BLETCHLEY PARK RESEARCH PAPERS

This page contains previously unpublished technical research reports written at Bletchley Park during World War Two by some of the key codebreaking figures. These papers consist mainly of proposed improvements to the variants of the British Bombe Machine, a key tool in the breaking, on an industrial scale, of the German Enigma system.  Research and development was a key part of the Bletchley Park operation during World War Two. When the Bombe machines were put into production, Hut 6 and 8 staff were continually looking for new ways to exploit and improve their operation. These research papers were written by Hut 6 and Hut 8 staff between 1940 and 1944. While a number of the ideas proposed were never put into action, they do show the innovative thinking which was encouraged in both sections.

1. Definitions 

Gordon Welchman 

9 September, 1940 

Describes the operation of a ‘Bombe’, a ‘Spider Bombe’ and a ‘Hand Bombe’. Other tools described include a ‘Turing attachment’, a ‘Welchman attachment’, a ‘machine gun’, ‘shortening plugs’ and ‘cut-out wheels’. It sets out some of the problems faced by Hut 6 and Hut 8 staff and gives a statement of their requirements.  

 

2. The need for spiders 

Gordon Welchman 

Autumn 1940 

Describes the number of ‘Spider Bombes’ needed to deal with the problems faced by Hut 6 and Hut 8. It estimates that between 50 and 60 machines are needed and recommends that all BTM (British Tabulating machine Company) work should be devoted to the ‘Spider Bombe’.  

 

3. Spider Number 3 

Gordon Welchman 

Autumn 1940 

Describes the operation of the ‘Spider Number 3’ or ‘Jumbo Bombe’ with three diagonal boards. It also describes the function of the ‘sensing relays’. It contrasts this to the ‘Standard Spider Bombe’ and the appropriate use for each variant of machine. 

  

4. Spiders (Second Note) 

Gordon Welchman 

Autumn 1940 

Describes ‘Banbury Jobs’ which involve the use of two inputs for each bank of drums on the Bombe. It also describes the use of a ‘circuit breaker’ in the ‘sensing relay’. 

 

5. Counts 

Gordon Welchman 

Autumn 1940 

Describes a new method of attack against Enigma and encourages staff in the Hut 6 Machine Room experiment as much as possible. This applies particularly to problems with the ‘Brown’ key. It describes a process called ‘running a tape’ and ‘count letters’ in decoded messages. 

 

6. Organisation of Bombe Section 

Elwyn Jones 

22 May, 1941 

Describes the organisation of the Bombe sections in Hut 11 at BP and at Wavendon. This includes processes in place and timings for specific jobs and maintenance tasks. 

 

7. Self-steckers on Jumbo 

Oliver Lawn 

1941 

Evaluating the chance of any ordinary straight on a ‘Jumbo Bombe’ involving one, two, tree, etc self-steckers. 

 

8. A wiring for a 676 relay machine 

Lionel Clarke 

1941 

Looks at non-energised points of the main chain rows during a run. 

 

9. Proposal for a slightly different design of testing Enigma 

Oliver Lawn 

1941 

Proposes a wiring very similar to the X – machines, except that the wheels are side by side instead of gripped together. 

 

10. Note on possible development 

Gordon Welchman 

1 September, 1941 

General description of various current methods of solving a key and problems with different Bombe configurations. Makes several recommendations. 

 

11. An idea for the ‘Super Jumbo’ 

Oliver Lawn 

12 September, 1941 

Considers implications of the ‘Super Jumbo Bombe’ having 676 relays, one to each point of the diagonal board. 

 

12. Second note on possible developments 

Gordon Welchman 

19 September, 1941 

Proposes the use of a one bank ‘Jumbo Bombe’ which is called a ‘Baby Jumbo’ and considers its use on ‘full range’ problems where 17,576 positions per wheel order needed to be tested and ‘short range’ problems’ in which only a few positions need to be tested. 

 

13. Note to Commander Travis 

Gordon Welchman 

12 September, 1941 

 Current problems are described along with a proposal to introduce three new machines: a ‘super test plate’, and two machines of the bombe type but with refinements which will save running and testing time. The names ‘Mammoth, ‘Baby Jumbo’ and ‘The Quagger’ are given to the machines. 

 

14. Third note on possible developments 

Gordon Welchman 

22 September, 1941 

Refinements to the proposals in paper 12 are described. 

 

15. Specifications, etc 

Oliver Lawn 

October, 1941 

Considers possible ways of running a given menu on various machines including: ‘Ordinary Jumbo’, ‘Mammoth B’, ‘Mammoth A’, ‘Baby Jumbo’. 

 

16. Interim report on developments in mechanization 

Oliver Lawn, Nigel Forward 

October, 1941 

Discusses the current position with different Bombe variants and how various menus would be run. 

 

17.  Report on ‘Intelligent Selection’ by the Junior Sub-Committee of Mechanization 

Nigel Forward 

October, 1941 

Describes the method of intelligent selection and compares it with more rigid methods.  

 

18. Notes on impossible developments I 

Author unknown (listed as D.B.S.) 

17 November, 1941 

Describes the idea of running two short cribs and comparing the stecker given, first with two or three fixed letters and then with the rest. 

 

19. Notes on impossible developments II 

Author unknown (listed as D.B.S.) 

17 November, 1941 

The theory given in paper 18 and a calculation of how many consistent pairs of stories we expect. 

 

20. Notes on impossible developments III 

Author unknown (listed as D.B.S.) 

17 November, 1941 

Papers 18 and 19 continued and discusses the possibilities of using short beginners (or endings) and reasonable menus.  

 

21. Notes on impossible developments IV 

Author unknown (listed as D.B.S.) 

17 November, 1941 

Describes a mechanical method of sorting various sets of steckers punched on two cards so that two cards are brought together if they have on them sets of non-contradictory steckers.  

 

22. Notes on impossible developments V. Application to present work 

Author unknown (listed as D.B.S.) 

17 November, 1941 

The ideas in papers 18-21 are applied to new developments with the Red key. 

 

23. Banbury bombe with applications to Wehrkries 

Author unknown (listed as D.B.S.) 

18 February, 1942 

Description of how to use the right hand wheel and possible middle wheel at the ‘testing’ or ‘machine gun’stage. 

 

24. Note to Gordon Welchman and Harold Fletcher 

Oliver Lawn 

16 March, 1943 

Note suggests several minor alterations be made soon to the panned alterations and improvements to the ‘Mammoth’ and ‘Jumbo’ Bombes. 

 

25. Permuted wheel orders 

Oliver Lawn 

27 July, 1942 

An account of the methods of fitting a permuted wheel order device on a Bombe. 

 

26. Baby Jumbo 

Oliver Lawn 

8 September, 1942 

Specification of a ‘Baby Jumbo’ with an account of what the Hut 6 team want it to do. 

 

27. Double inputs on ‘Fortress’, ‘Kanga’ and ‘Warspite’ type machines 

Author listed as Warrant Officer, R.A.F., Head of Section, Hut 11 

18 March, 1942 

A description of the method of scanning, testing and printing which occurs on Warspite and Fortress. 

 

28. Hoppity transcended (Peggity or non-stoppody) 

Nigel Forward 

Autumn, 1942 

Describes how if the ringstellung is known, use can be made of the fact that any particular position for the encoding of a message implies a particular value for the message setting. 

 

29. Bombes (H.S. Bombes) 

Gordon Welchman 

Autumn, 1942 

Presents ideas about ‘High Speed Bombe’ (produced entirely by Keen and recording stops); ‘Super High Speed Bombes’ (same as previous machine but with Wynn Williams attachment); ‘High Speed Mammoth’ (produced entirely by Keen and recording only stories, ie stops which involve no contradictions); ‘Super high Speed Mammoth’ (same as previous machine but with Wynn Williams attachment). 

 

30. Resistance method of Mammoth sensing 

Joseph Eachus 

15 October, 1942 

Suggests that Mammoth testing may be done with relatively little additional equipment if we depend on the sensing relays of the bombe for the detection of straights. 

 

31. Report on four wheel Bombes 

Gordon Welchman 

31 October, 1942 

Describes the main requirements and the relative merits of valves and relays. Reports on developments at BTM, by Flowers on input sensing and Wynn Williams ‘Cobra’ attachment. 

 

32. Selection tests 

Oliver Lawn 

5 November, 1942 

Describes how the Bombe looks for a ‘partial key’ and a possible discrepancy between what the Bombe is looking for and what the crytanalysts are looking for which makes certain ‘partial keys’ inherently more likely to be correct than others. 

 

33. Orange Bombe 

Lionel Clarke 

Autumn 1942 

Describes a Bombe running known stecker jobs with plug-in contacts to make specific connections and 12 inputs. 

 

34. The running of menus 

Oliver Lawn 

12 December, 1942 

Examines the time taken to run various menus and the merits of running a stroner menu on two banks only. 

 

35. The ‘Orange attachment’ to a Bombe 

Oliver Lawn 

29 December, 1942 

Proposes methods for plugging and using a known stecker. Two schemes are described along with how they would work on certain problems. 

 

36. Bombes (a note to Commander Travis) 

Gordon Welchman 

11 April, 1943 

Describes how general lines of policy are becoming fairly clear and that concentration should be on the best use of Bombes for three wheel jobs. Recommends lawn’s method for using a batch of five M4 machines. 

 

37. High speed Bombes for three wheel jobs 

Gordon Welchman 

28 March, 1943 

Describes how to make best use of high speed Bombes for three wheel problems until they are needed regularly for four wheel problems. 

 

38. Bombe copies 

Oliver Lawn 

Spring 1943 

Describes how menus are sent via telephone. 

 

39. Special jobs 

Oliver lawn 

4 June, 1943 

Describes jobs with ringsettung cut-in and stecker knock-out are sent to Hut 11A to simplify plugging. 

 

40. Menuranda 

Oliver Lawn 

24 June, 1943 

Tips and hints for menu making. 

41. The Click machine 

Oliver Lawn 

16 October, 1943 

Describes the machine which consists of the right-hand wheel and stecker of eight enigmas and the theory of its operation. 

 

42. The test plate 

Oliver Lawn 

16 October, 1943 

Describes the function of the test plate, an electrically driven enigma with separate stecker boards for the input and output. 

 

43. Application of ringstellung range to Bombe 

Autumn 1940 

John Herivel 

The first description of hoppity using rignstellung ranges and an estimate of the time saving involved with such a method. 

 

44. Sensing on the B.T.M. high speed machines 

Gordon Welchman 

August 1943 

Describes the timing of the pulsing gear and circuit breakers on the high speed Bombe and the improvement offered by a commutator design change to enable a continuous pule. 

 

45. ‘One self-stecker’ sensing 

Oliver Lawn 

30 August 1943 

Describes two single input methods and one double input method giving single input stops. 

 

46. Block stecker restriction 

Hugh Alexander 

Summer 1943 

Describes how to exploit the tendency on 4 German naval keys for letters close together to be stickered together. 

 

47. Delayed hoppities 

Oliver Lawn 

23 August, 1943 

A statement of when it is worth  making a short crib into a delayed hoppity rather than running a lot of menus. 

 

48. Use of high speed Bombes 

Oliver Lawn 

24 August, 1943 

A stamen of the use of 2 x 4-wheel high speed Bombes of the ‘Cobra’ type and 11 x 4-wheel Keen Bombes on 3-wheel jobs. 

 

49. Albatross steckers 

Oliver Lawn 

4 September, 1943 

Describes the albatross stecker which has ‘fixed stecker distances’ for each day and how to make up menus to deal with it. 

 

50. ‘Production model’ Bombes 

Joseph Eachus 

Describes the American naval Bombes with details of carry, etc but not of carry. 

 

51. G.P.O sening units 

Oliver Lawn 

23 August, 1943 

Description of the two sensing racks used with ‘Cobra’ Bombes. 

 

52. Breaking on the two-wheel Bombe 

James Aitken 

Description of the method of ‘column menus’ when a long crib is available along with a note by Oliver Lawn on changes to the Bombe required by the method.   

 

53. Preparation of material before sending to Hypo 

Author unknown 

March, 1944 

Description of the way Hypo works and the procedure for preparing jobs. 

 

54. Stecker knock out machine 

Hugh Alexander 

15 February, 1944 

Statement of the problem and of a possible method of attack which is the basis of the Duenna idea. Includes a covering letter to Welchman. 

 

55. Method for testing ‘Holmes Hypothesis for U.D. 

Hugh Alexander 

14 April, 1944 

A proof that (i) no two of the known D’s (1-9) are at a distance 13 on the Holmes Hypotheses and (ii) the D’s are not equally spaced on the Holmes Hypotheses. Uses the method of boxing. 

 

56. The analyser 

Oliver Lawn 

25 May, 1944 

Description of how the ‘Clarke test number’ is worked out gives a table of values. 

 

Image: Early staff list for part of the fledgling Hut 6 at Bletchley Park.

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