Scientists used an algorithm to read an unopened letter written 300 years ago – without breaking its seal.
The note had been securely closed through an archaic process known as “letterlocking”. The method was used to secure written communications for centuries before the widespread adoption of envelopes in the 1830s.
The complex system of folds, creases and slits efficiently transforms the paper into its own envelope. Often the banknotes were then sealed and rigged with anti-theft devices.
The method has been used by both ordinary people and historical figures from Queen Elizabeth I of England to Marie Antoinette.
While the hidden letters contain valuable information about the past, the packages themselves are also valuable historical artefacts.
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Researchers have developed a calculation method to discover their content while preserving the materials.
“Our work seeks to make an intervention in the conservation of cultural heritage,” they wrote in their study paper. “Once a document such as an unopened letter is damaged during the opening process, we lose the impression that the object is intact and intact.”
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The team first scanned the folded documents with x-ray imaging equipment designed for use in dentistry.
Computer flattening algorithms were then applied to the scans. This generated 2D and 3D reconstructions of the letters in both folded and flat states. He also produced images of writing surfaces and crease patterns in documents.
The technique revealed the entire contents of a letter dated July 31, 1697.
It was sent by a lawyer called Jacques Sennacques to his cousin Pierre Le Pers, a French trader living in The Hague.
The letter is marked “10” in red pencil on the address panel, indicating how much the recipient should have paid for it. The address and the price suggest that the document was sent from Lille.
Inside the unfolded mail, Sennacques asks his cousin – with some urgency – the death certificate of another relative:
I am writing to you a second time to remind you of the sorrows I have taken on your behalf. It is important for me to have this extract you will give me great pleasure to get it to send me at the same time news of your health from the whole family. I also pray that God will maintain you in His holy graces and cover you with the blessings necessary for your salvation. Nothing more for the moment, except that I beg you to believe that I am completely, sir and cousin, your most humble and obedient servant.
The missive was taken from a European postmaster’s trunk of a 300-year-old undelivered courier, known as the Brienne Collection.
“We could have just opened these letters, but instead we took the time to study them for their hidden, secret and unapproachable qualities,” said Daniel Starza Smith, professor of modern English literature at King’s College London. that letters can be much more revealing when they are not opened. “
The researchers say their technique could also virtually open up a range of other historical texts, such as scrolls and books.
Sennacques’ letter alone cannot reveal radical ideas about the 17th century. But analyzed alongside other documents, it could broaden our understanding of the culture, politics and peoples of modern Europe.
You can read the study paper and see the letter unfolded in the newspaper Nature communications.
Published March 3, 2021 – 15:33 UTC