OT: Wow, this is cool:

Two Centuries On, a Cryptologist Cracks a Presidential Code :

For more than 200 years, buried deep within Thomas Jefferson’s correspondence and papers, there lay a mysterious cipher — a coded message that appears to have remained unsolved. Until now.

The cryptic message was sent to President Jefferson in December 1801 by his friend and frequent correspondent, Robert Patterson, a mathematics professor at the University of Pennsylvania. President Jefferson and Mr. Patterson were both officials at the American Philosophical Society — a group that promoted scholarly research in the sciences and humanities — and were enthusiasts of ciphers and other codes, regularly exchanging letters about them.

(snip)
There is no evidence that Jefferson, or anyone else for that matter, ever solved the code. But Jefferson did believe the cipher was so inscrutable that he considered having the State Department use it, and passed it on to the ambassador to France, Robert Livingston

online.wsj.com