actually decrypt short German messages. They transferred longer messages to paper tape and ran them through an M-8. The M-8 was actually a converted U.S. encryption machine known in the Navy as an E.C.M.(42) The M-8 used rotors wired to match those on the Enigma. When cryptanalysts fed the paper tape into the machine, it automatically decrypted the message and printed it out in German. Linguists in another office translated the messages into English for use by the military commanders.

In some cases the Germans double-enciphered messages. They altered the message using a specific codebook before they actually enciphered it on the Enigma. This required additional cryptanalysis by the Allies before a message could be read. To break these messages, cryptanalysts used a captured or reconstructed codebook to strip off one layer of encryption. They could then proceed in the normal routine to retrieve the actual communication.

By the close of 1943, seventy-seven of the requested ninety-six Bombes ran continuously at the Naval Communications Annex. More machines continued to arrive throughout 1944. Improvements made to the standard N-530 resulted in the N-1530. Dayton personnel also built and sent other variations of the Bombe to Washington. These machines worked on other specialized Enigma-type problems. Throughout the remainder of the war, as the Germans altered their Enigmas, the U.S. Navy and National Cash Register kept pace.

With only eighteen four-rotor machines built, and only three of those running routinely, Britain's four-rotor Bombe project never met expectations. In fact, the U.S. Navy cryptanalytic Bombes proved so successful that Britain gave up production of its four-rotor Bombes. In a dispatch to the U.S. Navy, Britain admitted, 'Performance of our machine is still poor and likely to remain so. In view of your 4-wheel capacity being more than adequate, priority is being given here to the production of new 3-wheel