Alan Turing: The Enigma (3 page)

Much more positive detail
could now be given regarding his secret wartime work. Even in the 1992 preface to the Vintage edition, new material could be given from the third volume of F. H. Hinsley’s official history of British Intelligence. But since the mid-1990s, raw American and British documents on Second World War cryptanalysis have been officially released, and it has been possible to elucidate the internal story with far more details than Hinsley allowed. What has emerged has only enhanced the quality and significance of Bletchley Park work, and of Turing as its chief scientific figure. The Park itself is now a famous visitor attraction, though its lesson, that reason and scientific methods were the heroes of the hour, has not really caught on.

These documents show how on 1 November 1939 Turing could announce ‘the machine now being made at Letchworth, resembling, but far larger than the Bombe of the Poles (superbombe machine).’ That prefix ‘super’ dramatised the advance that my explanation (p. 183) was unable, for lack of supporting narrative detail, to highlight as the crucial breakthrough. Turing’s own 1940 report on the Enigma-breaking methods clarified how he made this advance, called ‘parallel scanning’. All of this is now working physically in the rebuilt Bombe at the Bletchley Park Museum. In addition to the document release, members of the original cryptanalytic team have written fully about the technical work, such as the details of the bigram tables which made the Naval Enigma so much more challenging, and the statistical Banburismus method. The super-fast bombes, the break into the Lorenz cipher, and the now-famous Colossus are all open to study, a great deal being due to the inspiring work of the late Tony Sale. The description in this book is now unnecessarily hazy. On the other hand, there was no room for any more codebreaking technicalities in the book, and the reader will not be seriously misled by its summary.

In particular, these revelations have only reinforced the significance of the ‘Bridge Passage’ between the logical and the physical, Turing’s top-level liaison visit to the United States in the winter of 1942-3. His report of 28 November 1942 from Washington, now released, documents the difficult and anomalous position he faced,
including an initial confinement to Ellis Island (p. 242). He was not overawed by the US Navy: ‘I am persuaded that one cannot very well trust these people where a matter of judgment in cryptography is concerned.’ Something that I had heard only as rumour in 1983 has been confirmed: on 21 December a train brought Turing to Dayton, Ohio, where the US Bombes were under construction. There is also more revealed on his initiation into the most secret US speech encipherment technology. There is more on his response to it, the Delilah speech scrambler − an interim report dated 6 June 1944, and a later complete description. As a precursor of the mobile phone, this belongs to the future, whilst the Enigma was a mediocre adaptation of 1920s mechanical engineering. This new material only underlines that in the post-war period, Turing had a unique knowledge of the most advanced American technology, as it emerged from victory in 1945.

This fact draws further attention to the question of what he did for GCHQ after 1948. In the 1992 preface I floated the suggestion that this might have been connected with the now famous Venona problem of Soviet messages. But there has been no comparable release of GCHQ or MI5 documents on 1948-54 to indicate the nature of his work, or to show how the British (and American) State dealt with the arrest and trial. The recently published history of GCHQ
³
opens by saying that ‘Today it is more important than ever — yet we know almost nothing about it’.

No Turing Diaries have emerged to reveal the enigma of Alan Turing’s inner life, or to pose new puzzles; no new lovers have told stories. No great treasure troves of correspondence have come to light. But a few gems of personal writing surfaced too late for the 1983 book, and were included in the 1992 preface. They are given again here.

A cosy continuity between King’s College, Cambridge, and the pre-war codebreaking establishment is evoked by some brief letters placed in the King’s archive in 1990. ‘Dilly Knox, who is my boss, sends you greetings,’ wrote Turing on 14 September 1939 to the Provost, John Sheppard. ‘It is always a joy to have you here’, wrote back the Provost, encouraging him to visit. The economist J. M. Keynes, who looked after the question of Turing’s fellowship for the duration of the war, also knew the older generation of codebreakers (and indeed had apparently enjoyed an intimate relation with the ‘boss’). These connections lend further colour to my description (p. 148) of how in 1938 Turing’s interest in ciphers could have been transmitted to the British government, thus making possible his fateful appointment.

The following
account, which in 1983 was only available in Polish, also concerns the early months of the war.
⁴
It settles the question raised in note (4.10) as to whether Turing was the personal emissary who took the new perforated sheets to the Polish and French cryptanalysts. Indeed he was: there is no mistaking his voice in this account of their farewell supper.

In a cosy restaurant outside Paris staffed by Deuxième Bureau workers, the cryptologists and the chiefs of the secret decryptment center, Bertrand and Langer, wished to spend an evening in a casual atmosphere free of everyday concerns. Before the dishes ordered and the choice wine selected for the occasion had been served, the attention of the diners was drawn to a crystal flower glass with flowers, placed on the middle of the tablecloth. They were delicate rosy-lilac flowers with slender, funnel-shaped calyces. It was probably Langer who uttered their German and then their Polish names: “Herbstzeitlose … Zimowity jesienne….”

This meant nothing to Turing, as he gazed in silence at the flowers and the dry lanceolate leaves. He was brought back from his reverie, however, by the Latin name, Colchicum
autumnale (autumn crocus, or meadow saffron), spoken by mathematician-geographer Jerzy Rózycki.

“Why, that’s a powerful poison!” said Turing in a raised voice.

To which Rózycki slowly, as though weighing each word, added: “It would suffice to bite into and suck at a couple of stalks in order to attain eternity.”

For a moment there was an awkward silence. Soon, however, the crocuses and the treacherous beauty of the autumnal flowers were forgotten, and an animated discussion began at the richly laid table. But despite the earnest intention of the participants not to raise professional questions, it proved impossible to get completely away from Enigma. Once again, there was talk of the errors committed by German operators and of the perforated sheets, now machine-rather than handmade, which the British sent in series from Bletchley to the Poles working at Gretz-Armainvillers, outside Paris. The inventor of the perforated sheets, Zygalski, wondered why their measurements were so peculiar, with each little square being about eight and a half millimeters on a side.

“That’s perfectly obvious,” laughed Alan Turing. “It’s simply one-third of an inch!”

This remark in turn gave rise to a dispute as to which system of measures and currency, the traditionally chaotic British one or the lucid decimal system used in France and Poland, could be regarded as the more logical and convenient. Turing jocularly and eloquently defended the former. What other currency in the world was as admirably divided as the pound sterling, composed of 240 pence (20 shillings, each containing 12 pence)? It alone enabled three, four, five, six or eight persons to precisely, to the penny, split a tab (with tip, generally rounded off to a full pound) at a restaurant or pub.

The dark tone of Turing’s knowledge of poisonous plants, arising unexpectedly in the midst of secret work and mathematical banter,
recalls the manner of his death. The shock of that event is vividly portrayed by another first-account, that written by Turing’s housekeeper Mrs Clayton on the night of Tuesday 8 June 1954:

My dear Mrs Turing

You will by now have heard of the death of Mr Alan. It was such an awfull shock. I just didn’t know what to do. So I flew across to Mrs Gibson’s and she rang Police & they wouldn’t let me touch or do a thing & I just couldn’t remember your address. I had been away for the weekend and went up tonight as usual to get his meal. Saw his bedroom light on the lounge curtains not drawn back, milk on steps & paper in door. So I thought he’d gone out early & forgot to put his light off so I went & knocked at his bedroom door. Got no answer so walked in, Saw him in bed he must have died during the night. The police have been up here, again tonight for me to make a statement & I understand the inquest will be Thursday. Shall you or Mr [John] Turing be coming over[?] I feel so helpless & not able to do anything. The Webbs removed last Wed. & I don’t know their new address yet. Mr & Mrs Gibson saw Mr Alan out walking Mon. evening he was perfectly all right then. The weekend before he’d had Mr Gandy over for the weekend & they seemed to have had a really good time. The Mr & Mrs Webb came to dinner Tues. & Mrs Webb had aftern[oon] tea with him Wed. the day she removed. You do know you have my very deepest sympathy in your great loss & what I can do to help at this end you know I will continue to do so.

Yours respectfully, S. Clayton

This account indicates how the police took charge of the house immediately, leaving open the possibility that there was information
in official hands not made public at the inquest. It is now in the archive at King’s College.

The police also feature in two valuable letters written by Alan Turing himself to his friend Norman Routledge, and now also in the archive. The first, undated, must be from early 1952:

My dear Norman,

I don’t think I really do know much about jobs, except the one I had during the war, and that certainly did not involve any travelling. I think they do take on conscripts. It certainly involved a good deal of hard thinking, but whether you’d be interested I don’t know. Philip Hall was in the same racket and on the whole, I should say, he didn’t care for it. However I am not at present in a state in which I am able to concentrate well, for reasons explained in next paragraph.

I’ve now got myself into the kind of trouble that I have always considered to be quite a possibility for me, though I have usually rated it at about 10:1 against. I shall shortly be pleading guilty to a charge of sexual offences with a young man. The story of how it call came to be found out is a long and fascinating one, which I shall have to make into a short story one day, but haven’t the time to tell you now. No doubt I shall emerge from it all a different man, but quite who I’ve not found out.

Glad you enjoyed broadcast. J[efferson] certanly was rather disappointing though. I’m rather afraid that the following syllogism may be used by some in the future

Turing believes machines think

Turing lies with men

Therefore machines do not think

Yours in distress, Alan.

The allusion to the traditional
syllogism about Socrates, who drank the hemlock, is an extraordinary piece of black humour. (It also stands as a superb example of how Turing himself fused the elements of his life.) The opening of the letter is perhaps equally remarkable in its absurdly off-hand description of six years of crucial wartime work, and in its inexplicable statement that the work had not involved any travelling.

The second is dated February 22, and must be from 1953:

My dear Norman

Thanks for your letter. I should have answered it earlier.

I have a delightful story to tell you of my adventurous life when next we meet. I’ve had another round with the gendarmes, and it’s positively round II to Turing. Half the police of N. England (by one report) were out searching for a supposed boyfriend of mine. It was all a mare’s nest.

Perfect virtue and chastity had governed all our proceedings. But the poor sweeties never knew this. A very light kiss beneath a foreign flag under the influence of drink, was all that had ever occurred. Everything is now cosy again except that the poor boy has had rather a raw deal I think. I’ll tell you all when we meet in March at Teddington. Being on probation my shining virtue was terrific, and had to be. If I had so much as parked my bicycle on the wrong side of the road there might have been 12 years for me. Of course the police are going to be a bit more nosy, so virtue must continue to shine.

I might try to get a job in France. But I’ve also been having psychoanalysis for a few months now, and it seems to be working a bit. It’s quite fun, and I think I’ve got a good man. 80% of the time we are working out the significance of my dreams. No time to write about logic now!

Ever, Alan

The style is a reminder that
whilst Turing’s plain-speaking English might be compared with that of Orwell or Shaw, it also had a strong element of P. G. Wodehouse. Both letters perhaps indicate a state of denial about the seriousness with which those in charge of the nosy ‘sweeties’ would contemplate his Euro-adventures.

Alan Turing used logarithms of betting odds as the key to the work he had done for the ‘racket’ of cryptography, and his sustained fascination with probability is illustrated by that reference to a one-in-ten chance of being caught. In his 1953 stoic humour there is a link with innocent Anti-War undergraduate days of twenty years earlier, when he analysed Alfred Beuttell’s Monte Carlo gambling system. While the tectonic forces of geopolitics ground away, Alan Turing dodged his way through as a nimble, insouciant, individual. The lucky streak did not last for ever.

As well as these addenda, this Preface should also confess to corrigenda. Inevitably, a number of errors are perpetuated by reprinting this text. Here are some examples. Note (2.11) on normal numbers understates the significance of normal numbers and of his friend David Champernowne’s 1933 contribution. It seems possible that Turing’s study of such infinite decimals suggested his model of ‘computable numbers’. The note (3.40) on Turing’s work on the Skewes number is inaccurate: his incomplete manuscript actually dates from about 1950 when he briefly resumed this work, and corresponded briefly with Skewes. Audrey née Bates (p. 401) did more interesting and substantial work than is suggested; her Master’s thesis involved representing Church’s lambda calculus on the Manchester computer, an advanced idea which was never published. This sharpens the point made on the footnote on that page, concerning how Turing failed to turn his vision for programming and logic into the creation of a lively school of research and innovation. One clue to the problems he faced comes from her recollection that ‘Max Newman made the immortal statement that “there is nothing to do with computers that merits a Ph.D.”’ The NDRC (p. 300) was the US National
Defense
Research Committee; a machine called EDVAC (p. 355, footnote)
was
built. In 1945-47 Alan Turing lodged in Hampton village, a mile
south of the Hampton Hill incorrectly mentioned on page 317, and the house is now marked by a blue plaque, as indeed are the places of his birth and death. Further additional and corrective material may be found on
www.turing.org.uk
.