A mysterious cryptogram was discovered in the secret pocket of a 135-year-old silk dress, leading to widespread speculation among the cryptoanalysis community.

• The dress contained 12 lines of seemingly random strings of words.
• It was discovered by Sarah Rivers Coffield, who bought the dress in 2013 and shared the cryptogram on her blog.
• Theories about the cryptogram's purpose included Civil War messages and secret communications.

Wayne Chan's extensive research through telegraph codebooks led to the identification of the cryptogram as a series of weather observations.

• Chan was drawn to the cryptogram by speculation and examined 170 codebooks without finding a match.
• He noticed similarities to telegraph weather transmissions and contacted the US National Oceanic and Atmospheric Administration.
• The cryptogram turned out to be US Army signal service weather code from May 27, 1888.

Despite solving the cryptogram's content, the reason why it was hidden in the dress pocket is still an unsolved mystery.

• The cryptogram included a weather report from Winnipeg on a cold spring day.
• Chan speculates that a woman working for the signal service office in Washington may have hidden the codes.
• The purpose of the codes being in the dress remains unknown, part of the ongoing mystery.