Using computer algorithms and an X-ray scanner designed for dental research, an international team of researchers has unlocked the secrets of a well-folded letter sealed since 1697, without opening it.
The letter’s “virtual deployment” —the culmination of a four-year project described in an article published Tuesday in the journal Nature Communications — points to a new line of historical research on the centuries-old practice of letter blocking. This is the term used to describe the use of origami-like folds to hide the contents of letters before envelopes became widely used in the mid-1800s.
“This is a dream come true in the field of conservation,” said Jana Dambrogio, curator of the Massachusetts Institute of Technology research library and one of the 11 authors in the article.
Experts say the technique used to reveal the text of the letter, which includes a type of imaging called X-ray microtomography, could also have applications in health and engineering.
Letter locks varied in complexity, depending on the experience of the sender and receiver and how they wanted their messages to be fake during traffic. Some involved dozens of folds, which resulted in packets the size of letters.