Letters from 17th-century European aristocrats read by scientists – without even being opened

CAMBRIDGE, Massachusetts – Scientists were able to read a sealed letter from the 17th century for the first time – without even opening it! The team digitally “unfolded” the letter using a dental scanner. They used the highly sensitive device to “virtually unfold” the 300-year-old document, protecting its precious seal.

The ingenious origami-style “letter lock” was common for secure communication in the 17th century, long before modern envelopes were used. The packages thus secured could only be studied by cutting them up – until the development of an automatic system. calculation algorithm. The algorithm enabled the international team of scientists – including researchers from the Massachusetts Institute of Technology – to decipher the contents of the Brienne Collection, a postmaster’s trunk containing 2,600 undelivered letters, of which nearly 600 remain. attached.

The safe belonged to Simon and Marie de Brienne, a couple at the heart of the European communication network. It was bequeathed to the Dutch Postal Museum.

17th century trunk of letters bequeathed to the Dutch Postal Museum in The Hague. The trunk belonged to one of the most active postmasters of the time, Simon and Marie de Brienne, a couple at the heart of the European communication network. The safe contains an extraordinary archive: 2,600 “locked” letters sent from all over Europe to this line of communication, none of which has ever been delivered. Sealed packets of letters from this trunk were X-ray microtomographically scanned and “virtually unfolded” to reveal their contents for the first time in centuries. (Queen Mary University of London)

The letters were sent from all over Europe to The Hague in the Netherlands between 1680 and 1706. The intended recipients could not be found or refused to pay the unpaid postage, so Brienne kept the documents, hoping someone would end up paying for them.

Written in French, Spanish, Latin, Italian, Dutch and English, some letters were written by aristocrats. They offer a fascinating glimpse into the life of Europeans at the time.

“Our work aims to make an intervention in the conservation of cultural heritage. Once a document such as an unopened letter is damaged during the opening process, we lose the feeling that the object is intact and intact, ”explain the authors. in their paper. “The physical evidence that a letter preserves for its internal security – including very fleeting evidence of the folds and order of the layers, which usually leaves no physical traces – can now be kept for investigation.” Our methods therefore create an opportunity for the heritage sector to protect the integrity of documents even when it is necessary to access their content.

The power of X-ray microtomography “virtually unfolds” 17th century letters

The extraordinary archive includes a message from Jacques Sennacques dated July 31, 1697, to his cousin Pierre Le Pers, French merchant, for a certified copy of the death notice of a Daniel Le Pers. A watermark in the center of the paper containing an image is also visible of a bird.

The letter provides a fascinating glimpse into the lives and concerns of ordinary people during a tumultuous period in European history, when networks of correspondence united families, communities and commerce over vast distances. “We demonstrate our method on four Renaissance Europe packages – by reading the contents of an unopened letter for the first time,” write the authors. “Before, we only knew the name of the intended recipient, written on the outside of the package of letters.”

Scientists first scanned the quartet of folded letters using X-ray microtomography. The machine created cross sections to produce a simulated 3D model.

“We designed our X-ray scanner to have unprecedented sensitivity to map the mineral content of teeth, which is invaluable in dental research,” says study co-author, Professor Graham Davis of the Queen Mary University of London, in a study declaration. “But this high sensitivity has also made it possible to resolve certain types of ink in paper and parchment. It’s amazing to think that a scanner designed to look at teeth has taken us this far.

The algorithm, based on an analysis of 250,000 historical letters, identifies and separates the different layers by “reverse engineering”. The words become visible because the ink produces a different contrast than the paper. This allowed the authors not only to read them, but also to see the crease patterns and to experience the locking process step by step.

“We were able to use our scanners to the history of x-raysSays study co-author Dr David Mills, also from Queen Mary University. “The scanning technology is similar to medical CT scanners, but uses much more intense X-rays that allow us to see the tiny traces of metal in the ink used to write these letters. The rest of the team were then able to take our scanned images and turn them into letters that they could virtually open and read for the first time in over 300 years.

17th century letter
The DB-1627 letter pack has been virtually unfolded and read for the first time since it was written 300 years ago. The letter contains a message from Jacques Sennacques dated July 31, 1697, to his cousin Pierre Le Pers, French merchant, for a certified copy of the death notice of a Daniel Le Pers. A watermark in the center of the paper containing the image of a bird is also visible. (Massachusetts Institute of Technology Libraries)

Similar methods have been used to virtually unwind and reconstruct famous manuscripts, such as the Dead Sea Scrolls.

‘Letterlocking’ a first form of security and confidentiality

The study sheds new light on the historical security of communications. The letters have unique wax seals, which capture the fingerprints of certain senders. They also turn and overlap to become their own envelopes, preventing thugs and spies from reading their secrets.

“The challenge is to reconstruct the intricate folds, creases and slits of unopened letters secured with ‘lettering’ – a practice that underpinned global communications security for centuries before modern envelopes,” the study explains. Before the proliferation of mass-produced envelopes in the 1830s, a letter, one of the most important communications technologies in human history, was sent using letterlocking.

“It was a daily activity for centuries across cultures, borders and social classes, and plays a vital role in the history of secrecy systems as the missing link between the world’s physical communications security techniques. ancient and modern digital cryptography, ”the authors write. .

‘Small time capsules of information’

Virtual unfolding could now be used on hundreds of unopened items in the Prize Papers, an archive of documents confiscated by the British from enemy ships between the 17th and 19th centuries. Scientists hope that the “Signed, Sealed and Undelivered” project will contribute to a wider policy studies, religion, migration, music, theater and postal networks in early modern Europe.

“This algorithm plunges us into the heart of a locked letter. Sometimes the past stands up to scrutiny. We could have just opened these letters, but instead we took the time to study them for their hidden, secret and inaccessible qualities, ”says co-author Dr Jana Dambrogio, of the Wunsch Conservation Laboratory at the Libraries of the United States of America. MIT, in a statement. by South West News Service.

“We have learned that letters can be much more revealing when they are not opened. Using virtual unfolding to read an intimate story that never saw the light of day – and never even reached its intended recipient – is truly extraordinary, ”she adds, describing the letters as“ little time capsules of information ”.

The results are published in Nature Communication.

South West News Service writer Mark Waghorn contributed to this report.

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