An Antique Dress Held a Secret: A Coded Message From 1888

Mr. Chan, the analyst, said in an interview that he first worked on the code in the summer of 2018, but gave up after a few months without getting anywhere. At the end of 2022, he revisited it, poring over some 170 telegraphic code books in an attempt to find the answer, to no avail. Another book, with a section detailing signals used by the U.S. Army Signal Corps, seemed to contain examples similar to the note found in the dress. After further research, he was finally able to decode it.

And, lo and behold, it was a weather report.

“When I first thought I cracked it, I did feel really excited,” Mr. Chan said, noting that it took a while to build enough evidence to confirm his theory was correct. “It is probably one of the most complex telegraphic codes that I’ve ever seen,” he said.

For example, “Bismark Omit leafage buck bank,” indicated the reading was taken at Bismarck station, in the Dakota Territory. “Omit” was for an air temperature of 56 degrees and pressure of 0.08 inches of mercury, though the National Oceanic and Atmospheric Administration has said the true reading could have been higher. “Leafage” for a dew point of 32 degrees, observed at 10 p.m. “Buck,” clear weather, with no precipitation and a northerly wind. “Bank,” a wind velocity of 12 miles per hour, and a clear sunset.

Old maps helped Mr. Chan figure out the exact date of the observations: May 27, 1888.

Some mysteries surrounding the dress, however, remain — including who owned it, and why she would have had weather codes stuffed in a secret pocket.

“It’s tantalizing,” said Ms. Rivers Cofield, who found the dress, noting that a name, “Bennet,” was written on a paper tag stitched into the garment.