to find a row that makes sense. For example, a simplified "toy" Bazeries cylinder using only ten disks might be organized as shown below, with each disk "unwrapped" into a line and each marked with a designating number: If the "key", the sequence of disks, for this Bazeries cylinder is 7,9,5,10,1,6,3,8,2,4 and the encrypter wants to send the message "" to the decrypter, the encrypter rearranges the disks as per the key and rotates each disk to obtain the plaintext, which is shown at the left, with spacing added for clarity: the encrypter then selects the ciphertext from the sixth row of the cylinder up from the plaintext. This ciphertext is also highlighted above with spacing, and gives: When the decrypter gets the ciphertext, they rearrange the disks on their cylinder to the key arrangement, rotate the disks to give the ciphertext, and then read the plaintext six rows down from the ciphertext, or look over the cylinder for a row that makes sense. Basis for later military ciphers The Bazeries cylinder was the basis for the US "M-94" cipher machine, which was introduced in 1922 and derived from work by Parker Hitt. In 1914, Hitt had 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 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. 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. Cryptanalysis The Bazeries cylinder was a relatively strong system at the time (compared to many other systems in use), and Etienne Bazeries, a French military cryptanalyst, is said to have regarded it as indecipherable. The