New York: McGraw-Hill Book Company, (1982). First printing. Black and white illustrations. Hardcover. Octavo. x, 326 pages. Fine in a fine dust jacket. Binding is still tight. Just a few slight extremity rubs to jacket. B.
Welchman was a mathematician working at Bletchley Park, analyzing Nazi German Enigma intercepts. Some progress had been made, but the decoding process took so long that the information was of little use by the time it was transcribed.
Welchman made a fundamental breakthrough when, late in 1939, a technological shortcut flashed into his mind that cut the process from several days to less than a thousandth of a second.
Welchman went on to head Hut 6 at Bletchley, and this is his first hand story. Clipped obituary of Welchman written by noted cryptographic historian, David Kahn, is laid in.