Hospital visit reveals medieval secrets hidden in books

Even in medieval times, recycling was fashionable: scraps of parchment salvaged from older handwritten manuscripts were often used to reinforce other books. Thanks to computed tomography, a team of researchers has now shown that these medieval remains hidden under the cover of certain books can be seen. Studying these fragments of medieval binding can help reveal how, when and where the first books were put together, and there is always the tantalizing possibility of finding a previously unknown manuscript.

In Europe, books were reproduced by hand until the middle of the 15th century. Known as manuscripts – the Latin root “manu” means “hand” – these written records were often works of art in their own right, with multiple colors of ink running down sheets of calfskin, goatskin or meticulously prepared mutton.

However, with printing becoming common in Europe in the 1450s, there was little need for such manuscripts. But some bookbinders chose to reuse their parchment pages.

“They could use the older, more durable manuscript to help strengthen the structure of a new print book,” said Eric Ensley, curator of rare books and maps at the University of Iowa.

Bookbinders cut out pieces of parchment—sometimes whole pages, sometimes just thin strips—and glued them to places like the spine of a book. The book would then be covered and most of these binding fragments would be hidden from view.

“There’s actually an entire library within a library in the form of these fragments,” said Joris Dik, a materials scientist who studies linking fragments at Delft University of Technology in the Netherlands and does not did not participate in the new study.

In recent decades, scholars have begun to look under the covers of books using non-invasive techniques to find fragments of medieval binding and read what is written on them. But many of these techniques have limitations, prompting Dr. Ensley and his colleagues to try CT scans, the same type available in a hospital. The technique’s three-dimensional view solves the debugging problems that plagued other methods, and an analysis can be performed in seconds rather than hours previously.

The team scanned a set of three books from “Historia animalium”, an encyclopedia of animals printed in the 16th century. One book would serve as a witness, the researchers decided, because its cover was damaged and could be peeled off to reveal fragments of medieval binding – featuring red and black ink – on the spine. The other two books were intact. However, researchers speculated that their spines might also contain fragments because the books appeared to have been bound in the same workshop, said Katherine H. Tachau, a historian at the University of Iowa and a member of the Research Team.

Under the watchful eye of Giselle Simon, curator of the University of Iowa Libraries, the team placed the three books on the bed of a CT scanner in Eric Hoffman’s lab at Carver College of Medicine in the university. The books had room to spare and scanning all three took less than a minute.

Along with Dr. Tachau, Dr. Ensley looked at the hidden text of some of the linking fragments revealed on the scanner screen.

“We both bent over and started reading Latin together,” he said. “It was a goosebumps moment.”

Many medieval binding fragments from the “Historia animalium” came from a Latin Bible dating to the 11th or 12th century, the team reported in April in the journal Heritage Science.

When the researchers analyzed CT scans from their checkbook, they found that letters written in red ink were the most pronounced in the images. Darker inks, however, do not show as clearly. The different chemicals in the inks affect how they absorb X-rays.

But by varying the energy of X-rays emitted by a CT scanner, it might be possible to better detect black inks in future studies, Dr. Ensley and his collaborators hypothesize.

The fragments discovered by the team will eventually be digitized in Fragmentarium, an online repository of more than 4,500 fragments of medieval bookbinding. Archives are a way to disseminate the information contained in these hidden pieces of history, said William Duba, a historian at the University of Friborg in Switzerland who coordinates the Fragmentarium.

“The spines of books hide treasures,” he said.