They managed to read a sealed letter over 300 years ago without opening it

The researchers read an unopened letter that was written over 300 years ago using a new technique based on a method of calculus. The letter, dated July 31, 1697 and sent by French merchant Jacques Sennacques in Lille to his cousin Pierre Le Pers in The Hague, had been closed by “letter blocking”, a process in which the letter is folded to become your own envelope. .

The researchers in charge of this project, the details of which have been published in the journal Nature, are part of MIT, King’s College London, Queen Mary University London, Utrecht and Leiden. They showcased a fully automated computer approach to virtually reconstruct and display volumetric scans of locked letters with complex internal folding. Using this technique, they were able to produce readable images of the content of the letter and the pattern of the folds, preserving the historical material without damaging it.

First, x-ray microtomographic scans of the letter were performed, which made it possible to see the document in detail and create a 3D image with this information. They then applied computational algorithms to the scans to virtually display the letter without opening it,

“One of our main results is to reveal for the first time the contents of DB-1627, a typical letter of daily communications of the time. It contains a request from Jacques Sennacques, dated July 31, 1697, to his cousin Pierre Le Pers, French merchant in The Hague, for a certified copy of a death notice of a certain Daniel Le Pers “, specify the researchers in the publication of Nature.

The big challenge was to reconstruct the intricate, unopened letter folds secured with a technique called “letter blocking,” and which was standard global communications security practice for centuries before the advent of modern envelopes.

The letter was from the Brienne Collection, a wooden chest from a European postmaster containing 3,148 items, including 577 letters that were never unlocked. The research team unlocked several letters using their new technique, which opens up possibilities for a new field of exploration.

“Virtual display can also have an impact far beyond this correspondence, as collections around the world contain unopened letters and documents from many places, cultures and historical periods. An important example is the hundreds of unopened articles among the 160,000 undelivered letters in the Prize Papers, an archive of documents confiscated by the British from enemy ships between the 17th and 19th centuries, ”the research authors point out.

The code for this development is publicly available on Github (https://github.com/UnlockingHistory/virtual-unfolding/), with a version archived at https://doi.org/10.7910/DVN/VBWOI6.

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