by R. V. Jones
Tuck gave me valuable help because as assistant to Lindemann he came to know a great deal about our own developments. He had already warned me about the prospects for a nuclear bomb, and he continued to brief me in this field. I was thus able to learn that the prospects for the bomb had at first dimmed because of an apparent snag in the physics, but that Rudolf Peierls had seen the way round this snag. Tuck also told me about the development of the jet engine. I was therefore well briefed about what to look for in Germany.
Tuck himself had an interesting and eventful time. On Lindemann’s behalf he had to attend various trials; one of these concerned new Army weapons, and he told me how in the lunch interval between demonstrations he had been shown into what he described as ‘a stockade full of Generals’. There were tall thin Generals, short fat Generals, Generals with flowing moustaches, Generals with clipped moustaches, and Generals with no moustaches at all. Most of them nucleated around one General who was shorter, fatter and younger than any of the rest, and he was clearly regarded as the bright boy of the General Staff. What Tuck heard him say, to general approbation was, ‘Of course, what we really need, chaps, is a gas that will go through gas masks.’ This was hailed as a brilliant idea.
Another episode from this period concerned ‘Job 74’, a project designed to settle the controversy over whether bombers could sink battleships, which still went on despite the fact that Billy Mitchell had demonstrated years before that it could be done. It would obviously be expensive to allow bombers to try to sink our own battleships, so before the war a mock-up section of a battleship had been erected on a bombing range. It was called ‘Job 74’ and by the outbreak of war, it was still unscathed despite the various bombs that the Air Force had aimed against it.
In the meantime, there had been an important development in explosive charges, using what is known as the ‘Munro Effect’. Munro had been an explosives tester in a U.S. Naval arsenal around 1900, and had noticed that when he exploded a test piece of cordite on a steel plate he found ‘U.S. Navy’ etched on the plate in mirror writing. Each piece of cordite had been stamped underneath with ‘U.S. Navy’ and it had been the hollows thus created that somehow focused the explosive effect. The effect was merely a curiosity for many years, but ultimately its potential was realized, and the ‘hollow charge’ resulted. In its simplest form this consisted of a block of explosive with a hollow cone on one face, the surface of the cone being thinly lined with a metal. If the charge were exploded in contact with armour plate, the metal liner was converted into an extremely hot tongue emerging from the axis of the cone, which proceeded to drill a deep hole in the plate.
Lindemann thought that such charges could be used in bombs against battleships, where they would easily penetrate the deck armour. He therefore proposed to explode a trial charge on the deck of Job 74. But by now the Admirals were almost as attached to Job 74 as they were to their real battleships. They argued that it was not sporting to place the charge in contact with the target, and insisted that an alternative rig of steel plates should be set up, each plate being tethered to the ground on suitable posts. Tuck was a witness of the test, which went wrong because one of the plates, weighing 50 tons, had not been properly fixed, and the force of the explosion caused it to bowl, cartwheel fashion, for one-and-a-half miles.
Tuck had his times with Lindemann. He came home one day extremely agitated. He told Elsie and me that he had just had a row with the Prof. It had started because Lindemann had badly exaggerated something Tuck had told him. Tuck had the idea of building a rocket with automatic controls so that it would run up a searchlight and therefore hit anything on which the searchlight was aimed. Many of us had previously had the same idea, and had soon found that it was at that stage impracticable, but Tuck had come in with a fresh mind and had put a scheme to Lindemann which involved building the electronic controls into a rocket of the type that was then being developed for anti-aircraft defence. The control section, Tuck estimated, would occupy about eighteen inches of the length of the rocket.
Lindemann became enthusiastic, and said that he would see whether he could get support from the War Office to make a few trial weapons. He came back telling Tuck that he had convinced them and that now all Tuck had to do was to make the weapon. It turned out that Lindemann had succeeded in convincing the War Office by telling them that Tuck could make the electronics so small that they would occupy a length of only six inches. When Tuck realized how he had been committed to something that he could not do he flared up and, according to his words to me immediately afterwards, told the Prof that he had had ‘enough of his bloody double-dealing’. A fierce row had ensued, and Tuck had retired to steady himself in the Admiralty bar before returning home. He thought that Lindemann would surely have finished with him; but to Lindemann’s credit and good sense, he backed down and Tuck stayed.
My own association with Tuck ultimately led to my being trapped by Lindemann. The incident was trivial in itself, but without it Lindemann and I might not have come together until very much later and some aspects of the war might then have gone differently. It happened that I had telephoned Tuck one day to suggest that we lunch together, but he was out of his office and a colleague left a message on his desk saying that I would telephone again at a particular time. When I did so, the telephone was answered not by Tuck but by the Prof, who had seen the note on Tuck’s desk and had sat by the telephone waiting for it to ring. He asked me why I had not been to see him, and I told him that my position was not easy because of my being on the Air Staff with Tizard but that if he would like me to come, I would do so. We arranged a meeting, and I at once went to Tizard to tell him that although I had stayed as low as possible, and well out of Lindemann’s way, I was now compromised into meeting him, and I thought that Tizard ought to know. To my surprise Tizard replied, ‘I’m glad. You could do some good. Tell him from me that I should be glad if we could stop this ridiculous quarrel at least for the period of the war and concentrate on fighting the Germans.’ I went off delighted, seeing myself as the bearer of an olive branch, and about to effect the great reconciliation. It did not turn out that way—when I told Lindemann what Tizard had said, his only response was to give a mild snort and say, ‘Now that I am in a position of power, a lot of my old friends have come sniffing around!’ So that was that.
One of my diversions during the Phoney War period was to join a Committee which Tizard had proposed with the aim of tapping the knowledge of Jewish emigrés about developments in Germany. Its chairman was C. H. Lander, a professor of engineering at the City and Guilds Institute, with British and German Jews as its main members. I was the one Anglo-Saxon apart from the chairman, and the only member in a Government position. Simon Marks, the head of Marks and Spencer, was one of the members, and we met in his headquarters. The most outstanding member of the Committee was Chaim Weizmann, who had an immense oriental presence—in fact the only other man I have ever known with such a presence was the Mahdi. I was embarrassed to find myself treated by Weizmann as the official representative of His Majesty’s Government, and he and the others seemed to imagine that they had only to suggest to me that something should be done, and H.M.G. would immediately do it. It turned out that they could not help much with information about technical processes in Germany, and so they turned to suggesting bright ideas by which Britain could win the war. Later some of the Jewish refugees helped Intelligence most courageously by going back under cover to Germany.
It was from my contact with one refugee that I found at last the explanation for the stories about engine-stopping rays. This particular refugee had been an announcer at the Frankfurt radio station, and I therefore wondered whether he might know anything about the work on the nearby Feldberg television tower that was said to be one of the engine-stopping transmitters. When I told him the story he said that he had not heard it, but he could see how it might have happened. When the site for the transmitter was being surveyed, trials were done by placing a transmitter at a promising spot, and then
measuring the field strength that it would provide for radio signals in the areas around it. Since the signals concerned were of very high frequency, the receivers could easily be jammed by the unscreened ignition system of the average motor car. Any car travelling through the area at the time of the trial would cause so much interference as to ruin the test. In Germany, with its authoritarian regime, it was a simple matter to decide that no cars should run in the area at the relevant time, and so sentries were posted on all the roads to stop the cars. After the twenty minutes or so of a test the sentries would then tell the cars that they could proceed. In retailing the incident it only required the driver to transpose the first appearance of the sentry and the stopping of his engine for the story to give rise to the engine-stopping ray.
Radar and radio aids to navigation were of course very much in my mind the whole time, and I was much excited by a recorded fragment of conversation between two prisoners of war that was given a very limited circulation by Denys Felkin from his headquarters at Cockfosters. One prisoner was telling the other about something which he called the the ‘X-Gerät’ or X-Apparatus. The beginning of a thriller could hardly have had a more intriguing title. From what little he had said it appeared that the X-Apparatus was something to be used in a bomber and, if we had overheard correctly, it seemed to involve pulses, which were presumably radio pulses. I telephoned Felkin, telling him of my interest, and we arranged to meet at his club, The Bath.
After a cautious exchange of identity cards he listened to my ideas about what the device might be, so that he could prompt the prisoners by questions that they might afterwards discuss among themselves. We in fact obtained very little more, but I thought that I ought to draw attention to the problem, and on 4th March I reported that the X-Gerät was a bombing apparatus involving an application of pulse radio technique and that there appeared to be confusion in the minds of the prisoners between two separate systems:
(a) The setting up of a system of intersecting radio beams from German transmitters so that a small area of intersection occurs in which the characteristic signals of two stations combine and give a signal which might even be made to operate the bomb release gear automatically. The significance of the X as a cross supported this.
(b) The use of an elaborated form of radio altimeter perhaps scanning the ground below and giving the position of reflecting obstacles with sufficient accuracy for bombing.
I heard nothing more about the X-Apparatus, but there was an interesting fragmentary entry on a paper salvaged during March from a shot-down Heinkel aircraft with the call sign IH+AC, which showed that it belonged to a bomber formation designated as Kampf Geschwader 26. Felkin drew my attention to the entry, of which the translation ran:
Navigational Aid: Radio Beacons working on Beacon Plan A. Additionally from 0600 hours Beacon Dühnen. Light Beacon after dark. Radio Beacon Knickebein from 0600 hours on 315°.
Much could be inferred from this entry. Ordinary radio beacons were standard navigational aids, and the navigator in a bomber could take bearings on them—knowing their positions, he could work out where he was. Typically if he were attacking England from Germany these bearings would lie somewhere to the east, say between 45° and 135° round from north. But ‘Knickebein’ seemed to be something different: 315° points due north-west, and in any event it seemed to be pre-set at the beacon itself. It therefore looked to me as though Knickebein might be some kind of beamed beacon which that day had been set to transmit in a north-westerly direction. By interrogation, Felkin obtained the further clue from one of the prisoners that it was something like the X-Apparatus, and that a short wave beam was sent that would not be more than a kilometre wide over London.
Meanwhile, Vera and I were married on 21st March and had found a very pleasant flat in Richmond Hill Court, a large-ish block situated near the brow of Richmond Hill. It was on the top floor, and commanded a view ranging from Kew Gardens round to Windsor Castle some ten miles away. With the wartime exodus from London, it had not been too difficult to find, because landlords were only too anxious to let their properties. A few weeks after we had settled in Richmond Hill Court, Gerald and Phyllis Touch came to spend the weekend with us; and as Gerald and I walked in Richmond Park on the Sunday morning I tried out my ideas on him. He was clearly in a good position to comment on the possibility of the X-Apparatus being something in the bomber which would emit pulses and from the reflected echoes show up towns, as in a map. Although he was largely responsible for this very device for use against ships, he did not think that it would work against towns because such a use would involve two contradictory requirements. In order to get sufficient sharpness of the radar beam to give useful information, a wavelength of a few centimetres would be necessary; but to give echoes that would show up towns, a much longer wavelength would be required, because with a short wavelength even the roughness of ploughed fields would give strong echoes which could be confused with those from towns. As it later turned out, this argument was incorrect, but it served its purpose in convincing me that the second of my two hypotheses about the X-Gerät was wrong, and this left only the possibility of intersecting beams.
A further encouragement to thinking about beams came from a lunch I had with Woodward-Nutt. At the beginning of the war he had suggested that he and I should lunch periodically to brief one another, with him providing a background about what was going on in our own developments and me supplying what I could about what was happening on the German side. At this particular lunch he mentioned to me that there had been a rumour from the French that the Germans had been setting up some kind of radio beam station on their frontier; and he added that he had consulted our own radio experts at Farnborough and had been surprised by the narrowness of a beam that they thought could be made.
It almost went without saying, though, that a narrow beam would require a short wavelength, and so I should be up against the old objection that I had encountered two years before in proposing the hyperbolic navigation system: short waves would not bend sufficiently around the curve of the earth to permit bombing at long range. I was therefore sensitive to any light that might be thrown on the point. One day I was talking to a relative newcomer to Signals Intelligence, Flight Lieutenant Rowley Scott-Farnie, a generous-natured rugby player who had badly injured a leg and who before the war had been in a bank. An enthusiastic radio amateur, he had joined the R.A.F. Signals Intelligence Service at the outbreak of war. Incidentally, our community of radio amateurs in Britain was to prove an invaluable reserve, both in Signals Intelligence and in Signals proper, as well as furnishing many of the staff for our rapidly increasing number of radar stations.
Scott-Farnie and I were discussing the possibility that the Germans might already be working on centimetric wavelengths, and wondering what our chances of interception were if they were doing so. Scott-Farnie showed me a short report by Mr. T. L. Eckersley of the Marconi Company, who was the country’s leading expert in radio propagation. On a purely theoretical basis, Eckersley had computed the range at which a transmitter sited at the top of the Brocken (the earlier object of Charles Frank’s and my attention) and working on a wavelength of 20 centimetres, could be heard. If Eckersley’s calculations were correct, the waves would bend round the earth to a surprising extent, and might well be received by a bomber flying at twenty thousand feet over our east coast. I asked Scott-Farnie for a copy of Eckersley’s map, which I placed in my files.
War had now started in earnest. On 9th April the Germans invaded Norway. There was an Intelligence lesson for us to learn, because a day or so before one of our reconnaissance aircraft had taken photographs of Bremen harbour, which was full of shipping for the intended invasion; but because this was our first photograph there was nothing with which to compare it, and so the photographic interpreters did not realize that the state in the port was anything other than normal. This taught us the value of routine cover.
A minor aspect of the Norwegian Campaign was afterwards related to me by Colonel Ar
chie Crabbe of the Scots Guards. The Guards had instructions to land near Narvik and make contact with the local Norwegian Forces. Determined to do everything properly, despite the danger of the situation, they marched from the beach and set up headquarters with neat precision, as though they might still have been at Pirbright. This sang froid defeated them in their main purpose, because the few cautious Norwegians who observed them decided that a Force behaving with such cool confidence in the prevailing military situation could only be German, and it took two days before they were able to make any contact with the Norwegians at all.
On 10th May the Germans invaded the Low Countries, and with astonishing ease captured the very strong and key fortress of Eben Emael, near Liège. No more than 85 glider-borne troops had mastered a garrison of 750: how had they done it? Hitler gave orders that the method was to be kept secret, and so I spent some time finding out. It transpired that, like ourselves, the Germans had at last decided to exploit the possibilities of the hollow charge: their troops had placed such charges on the cupolas of the fort, blowing holes in them and immobilizing the guns. It was an instance where both sides in secrecy had undertaken exactly the same development, in contrast to others like centimetric radar or the V-2 rocket, where one side built up an overwhelming lead.
Within a few days it was clear that our Army was in dire trouble. Once again, there was the kind of alarm that we had experienced at the beginning of the war, and S.I.S. wanted to ensure that the new Prime Minister, who had taken over on the same day as the invasion of Holland and Belgium, could not hold it against them for failing to warn him about any weapon that might appear, and so I was asked to up-date my secret weapon report. I did not like the way things were going, not only because of our military situation but because of the way people were ‘flapping’ about it. I therefore used the occasion to inject a sense of proportion and one of my opening paragraphs, which admittedly drew on the wisdom of my old colleague E. G. Hill at Teddington, ran:
