Typex Mk III Exp ciphering machine, complete in fibre transit case, c. 1945. Electrical impulses were transmitted through 5 drums or wheels, arranged in a pre-determined order. A message was typed with the left hand whilst turning the handle with the right, achieving 20 words a minute. Cypher, or plain text, was printed onto paper tape, to be transcribed into a communication system. Typex Mk III Exp ciphering machine in case c. 1945