Turing Sources

Alan Turing's Dayton Report, 1942

See the Alan Turing Home Page for a guide to this website

The document was found in 'Bombe Correspondence' (Crane Collection) CSNG LIB, Box 139, RG 38, Records of the Office of Naval Intelligence. I owe this discovery entirely to Lee A. Gladwin of the National Archives and Records Administration, Washington DC.

This report has also been published with an introduction and annotation by Lee A. Gladwin: Visit to National Cash Register Corporation of Dayton, Ohio, and the following article Alan Turing's visit to Dayton, Cryptologia XXV, pp. 1-17 (2001).

Turing's report runs to nine typescript pages. Pages 1, 2 and 3 are on this web-page; pages 4, 5 and 6 are on the next; pages 7, 8 and 9 are on a third.

Turing was inspecting, on behalf of the British government, the progress and plans of the U. S. Navy in building a large number of Bombes for the attack on the 4-rotor naval Enigma problem. Since February 1942 the switch to the 4-rotor machine had prevented Turing's section at Bletchley Park from reading the Atlantic U-boat traffic, with disastrous consequences. The U. S. Navy had insisted on taking over the problem. It has effectively requisitioned the National Cash Register works at Dayton for a massive building programme that was beyond the resources of British industry. The British were far from enthusiastic about losing control of the process to the United States, and Turing's report reflects a certain scepticism about American methods.

At the end of the report Turing comments on a quite different topic: progress with the 'Tunny' work on the Lorenz machine.

For more on the context of this report, go to this page of the Alan Turing Internet Scrapbook.

Continue to pages 4, 5 and 6


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Andrew Hodges