Editing Jefferson disk (section)

=== Basis for later military ciphers ===
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]].{{sfn|Friedman|1918|p=225}} In 1893, French mathematician Arthur Joseph Hermann (better known for founding [[Éditions Hermann]]) redesigned the device to use 18 flat wooden or cardboard strips.<ref name=":0" /> Cryptologists in other countries also considered similar devices.

The Bazeries cylinder was the basis for the US "[[M-94]]" cipher machine, which was introduced in 1922 and remained in service until 1942. In 1914, Parker Hitt experimented with the Bazeries device, building one prototype using slides on a wooden frame, with the cipher alphabets printed twice consecutively on the slides, and then another using disks of wood. 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.

The M-94 used 25 aluminium disks on a spindle. It was used by the [[United States Army|Army]], [[United States Coast Guard|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. The M-138-A featured 100 strips, with 30 selected for use in any one cipher session. It was an improvement in security for the [[State Department]], which during the interwar years had used insecure codes, even in one case a standard commercial [[telegraph]] code.