Jefferson disk

[8] The manuscript was apparently forgotten until it was discovered in 1922 (a year after M-94 entered service, see below) by historian Edmund C. Burnett studying the Continental Congress.

[9] It doesn't appear that the device was ever fabricated,[6] and Jefferson abandoned the idea after receiving a description of columnar transposition cipher from Robert Patterson in 1803, which he found more practical.

[10] In the early 1980s NSA acquired for its museum a large incomplete device of Jefferson's type (picture 1 of this article) with 35 remnant disks (out of 40 originally) and 42 characters, including French letters, on each.

A device mechanically similar to Jefferson's but somewhat improved was independently re-invented in 1891 by Commandant Etienne Bazeries, but did not become well known until he broke the Great Cipher, of Rossignols.

He forwarded his experiments up the Signal Corps chain of command, and in 1917 Joseph Mauborgne refined the scheme, with the final result being the M-94.

It was used by the Army, Coast Guard, and the Radio Intelligence Division of the Federal Communications Commission until early in World War II.

The Army changed back to Hitt's original slide scheme with the "M-138-A" cipher machine, which was introduced in the 1930s and was used by the US Navy and US State Department through World War II.

Marquis Gaetan Henri Leon Viarizio di Lesegno), who is famous for one of the first printing cipher devices (1874), solved the Bazeries cylinder in 1893.

Due to the large size of this number, trial and error testing of the arrangement of the disks is difficult to perform by hand.