Machine against Machine

As explained in the preceding chapter, Tutte invented a way of finding the settings of the Tunny’s chi-wheels, but the rub was that his method seemed impractical. It involved calculations which, if done by hand, would consume a vast amount of time—probably as much as several hundred years for a single, long message, Newman once estimated. The necessary calculations were straightforward enough, consisting basically of comparing two streams made up of dots and crosses, and counting the number of times that each had a dot, or cross, in the same position. Today, of course, we turn such work over to electronic computers. When Tutte shyly explained his method to Newman, Newman suggested using high-speed electronic counters to mechanise the process. It was a brilliant idea. Within a surprisingly short time, Newman’s factory of monstrous electronic computers, dedicated to breaking Tunny, was affording a glimpse of the future. Electronic counters had been developed in Cambridge before the war. Used for counting emissions of subatomic particles, these had been designed by C. E. Wynn-Williams, then like Newman a Cambridge don. Newman knew of Wynn-Williams’ work, and in a moment of inspiration he saw that the same idea could be applied to the Tunny problem. Tutte invented his method in November 1942 and the following month Newman was given the job of developing the necessary machinery. Newman worked out the cryptanalytical requirements for the planned machine and called in Wynn-Williams to design the electronic counters. Wynn-Williams was by then involved in wartime research at the Telecommunications Research Establishment (TRE) in Malvern. Newman and TRE approached an expert on teleprinter equipment, F. O. Morrell, head of the telegraph and teleprinter group of the Post Office Research Station at Dollis Hill in North London, to engineer the other parts of the machine. Construction of Newman’s machine started in January 1943 and a prototype began operating in June of that year, in the newly formed Newmanry. The Newmanry consisted initially of Newman himself, Michie, two engineers, and 16 ‘Wrens’—members of the Women’s Royal Naval Service. The section was housed in a two-roomed hut, Hut 11, originally the first Bombe room.