Image: Smithsonian's National Postal Museum
Swedish feather letter, c. 1808.
“Feather letters” like this one appeared in Sweden from the mid-1700s to mid-1800s. The feather indicated that the letter needed to be delivered quickly, and the squiggly line is a kind of shorthand for Sweden’s national symbol: three crowns. It directed that the letter be sent through the royal mail.
