Ralph Erskine

Alan Turing: The Enigma, by Andrew Hodges. London: Burnett Books, 1983. 18.00. New York: Simon and Schuster. $22.50. 587 pp. 8(4): 332 336.

The title, of course, holds the key - and not only for readers of this journal. Alan Turing worked at the United Kingdom's Government Code and Cypher School ("GC&CS") at Bletchley Park in World War II, mainly on cracking Enigma. He was also a fascinating, and complex, person. He played a major part in designing the British electro-mechanical bombes, which were used to ascertain the key settings of Enigma machines by the probable word method, a task for which his talents and prewar research made him almost uniquely qualified [1]. It was a massive stroke of good fortune for GC&CS and his country that, while at Princeton in 1938, he declined the offer of a post as assistant to John von Neumann unless, as seems unlikely, he had been approached by GC&CS before his departure for America in 1936. However, Bletchley was only a small part of Turing's life, notwithstanding that it was vital to the Allied cause. He was, first and foremost, an applied mathematician of genius and a profoundly original thinker in the fields of computers and machine intelligence.

This review concentrates on the author's treatment of Turing's work at GC&CS (pages 160 to 314). One reviewer has commented that "Andrew Hodges' account of the mathematical, logical and engineering work in the whole Enigma story is, perhaps, the...