologist and papyrologist at UC Berkeley.

"The stakes are the largest in the history of Greek literature."

The team then rotated the scrolls while exposing them to X-rays, rather like a rotisserie chicken being scanned for a sprained ankle, using NIST’s neutron and X-ray tomography (NeXT) system in Gaithersburg, Maryland.

Through 3D tomography, these X-ray-image ‘slices’ became a three-dimensional representation.

"If you look at the images, the letters light up like a Christmas tree," Seiler says.

A bespoke algorithm created by study co-author Michael Cyrus Daugherty, a NIST physicist, had originally been designed to virtually unroll scans of lithium-ion batteries. It proved equally capable of virtually unrolling the model scrolls.

"He just had to tweak his code to follow the uneven and changing thickness along the length of the scroll," explains Jacob LaManna, the NIST physicist who prompted Daugherty to apply his algorithm to the scrolls.

The researchers were then able to reveal their writing.

Lead detection and the future of Herculaneum research

Crucially, they also established that a commercially available handheld X-ray fluorescence (XRF) device could identify lead in scrolls and help select candidates for further investigation. The device resembles the gun used to scan gummy-bear barcodes at a self-service checkout.

This is encouraging because the Herculaneum scrolls include epic poems of battle, Seneca the Elder’s Histories, Stoic works and philosophical treatises by prominent literary figures, including Epicurus himself and other Epicureans known for leisurely living.

And there may be much else besides.

Once opened, scrolls can commonly extend to 10 metres in length.

Unlike modern newspapers, they contain more than a collection of Hyundai adverts and Marmaduke, however illuminating the behaviour of "America's favorite Great Dane" might be.

Not every ancient text used lead in its lettering, but at least some did.

An earlier study determined that several genuine Herculaneum scrolls contain lead, although its source remains uncertain and may have been a drying agent. Similar previous research identified lead in Egyptian letters dating from roughly the same Roman era.

"What I would like to see and what I'd like to do is a much more rigorous study into the ink concentrations or what's in the ink, not just lead," says LaManna.

"And see how far we could push this into making training data sets to actually make more robust algorithms for reading the real ones."

This could therefore enable “blinded” training: researchers could make further model scrolls in different styles, languages and inks, carbonise them, and test how effectively AI agents can recover their text, whether the ink contains lead or not.

As human imagination has never recognised limits, the discoveries may include fanciful works: old love letters or Biblical affection spells, extensive philosophy, and perhaps even ancient science fiction about space travel and alien conflicts from cultures beyond the reach of modern ways of thinking.

The research was published in PLOS One.

This article was fact-checked by Rachel Garner and edited by Rebecca Dyer. While we take pride in our process, we are only human. If you notice an error, please let us know.