The old letters were protected from prying eyes as the sheets of writing paper were carefully folded to become their own safe envelopes.
The first step of their digital opening is to scan a target letter with an advanced X-ray machine. The resulting three-dimensional image – like a medical scan – reveals the letter’s internal configuration. A computer analyzes the image to undo the folds and makes the layers almost magically a flat sheet, revealing the handwritten text that can be read.
The team translated one of the digitally opened letters from the Brienne collection. It was dated 31 July 1697 and sent from Lille, France, to a French merchant in The Hague. This appears to be a request for a certified copy of a death certificate. The letter also asked for ‘news about your health’.
More information about the Brienne collection, the article added, could enrich studies not only of postal networks in early modern Europe, but also of the region’s politics, religion, music, drama and migration patterns.
In addition to announcing the technique of unlocking the letters without damaging them, the team studied 250,000 historical letters that led to ‘the first systematization of letter-locking techniques’. The scientists and scholars found 12 formats of closed letters – the most complex with an overall shape defined by 12 edges – as well as 64 categories that include manipulations such as stitches, slits and folds. The team gave each lock letter a security score.
Dr Smith of King’s College London, who gives lectures on early modern English literature, said that art is so diverse that a person’s lock can almost serve as a signature. He says a letter becomes an ambassador for you and must embody something of you. ‘
Without the ability to digitally unlock letters, it took a decade before scholars concluded that Mary, the Queen of Scots, had secured the letter to her brother-in-law with a distinctive spiral pattern. According to the team, the virtual unfolding could have documented the move ‘within a few days’.