Reading a 300-year-old letter that can never be opened4 min read

Reading Time: 3 minutes

Have you ever wondered how letters were kept private before the invention of the envelope? Did all secret information have to be conveyed in person? Was nothing a secret? Well, humans have had secrets forever, and we’ve also always had the urge to share them. But at the same time, we want privacy, and oh! the lengths that we’ll go to ensure of it!

Before the simple sticky envelope and now encrypted text messages, people practised vintage anti-snooping techniques. There was a well-established process involving intricate folds and slits that secured the letters of even the Queen. Welcome to the world of “letterlocking“. A complex system where simple cuts and folds can prevent you from opening letters for over 300 years!

Watch the letterlocking technique that was used by Mary Queen of Scots, the queen of Scotland, to secure her letter:

In a letter dated July 31, 1697, Jacques Sennacques wrote a letter to his cousin Pierre Le Pers. He had letterlocked it to make sure its contents remained private. If anyone had tried to tamper with the letter, they would have had to cut the paper itself. With no way to un-tear the sheet of paper, the snooping perpetrator would always get caught. Unfortunately, his cousin never got the letter, and it remained tucked away in a wooden chest with 2000 other undelivered letters.

Conservationists held this chest of letters close but didn’t have the heart to open them. Once they tore open the letters, the intricate letterlocking system would be lost. They compromised and gave up historical information to preserve a lost art. That was until the snooping, prying ways of dentists gave researchers an idea. What if they could read the letters without opening them at all?

The Dental Link

Enter the X-ray machines that are commonly used by dentists. These machines look into your mouth and paint a 3D picture of your teeth by making them look bright against a dark background. They identify the minerals in your teeth and make them glow. What if the ink on the letters could glow in the same way?
The ink that was used in the 1700s to write letters has very high metal content. The X-ray identifies the metal in the ink, and makes the writing stand out. But it’s all folded up, so how do they decipher what’s being said? That’s where good old technology comes in.

The X-ray generates a 3d picture of the letter, its writing and its folds, and then an algorithm unfolds the letter and reads it. This algorithm can be used to read all sorts of damaged texts and tightly wound scrolls. Thanks to this odd pairing of dentistry and letterlocking, we now have the potential to unlock a whole lot more of human history.

The Letter

With Excerpts From: CNet, The Hindu, SciNews, Letterlocking.net and, ArtNet.