“Laid off” for 300 years: Virtual Disclosure has now revealed the secrets of this letter

In 1697, a man named Jacques Senacak wrote a letter to his cousin, a French merchant named Pierre Le Purse, requesting a certified death certificate for another man named Daniel Le Purse (possibly also related). Senakke used a folding method called “letterlocking,” a type of physical cryptography, to protect the material from direct contact with the letter. The letter was never delivered or opened. For more than 30,000 years, researchers have virtually “unlocked” the letter to reveal its contents, in the shape of a bird and below the reveal mark. They described their results in a new paper published in the journal Nature Communications.

The term “letterlocking” was coined in 2000 by Jana Dambroggo, a conservative co-author of MIT Libraries, who discovered such letters as a companion to the Vatican Secret Archives in 2000. The Vatican letters date from the 15th and 16th centuries, and feature a strange slit. And the corners that were cut. Dambrogoyo realized that the letters were originally folded in an ingenious way, essentially “locked” by inserting a piece of paper into a slip, and then sealing it with wax. It was not possible to open the letter without tearing pieces of paper, – evidence that the letter was tampered with.

Dembrogio has been studying the practice of letterlocking ever since, often creating his own models to demonstrate various techniques. The practice dates back to the 13th century – at least in Western history – and has evolved folding and locking techniques over many centuries. Queen Elizabeth I, Machiavelli, Galileo Galilei and Marie Antoinette, are believed to have employed letterlocking for their correspondence.

For example, on February 8, 1587, a letter written by King Henry III of France, Mary, Queen of Scots, was sealed using the so-called “butterfly l” c – adjust one of hundreds of l king king techniques Dambroggo has compiled into a dictionary of letterlocking. Other techniques include a simple triangular fold-and-tuck and a skillful method known as a “dagger-trap”, in which one booby-trap is disguised as another, simpler type of letter lock.

According to Dambrogrio, individuals often had their own unique style of letterlocking, especially the English poet John Don, who used at least five different letterlocking styles that were unique to him. “So we’ve got this guy who is known as the most inventive and witty poet of his generation, and he’s doing one of the most inventive and witty and brilliant interlocking methods you can imagine.” He told Atlas bs Bscura in 2018. What kind of evidence can you use to say, ‘Ah, so that you can really see something in the way they put letters into people’s personalities. “

In 2012, Dembrozio hit the jackpot: a Yale researcher named Rebecca Ahrent found a trunk of 17th-century dependent characters preserved in the Postal Museum in The Hague, Netherlands. The trunk belonged to Simon and Mary D. Bryan, the highly connected postmasters and postmistresses of their day. Now known as the Bryan Collection, the trunk contains 2600 “locked” letters sent from all over Europe, 600 of which were never opened.

And challenges it. The authors wrote in their paper, “Once a document like an unopened letter is opened, we lose the sense of the object as disorganized and intact.” Virtually opening these letters helps to preserve “material evidence” about the internal security of a given letter, including “surreal evidence about tux and layer orders, which usually leave no trace.”

So Dambrogo Et al. Turning to the increasingly popular virtual “un-wrapping” techniques for the study of delicate historical documents. For example, in 2016, an international team of scientists developed a method of virtually registering badly damaged ancient scrolls found on the west shore of the Dead Sea, in which the first few verses of Leviticus’ book came out. The so-called N-Gaddy scroll was found in a river of ancient monasteries destroyed by fire around 600 CE.

In 2019, we reported that German scientists used a combination of cutting-edge physics techniques to virtually “uncover” an ancient Egyptian papyrus, part of a vast collection housed in a museum in Berlin, Egypt. Their analysis revealed that the apparent blank patch on the papyrus contained characters that had become “invisible ink” centuries later in the light. And earlier this year, we reported that scientists used multispectral imaging on four supposed Cora Dead Sea scrolls and found text hidden in the scroll that was probably a passage from Ezekiel’s book. When Queen Mary of the Scots final letter took 10 years to determine if the letterlocking technique, Dembrogio, was working Et al. Emphasize that their new virtual progress method can only be determined in those days.

For the first phase of analysis of the Brian Collection Letters, Dembrogo created his own test set of 10 model papers, which were then conceived using X-ray tomography, along with four of his original papers, by colleagues at Queen Mary University of London’s Dental Research Labs. Trunk. The scanner in question was specifically designed to be sensitive to mapping the mineral content of teeth, but it only works on certain types of ink in old paper and parchment. This was followed by a friendly process of developing algorithms to identify and differentiate different layers of folder characters, which enabled Dambrogo. Et al. Virtual disclosure and “reading” of deprived characters. It also allowed them to better detect different complex folding systems of each character as the algorithm could visualize the crease pattern.

“We’ve been able to use our scanners for X-ray history,” said David Mills, co-author of Queen Mary University in London. “The scanning technology is similar to medical CT scanners, but using more intense X-rays that allow us to see minute traces of metal in the ink used to write these letters. The rest of the team was then able to take our scans to images and turn them into letters. Which they can virtually open and read for the first time in 300 years. “

Eventually, in addition to reading Jacques Senack’s 1697 letter, the team found evidence for the development of the letterlocking technology. Letters from the Brian Collection have seen significant changes in letterlocking techniques over time, moving away from the “fold, tuck and stick” method, for example, to a more “fold and follow” approach that previews modern envelopes. Subsequent analysis is also likely to reveal deep historical insights.

“Keeping this record of human interaction with content intact, while making their secrets visible, enables a new perspective on history that is both dynamic and tactile, and that promotes new ways of thinking about the lives, feelings and creativity of historical individuals and communities. , “The authors wrote. “Doing so also challenges cultural historians to re-accept hidden, confidential, and inaccessible material as places of complex inquiry. The way letterlocking and virtual disclosure resist the way history investigates, and that resistance itself deserves patient study.”

A possible source for further study is the hundreds of undelivered letters, which were confiscated by the British from an enemy shop between the 17th and 19th centuries, without opening the archives known as prize papers. Ultimately, “we envision a complete, data-driven study that includes millions of more open letters in addition to thousands of well-known undisclosed letters, and letterlocking data globally to draw persuasive, result-oriented statements about historical epistemological security trends.” “By synthesizing traditional and computational defense techniques, we can help integrate computing tools into defense and humanity – and show that the letters become more pronounced when left unopened.”

DOI: Nature Communications, 2021. 10.1038 / s41467-021-21326-w (About DOI).

List of images by unlinking the History Research Group archive