CT Scans Help Crack a 400-Year-Old Lock Recovered From the Ann Francis Shipwreck

In 1583, the merchant ship Ann Francis sailed from Spain to Norfolk, England, only to be struck by a storm and driven off course on New Year's Eve that same year. The ship eventually landed on Margam Beach in southern Wales. Despite the catastrophic loss of life, including 14 crew members, the ship's treasure remained hidden for centuries.

In 2017, a metal detectorist named Peter Hughes discovered a brass combination lock among the ship's remaining treasures. The lock, along with 870 coins of Spanish, Portuguese, and Saxon origin, lay buried for over 400 years.

Researchers at Amgueddfa Cymru (Museum Wales) used micro-CT scanning technology, typically used to study biological tissue, to determine the lock's code without damaging the artifact. The technique allowed them to examine the internal structure of the brass lock and assess how the notches aligned with the letters.

Using the code "ANCE," the researchers successfully unlocked the lock. Williams, a postdoctoral research associate at Cardiff University, explained the advantage of CT scanning in examining the internal structure of objects without causing damage. The lock's four rings, each with six letters, created 1,296 possible combinations, making it a time-consuming process even with a rapid combination rate.

Hughes, the metal detectorist who found the lock, was astonished by its craftsmanship and condition after being buried for centuries. The lock, along with the coins and other artifacts, sheds light on the ship's history and the tragic fate of the Ann Francis.