Historical Document · 1945
The Newmanry part of Bletchley Park's 1945 General Report on Tunny: Heath Robinson, Colossus and the statistical methods, as formatted by Tony Sale in 2001.
Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 INTRODUCTION This is part of a very large (200 page) document. This section has been tackled first 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 by the Colossus Rebuild Project under the direction of Tony Sale. A complete copy of the original document is held in the Public Record Office, UK. It was written by Donald Michie, Jack Good and other members of the Newmanry, after the end of World War II and has only recently been declassified. It was found to be impossible to meet the original objective of a "photo-copy" reproduction because many pages contained over 70 lines of text. As a compromise, Courier Font has been retained, together with the original page numbers. However, a wider page width has allowed re-formatting of paragraphs to "gain some lines" and fit it onto an A4 page. The document has been produce using Optical Character Recognition (OCR), from photo copies of the original. This is a notoriously error prone task. I am indebted to Frode Weierud, Andrew Hodges and many others for correcting "garbles". Any remaining that are reported would be gratefully received and corrected. Tony Sale March 2001 Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 31B Page 276 __________________________ 31 - MR. NEWMAN'S SECTION __________________________ 31A. 31B. 31C. 31D. 31E. 31F. 31G. 31H. Growth Staff Requirements Administration Cryptographic Staff W.R.N.S. Engineer. Education Statistics Bureau 31A GROWTH In December, 1942 Mr.M.H.A.Newman was given the job of developing machine methods of setting Tunny. In April, 1943 the first machines arrived, a Robinson and a Tunny, pilot models of somewhat uncertain behaviour. Mr. Newman formed his section with one cryptographer, two engineers and 16 Wrens. The section was founded and lived (for the most part) in a single room. After three months two or three messages were set each week. By May, 1945 there were 26 cryptographers, 28 Engineers, and 273 Wrens with 10 Colossi, 3 Robinsons, 3 Tunnies and 20 smaller electrical machines. The section moved into Block F in Nov. 1943, and expanded into a new and additional Block (H) in September, 1944 in which all chi-breaking was done. In the week ending March 31st, 358 messages were set on Chis, 151 on Motors and Psis and 23 sets of new wheels were broken. The total number of log books used in 2 years was about 500. 31B STAFF REQUIREMENTS The allocation of staff at 6 monthly intervals is shown in the following table. Apr.43 Sep.43 Apr.44 Sep.44 Apr.45 (Administration | | | 1 | 2 | 2 | (Cryptographers | 2 | 5 | 6 | 20 | 22 | | | | | | | Engineers- (Maintenance | | 3 | 9 | 12 | 15 | (Construction | | 4 | 9 | 11 | 13 | | | | | | | Wrens | 16 | 16 | 28 | 180 | 273 | | | | | | | TOTAL | 18 | 28 | 93 | 225 | 325 | Finally the staff per shift was as follows: 7 Cryptographers : DO in charge of setting ( TS note: DO is Duty Officer) 1 Wheel-man in charge of wheel-breaking 1 in charge of Cribs and Robinson work 2 to supervise Colossus setting 2 to supervise Colossus wheel breaking 67 Wrens : 7 Registrars 17 Tunny Operators 2 Robinson operators 20 Colossus operators Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 31D Page 277 15 computers 1 "Cribs" assistant 5 "Room 11" maintaining contact with Knockholt. 5 Engineers and a daily requirement of 2 Research cryptographers 2 Research Wrens 13 Construction Engineers 6 Administrative Staff. 31C ADMINISTRATION As the section expanded, administrative problems became considerable. Coordinated policy was established through a "Fish Committee" under Mr. Welchman's chairmanship during the period of fastest development (May 1944 - January 1945) to determine the policy of machines to be ordered and staff to be recruited. A good deal of attention was given by this committee to the slip-reading and perforation of tape at Knockholt and every effort was made to encourage the production of material at Knockholt on a scale commensurate with the rapidly expanding capacity at this end. The administration had to keep in touch with operational results. It did this by collecting and analysing facts about success achieved in each part of the section and issuing suitable reports. The log books kept by all operators provided the required information in addition to making operators conscious of their own efficiency. 31D. CRYPTOGRAPHIC STAF F The first thirteen men to join the Section as cryptographers were drawn from other sections of GC & CS. In experience and infectious enthusiasm they preserved their lead to the end, and there were few in the section not affected by their keenness. After July, 1944 they were joined by men from other war jobs and men straight from the universities. The qualifications of men chosen are given in the following table: June 43Aug.44Date of Arrival July 44 May 45. Professional Mathematicians etc Research Students Other University Mathematicians Others ) ) 8 3 2 4 11 1 Previous cryptographic experience Enigma Fish 12 5 3 3 2 1 Age on joining 5 3 3 1 2 3 5 6 British American 11 2 13 3 TOTAL 13 16 over 30 25 - 30 20 - 25 under 20 Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 31F Page 278 Cryptographers were not organised into fixed shifts, but worked with different people each week and took it in turn to do research work and the various operational jobs. This system kept everybody in touch with up to date technique and alive to possible improvements. A weekly change of job led at times to minor administrative inefficiency and the normal term of offices for Duty officers and wheel-men was eventually extended to three weeks, these two jobs were normally filled by more experienced men. After the Section was fully staffed there were often two research men each week. Most of the important ideas were developed by men as a result of practical routine work and written up in the Research Logs. In a subsequent research period of a week or more they were at leisure to elaborate their ideas and to tackle any other problems of a pressing operational nature. Ideas for new methods, and routines for immediate instruction were discussed at the weekly "Tea Party" - a democratic assembly of cryptographic staff. 31E. W.R.N.S. Wrens were chosen by interview from those in H.M.S.Pembroke V (Category Special Duties X ). No fixed qualifications were required, though a pass in mathematics in School Certificate or apparently "good social recommendations" was normally considered essential. Though a few of the earlier Wrens were rather older and more experienced, 96 per cent of those who came were between the ages of 17 1/2 and 20. 21 per cent had Higher Certificate, 9 per cent had been to a University, 22 per cent had some other training after school training and 28 per cent had previous paid employment. None had studied mathematics at the university. On arrival a11 Wrens were given up to a fortnight's training in the teleprinter alphabet, the workings of the Tunny machine and (in some cases) in computing. This was followed by a conducted tour of the section and a written test. Wrens (unlike men) were organised in fixed watches and given fixed jobs in which they could become technically proficient. While the section remained small it was possible to try new Wrens at various jobs soon after arrival, but later, allocation was made on the basis of the test held at the end of their initial training period, and on the basis of the jobs available. The cheerful common sense of the Wrens was a great asset. Several of them showed ability in cryptographic work and several others were trained by the engineers to undertake routine testing of machines. 31F.ENG1NEERS It was decided at the beginning of the association of the P.O. Research Branch with GC and CS that maintenance of equipment would be an increasingly important part of the undertaking. It was agreed to recruit the best available men from the automatic telephone construction and maintenance staff throughout the country, to employ them at Dollis Hill and the P.O. Factory at Birmingham to build the equipment so that they should be thoroughly familiar with it, and to give them, before taking up their maintenance duties, any supplementary instruction that was necessary. As the work developed, the complexity and novelty of the equipment increased and further maintenance training was needed but the technical staff were often hard pressed to produce the equipment and instruction was neglected. A number of maintenance men made up for this deficiency by their own initiative and exertions, and passed their knowledge on to others. Full maintenance efficiency can be achieved only after some months Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 31H Page 279 of experience, and by May, 1945 equipment and maintenance had reached a very high level of performance. Telephone maintenance work is mainly done by unestablished skilled workmen and skilled workmen Class II. Recruitment for the maintenance force at Station X was made almost entirely from men in these grades aged 20 - 22 years. The first eight men came to Dollis Hill in April, 1942 a number of Chief Regional Engineers having been asked to recommend good men. A selection was made on the basis of paper qualifications, mostly City and Guilds certificates. The selection of the men after the first eight was based solely on their technical qualifications, the type of work on which they bad been engaged and (where possible) their performance at the Post office Training Centre, where men are trained for normal Post office work. The total number of men engaged in maintenance on "Fish" traffic eventually reached 45. The allocation of duties to the maintenance men was based on their previous Post office experience and the aptitude which they had shown for various kinds of work during the time they spent at Dollis Hill. For a long time a rather critical balance of manpower had to be held between maintenance and further construction. The total manpower available at the beginning of 1944 had been so depleted by the demands of the Armed Forces on the Post office Staff that no further suitable men were available, and the men already engaged - including all the manufacturing force at Dollis Hill and the P.O. Factory worked over 70 hours a week for many months. 31G. EDUCATION It was the policy of the section that all its members should be encouraged to interest themselves in all its activities and to improve their theoretical knowledge. In practice it became increasingly hard for Wrens to get a complete picture of an organisation in which they might have only done one job. Moreover the mathematical style of the Research Logs made them unreadable for Wrens, and before they (or new men) undertook chi-breaking and Colossus-setting on their own, some other introduction to the theoretical side was needed. Screeds and lectures on aspects of the work were issued or given from time to time in 1944, but nothing was done systematically till the Education Committee was founded in January, 1945. This committee of four men and 14 Wrens chosen democratically arranged general lectures end "seminars" for small parties of Colossus operators or other specialised groups. All lectures and Seminars were given outside working hours and were voluntary. The Seminars for Colossus operators were a complete success. The less mathematical general lectures were also appreciated. The Education Committee co-ordinated the production of screeds and started a General Fish Series of papers which were duplicated and available in every room. 31H STATISTICS BUREAU Wrens. In August, l944 a permanent Statistics Section was set up employing one or two The Statistics Bureau: (i) Collected routine statistics , in particular 32 letter-counts of various types, significant rectangles and numbers of messages set. (ii)Helped the administration to prepare statistical reports. (iii) Looked after the library and the publication of screeds. (iv) Helped the research man to complete any statistics that he required. Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 32 Page 280 ________________________________ 32 - ORGANISATION OF THE TESTERY ________________________________ The organisation of Major Tester's Section has been described briefly in 14B (c), and more fully in "Report on Tunny (Major Tester's Section)" and also in the separate report entitled "History of the Fish Sub-section of the German Military Section". We do not go into further details here as they are of no great cryptographic interest and are not necessary for the understanding of the present report. Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 33B Page 281 _____________ 33 KNOCKHOLT _____________ 33A ORDERING TAPES The work of Knockholt was the preparation of tapes and Red Forms (RF) for Station X and consisted of (i) Interception (ii) Slip Reading (iii) Reperforation. A tape with a single letter inserted or omitted in the middle would almost certainly fail to set, hence the need for accuracy at Knockholt. Approximately 600 people were employed there. Nevertheless there were times when the traffic ordered by us was more than they could handle. Once (Aug. 1944) an abortive attempt was made to perforate tapes in Block F. The priorities of ordering were decided by a morning meeting of various interested parties in station X. This meeting also decided priorities for machine setting and wheel-breaking. All ordering was done through the 'Control Officer' at Station X by the following procedures: A procedure Long tapes on unbroken days (according to a link priority list). B procedure Other tapes for wheel-breaking ordered individually. C procedure Tapes for setting on broken days. D procedure Messages required for Crib purposes. Depths The Control Officer was responsible for ensuring that these were teleprinted at once. 33B TREATMENT OF TAPES There were 30 receiving sets (in the Set Room). 26 covered priority links and the rest were on directed and general search. Intercepted impulses were automatically recorded on undulator tape and usually on printed and perforated tape. The undulator tape was the most reliable and was used by the "slip-readers" for improving the RF and perforated tape. In March 1945 efforts were made to save time by using the automatic perforation (RAW TAPE) when interception conditions were good. Blurred patches were marked by the operator. Sometimes dubious portions were also slip-read. The method of raw tapes is a good one provided that full slip-reading is continued until and if positive cryptographic results are obtained with the raw tape. Completely slip-read messages were passed to the reperforating room. The final tape was checked against the RF with the use of a 'hand counter', though it was not until Autumn, 1944 that a hand counter was issued to Knockholt. Increased accuracy was immediately noticeable. There were 10 transmission lines to our section. At its best the reperforation room achieved an average daily output of 400,000 letters. For further details, including auxiliary interception stations, the report by Sixta should be consulted. Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 34 Page 282 _________________________________ 34 - REGISTRATION AND CIRCULATION _________________________________ (a) Foundation of the Joint Registry Registration methods were, of course, developed early and in January, 1944 a joint registry was founded for Major Tester's and Mr. Newman's sections. This registry kept track of all material entering or circulating in either section, and itself kept all tapes, or documents for tapes, not being worked on. This avoided congestion and delays in the Newmanry. Few messages strayed and those that did were quickly recovered. (b) Division of work Work was divided between Room 12 and Block H. Room 12 dealt with tapes required for setting and the T registry in Room A, Block H, with tapes required for wheel-breaking or Cribs. An soon as a days' wheels were broken all tapes and documents for the wheel-day were sent over from Block H to Block F. (c) Cards and Circulation The basic system for all procedures was the same: the copies of each tape perforated were teleprinted from Knockholt. Later on the RF (Red Form) and Master Tape were sent by DR.(Dispatch Rider). A procedure card was started for each message and a pigeon hole allotted for the tapes and RF (See Fig 34 (I) ). In addition to the procedure card, a card was made out for each message, which accompanied the tapes on their journeys. These were used in Ops or Block H for the registration of various setting and rectangling processes. The "Ops Card" for instance was used for setting messages and it was returned to Room 12 when the message was abandoned or set. When a set of wheels was broken the relevant material was transferred from the T-Registry to Room 12 and from the H-Registry to Ops. On the other hand if the wheels for a day were not broken within a month the pigeon holes in Block H were emptied, the RF was filed and the master and another tape were stored. The pigeon holes in Block F were not cleared until a setting message was abandoned or completely decoded. In the latter case one copy of the decode was sent to the appropriate intelligence section and one copy was filed in Room 41. (d) Other Records Other records kept include registers of: All tapes intercepted. 'A' tapes and their history. Tapes for setting on broken days. Tapes transmitted from Knockholt Depths. Settings of decoded messages. Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 34 Page 283 W.S. 31a MK P.H. No.___________ Decode No. _________ Serial No.__________ Q.E.P. Date T.S. T.E. Freq. Pages __________________________________________________________________________________ Trans Date Time Pages Length Copies 1st 5 Letters Start Quality Sent to 'H' Registrar Sent to Ops. Set on Chis Set on Psis Decoded Abandoned __________________________________________________________________________________ Red Form received from KN Red Form to Ops. Red Form Returned Extra Routine Movements A. Fig 34(I) Procedure Card. Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale ____________________________ (c) March 2001 35C Page 284 35 TAPE MAKING AND CHECKING ____________________________ 35A INTRODUCTION The successful working of all parts of Mr.Newman's section depended on the accuracy and efficiency of the Tunny rooms which were responsible for looking after all copying, reading and tape-making machinery. An elaborate system of checks for all tapes made was found to be essential to prevent the early introduction of mistakes which might be reproduced unnoticed. The importance of cheeks was not realised at first and it is generally believed that the comparative lack of success in the earliest days was largely due to the use ofincorrect tapes. 35B GENERAL RULES All tapes were made twice independently and compared to ensure that no letters had been inserted or omitted. Before newly-made tapes were returned to the appropriate registrar their text length was measured on a Hand Counter and marked on the tape. All jobs involving the making of tapes (or prints) other than exact copies, were sent to Tunny with a Hand Check for the beginning which had been worked out by the Registrar. For every tape made two copies (at least) were ordered to save time in case of damage to one of them. All work was very fully labelled. 35C CHECKING AND ALTERATION OF TAPES (a) Checking tapes against Red Forms This was not strictly a Tunny Room job, but may logically be described here. For a long time every long rectangling tape and every setting tape which failed to set was checked against the appropriate Red Form. First Method The number of letters on each page of the RF was calculated and the first few letters at the top of each page recorded, The tape was wound through the hand counter and stopped at the calculated position corresponding to the end of each page. The position of the entries corresponding to the top of the next page were checked on the tape. Second Method The tape was measured out on a hand counter, marked at every multiple of 1271, and 10 letters after each mark recorded. When the RF arrived, the letters at similar positions on it, were independently noted, and the results compared. This method was suitable for rectangling tapes as it enabled a hand check for the rectangle to be made at once from the tape check. (b) Comparing two versions of the same tape It was sometimes necessary to compare two versions of the same tape, ( say an original version with its rewrite). The tapes were added together on Miles until the output tape showed that there was a slide. The place at which this occurred was marked on both tapes and the tapes were reset (to account for the slide) and the operation continued. A print-out of both versions was made on Garbo wherever discrepancies had been noted so that Knockholt could be asked to reread the undulator tape at these places and decide which version was the most likely. A composite tape could then be made embodying the best of both tapes. (e) Correction and Doctoring of tapes. This was normally done on an IBM (preferably) or Angel. The tape to be corrected was marked (with the help of a hand counter) at the places at which a letter was to be inserted or omitted. The IBM or Angel was stopped when the marks were reached and the correction made. Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 35 E Page 285 The corrected or doctored tape was compared with the first version by hand and the corrected length verified on a hand counter. It was marked CORRECTED TAPE or DOCTORED TAPE in block capitals. 35D PREPARATION OF MESSAGE TAPES (a) For Colossus Tapes were copied (on Angel) if sufficient copies were not available, or if available copies had not sufficient blanks at either end. Tapes issued were stuck into closed circuits as shown, and stop and start signs punched with a special metal gadget. An overlap of two sprocket holes was allowed at the join; the join had to be made with smooth edges and the end ( as opposed to the beginning) of the tape on the outside of the circuit. The text length was measured before the tapes were returned to the Registrar and if it failed to agree with the Knockholt estimate, Knockholt were informed. If the text length was below 1500, copied tapes were made on which the text was followed by RYRY... till the total length of text exceeded 1500. This was done by feeding a tape reading RYRY.. into the Angel input as soon as the real text had been copied. For issue to Colossi with short bedsteads very long tapes were stuck in parts of text length 10172 with an overlay of 4 between each part ( 1-10172, 10169 20340, 20337 - end) [see 53B(b)] (b) For Robinson Message tapes were prepared for Robinson as for Colossus except that a mixture of Bostick and benzene was used for sticking. The tape to be stuck was inserted between two electrically heated plates ( a 'hot sticker' ) and the benzene was evaporated. 35E MAKING OF DE-CHIS (a) Without Colossus check The settings and wheels for the de-chi were written on the chit by the Tapes Registrar with a hand check of the first 41 letters of the de-chi. The dechi was made on a Tunny machine twice, and if both makes agreed one make was stuck for Colossus or Robinson and returned to the Registrar. The Tunny was not stopped during either make. If the Delta-D count on the de-chi tape checked with that on the Z tape, the dechi tape was returned to the Tunny Room for printing (on Garbo) in rows of 31 with double spacing. To check the print the de-chi tape was marked at positions 1,621,1241 etc. Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 35 F Page 286 and the start of every 20th line on the print verified. Lines of the de-chi were numbered and the print marked with the 1st 10 letters of Z. If the Delta-D count on the de-chi tape did not check the wheels set up on the Tunny machine were checked and if no mistake was discovered the Z tape was recounted on a different Colossus. (b) With Colossus check The Tunny room was supplied with a chit giving setting and wheels and a Colossus check giving the following letters of de-chi :- 2-9,62i-624,1241-1244,18611864,2481-2484, 3101-3104 and the last 5 letters. To this the Tapes Registrar had added the settings for letters 621,1241 etc. The de-chi was made on Tunny twice. The first make was stopped automatically every 620 letters and the settings checked. This make was printed while the second make was being made. If the two makes were identical, and the print checked with the Colossus check the de-chi was assumed correct and marked and sent over as before. When the two makes agreed, but the print did not agree with the Colossus check, the Tunny wheels were checked and if correct, the Colossus check was assumed invalid, a hand check made, and the de-chi tape stuck and counted on Colossus. (c) Contraction of de-chis In days when psis were set on Robinson (on messages with X2oneback lim) the psis were run against a de-chi tape from which all letters occurring against Total Motor dots were omitted. The contracted de-chi was made on a Tunny on which motors and X2 were set up. A special switch was used and a hand check supplied. 35F WHEEL TAPES AID TEST TAPES (a) Chi test tapes These were made on Tunny. The appropriate wheels were set up at 01 01 01 01 01 and 2002 letters of chi-stream perforated. Before sticking for Colossus every impulse was checked by sliding the tape against itself at a multiple of each wheel in turn. (b) Psi test tapes These were made on Tunny with setting 01 01 01 01 01 for Psis and 01 01 for Motors. The limitation appropriate to the wheel-day concerned was used and a hand check of 61 letters supplied by the registrar. Final copies were stuck for Colossus. (c) Motor tapes Tunny can be made to perforate Basic Motor tapes from the plugged patterns of M37 and M61 and Total Motor tapes (for X2oneback lim) if X2 also set up. Motor tapes were sometimes required for printing the motor over a dechi or for doing motor runs on Robinson. A hand check of 15 letters was supplied. Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 35 H 35G Page 287 RECTANGLES (a) Garbo Rectangles. The method of making 1+2/ Rectangles on Garbo is described in 24B(c). The following practical steps were taken to ensure accuracy. The tape was measured on a hand counter and positions of the form (1271 n +2) were marked. The second letter of the tape was put in the Garbo (which deltas backwards) and the print-out was started and compared with a hand check prepared for the first few characters. Whenever 1271 characters had been printed and the paper was reset, the tape should have been on the appropriate mark and this was checked. A hand check for the last few characters was prepared, and the position of the last character printed was verified by calculation. Garbo rectangles were only made once. Different markings of the tape would have been required for a 3+4x/ or 4+5/ Rectangle. These were not made on a routine basis. A further hand check was applied to rectangles when they were returned to the H Registrar. From the check sheet prepared by her from the Z tape [see 35c(b)] a hand check for the first entries of each cycle of 1271 was made. (b) Miles and Garbo (Thurlow) Rectangles. This method of rectangling is described in 24B(d). The tape was measured and marked at positions of the form (1271 n +1). Hand checks for letters 1-10, 12711281 etc. of the Thurlow tape were prepared. Marks 1-5 on the Z tape were put in the 5 heads of Miles and the resulting Thurlow tape compared with the hand check. After it had moved 1271 times the Miles was stopped and it was verified that the second mark was in the first head, the third in the second etc. The tape was removed and marks 6-10 put in the 5 heads and so on. The start of each new stretch of 1271 was compared with the hand check. Thurlow tapes were made twice and measured to ensure that their length was a multiple of 1271 before printing. The positions 2,1273 etc. were marked and the Thurlow tape printed like a Garbo rectangle. The position of the change of depth was calculated from the Z tape, checked on the Thurlow tape and marked on the print out. A further hand check, similar to that for Garbo Rectangles, was done by the H Registrar when a Thurlow Rectangle was returned. 35H OTHER TUNNY JOBS (a) Hand Perforation. Hand perforations were most easily checked by printing out the perforated text and checking the print-out against the original. (b) Cribs. The various tapes required for Crib work are described in detail in Ch 27. (a) Other jobs. Tunny Room machinery was very adaptable and numerous non-routine jobs were undertaken. In certain cases it was necessary for hand checks to be prepared by a cryptographer who (at most) supervised the job in person or (at least) provided a sheet of careful instructions. Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 36A Page 288 ______________________________ 36 CHI-BREAKING FROM CIPHER ______________________________ 36A (a) 36A History and Resource. 36B Rectangles and Chi 2 Cap Runs 36C Times HISTORY AND RESOURCES Early wheel-breaking. Mr. Newman's section began as a section for setting messages on wheels broken from depths in Room 41. Wheel-breaking activities came later. Bream started to use P5 limitation regularly in the middle of December, 1943, and as there seemed every chance that the use of this gadget would be extended, research activities were devoted to the statistical solution of chis from Z. Tutte's method of rectangles (see Ch.44) was elaborated and from January 1944 monthly keys were tackled operationally. Significance tests were gradually instituted and methods improved. Soon after Colossus 1 arrived in February 1944 it was discovered that it could be used for chibreaking. It was this discovery that made large scale wheel-breaking possible oven after the introduction of the daily wheel change in July 1944. (b) The period of expansion. Between July and November 1944 the number of computers increased from 4 to about 16 a watch, and the number of Colossi from three to six, of which three were fitted with a rectangling device. New Garbos, Miles and arrival terminals from Knockholt were installed in Block H which opened in September and housed all wheelbreaking operators from the middle of November onwards. From August onwards extensive rectangling was rarely applied to any particular day's messages. A few long tapes on each day were rectangled and it was assumed that when the dottage was high and the interception good the rectangle would be significant. Colossus work on significant rectangles largely replaced the more laborious method of the conditional rectangle, and from the end of August a machine and a man to supervise operation could be spared most of the time. From the middle of November 1944 to May 1945 the number of machines and trained staff continued to increase, and about 15 sets of wheels broken on rectangles each week. In 1945 there were about 15 Computers per shift, whose main job was to converge rectangles on paper. The head of Computers was called the Rectangles Registrar. A man, called the Wheel Man (WM) was in charge of wheel-breaking operators and there were other men called wheel-breakers, each of whom took charge of one wheel-breaking job on a Colossus. Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 36C Page 289 (c) Checking of tapes . Needless to say the long tapes ordered on A (or B) procedure for rectangling needed to be particularly carefully checked. Therefore they were checked by us against The Red Form, as described in Ch. 35. However, after Knockholt had been supplied with a hand counter in Autumn 1944, There were so few mistakes that we stopped checking the tapes in Bletchley. 36B RECTANGLES AND CHI2 CAP RUNS There were four methods of rectangling, decried in ch. 24. Priorities were decided by intelligence value, length of tape, supporting tapes and many other considerations. Tapes were often rectangled in parts, in case of a slide in the tape. The Sum theta(i,j)^2 test was done when the Colossus had the required meter. In addition chi 2 cap runs were done on each third and the whole of each message rectangled. If X >7(tau)^1/2 the WM might start Colossus chi-breaking at once, before the rectangle was converged. If 5.6(v)^1/2<X<7(tau)^1/2 the rectangle was given priority. Very rarely the chi 2 cap run revealed a slide in the tape. (See R5 p.98.) 36C TIMES Here are the average times in hours for various processes and over various periods. The unbracketed figures are for high priority and bracketed for low priority groups. Time of interception-Arrival in Block H Time of arrival - Issue of rectangle Issue - Abandoning Issue - Significance Completion of wheels on Colossus 1944 NOV-DEC 39(56) 5(6) 21(26) 11(13) 31(27) 19145 JAN-FEB 29(41) 3(5) 11(12) 9(8) 15(14) 1945 MAR-APR 25(30) 3(4) 12(14) 7(12) 13(11) - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - W.S. 33. Date TS. TE. Lgth. Serial No. R/F. Checked Remake Ops. Rectangle Converged Significant Returned to Ops Action - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Rectangle card used by H Registry. Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 37 Page 290 _______________________________ 37 MACHINE SETTING ORGANISATION _______________________________ (a) Ops The following were housed with the Duty Officer (D.O.) (i) The Runs Registry, which organised jobs for Robinson and Colossi. (ii) The Tapes Registry, which organised jobs for the Tunny Rooms. (iii)The Logs Registrar, who maintained liaison with the Joint Registry (Rooms 11 and 12) and the T-Registry (which was the Block H branch of the Joint Registry - see Ch.34) see also Fig.37 (I). In addition there was an H registrar who warn effectively the Block H representative of the Runs Registry. The Runs and Tapes Registrars issued chits with every job ordered. These chits contained accurate descriptions of the job required and were returned with the tapes when the job wascompleted. When the Colossus tapes were returned from the Tunny Room the T.R. checked that they were correctly marked, had an adequate join, and stop and start signs in the correct place. To ensure this the first few letters of the tape were checked with those on the Ops. card. The tapes were then passed to the Runs Registrar. After a successful setting job the tapes were returned to Ops with a decode check or de-chi check and Delta-D letter count. If the job was partially successful a Delta-D letter count using as many wheels as possible was provided. When a dossier was given to the D.O. he ordered one of the following: Further runs, Decode, De-chi, or Abandon and returned the dossier to the runs Registrar. The Registries had several additional jobs. For example the Tapes Registrar kept an index of Delta-X5's so that any repetition of the same set of wheels could be spotted. (b) Robinsons and Colossi In June, 1943, when there was only one Robinson available, each message tried was a research job in itself, and every run Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 37 Page 291 was ordered separately by the Runs Registrar the Duty Officer being consulted if necessary. At this time the D.O. was responsible for all work on messages tried in the Newmanry and it was in Ops. that the psis were first set by hand in November, 1943. After this there was an almost immediate change of policy, Room 41 took over the job of psi-setting by hand, and Robinsons were used to set all five chis on as many messages as possible. This policy remained unchanged for almost a year though spasmodic efforts at machine psi and motor-setting were made. The Newmanry moved to Block F late in November, 1943: the first 'Heath' Robinson was replaced by 2 production models and others came later. Colossus 1 came in February 1944 and runs on the new machine took so short a time that it was necessary to decide policy on the spot and a Colossus man was appointed. Colossi soon replaced Robinsons for setting purposes and the duties of the Runs Registrar were increasingly confined to issuing tapes to machines in the right order and seeing that they did not stay there for too long. By the end or August no Robinsons and up to 4 Colossi were used for setting. As the number of Colossi increased Wren operators were left more and more on their own. A Colossus man was always available for consultation, and the D.O. kept a check on the accuracy of all Colossus work. From July, 1944 onwards the D.O. saw every Colossus dossier as it returned to Ops. and took over the responsibility for abandoning messages and ordering de-chis. This had previously been done by the Colossus man. By November, 1944 many new Wrens were working Colossi on their own and considerable time was being wasted. Either too many runs were done, or so few that further runs had to be ordered by the D.O. For this reason the runs normally done were standardised, the 'trees' or runs schedules varying according to the type of language and limitation expected. Departures from schedule were only made in consultation with the Colossus man. The new 'rules' had a remarkably good effect and were interpreted in an increasingly liberal way. In the Summer and Autumn of 1944 there was so much chi- setting to do that psi runs were not done. But in November, when there were 6 Colossi, Motor and Psi runs were done more often, and after December 25th it became a routine to do them on low dottage days. From March 5th, 1945, a new policy of setting motors and psis on Colossus in every possible case was adopted, exceptions only occurring on days of high dottage, or days for which motor patterns were not yet broken. Wrens soon picked up the technique and were able to do motor and psi runs on their own. The machine resources in 1945 are given in part 5. (c) Ordering The D.O. was responsible for knowing what wheel-breaking was in progress, whether on significant rectangles, key, or crib. As soon as it appeared likely that a day would come out, the D.O. (in consultation with the W.M. or head of Room 41) asked the C.O. to order the traffic from Knockholt on C-procedure, and recommended whatever priority and procedure seemed to fit the general priority of the link, date, estimated dottage, and estimated time of completion of the wheels. The priority of the wheel day was assigned by the morning meeting if it was being worked on when this took place : otherwise the priority had to be decided from the general priority list or in consultation with Hut 3 (See 33A). (d) Further Runs We referred in 37(a) to 'Further Runs'. These were of 5 main types. Part of the "General Report on Tunny", the Newmanry History, formatted by Tony Sale (c) March 2001 37 Page 292 (i) Correct Runs, where incorrect runs had been done before. (ii) More runs, runs with spannin