Neither Snow nor Rain nor Gloom of Night nor PUZZLES

While Harriet Russell was a student at the Glasgow School of Art, she decided to put the local post office to the test. She sent herself a series of letters. On each envelope, she hid the address inside a puzzle or cipher.

It was only a game. She didn't expect the letters to ever arrive. But out of the 130 she sent, only 10 failed to reach her. The Glasgow postal employees, as it turns out, were happy to play along. Even as the puzzles grew more and more complex, the letters kept arriving.

(In an odd turn of events, Russell later discovered that her own great-great grandfather had engaged in a similar battle of wits with the postmen of his day. A private secretary to Queen Victoria, he regularly sent letters to his children with their addresses hidden inside elaborate illustrations.)

Russell's puzzles can now be found in a book entitled, Envelopes: A Puzzling Journey Through the Royal Mail. Read more (and see more illustrations) here.