More than 600 years ago, someone folded, sealed, and posted a letter that was never delivered. Now scientists have digitally “unfolded” these and other similarly locked letters, found in a 17th-century suitcase in The Hague, using X-rays.
For centuries before sealed envelopes were invented, sensitive correspondence was protected from prying eyes by means of complex folding techniques called letterlocking that turned a letter into its own secure envelope.
However, locked letters that survive to this day are fragile and can only be physically opened by cutting them into pieces.
The new X-ray method offers researchers a non-invasive alternative, preserving the original folded shape of a letter package.
For the first time, scientists applied this method to ‘closed’ letters from the Renaissance period, kept in a suitcase that had been in the collection of the Dutch postal museum in The Hague since 1926.
Computer generated animation of sealed letter DB-1538. (Unlock the History Research Group Archive)
See also: Photos: Treasury with unopened 17th century letters
The contents of the trunk contains more than 3,100 undelivered letters, of which 577 are unopened and with a letter lock. Known as the Brienne Collection, the letters are written in Dutch, English, French, Italian, Latin and Spanish.
For unknown reasons, once they reached The Hague, the missives were never delivered to their intended recipients and were instead kept by a postmaster named Simon de Brienne, Live Science previously reported.
Locked letters used a variety of mechanisms to keep them securely closed, including folding and rolling; crevices and holes; pleats and adhesives; and a variety of cleverly constructed locks, according to a study published online March 2 in the journal Nature Communications
To penetrate the layers of folded paper, the study authors used an X-ray microtomography scanner designed in the dental research labs at Queen Mary University of London (QMU).
Researchers designed the scanner to be exceptionally sensitive so that it could map the mineral content of teeth, “which is invaluable in dental research,” study co-author Graham Davis, a QMU professor of 3-D X-ray imaging, in a study. statement.
“But this high sensitivity has also made it possible to dissolve certain inks in paper and parchment,” added Davis.
The trunk filled with sealed letters. (Unlock the History Research Group Archive)
“The rest of the team was then able to take our scan images and convert them into letters that they could open virtually and read for the first time in over 300 years,” study co-author David Mills, a facilities manager. X-ray microtomography at QMU, the statement said.
Based on the scans, the team built digital 3D reconstructions of the letters and then created a computer algorithm that deciphered the advanced folding techniques fold-by-fold and virtually opened the letters “while retaining letter blocking,” the study said.
The scientists digitally opened four letters using this groundbreaking method, deciphering the contents of one letter, DB-1627.
It was written on July 31, 1697 by a man named Jacques Sennacques to his cousin Pierre Le Pers, who lived in The Hague. Sennacques, a legal professional in Lille, France, requested an official death certificate for a relative named Daniel Le Pers, “perhaps because of a legacy issue,” the scientists wrote.
“His request was made, Sennacques then spends the rest of the letter asking for news about the family and recommending his cousin to the grace of God,” the authors wrote. “We don’t know exactly why Le Pers did not receive the letter from Sennacques, but given the traveling merchants it is likely that Le Pers has moved on.”
(Unlock the History Research Group Archive)
Tens of thousands of such sealed documents can now be unfolded and read virtually, the researchers reported.
“This algorithm takes us straight to the heart of a closed letter,” the research team said in the statement. “Using virtual unfold to read an intimate story that has never seen the light of day – and never even reached the recipient – is truly extraordinary.”
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This article was originally published by Live Science. Read the original article here.