The Special Fish Report

The original document is held in The National Archives and Records Administration (NARA) 8601 Adelphi Road, College Park, Maryland

NR 4628 SPECIAL FISH REPORT (BOX 1417)

This Report was written by Albert W. Small an American cryptanalyst in the US Signal Corps who was seconded to Bletchley Park and joined the Newmanry to work on breaking the German Lorenz cipher.

Formatted for HTML and PDF by Tony Sale © March 2001

Note: These pages should be read only as a convenient web-based overview of the document and not as a definitive edition. As you will be able to see from those portions of the document left as GIF scans, Albert Small's report was typed, informally and inexpertly, on a non-mathematical typewriter, with many characters blurred. Handwritten characters, diagrams and marginal notes were added. It is logically impossible to render the content faithfully on the screen. In fact to make the work even more difficult, the document as made available from NARA was a white-on-black photographic inversion of the original typescript.

A technique has been developed using scanning, image inversion, Optical Character Reading, and translation into HTML format, which attempts to display each page as closely to the original as possible, respecting the idiosyncratic use of spaces and punctuation by the author. However because different browsers interpret HTML code differently, this cannot be achieved with real consistency.

The representation of the mathematical and technical symbols is also only offered in a preliminary version. As an illustration of the problems encountered, one has to distinguish x as a 'cross' in ciphertext, x as a 'score' measuring excess of dots or crosses, capital X as a sum of scores, and the Greek Chi character referring to the Chi-wheels of the Lorenz machine. An additional difficulty with HTML is that not all browsers support the Greek alphabet. As a temporary solution, a text representation has been adopted, as explained on the "Current Notations" page at the end of the document. The results are not entirely satisfactory and it is intended to go on to a second stage of editing in which subscripts, superscripts and Greek letters are more properly represented.

A further problem is that pages 30-54 and 85-92 are work sheets, some of which are A3 size. For the time being these have been omitted. It is hoped to add these when a suitable method has been found for displaying them.

The OCR technique has required an enormous amount of editing to clear up mis-read characters. I am indebted to Frode Weierud and many others for help in proof-reading. Reporting of any remaining "garbles" would be greatly appreciated.

For all the above reasons, anyone conducting research into this material should obtain their own copy of the original document, and not rely on this webpage version for quotation or citation.

However, despite all these deficiencies, it has seemed important and worthwhile to place this 'overview' version of the document on the Web. It gives a unique insight into the work of Bletchley Park at the height of its powers, as well as a fascinating reflection on Anglo-American relations. Above all, this arduous task has been undertaken because of the interest in Colossus and the need to fully understand and debate the wartime use of Colossus to enable the completion of the Colossus Rebuild Project under the direction of Tony Sale.



Click here for PDF version (370Kb)

Go to document start or browse using the INDEX

INDEX

Introduction Breaking Key from Anagramming Breaking Motor Wheels Characteristics of D Characteristics of Delta-D Colossus Colossus Key Control Board "Cribbing" Dragon Garbo Key Breaking on Colossus

Machines Used in Newmanry Messages in Depth Motor and Psi Runs Mrs. Miles Other Aids to Key Solution Psi Breaking by Hand Setting PSI's by Hand The Tunny Machine Wheel Breaking Wheel Setting Appendix: Current Notations

Back to the index page for Tony Sale's Codes and Ciphers in the Second World War.

This page is created by Tony Sale (tsale@qufaro.demon.co.uk) the original curator of the Bletchley Park Museum, and Secretary of the Bletchley Park Heritage Society.

Technical assistance from Andrew Hodges