A series of previously undiscovered texts by Archimedes, one of the foremost mathematicians of ancient Greece, have been revealed.
Hidden since the 13th century under religious writings and drawings, the single parchment on which they are written is made from goat skin. It includes seven treatises by the mathematician, who was particularly noted for calculating a value for Pi and for being the first recorded person to conceive of infinity.
Will Noel, curator of manuscripts and rare books at the Walters Art Museum in Baltimore, Maryland, and director of the imaging project, described the palimpsest as "the eighth wonder of the world".
Two of the treatises, "The Method of Mechanical Theorems" and the "Stomachion", are the only known copies in the world to have survived. The writings also include the only known version of "On Floating Bodies" in Greek.
Dr Noel said: "Editions of most of the great texts of the ancient world, like Homer, Plato and Euclid, came out in the 15th and 16th centuries, which capture most of what they have to say. With this palimpsest we are in the unique and exciting position of making radical additions and corrections to the basic texts of Archimedes in the 21st century. This is only possible with current technology."
Archimedes' writings, transcribed in the 10th century by an anonymous scribe on to parchment, are being revealed using a non-destructive technique known as X-ray fluorescence, by scientists in the Stanford Synchrotron Radiation Laboratory in the United States.
In the 13th century, the original manuscript was recycled by a monk in Jerusalem called Johannes Myronas, to create a palimpsest. Using a pumice and lemon juice or milk, the monk faded the writings, cut the parchment in half and rotated the pages. These were then filled by the monks with Greek Orthodox prayers.
Then, in the 20th century, a Parisian art forger added gold paintings of the writers of the four Gospels of the New Testament - Matthew, Mark, Luke and John - to add value to the palimpsest - but nearly obliterated the work of the 10th century scribe.
Dr Noel said that the eight years of work that has been undertaken on the palimpsest has also revealed other ancient texts. Among these is a speech made by Hyperides, an Athenian orator in the 4th century BC and a contemporary of Aristotle and Demostenes.
"It is a speech, probably made in 338BC, at the twilight of the Athenian age of democracy. It concerns Athenian reaction to their loss of a battle against Phillip of Macedon and his son Alexander the Great," Dr Noel said. In 338BC, the father and son defeated Athens and Thebes.
The privately owned palimpsest, bought by a philanthropist for $2m in 1998 and loaned to the Walters Art Museum, has been investigated previously using optical and digital imaging techniques. But most of the text was indecipherable behind paint. Now, X-ray fluoresence has enabled them to make out the works. Each page takes 12 hours to reconstruct, with X-ray beams the width of a human hair sweeping the pages. As the scientists revealed the first glimpse of the text in 800 years, Dr Noel said the work was "like receiving a fax from the 3rd century BC."