Tuxedo Park

by Jennet Conant

  In late August, Compton and Loomis were asked to attend the army maneuvers taking place at Ogdensburg in upstate New York and were flown up in Secretary Stimson’s private plane. They were there to observe one of the first field tests of the army’s top-secret pulse radar system, the SCR-268. As Compton later recalled, they “were quite the envy of the high officers attending the maneuvers because not even the generals were allowed to get near enough the equipment to find out anything about its operation.” During two days at Ogdensburg, they saw the chief test, which consisted of a comparison of an airplane detection by pulse radar and by a network of volunteer observers reporting in by telephone. A huge plotting board was set up, and the army had acquired priority phone lines for volunteer observers scattered all over the upper part of the state. On the big board, all planes reported by the observers were marked down and tracked as to the type of plane, location, and heading. A parallel plotting system was set up using information acquired by the SCR-268, which, of course, won the day. They were greatly encouraged by the results with the army radar sets, which detected a flight of army planes at a range of about seventy miles.

  Loomis was largely responsible for the committee’s wholehearted sponsoring of microwave radar research. The army was skeptical, believing that microwave radar “was for the next war, not this one.” The army had already worked to improve its transmitting tubes so that the wavelength could be reduced to 11/2 meters and thought anything much shorter than that could not be perfected anytime soon. Given how slow they had been to capitalize on new technology in the past, Loomis regarded the army’s attitude as more of a reflection of their own bureaucracy than those posed by the research challenge. The opinion was also based on the peacetime experience of longer-wave radar and the fact that big companies like GE and RCA had been on the verge of shutting down their microwave work because they could not find any commercial applications. The navy viewed itself as the aristocracy of the armed forces and jealousy guarded its radar technology, making it clear that they wanted as little to do with Loomis’ committee as possible.

  But Loomis, from the outset, believed pursuing the field of microwaves was a matter of the utmost urgency. As usual, he was not afraid of advancing an idea that might be unpopular; and he was used to relying on his own counsel. Just before the Battle of Britain in July 1940, he had made a tour of the English radar research laboratories and learned that their most pressing need was for a microwave system for night fighters and antiaircraft guns. Loomis had even talked to the British about ways in which they might cooperate in the area of microwave radar, so that America could carry on the work started in the United Kingdom. Loomis knew from his own research that the chief obstacle to microwave radar was the lack of a vacuum tube capable of generating sufficient energetic radiation at such short wavelengths. Only two tubes held out any immediate hope of providing real power on wavelengths below one meter: the klystron, which they were working on at Tuxedo Park, and the Sloan-Marshall resnatron at Berkeley. Loomis was convinced that if they could just find a solution to this problem, it would lead to an enormous widening of the powers of radar.

  Almost as soon as he took charge of the microwave project, Loomis called on Lawrence to help him advance the development of the Sloan-Marshall tube with “the utmost vigor.” They desperately needed an oscillator to produce still shorter wavelengths and a satisfactory power source to go with it. “Can’t you step in and take responsibility for organizing it in a large way and have it the major war research of the University?” he asked in a hasty letter on July 9. “If a tube of 25 to 50 kilowatts at 20 to 35 centimeters were available there are some very pressing problems that could be powerfully attacked.” Loomis promised Lawrence $20,000 from the NDRC; raised $4,500 from the Research Corporation, which had patented the tube; and threw in an additional $1,500 of his own money. He concluded on a wistful note, worrying that he must be missing out on everything at the Rad Lab: “I have been thinking a great deal about the cyclotron, and I can’t tell you how anxious I am to catch up on all the new developments. . . . [Ellen] was talking last night about how wonderful it had been out there last winter ‘before the war.’ ”

  Lawrence immediately wrote back that he would take the necessary steps to see that the project proceeded “full speed ahead” and, if need be, would draw on funds from his precious 184-inch cyclotron to get the job done. It was the first microwave contract Loomis would approve, and one of the very earliest of the war effort. Loomis would go on to ask for Lawrence’s help on any number of other war-related devices, and their enthusiasm for invention and shared pleasure in pooling their imaginative ideas and practical skills are evident as they worked out their ideas for various ingenious gadgets. Taking a page right out of one of Wood’s infamous investigations on behalf of the police, as in the bombing of Morgan Bank, Loomis soon invited Lawrence’s collaboration on an important and mysterious “FBI problem” he had been approached about:

  Suppose the FBI or the Naval Intelligence Unit would like to mark certain confidential documents for the purpose of catching a person that they suspected of being a spy, especially in the case where such a person was so high up in the organization that they could not afford to make any false accusations and must have absolute and immediate proof. I suggested that a few drops of a radio active preparation could be placed at the exit of the building or other suitable place and that if such a suspected person passed near the counter they would have conclusive evidence on which to arrest and search him, whether he carried a document on his person or in his briefcase. Could you let me know what substance you would suggest and whether you could supply some small amount for test. It should of course be a substance whose radiations could easily be distinguished from those coming from the luminous dial of a wrist watch. I think we can assume that the suspect would not know the method and would not provide a lead container.

  Lawrence considered Loomis’ solution to the FBI problem “thoroughly practical” and passed along his own inspired idea for a spy-catching device:

  There are numerous radioactive substances suitable for such purposes. One that comes to mind immediately is radio-yttrium, having a half-life of 105 days and emitting a very penetrating gamma-ray . . . the radioactivity can be concentrated into hardly more than a pinpoint of material which would have its advantages if it were to be used for labelling a document. . . . I have gone ahead and assigned an assistant to Luis Alvarez to work out the design and build an extremely portable Geiger counter which could be worn inconspicuously on the person in order that a special agent might carry it and, by walking near an individual, determine whether he was carrying any radioactive material. I suggested that instead of an earphone to detect the Geiger counts that they develop an arrangement whereby the counts produce tiny electric shocks on the skin of the individual carrying the counter so that the arrangements could be kept completely out of sight. I think such a gadget might prove to be very useful.

  Loomis heartily approved the idea and wrote back that he would like to pick up the portable Geiger counter and a sample of radio yttrium when he was in California the following month so he could demonstrate the idea before naval intelligence and the FBI in Washington. He added, “I do believe that after the battle for England starts, and after we have universal conscription, this country will appreciate more and more the gravity of our situation.” After Loomis’ trip west was postponed indefinitely because of the intensifying demands of the radar work, Lawrence’s little vest-pocket Geiger counter, which he boasted was now so compact that it “takes about as much space as a New York gangster would allow for his guns,” was shipped to Tuxedo Park. Loomis showed it to “several important people” in Washington and reported that it worked perfectly. But it seemed that “carrying it on the person is not so convenient,” and he had given some thought as to how best to conceal it. He went on to elaborate his idea:

  It occurred to me yesterday that a book would probably be the most suitable. If a book was used the high tension source
could probably be obtained in a smaller space by charging a group of condensers in parallel. This would involve pressing a button on the side from time to time, but that would not be serious, especially as in that method there would be no danger of a current drain on the batteries. Could you send me two or three of the counting tubes themselves? Would you also think over the best solution to put the radio yttrium in? I should think there would have to be some chemical compound that would unite with the paper in such a way as not to make too noticeable a stain, and yet would hold the yttrium in the paper when it was dry.

  In the midst of all the urgent business at hand, the two physicists spent months writing letters back and forth detailing further refinements of the little Geiger counter, each adding his own whimsical embellishments. Lawrence pooh-poohed Loomis’ book idea as impractical and instead reported that he would be sending a new outfit based on a design cooked up by Alvarez and his assistant. The new design “gets away from the mechanical vibrator and transformer and instead uses a tiny radio frequency oscillator from which the voltage was stepped up to about 900 volts from a 45-volt battery,” Lawrence wrote, adding that it would be “compact enough to carry in one’s coat pocket with the necessary batteries in one’s hip pockets. Needless to say, the whole unit including batteries could very readily be incorporated in a book as you suggest.” He also addressed Loomis’ suggestion that they change their approach on another front—namely, the Sloan tube. Loomis had written about Sloan’s idea of producing high-speed electrons by sending powerful waves down a hollow pipe that contained bulges at proper intervals. In this case, the energy of the waves was progressively transferred to the electrons. Loomis had requested they “think carefully of the reverse process, namely, sending high speed electrons down such a tube and taking out power waves at the other end. These waves might never have to see a transmission line and might go right on out from the generator to a hollow pipe to a horn.” Lawrence exercised great care in replying to his brilliant but meddlesome friend, who was in the habit of telling everyone what to do:

  As regards your thought about reversing Sloan’s electron accelerator and using it as a micro wave generator, it is, as I can judge, a good idea and completely feasible. I discussed the matter with Sloan and Marshall, and they agreed that it is certainly a feasible idea. They said of course that they had given it much consideration, and they pointed out the Sloan tube is indeed a special case of such an idea, i.e., in which there is but one section—the first resonator. . . . It seems to me, however, that a matter of this sort is not susceptible to complete paper analysis, and I would be in favor of someone’s experimentally developing the multiple resonator arrangement to find out its good and bad points. You know as well as I do that experimental work always brings to light things of which one does not think by any amount of cerebration. . . .

  Back at Tuxedo Park, Loomis, having anticipated events, had a running start on the NDRC in more ways than one. His independent investigation of microwave radar was well under way, and as he wrote Lawrence, “We have a big group now going at Tuxedo on microwaves, it means that I am going pretty hard seven days a week.” By the time various members of the microwave committee and the NDRC started beating a path to Tower House late that summer and early fall to see what Loomis’ band of researchers had developed, an experimental apparatus had been constructed in the laboratory and was being tested with a makeshift moving Doppler target that consisted of a row of copper wires on a moving belt. The Doppler target could be run in the lab or set up in a nearby wood and detected by the lab set. Visitors were impressed that it was possible to tell whether the belt machine was running or not when it was remote from the actual detection device.

  A second detection device had been assembled and installed in a large delivery van that Loomis bought expressly for that purpose. The staff immediately dubbed it “the didey wagon” because it had been used for delivering diapers. Loomis arranged to have the truck painted the traditional Tuxedo Park colors, green with gold trim, with “Loomis Laboratories” handsomely lettered on the side. Whether this was to impress the dignitaries from Washington or to make the truck less of an eyesore to the neighboring swells, it lent the backyard enterprise a nice official air.

  “When we took [it] out to the golf course, the thing was a microwave radar,” recalled Lewis. “It had an indicator system that was capable of showing what we were looking at and getting us a reading on the speed. We took it out there and pointed it down the highway that went through Tuxedo Park. After we’d spent five minutes looking at it, I said, ‘Hey, don’t let the cops get a hold of that. These guys are all going over the speed limit.’ Nobody else had one,” added Lewis, who had immediately recognized the obvious application for their radar gun. “There weren’t any microwave speed measuring sets in those days until we got that one.”

  The apparatus they had invented used an 8.6 cm klystron transmitter feeding energy into a novel antenna system called a “Tuxedo horn,” which was a modified version of Hansen’s leaky-pipe antenna. According to Lewis, after a considerable amount of work, they had settled on two so-called leaky pipes along two sides of a triangular horn, to make the radiator mechanically more solid and improve the shape of the beam. The Tuxedo horns were mounted together on a rotating platform, resembling a gun mount, protruding from the back of the truck. The receiver consisted of a crystal detector and audio amplifier. A “wave trap” fitted along the front edge of the two horns prevented the transmitted signal from leaking back into the receiver. According to the laboratory notes, the system’s operation depended on the interference effects between the radiation directly picked up by the transmitter and the reflected energy of the moving target:

  A moving object will produce a doppler effect, the signal returning from the moving object beating against outgoing signal, part of which is picked up directly by the receiving horn. The audio note thus received will be proportional to the radial speed of the moving object. Thus, a plane moving at a radial speed of 100 meters per second, thus producing a note of 2,000 cycles per second (assuming half wave length equals five centimeters). . . .

  All that summer, Loomis and his team experimented on a variety of moving targets, using whatever was at hand in the sleepy resort. Hobart tried testing the device on balloons he sent floating up over the tree-tops. Outdoor tests were also done on motorboats in the lake, marked by a corner reflector. As their experiments tracking automobiles progressed, they were able to measure the speed of the cars with “considerable accuracy: the Doppler shift being at the rate of 10 cycles per mile an hour.” In late August, they drove the “didey wagon” down to Bendix Airport, where, according to Lewis, they managed “to follow without difficulty the comings and goings of a number of small planes, [Piper] Cubs and the like.” A Luscombe, with its large metal surface, proved to be the best target. Henry Loomis, now twenty-one, often piloted the small Cub, which they learned they could follow at a maximum distance of two miles. Beyond that, the “fourth-power law” began to defeat their efforts and the signals were lost in the noise. At one point, they even tried to track the Goodyear blimp, but it moved too slowly to be detected with their system. Some efforts to do experiments on the movements of the Nyack ferry also failed, though in making their measurements and modifying the set to improve their range, Lewis and his co-workers came very close to the idea of pulse radar.

  While they did not know it at the time, their leader had just been informed of its existence during the army maneuvers in Ogdensburg. As Lewis would learn later, Loomis understood full well the superiority of the pulsed radar he had been shown but was not permitted to begin doing similar experiments at his own facility without clearance, so he “had to bide his time with the Doppler system, just to show the principles.” Stymied by the lack of a tube that could supply enough power, the microwave committee had decided to write a report. “A sign,” as one of its members observed, “that we didn’t know what to do next.” But before the end of summer, Loomis’ work was interrupted by th
e dramatic arrival in Washington of the British Technical and Scientific Mission, led by Sir Henry Tizard, an influential defense scientist. When he hurried off to the nation’s capital to meet with the British, Loomis had no idea his days in Tuxedo Park were drawing to a close.

  Chapter 9

  PRECIOUS CARGO

  But first will you let me introduce my guests to you when they are all together? Some scientists are like prima donnas, you know, and they may be getting pretty nervous.

  —WR, from Brain Waves and Death

  BY the summer of 1940, Britain was teetering on the edge of despair. Germany had begun relentless air attacks on England as a prelude to invasion, and Tizard, who was chairman of the key scientific committee on air defense, realized that they would not be able to stand alone for long. Hitler occupied a large part of Europe, and it was only a matter of time before England was outmatched by Germany’s productive power. Tizard foresaw, with greater clarity than either the politicians or the military leaders, that the war had become harnessed to technology and technical superiority. The ability to produce powerful new weapons was the key to victory.