I had known that Thomas Jefferson was a well-read and well-traveled man. However, I had not known that he was a gifted inventor and scientist as well.
Before he was elected President, Jerfferson maintained homes on the Champs-Elysees in Paris and a small suite of private rooms at the Carthusian monastery in the Jardin Du Luxembourg where he could work and think in peace. Because his home on the Champs Elysees had been broken into three times in 1789, he did much of his work at the monastery.
Jefferson had an obsession with codes. One code was created using an ingenious machine he invented called the wheel cipher. The cipher had twenty-six wooden discs, like donuts or circular coasters with a hole drilled through the center of each. Each disc was a quarter of an inch thick and four inches in diameter. The letters of the alphabet were printed in random order around the edge. The donuts slid into a metal axle. From there the discs could be rotated to spell out the decoded message.
For the message to be decoded, the recipient had to have his own wheel cipher and also needed to know the order in which to place the wooden wheels along the code. Without that, any encoded message was worthless.
Jefferson felt two books were important enough to be encrypted on his wheel cipher.