‘Unsolvable’ Code Hidden in Antique Dress Pocket Is Finally Cracked

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The National Oceanic and Atmospheric Administration (NOAA) has revealed a fascinating tale hidden within two mysterious messages found in a secret pocket. A decade ago, archaeologist and vintage dress enthusiast Sara Rivers Cofield stumbled upon a hidden pocket in an 1880s dress, unveiling two crumpled pieces of paper. What did she find written on those pieces of paper?

Deciphering the Mysterious Code

In a blog post in February 2014, Rivers Cofield shared the astonishing discovery of the dress and its intriguing content. The cryptic words, initially deemed among the 50 most “unsolvable” codes globally by NOAA, sparked widespread fascination.

However, the tide turned last year when Wayne Chan, a research computer analyst at the University of Manitoba in Canada, unraveled the mystery. It turns out that these enigmatic words were once a covert language for transmitting local weather updates via telegraph—that’s right, the secret codes were weather forecasts.

The Antique Dress’s Secrets

Cofield’s blog about the bronze-colored dress set the internet abuzz. Some speculated ties to the Civil War, but the dress’s age made that unlikely. A more plausible explanation that emerged was transmission.

Shutterstock // Everett Collection

Back in the telegraph era, condensing information was crucial to save costs, as telegraph companies charged by the word. In a fascinating 2023 paper published in the journal Cryptologia, Chan shed light on this practice. Encoding messages proved to be an effective strategy to reduce expenses.

Wayne Chan’s Decoding Journey

The quest to decode the telegraphic messages led Wayne Chan on a thorough search through 170 different codebooks, initially yielding no success. However, his persistence paid off when he stumbled upon a book containing the U.S. Army Signal Corps’ weather code.

Wikimedia Commons // United States Department of Commerce — Weather Bureau // Public Domain

Armed with the code book and additional resources, Chan deciphered that the messages originated from US and Canadian Army Signal Service weather stations. For instance, the line “Bismark, omit, leafage, buck, bank” conveyed that in Bismark, the temperature was 56 degrees Fahrenheit with a barometric pressure of 30.08 Hg (encoded as “omit”). “Leafage” indicated a dew point of 32 degrees at 10 p.m., while clear skies, no precipitation, and a northward wind at 12 miles per hour (“buck”) completed the weather report. How clever is that?