Scientists use technology to read centuries-old letters sealed with ‘letterlock’.
Nature communication
The contents of a handwritten European letter sealed for 300 years are no longer a secret, thanks to a technique that allows scholars to virtually look inside without damaging the complex historical document.
In the letter, dated 31 July 1697, Jacques Sennacques asks his cousin Pierre Le Pers, a French merchant in The Hague, for a certified copy of a death certificate for Daniel Le Pers. This is no revelation in history, but the technique revealed by the request may hold the promise of unlocking sealed correspondence with historical gems about time and place.
All these years ago, Sennacques’ letter was concluded with a process called ‘letterlocking’, a complex folding technique used worldwide to secure the mail before the envelopes were invented. Think of it like ancient encryption: letters sealed in this way could not be opened without tearing, and tears indicated that a note had been tampered with before reaching the intended recipient.
“Letterlocking has been an everyday activity for centuries, across cultures, borders and social classes,” said Jana Dambrogio, the Thomas F. Peterson Conservator at MIT Libraries and one of the authors of an article published Tuesday in the journal Nature Communications. is, in which the virtual details are set out. unlocking technique.
No paper was damaged while reading this letter: it was virtually unfolded.
Nature communication
Letterlocking played an integral role in securing physical communication before the era of modern digital cryptography. Some of the earliest examples of letters can be found in the Vatican Secret Archives dating back to 1494. Researchers could only have torn the letter open, but they wanted to preserve all its folds and folds, which itself amounts to evidence of communication practices.
“This research leads us to the heart of a closed letter,” Dambrogio said in a statement.
To unlock the letter, an interdisciplinary team of researchers from MIT and King’s College in London turned to advanced X-ray machines designed for dentistry to compile high-resolution 3D scans that show exactly how the paper is set up. An automated computational algorithm developed by one former and one current MIT student then yielded readable images of the contents of the letter and intricate fold patterns.
“Virtual unfolding is a computational process that analyzes CT scans of folded letter packets and creates a flattened image of their contents,” the team said. “Our virtual unfolding pipeline generates a 3D reconstruction of the folded letter, a corresponding 2D reconstruction representing its flat state and flat images of both the surface … and the folding pattern of each letter packet.”
Calculation algorithms have been successfully applied to scans of scrolls, books and documents with one or two folds. But the complexity of the letter-locked documents posed their own challenges.
The letter comes from the Brienne collection, a wooden post of a European postmaster with 3,148 objects, including 577 letters that were never unlocked. The research team has unlocked several letters using their new technique and believes it holds promise for many other unopened letters.
“One important example is the hundreds of unopened articles among the 160,000 unsolicited letters in the Prize Papers, an archive of documents confiscated by British ships from enemy ships between the 17th and 19th centuries,” the study reads. “If it can be read without physically opening it, very rare letters for letter closing can be kept.”
Before calculating the researchers, they only knew the name of the intended recipient that was written on the outside of the lock.
“When we got the first scans of the letter packets back, we were immediately addicted,” said Amanda Ghassaei, who helped write the publicly available code to virtually unfold the letters. “Sealed letters are very interesting objects, and these examples are particularly interesting because of the special attention paid to keeping them closed.”
Let the epistolary history unfold.
CNET’s Corinne Reichert contributed to this report.