The Dorabella Cipher

It was the year of Queen Victoria’s Diamond Jubilee, 1897. Through a periscope, England was sailing along in all its hope and glory. That summer Edward Elgar turned 40 and was slowly emerging as the country’s greatest composer.
...
On July 14, following a visit the previous weekend to some family friends, the Reverend and Mrs. Alfred Penny, Elgar spun off what looked like a drawing or scribble and gave it to his wife, Alice, to attach to a thank-you note. It was intended for Dora Penny, a 23-year-old ardent admirer, who sang in a local choral group and liked to dance.
...
The scribble, known as the Dorabella Cipher, has never been decrypted and stands with such other famous unsolved puzzles as the Voynich Manuscript, a 240-page codex dating from the 15th century; the Phaistos Disk, an apparently Bronze-age piece of clay found in Crete in 1908; and the Zodiac Killer ciphers of the 1960s and ’70s.