Waves to look for texts hidden in book bindings
· BehindLines newsroom
Fragments of manuscripts can remain hidden inside the covers of other books. On 30 October, Georgia Tech presented a project that aims to locate them without taking the bindings apart. David Citrin's team is working with Leor Jacobi of Bar-Ilan University on an imaging technique that uses terahertz waves, which sit between microwaves and infrared.
Old sheets were sometimes used to make covers, and this reuse interests historians. The announcement nonetheless describes research still in development, not a medieval library that has already been deciphered automatically.
A methodological study by the team helps explain the difference. The abstract of their article in Data in Brief describes contemporary samples: ordinary copy paper carrying patterns or characters on both sides. The researchers used several writing or printing materials, including iron gall ink, a historical type, and graphite, to build reference data.
Each measurement is paired with a category showing where the ink is: on the front, on the back, on both sides or nowhere. A neural network serves as a baseline model for classifying the signals. The task is therefore to identify the presence and position of ink, which is not yet the same as understanding the meaning of a text.
Moving on to historical bindings is a separate step. According to Georgia Tech, some medieval pasteboard bindings can contain up to twenty recycled sheets, whereas the experiments described involve one sheet written on both sides and two stacked sheets. Thickness and ageing complicate the problem. Spotting characters could already help choose which volumes to study more closely, even without reading every sentence. The prospect is a screening tool for archives; its performance on these old objects remains to be established.