X-rays help scientists read Renaissance mail ‘closed with letters’

A computer generated description of the virtual step-by-step display of the chart.

A computer generated description of the virtual step-by-step display of the chart.
Picture: Courtesy of the Unlocking History Research Group archive.

In July 1697, Jacques Sennacques of Lille, France, wrote a letter to his merchant cousin, Pierre le Pers, in The Hague. The topic of discussion was a death certificate for their relative, a topic the cousins ​​had previously discussed, but which Pers had forgotten to follow up on. The letter was the Renaissance equivalent of “according to my previous email”, and has just been read for the first time since it was sealed 324 years ago.

But even though it was read, the letter remains unopened. It’s lettered, a term coined by MIT curator Jana Dambrogio for letters that use specific folds and grooves to seal them, without the need for an envelope. Letter lock it was the typical way to seal messages in the days before mass-produced envelopes; Queen Elizabeth I of England had at least five different variations of letter blocking to privatize her correspondence.

In a unique application of the technology, Dambrogio’s team “unfolded” Sennacques’s epistle virtually using X-ray microtomography, allowing the researchers to bypass the often damaging process of manually opening a letter. The team’s investigation was published Tuesday in the journal Nature Communications.

A virtual display of the centenary letter.
Gif: Courtesy of the Unlocking History Research Group archive.

“I remember a feeling of glee, as in, [oh my god] we finally did, ”said co-author Rebekah Ahrendt, a musicologist at Utrecht University, in an email. “After having worked with this collection for several years, the effect of ‘I am probably the first person to read this since it was written’ has faded a bit … That said, this letter is a wonderful example of the concerns of normal people right now. “

It is not known why Pers never received the letter; Given your profession, you may have moved. But the sealed letter was left in the care of the Hague postmasters, Simone de Brienne, and his wife, Marie Germain. The couple did not rule out the attached family matter because in those days the letters were bought by the recipients, not paid for by their senders. Some postal administrators were left with unclaimed letters in case someone came to buy them. The couple in charge of the Hague post office were either hoarders or decidedly optimistic, because they held onto the letters until they died. Thousands of letters from Brienne and Germain were kept in an old trunk, and 600 of them are unopened messages with shrapnel; is an astonishing set of European conversations suspended in time, now called the Brienne Collection. The collection is housed in the Sound and Vision museum in The Hague.

By shooting X-rays through the letter written by Sennacques, he obtained the iron-rich ink smear that he noted on each fold of the letter. The intensity of the X-rays was about a third of that used by the same machine for its original purpose: imaging teeth and bones.

Computer-readable results, with the letter's faint watermark in the center.

Computer-readable results, with the letter’s faint watermark in the center.
Picture: Courtesy of the Unlocking History Research Group archive.

“We started with a very high resolution CT scan of the folded letter pack, basically a 3D X-ray image,” said co-lead author Amanda Ghassaei, the lead algorithm engineer on the project who has previously worked on the simulation of the origami folds, in an email. “From there, our algorithm detects individual layers of paper in the scan and reconstructs the folded geometry. This computational pipeline allows us to observe the writing, watermarks, stamps, internal folds and any other information hidden within the packet of letters without damaging the original artifact. “

But that was not enough. The team also had to decipher the folded letter, understanding which characters fell on the unfolded version. To do this, they employed a computational flattening script, to deconstruct the letter without touching it. Although it was an imperceptible hodgepodge of outsiders, sheathed in khaki paper, the research team was able to extract the message without problems.

The research team did not code any of the folded designs of Sennacques’ handwriting; the algorithm made the geometric elevation heavy.

The Renaissance casket contains missives from around the world sent to The Hague.

The Renaissance casket contains missives from around the world sent to The Hague.
Photo: Courtesy of the Unlocking History Research Group archive.

“The message and the intricate internal mechanics of these letters are only known to us because they have been virtually reconstructed,” said co-author Holly Jackson, an undergraduate student at MIT and the project’s algorithm engineer. “Our methods are completely automatic, without biases in the orientation of the scan and do not require prior knowledge of the folded geometry of a pack of letters.”

So, to create the new article, the team used X-rays to detect the ink design on a hundred-year-old piece of paper, built and implemented an algorithm to virtually unfold that paper, and described the contents of that letter alongside. a complex dictionary for the various letter blocking techniques as a major practice in days before envelopes. Essentially, the job was threefold.

The sum of these efforts is a well-defined plan of attack for the roughly 600 lettered items left in the chest. The scruples of cousins, the marital disputes, the state secrets, who knows?

It’s the closest history can get to holding your breath.


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