Researchers read sealed 17th century letter without opening it

‘Virtual unfolding’ is hailed a breakthrough in the study of historic documents as unopened letter from 1697 is read for the first time using X-ray technology

In a world first for the study of historic documents, an unopened letter written in 1697 has been read by researchers without breaking the seal.

The letter, dated 31 July 1697 and sent from French merchant Jacques Sennacques in Lille to his cousin Pierre Le Pers in The Hague, had been closed using “letterlocking”, a process in which the letter is folded to become its own envelope, in effect locking it to keep it private. It is part of a collection of some 2,600 undelivered letters sent from all over Europe to The Hague between 1689 and 1706, 600 of which have never been opened.

The international team of researchers from universities including MIT, King’s College London, Queen Mary University London, Utrecht and Leiden, worked with X-ray microtomography scans of the letter, which use X-rays to see inside the document, slice by slice, and create a 3D image. They applied computational flattening algorithms to the scans to enable them to virtually unfold the letter without ever opening it, and discovered that Sennacques had been asking his cousin for a certified copy of a death notice of one Daniel Le Pers.

Computer-generated unfolding sequence of a sealed letter.
Computer-generated unfolding sequence of a sealed letter. Photograph: Unlocking History Research Group archive

“It has been a few weeks since I wrote to you in order to ask you to have drawn up for me a legalised excerpt of the death of sieur Daniel Le Pers, which took place in The Hague in the month of December 1695, without hearing from you,” runs the letter. “I am writing to you a second time in order to remind you of the pains that I took on your behalf. It is important to me to have this extract & you will do me a great pleasure to procure it for me & to send me at the same time news of your health & of all the family.”

The Unlocking History research group, which includes historians, conservators and scientists, published their findings on Tuesday in an article in Nature Communications. They say this is the first time an unopened letter from Renaissance Europe has been read without breaking its seal or damaging it in any way. It is a breakthrough for the study of historic documents because the papers’ folds, tucks, and slits provide valuable evidence for historians and conservators.

“This algorithm takes us right into the heart of a locked letter,” write the research team in the paper, led by Jana Dambrogio and Amanda Ghassaei. “Sometimes the past resists scrutiny. We could simply have cut these letters open, but instead we took the time to study them for their hidden, secret and inaccessible qualities. We’ve learned that letters can be a lot more revealing when they are left unopened. Using virtual unfolding to read an intimate story that has never seen the light of day – and never even reached its recipient – is truly extraordinary.”

The letters had been preserved by the chief postmasters of The Hague, Simon de Brienne and Marie Germain and donated to the postal museum in 1926. When letters could not be delivered in the 17th and 18th century, they were held on to by employees because the recipient, rather than the sender, paid for a letter. Undelivered letters could be worth something if someone came to claim them.

The letters in the Brienne collection, say the researchers, “bear witness to the fragility of lines of communication at a time when Europe was torn by war, economic crisis, and religious differences”, and where “people moved frequently, sometimes in haste, leaving no forwarding address because they did not have one, or they were not at liberty to divulge it”.

More than 2,600 17th century letters, including 600 which had never been opened, found in a leather trunk donated to a postal museum in the Hague in 1926.
More than 2,600 17th-century letters, including 600 which had never been opened, found in a leather trunk donated to a postal museum in the Hague in 1926. Photograph: The Museum Voor Communicatie, the Hague

“The opportunity to study a letter in its closed state is really rare. Once you open a letter, you can’t study it as an unopened letter any more, so it is incredibly precious historical material to be able to study a letter packet in its closed state,” said Dr Daniel Starza Smith, a lecturer in early modern English literature at KCL and part of the Unlocking History team. “We’re actually interested in how letters work as engineered objects, and how they’re made into packets. This is really poignant material. People pour their hearts out into letters, they build emotional connections over vast distances. To think of these messages never quite getting through it is really evocative.”

The researchers believe that virtual unfolding will have an impact “far beyond” the Brienne collection, because so many collections around the world contain unopened documents.

“One important example is the hundreds of unopened items 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,” they write in the article, titled Unlocking History Through Automated Virtual Unfolding of Sealed Documents Imaged by X-ray Microtomography. “If these can be read without physically opening them, much rare letterlocking data can be preserved.”


Alison Flood

The GuardianTramp

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