X-rays reveal Archimedes' secrets

A series of hidden texts written by the ancient Greek mathematician Archimedes are being revealed by US scientists.

Until now, the pages have remained obscured by paintings and texts laid down on top of the original writings.

Using a non-destructive technique known as X-ray fluorescence, the researchers are able to peer through these later additions to read the underlying text.

The goatskin parchment records key details of Archimedes' work, considered the foundation of modern mathematics.

The writings include the only Greek version of On Floating Bodies known to exist, and the only surviving ancient copies of The Method of Mechanical Theorems and the Stomachion.

In the treatises, the 3rd Century BC mathematician develops numerical descriptions of the real world.

"Archimedes was like no-one before him," says Will Noel, curator of manuscripts and rare books at the Walters Art Museum in Baltimore, Maryland and director of the imaging project.

"It just doesn't get any better than re-reading the mind of one of the greatest figures of Western civilisation."

'Eighth wonder'

Revealing Archimedes' writings presents a huge challenge to the imaging team.

The original texts were transcribed in the 10th Century by an anonymous scribe on to parchment.

Imaging a page for sulphur content, using helium (Credit: SLAC, Diana Rogers)

Three centuries later a monk in Jerusalem called Johannes Myronas recycled the manuscript to create a palimpsest.

Palimpsesting involves scraping away the original text so the parchments can be used again. To create a book, the monk cut the pages in half and turned them sideways.

To create a book Myronas also used recycled pages from works by the 4th Century Orator Hyperides and other philosophical texts.

Mr Noel describes the palimpsest as "the eighth wonder of the world".

"You never get three unique palimpsested texts from the ancient world together in one book," he told the BBC News website. "That's just completely unheard of."

The monks filled the recycled pages with Greek Orthodox prayers.

"It's like receiving a fax from the 3rd Century BC"
Will Noel

Later, forgers in the 20th Century added gold paintings of religious imagery to try to boost the value of the tome.

The result was the near total obliteration of the original texts apart from faint traces of the ink used by the 10th Century Scribe.

Bright light

Previously the privately-owned palimpsest has been investigated using various optical and digital imaging techniques.

However, much of the text remained hidden behind paint and stains.

The researchers have now turned to a technique known as X-ray fluorescence to tease out the final details of the writings.

Pages from the Archimedes Palimpsest

The method is used in many branches of science including geology and biology. It has previously been used by other researchers to decode ancient texts.

In August 2005 a team from Cornell University successfully deciphered a series of 2,000-year-old worn down stone inscriptions.

The X-rays are formed in a synchrotron - a particle accelerator that uses electrons travelling at close to the speed of light to generate powerful "synchrotron" light.

The light covers a wide range of the electromagnetic spectrum, including powerful X-rays, a million times more intense than a transmission X-ray used in medical imaging.

"In fluorescence it's like looking at the stars at night whereas in transmission it's like looking during the day," explains Dr Uwe Bergmann of the Stanford Synchrotron Radiation Lab in the US, where the work is being done.

The light enables scientists to look inside matter at the molecular and atomic scale.

Glowing words

The technique is particularly useful for probing the palimpsest because the ink used by the scribe to record Archimedes' work contains iron.

"When the X-rays hit an iron atom it emits a characteristic radiation, it glows," says Dr Bergmann. "When you record the glow you can reconstruct an image of all of the iron in the book."

ARCHIMEDES TEXTS IN THE PALIMPSEST

• Equilibrium of Planes
• Spiral Lines
• The Measurement of the Circle
• Sphere and Cylinder
• On Floating Bodies
• The Method of Mechanical Theorems
• Stomachion

The glowing words are displayed on a computer screen, giving the researchers the first glimpse of the text in nearly 800 years.

"It's like receiving a fax from the 3rd Century BC," said Mr Noel. "It's the most sensational feeling."

Each page takes 12 hours to reconstruct as the highly focused beam of X-rays, the width of a human hair, sweeps across the page.

The team have until the 7 August this year to scrutinise the palimpsest, before the synchrotron is switched off for maintenance.

During that time they hope to scan between 12 and 14 pages, paying particular attention to the areas covered with the forged paintings.

The public can watch the researchers as they reveal the glowing ancient text during a live webcast at 2300 GMT on 4 August.