# Oral-History:Robert Pound

Pound was a Physics undergrad at the University of Buffalo in 1940. He went to work for the Submarine Signal Company (SSC) in 1940 as a way to avoid the draft. In late 1941 he was sent to the MIT Rad Lab as an industrial visitor, realized that was where the research action was, and arranged to be transferred there in March 1942. He worked in the RF group, as a section chief of microwave mixers and converters. He also developed broadband stub support for coaxial transmission lines. In his research he came near to developing the transistor, along with some other Rad Labbers.

ROBERT V. POUND: An Interview Conducted by John Bryant, IEEE History Center, 14 June 19

Interview # 102 for the IEEE History Center, The Institute of Electrical and Electronics Engineers, Inc.

This manuscript is being made available for research purposes only. All literary rights in the manuscript, including the right to publish, are reserved to the IEEE History Center. No part of the manuscript may be quoted for publication without the written permission of the Director of IEEE History Center.

Request for permission to quote for publication should be addressed to the IEEE History Center Oral History Program, IEEE History Center, 445 Hoes Lane, Piscataway, NJ 08854 USA or ieee-history@ieee.org. It should include identification of the specific passages to be quoted, anticipated use of the passages, and identification of the user.

It is recommended that this oral history be cited as follows:

Robert V. Pound, an oral history conducted in 1991 by John Bryant, IEEE History Center, Piscataway, NJ, USA.

## Interview

Interview: Robert V. Pound

Interviewer: John Bryant

Date: 14 June 1991

Location: Cambridge, Massachusetts

### Family and Educational Background

Bryant:

This is John H. Bryant, here in Professor Robert V. Pound's office, in the physics department of Harvard University. Professor Pound, could we start by your giving some background, perhaps about your father and why you chose physics?

Pound:

I guess I never really thought of anything else because my father was a physicist. He held the fourth Ph.D. awarded in physics by the University of Toronto, which was in 1913. I don't know about other fields. He worked with J. C. McClennan when he was an undergraduate, until he left there in 1912. That's why they coughed up the degree, I think. He then went to Queens University in Kingston, Ontario, and he was there until 1917. I was born in 1919, but in Ridgeway, Ontario, which was our family homestead where his ancestors went back to 1786 when they became United Empire Loyalists. He joined his father in a small business, a flour milling company. But in 1922 he decided that the academic life was alright after all. He heard that there was a new university in Buffalo. The University of Buffalo had created the faculty of Arts and Sciences. He went there to find out whether they were interested in a physicist. They said that they were looking for a mathematician. So he went to see a man named Sherk, who was the chairman of the math department, and they hired my father immediately.

He became a mathematician, although at Buffalo he taught all the mathematical physics: he taught analytical mechanics, vector and tensor analysis and differential equations — all that analytical mathematics. He never did very much research after that. As a matter of fact, my mother said more recently that if there had been a theoretical physics branch in Canada, he would probably have been in that rather than experimental physics. His thesis was on secondary rays produced by the beta rays from polonium. Radioactivity was the interesting subject in those days. He had an awful lot of trouble with vacuum pumps and all that sort of thing. McClennan, for whom the laboratories at Toronto are named, was knighted in England after the First World War for contributions to the detection of submarines in the English Channel. He put Toronto into low temperature physics before any other university in this hemisphere because he worked with Kamerlingh Onnes at Leiden and learned how to build a helium liquefier. They had an operating helium liquefier by 1926 in Toronto. We always maintained a certain contact with the Canadian base because all my relatives were there.

I started doing things — building gadgets — for Hector when I was a freshman. The main reason that I was involved in all that was I had started in amateur radio when I was 12. I had built many things by the time I got to college. I never learned much about electronics in college; I knew more than I ever learned in college before I came. Among the things we built was an instrument for measuring architectural acoustic reverberation times. That got fairly widely publicized because we got to use it. Some time after I came to Cambridge, Hector made measurements on the new Kleinhans Music Hall, which was designed by Saarinen and supposedly had elegant acoustical design.

Bryant:

Located in Buffalo.

Pound:

In Buffalo, yes. It was a new music hall, and they were very proud of it. Kleinhans was a name attached to a men's furnishing store in Buffalo. They were a well-to-do family there, and they had endowed the new hall. They engaged Stokowski with the Philadelphia Orchestra for the opening concert. He gave very high praise to the acoustics but the audience wasn't that impressed. It turned out the auditorium was very dead as far as the audience was concerned. When Hector got to use the reverberation time meter, he confirmed that it was very dead. It seems that society women in Buffalo had contributed carpeting for the whole place, after the hall had been designed. It was very much more damped than was intended. Happily, it was built with adjustable panels, perforated panels behind which the absorber was located, so you could reduce the absorption in the ceilings to compensate. It came out better after such changes. Anyway, I gather that it got written up in various acoustical journals because I talked to Leo Beranek not long ago, and he knew about it. That's why I was recognized as more able in electronics than most of the undergraduates at that time.

I was pursuing an experiment in research the last year, having built a new device for generating reference frequencies. The project was to measure the dielectric constant of gases. This was done by filling a vacuum container with the gas and measuring the shift in frequency of a self-excited oscillator due to capacitance change. To measure that small a frequency change, perhaps 40 cycles in about 1 MHz, we had to have a good frequency measuring device. We didn't have the money to buy a quartz crystal clock or that sort of thing in those days so we built a device. I devised one that used multi-vibrators to scale-down a local radio signal. We got a 100 Hz reference signal from WBEN, which is a 900 KHz carrier. I was just talking yesterday, or Tuesday, with a young man that was my associate at Radiation Lab — he joined my section — who had been in my class at Buffalo. It turned out he stayed on and actually helped make the measurements in the Kleinhans Music Hall and also measured the dielectric constant of carbon dioxide with that apparatus. So that's why they were interested in hiring me at a place like Submarine Signal. My other brother-in-law, Howard Hart, was chief of the radar development there.

### Submarine Signal Company

Bryant:

The Submarine Signal Company was located in downtown Boston?

Pound:

The headquarters was on State Street, but the laboratories and manufacturing facilities were on Atlantic Avenue in a five-story building that overlooked Boston Harbor. There was Eastern Steamship lines that ran overnight cruise boats to New York. You could go to New York by overnight boat in those days. Our 5th floor lab overlooked the New York pier, and the pier for the Acadia and St John that went to the Canadian Maritimes in the summer months. I came first on a visit in December of 1940 for an interview there. I had luncheon that day at the St. Bostolph Club, with the president and vice-president as I remember, and the chief engineer, and Harold Hart.

Bryant:

What were their main activities?

Pound:

Submarine Signal? They were the underwater sound experts of the country. They were the main supplier to the Navy for sonar, although they didn't call it sonar then. They had started in World War I. I don't know whether they were initially a non-profit organization or not, but they managed to survive through the Depression years, always paying dividends to their stockholders. I got the impression that they looked down on Raytheon. They become part of Raytheon a couple of years after the War.

Bryant:

When did you first learn the then-secret subject, what we call radar?

Pound:

On the occasion of my visit in 1940. They had an operating radar that they had developed on their own initiative.

Bryant:

Aimed toward a Navy application?

Pound:

Well, no. It was for research. Well, it was supposedly a ground-based system or a ship based. It used two tapered horns with apertures about 4 x 6 feet that were mounted on a big rotatable platform that they had built up on the roof. I'm not sure if that was finished when I first came, but we had it running the next year. It was a 50 cm system, and it used a Western Electric 316A doorknob tube. They hit it with 2500 volts pulses. It was a 300 volt tube. The input pulse power was two kilowatts.

The staff at Submarine Signal had very high respect from the Navy. They worked a lot with experimental apparatus in the underwater sound game, using the USS Semmes, that same destroyer which later performed experiments for the Radiation Lab.

Bryant:

Where was that docked?

Pound:

I'm not sure. It came into Boston only for these purposes. I think it may have come out of Newport. I believe I heard about the magnetrons even on that December visit. They were so much into the purely classified business of the Navy that they were phased into information about the magnetron right away.

Bryant:

They must have been one of the very few industrial concerns that had a clearance for information about radar.

Pound:

That's right, they were. Of course they had their own 50 cm system. The Navy knew they were doing this. They would give demonstrations of it. In fact, they held a patent from 1930. You'll find that discussed in Guerlac's book. They held a patent that was created by a man named Robert Hart. This patent was on the use of a cathode ray tube as a range indicator for radar. That was dated 1930. I believe they sold that patent to RCA finally, some time during the war, for about a hundred thousand dollars, which, in those days, was not so trivial. So, in the end. they became phased into Radiation Lab programs and built first the SF and then the SU radars. The SO and the SU had components in common, and were built by Raytheon and Submarine Signal. Those were meant mainly for PT Boats. The SU was also aimed at Destroyer Escorts, DEs.

Bryant:

Those were the ten centimeter sets?

Pound:

No, three, was it? The first SO's were at ten. The SU was on 3 cm at the beginning. The SO went to three later. I was out of it, I was only on the components end of things by the time all that was going on. Three of us (actually Harold Hart and I and a man named Charlie Barber) were sent over when Radiation Lab suggested having this industrial visitor program, in either summer or fall of 1941, to get what would now be called technology transfer. I came over and joined the indicator group, which then was chaired by Bob Bacher, who later went to Los Alamos. I was assigned the task of building an electrostatic plan position indicator (PPI), which I did in a matter of few weeks. I was considered then relatively experienced in designing circuits for doing things like that. I had already designed the circuits for the kind of circular scans that was used at Submarine Signal. Their range system comprised the thing that was patented, basically a circumferential scan on the face of a twelve inch cathode ray tube (CRT) display, intensity modulated. RL used such a thing on an SCR-584 radar, with a radial modulation, so the blips went inwards. But ours was intensity modulated, with a grid in the CRT.

Bryant:

The time base was on the circumference?

Pound:

The time base was the circumference. So I generated the x-y deflections and so forth.

Bryant:

Did you get a good circle?

Pound:

Oh, yes, I got a pretty good circle. For those days it was sort of a surprise.

Bryant:

Did you see any magnetic field effect, from residual field in the deflection plates?

Pound:

I didn't have too much trouble with that. One of the things I built at Submarine Signal, with Randy Willard the technician, was a copy of the Radiation Lab magnetron pulser. It was Curry Street's invention, using 304TH output tubes driven by 807s and with 884 gas tubes bootstrapped on the 807s. We wanted to examine the nature of the pulses, and all we had were waveform scopes, DuMont 208 scopes. All you could see was just a tangle of deflection with multi-valued amplitude. The scope just couldn't handle a micro-second pulse, not with that rise time.

### Industrial Visitor Program

Bryant:

Could you tell us more about the industrial visitor program?

Pound:

Yes, I haven't seen anything mentioned about it in the books. I definitely recall having a talk, sort of greeting in that group. There were twenty or thirty people from other organizations, General Electric and such places, I believe. The talk was from J. C. Street. That was my first encounter with this — was it an Alabamian Accent? His wife was from South Carolina. They were both from the deep south.

Bryant:

Distinctive.

Pound:

Yes, very distinctive speech. He later became my colleague here at Harvard. We used his magnet for the first NMR experiments downstairs here.

Bryant:

December 1945.

Pound:

Yes, we started using it probably in November, calibrating it all there.

Bryant:

What was the actual name of the program?

Pound:

I thought it was just called Industrial Visitor Program.

Bryant:

Pound:

At Radiation, I thought Street did, but I've never been sure because I was only a young participant. One of the things that it enabled me to do was to be there at the start of Bill Hansen's lectures.

Bryant:

When was the first one of those given, do you know?

Pound:

It was in the fall of 1941, but whether it was September or later, I don't know. I began having misgivings, thinking that I should really be at the Radiation Lab instead of Submarine Signal because I wasn't an engineer and I could see that the way things were going at Radiation Lab all of the fundamental developments and research would be there. Submarine Signal would end up as a manufacturing base, which is true. That's what happened. I started raising questions about the possibility. It was my initiative to make the change, and I started raising the questions. Submarine Signal's president was a man named Madden, and its vice president a man named Fay. The chief engineer was I.C. Clement. Wheeler Loomis said he couldn't do anything about offering a position so long as I had draft deferment because of my sensitive position at Submarine Signal. So I would have to get a release from Submarine Signal because he wasn't allowed to go into competition that way with people that were already in the system. I talked to the management at Submarine Signal. Fay said that he would give me a release if I finished that 50 cm radar system into a package that could be shown off when they had visitors and so forth. With the help of Randy Willard, the technician, I took that responsibility. Finally, it was in March or late February of 1942 that I quit my visiting and came back except for going over to the continuing Hansen lectures.

### Hansen Lectures

Bryant:

Were they given as part of the Monday night series?

Pound:

No, they were in the afternoon. Hansen came up every week from Sperry Gyroscope Co.

Bryant:

Was he recognized as a Sperry employee?

Pound:

Yes, he was a Sperry employee as far as I know.

Bryant:

As far as you know, Sperry was sponsoring his expenses?

Pound:

No, I think Radiation Lab probably sponsored the expense of his coming. I wouldn't be sure, but I think they actually hired him as a consultant. He was one of the few people that had a real background of experience. He invented the rhumbatrons and all the cavities and of course had a physicists approach to how you deal with waveguides, coax lines and so forth. I learned about that for the first time really from him. I still have the Hansen notes, which form a package about that thick of hectagraph stuff. In those days I had never looked at that.

Bryant:

One of my colleagues says that Samuel Seely was the one that coordinated and put the package together.

Pound:

Sam Seely? Yes, I guess so. Sam Seely served as a kind of Boswell for that. There was somebody else though that really sat in front and always took the notes. It was "Monty" Johnson, who I believe was a Stanford colleague of Hansen.

Bryant:

Who would have coordinated the meetings?

Pound:

They were set up on a regular schedule and Hansen himself decided the agenda of what he was going to give. It was almost like a class.

Bryant:

Was attendance encouraged? It wasn't mandatory?

Pound:

No, it wasn't mandatory, but I think that there were many people that wished they knew enough. It fell off in later times. It was the first several months, I think, that was the critical time, where he presented his way of looking at microwave technology: coax lines, waveguides, resonators, antennas. But by the time he got to antennas I got the impression that the trade had somewhat passed him by at Radiation Lab. He kept talking about various other more applied things, IF amplifiers and so forth. The concentration at Radiation Lab was more than he could match, however, so I think it was really only the first volume in which he had a primary position.

Bryant:

I inspected one at Stanford about two years ago and I had the impression you would have to edit it very heavily if you wanted to publish it.

Pound:

Oh, yes. But I think as compared with other sources of microwave technology in those times... I know that Slater wrote a microwave techniques book, which I don't think was anything like as nice as what Hansen did. The two people who were developing waveguide technology were Barrow at MIT and I gather, Page and Adams at Yale.

Bryant:

They had done some analytical work.

Pound:

Bryant:

Bell Labs had done the circular waveguide.

Pound:

My brother-in-law, Harold Hart, had been a graduate student at Yale, and in his qualifying exam Page asked him whether he could possibly put electromagnetic waves through a pipe without a center conductor. And he didn't know at that point. Page said, "I wonder why we wrote that paper." So that's how we knew about Page's work.

Bryant:

J.J. Thompson wrote it first in 1892.

Pound:

That's true, isn't it?

Bryant:

Rayleigh in 1896.

Pound:

Rayleigh's the one that we were always hearing about.

Bryant:

You should never say that something is a first.

Pound:

Should always check that out. That which Marcuvitz brought up at the talk was in fact a well-known story around the Lab.

### Other Industrial Visitors

Bryant:

You're the only one that's brought up this industrial visitors program. The reason I've dwelled on it is that its not in Rad Lab publications or in Guerlac's book.

Pound:

Yes, I don't know anyone else who transferred over from industrial visitor situation to the Lab, which was not its purpose.

Bryant:

But you recall quite a number of companies whose staff members who did come?

Pound:

The only time I remember that I saw that group together was the first day out, when we had this little introductory talk from J. C. Street. After that, there was no contact because they were all assigned to different places. Harold Hart was one them, but he didn't spend his time working in the Lab. I think he became a kind of administrator with whom they negotiated about contracting to build a ten centimeter system, to Radiation Lab design, the SF radar. Submarine Signal built 1655 of them, according to Guerlac. You'll find some mention of Hart and the problems that developed between the Lab and Submarine Signal in the Guerlac book, if you look under his name in the index. There was apparently some business between the Navy, Submarine Signal, and the Radiation Lab as to just who was being responsible for the design. I remember P.R. Bell getting furious once when he discovered that Submarine Signal had redesigned, re laid-out the wiring for an IF strip.

Bryant:

Who was it at the Radiation Lab?

Pound:

P.R. Bell. I believe I have that story from him, because he designed the IF amplifier for this system, and they had destroyed it because they wanted to cable the wiring. At least that's the possibly apocryphal story. Instead of using the point-to-point, shortest path, sort of wiring for 30 MHz, you don't go around and put it all in cables. They used to do a beautiful job at Submarine Signal in those days on the underwater sound equipment. Every unit was mounted on a hinged panel that you could swing out, and all the interconnects were in cable. That was the kind of thing that became much more common later, but I had never seen that kind of thing. And they claimed that I was being disloyal by leaving the company for the fact that they were one of the only companies who knew how to build things the way the Navy needed it.

There were two areas in which I encountered Radiation Lab people early on in the Spring of 1941, when I was first at Submarine Signal. I saw Ken Bainbridge, who went on a tour to see where other radar programs were going. They had a shake table at Submarine Signal, which nobody else in the area had. The first Radiation Lab stuff they put on it, all of the resistors fell off. It was a mess. That's why the Submarine Signal people had this other attitude about how to do things. Then they had some mechanical tests. I saw Ed Purcell, who was involved with the design of the conical scan for the original AI in which they had this problem of dynamical balance.

Bryant:

They rotated the reflector?

Pound:

Yes, that's right. I had learned a little bit in college about what you call the ellipsoid of inertia and realized that to rotate things about other than the axis of symmetry is a real pain. You had to add counterweights.

The Submarine Signal people used to look very much down on Raytheon at that time. Raytheon was nearly bankrupt, and in comparison Submarine Signal was a thriving organization. During the depression years, it developed a business leasing fathometers to the fishing fleet.

Bryant:

So you went to work for the Radiation Lab about March of 1942?

Pound:

Early March of 1942. I joined the RF group as it was beginning, after Zacharias came back from Bell Labs.

Bryant:

What was the procedure for getting on the payroll? Did you negotiate salary?

Pound:

I called up and went into State Street and got Mr. Fay to sign my release, and then went over to see Wheeler Loomis at Rad Lab. He put me on the staff and translated my Submarine Signal salary into the equivalent monthly scale. My salary was $55 a week at Submarine Signal and it translated into$238 a month at MIT Radiation Lab. I'd had started a year before at \$40 a week, but it went up a bit. I used to see Wheeler Loomis quite often in the post-war era, and he always reminded me, "Wasn't it a good thing you did that?" because he knew I wanted to do that.

Bryant:

And you agreed with him I assume?

Pound:

Oh, yes.

### Microwave Mixer and Converter Group

Bryant:

You were a section chief of microwave mixers and converters?

Pound:

That's right, after about a year as a general member of the group.

Bryant:

Whose group was that in?

Pound:

53.2, my section was called. Zacharias was the chairman of group 53 from that March 1942 until January 1944. Al Hill took over when Zacharias moved up to be head of Division 5. After Zacharias moved off to Los Alamos, and Hill moved up to Division Head A.E. Whitford became the group chairman for the last few months. Jerry Wiesner was one of the other members in 53.

Bryant:

What would you like to tell us about the happenings or problems or accomplishments?

Pound:

Well, you heard about some of those yesterday in my presentation [Tuesday, June 11, 1991].

Bryant:

Yes, I thoroughly enjoyed it. [Professor Pound's paper is printed in the Symposium Digest.]

### Julian Schwinger and Sam Goudsmit

Pound:

I mentioned that Marcuvitz didn't know that Julian Schwinger had visited here at an earlier time. Schwinger came permanently in 1942 or so. Every day that I came in — I had a ride-sharing, and I was the driver of a car that had a B-ration sticker — I drove Howard and Phyllis Doolittle. Howard was the chairman of the Modulator Group and his wife had taken up "technicianing." She worked for Jack Steinberger in the Antenna Group much of the time. They were at the meeting Tuesday, just briefly. I drove them every day down to MIT from up here north of Harvard Square, where we lived in the same apartment block. We had to do our schedule based on hers. Because she was a technician she had to punch the time clock and we had to get there at 8:30 in the morning. Every day as we were coming in we encountered Julian Schwinger on his way home because he spent the nights there. We would often see him coming in about the time we were going out in the evening or in the afternoon. Of course, I went back quite a lot in the evenings. We worked certainly-six and sometimes seven days a week during those times.

Bryant:

Schwinger was later in the department here at Harvard.

Pound:

After the war he was hired as Associate Professor (which meant tenure then), and he was appointed as the youngest full professor in, it must have been in 1947. He left to go to UCLA in 1972.

Bryant:

What kind of interaction did you have with the theoretical group?

Pound:

I was quite aware of what they were doing, not that I tracked it that much. I used Schwinger's methods once to calculate the waveguide structures for the correct amount of coupling between a local oscillator and a mixer, based on his equivalent circuitry wherein he gave the way to calculate all the coefficients, the sizes of inductance — negative inductances — and things that represented what the various discontinuities in waveguides would do. I spent days doing the numerical work to reduce some of these things to practice. I think one of those mixers which I showed was designed that way. It's the coupling between this waveguide and the other two mixers that were designed in which the width and height were from that approach. Of course they had a variability anyway with these adjustment screws. But I found it usually was much easier just to do things by cut-and-try. I don't think that all of those fancy theoretical derivations paid off in those days, for what we were able to design then. I think now with computers and the way you can program something to use that technique, I'm sure you can actually design things that work right away. But this was a harder job than actually making several tries, seeing how it worked. One of the things you had to do in this case was to make the length of these cross-coupling waveguides, their lengths and heights, such that they coupled the maximum for a minimum of reflection at the junctions. That all depended on making end corrections. Nominally, you'd say something's a quarter wavelength, but you really don't know how long to make it because it's in waveguide.

Bryant:

I made a mistake a moment ago. I was thinking that Bethe was at Cornell.

Pound:

No, he was at Radiation Lab, although nominally at Cornell. In fact, it was Bethe who brought Julian Schwinger to see us that first visit in 1942. Schwinger had left Columbia and had been hired at Purdue as an associate professor. He was going out to report to Purdue, but before he went he came to visit Rabi and company, I guess. So Bethe brought him to see us, I don't know exactly why. I guess it was Zacharias who suggested it. Schwinger was part of the Rabi-Zacharias group. He had been the house theorist for the molecular beam people at Columbia from the age of sixteen or so. Bethe brought him over to see our group, and we told him about the problem of crystal burn out, or the feed-through that we were worrying about, and the TR boxes. So he came up with a suggestion of making the cavity resonator a different shape. That didn't turn out to be the solution. In fact, it didn't even help.

Bryant:

Did you have a library at the Radiation Laboratory?

Pound:

I didn't think of there being much available in references that had any value to what I was doing so. There was the document room operated by Sam Goudsmit, for making our own publications. There were collections of classified documents from the other organizations as well. I saw a report, memorandum for file, from Bell Labs. I think the name on it was Tyrrell, on hybrid circuits for microwaves. There is a picture, which was interpreted to be a picture of a magic tee, but it was not recognized as doing all the things which the hybrid circuit was invented to do.

Bryant:

That's very interesting because that derived from low-frequency telephone circuits.

Pound:

The hybrid circuit, yes.

Bryant:

And this was a high frequency application of it.

Pound:

Bryant:

Goudsmit was there from 1941 to 1946.

Pound:

Yes, he was one of the early... In 1945 he went off. He ran the Alsos Mission.

Bryant:

Mission to Europe.

Pound:

To Europe to investigate what they had done in nuclear physics, particularly in fission. Yes, the atomic bomb. That continues to be controversial as to whether what he said was biased or otherwise. I remember he came back and gave us a colloquium talk. It included evidence that the Army had no sense of humor. They were supposed to ship things back to have them tested for whether there was evidence of radioactivity, and they captured a lot of wine in the Moselle, in the Rhine wine district, and sent those back too. The Army went ahead and tested that for radioactivity. Goudsmit didn't think they'd take it that seriously. I think they found it had a higher level of radioactivity than most other things. The story is probably in his book. I haven't read it lately.

### Fundamental Development Group

Bryant:

I have a copy. On another subject, how much consultation did you seek from others, or other groups?

Pound:

There was quite a lot of circulation. I was checking off a list of the people who were coming to the meeting this week. I wondered how many of them I knew personally from those days. I found that only a third or so of the people on that 400-person list were saying "Yes" to come, so I put a check on the ones that I knew. That came out to be about sixty, which I think is fairly extensive. That's because many of those people came to consult about how to develop, to build a thing for their particular project for example. As time went on, I ended up spending quite a lot of time talking with Purcell. His office was conveniently not far from mine. When we got into building the K-band mixers I was developing the microwave discriminator for example. I remember talking to Carol Montgomery who was there as well. He was often in Purcell's office too, and Bob Dicke. Almost every day I got in the habit, for maybe two years of going to lunch with E.R. Beringer, who was one of that group. He's in that picture with Dicke and the radiometer. But Beringer's particular project for most of the time I was talking about was studying the oxygen absorption. He built a millimeter-wave spectrometer, which was quite an enterprise because he had to develop a harmonic generator for the four to six millimeter range of frequencies from a K-band source.

Bryant:

At what time?

Pound:

That was probably 1944 into 1945.

Bryant:

So this was in the fundamental group.

Pound:

That was in the fundamental development group.

Bryant:

Did it have an objective?

Pound:

Yes, it's objective was fundamental: to check out the breadth and depth of the oxygen absorption, to see what other wavelengths were usable or not usable. The oxygen absorption is so intense that you can't use those frequencies for radar at all. In fact, there has been a proposal of using them for ship-to-ship communication for security reasons, because the damping is so fast. Van Vleck was proposing to use it as a basis for a collision avoidance system for aircraft because you can have such a steep cutoff. When you get closer than something you could have a bell ring. I thought that was kind of cute.

Bryant:

I'm afraid we missed discussion on the subject of discriminators.

Pound:

That picture is of the frequency stabilization devices. This was the so-called IF version, which had a tighter control and didn't have flicker effect noise.

Bryant:

That's slide number 31.

Pound:

It had tighter control and didn't have the problem of low-frequency noise that DC amplifiers had, the drift, which would have been a fundamental thing. This achieved the error signal through a phase detector at 30 MHz. One modulated the wave reflected from the cavity by a crystal modulator in the waveguide and used that in a mixer crystal through an IF strip to a phase detector. So the DC error voltage only came out after all those high frequency amplifications. So that was a very stable system. Well, it wasn't quite so clean to modulate as was the DC system because you had to put in the modulation voltage after the IF gain, which was the only place there was a low frequency. Thereby, it would be dependent on the gain in the IF system as to what the modulation index would be. I realized that it might be fun to make a communication system, so we built these things.

Bryant:

That's slide number 32.

### Project to Identify Individual Aircraft

Pound:

Anyway, he put together a group and I guess that must have been the winter of 1945. He had about fifteen technical people. He wasn't very happy about the kind of people that he could extract from other groups at that time. He said, "Oh well, they're hands." He thought he was getting the dregs, more or less. He had a Naval lieutenant who was attached as a liaison. He gave a colloquium talk on the progress and showed it off on the Monday night colloquium. Then I heard from him that he had been taken off it because they decided it belonged to Division 13 instead of 14, or something like that.

Bryant:

So the roles and missions took it away?

Pound:

That's right, the project was moved out here to Harvard. And I think it came to Chaffee's ERL. Not RRL. It was Electronics Research. I think that was just starting then, I'm not sure.

Bryant:

I don't know. Located where?

Pound:

Here at Harvard. I know that outside of Cruft Lab here when I first came there was an airplane mounted on a post out here I came here in 1945, although I stayed on at MIT until 1946. I was in and out.

Bryant:

A model airplane?

Pound:

No, it was the fuselage of a Navy fighter plane. I heard the possibly apocryphal story that they were trying to get rid of having little antennas sticking out for communications by making the whole surface of the airplane into an antenna. It was suggested that they thought you could make use of all that surface for collection area. We used to snicker saying, "Somebody didn't know about the reciprocity law," that the best one could do if it's omnidirectional is wavelength squared over two pi. It's kind of a will-o-the-wisp to see all that nice surface that you ought to be able to collect the information from, but there's no way to do it without making it directional. Anyway, I believe that was part of that Communications Lab. I don't know whether it was a whole division of the NDRC, I think they probably supported things elsewhere, too, as did Division 14.

### Crystal Diodes and Transistors

Pound:

I mean all those microwave crystal diode development labs... Let's see, Henry Torrey was the contract overseer for the crystal diode development labs at Purdue and at Pennsylvania. Perhaps some of the commercial ones. I don't know. Sylvania, Raytheon, Westinghouse, and General Electric, all had crystal development labs. Whether they were operating under contract or whether they were self-supporting, I don't know. But I know that Torrey frequently had visits from and to them. Fred Seitz was the director of the one in Pennsylvania, although he left and went into something else, eventually becoming President of the National Academy of Sciences and then Rockefeller University.

Bryant:

MIT Radiation Lab put out lots of contracts for services, research, samples, and...

Pound:

Yes, that's right. K. Lark Horovitz, who had been Purcell's teacher as an undergraduate at Purdue, was the one who was pushing germanium. There was a lot of progress in the understanding of germanium that had a very important impact on the post-war development of transistors. I mentioned it, but I didn't get to mention one of the things we used whimsically to say, "Why can't we put a third element on these damned crystals?" I was going to mention that the first paper of Bardeen and Brattain was titled, "The Transistor: a Semi-Conducting Triode," which was exactly what was always being looked for. They really did put another electrode on it, although they did it in such a way that it worked, choosing the character of the semiconductor.

Bryant:

Did you ever observe a negative resistance characteristic in any diode that you worked with?

Pound:

Oh, yes, I did describe that, didn't I, the Harper-North welded-contact germanium crystal. In fact, I demonstrated that it amplified. Because my method of measuring... I had built up a crystal test, a mixer test, the operation of which depended somewhat on the reciprocity law working for microwave crystal diodes. R.H. Dicke had a paper, one of the early Radiation Lab reports, showing that the reciprocity law and linear behavior would apply for crystal detectors if harmonics across the junction had a certain phase relationship to the fundamental. It turned out that this welded-contact germanium violated reciprocity law. What I had for testing the crystal gain was a local oscillator feeding a mixer, but I could also have a small signal fed into the mixer and adjust the input to the mixer so there was no reflection. I could standardize how much was going in by putting a shutter into the waveguide, and it would come back out the other branch of a magic-tee so I could measure the power level there. Then I would adjust the mixer to match. With the welded-contact crystal I would do that with the output on the IF side short-circuited. I could still adjust some RF tuning so that it was matched. I would throw the switch to open circuit and adjust the output IF tuning to a maximum reflection, and I'd get more reflection than if I put the shutter in. So that was an amplifier, and that's part of what we did to demonstrate it.

Bryant:

Did you think of any possible uses?

Pound:

Well, of course, in fact it was also an amplifier of RF to IF. We had assumed in the beginning that that might mean that we had overcome a factor of at least 6 db or so in the mixer loss. That could have made a factor of four in power level.

Bryant:

Was it reproducible?

Pound:

Perhaps the amplification was, but the noise went up with it. The noise temperature was just as correspondingly high. The adjustment all depended on peaking things in such a way that the bandwidth was poor, so you couldn't run a wideband amplifier with it. But I contend that the way Henry Torrey then explained it as depending on the non-linear capacitance, or the voltage-dependent capacitance at the junction, which is what you'd call an varacter now, constitutes the invention of the parametric amplifier. Which is what it was. Then it had the idler, which we called a local oscillator. It comes to the same thing.

Bryant:

How close did you get to inventing the parametric amplifier?

Pound:

Since it didn't improve the signal-to-noise ratio we didn't do any more with it. It was Harper North's gadget from General Electric in the first place. That's as far as we went. I pointed out the reason that we bothered in fact to look into it. In the fall of 1944, when our troops were crossing Europe, it looked rather as if there wasn't going to be time to invent something that would have an impact any more. I knew that our friends at Holmdel — Bell Labs — were already working on microwave relays rather than wartime things. Then came the Battle of the Bulge, and the Bell Lab people came visiting some more, and we got into the magic-tee business. Then this crystal thing came along, and it looked, well, maybe it will be something important that we should do. So we kept at it.

Bryant:

In your group, you had the freedom to pursue interesting things that showed up?

Pound:

Apparently. It was never made explicit, but if you came along with an idea... The nature of our groups — I think that's partly from being physicists. On the whole we were differently oriented from what we might have been if we had been engineers.

### Machine Shops and Outside Manufacturers

Bryant:

You had technicians and mechanics building experimental things for you?

Pound:

Yes. I had Charlie Rowe, who was basically an electronics technician. Most of the time he built circuits.

Bryant:

Electronic circuits.

Pound:

He built circuits, and he also did machine work. He was very good with machine work. He was a graduate of some Boston-based radio/electricity school, I forget what it was.

Bryant:

Did you have machine tools, lathes, etc?

Pound:

Yes. We had lathes, drill presses, saws, etc. His bench was in my lab, and I could use it if necessary.

Bryant:

So you were independent of the shop to that extent?

Pound:

And our group, 53, had its own larger shop too.

Bryant:

Nearby?

Pound:

Right across the hall from where I was, in the same wing of Building 22. In fact, there was an unfortunate episode there. The shop foreman, who was very good, got fired because he was found dishonest. Wartime machine tools were very difficult to come by, and he had managed to get some machine tools, with wartime priorities, delivered to his home. There was some scandal. I don't know whatever happened after that, but he was kicked out. I think he was prosecuted.

Bryant:

Who would have been his supervisor?

Pound:

I think Joel Simmons was probably directly in charge of that group. This was all within Zacharias' RF group. This was after we had moved over to Building 22. We had our own shop. There was the main shop on the ground floor of building 22, but we never used that because it was hard to go through the routines. It was much more like a physics lab the way we worked. The mechanics of being able to go and talk to the machinist that was doing these things made a big difference.

Bryant:

Did you usually make a practice of committing designs to drawings, just for the record or to show the machinist or to illustrate?

Pound:

Yes, we had two very excellent draftsmen, but our initial jobs were usually pencil sketches.

Bryant:

Were the draftsmen assigned to you?

Pound:

Not just to me, but to the group. But I think I made more use of the two Charlie Davises. There was C.H. Davis and C.W. Davis, and they were almost like a Mutt and Jeff. C.W. was a tall, lanky fellow, and C.H. was a small guy. But they had drafting tables side by side and they did drawings of all these mixer things, which are fairly elaborate.

Bryant:

They would have made shop drawings with tolerances and everything?

Pound:

Yes, we got that far. But usually, in an initial stage, if we wanted to try something out we did it by sketches and such. When we decided we were going to make something for a prototype...

Bryant:

Audio File
MP3 Audio
(102 - pound - clip 1.mp3)

What was the formality on recordkeeping for drawings and designs as they progressed?

Pound:

Nothing very much. I guess formal ones from them were all given special group numbering.

Bryant:

There was a master number system?

Pound:

Yes, a master numbering system within that group. Did I mention that this balanced mixer which I described had been built by Yale and Town by diecasting? I intended to, but I think I didn't get to say that the original one was machined out of solid brass at William S. Haynes, which is one of the world's most distinguished flute manufacturers. Their main shop was upstairs on Mass Avenue in Boston, right near where the Hynes Center is now. Jules Simmonds, who was our procurement person, had arranged for their doing certain model-building for us. They were building the prototype mixer. We went over to visit them whilst they were in mid-course in building the first one, and they did a beautiful job. It's a very complicated thing to machine that out of solid metal, with all the matching irises and things inside it. There was a mathematician at Case Institute who was famous for having a flute collection and for having done some mathematics to identify a bad note on the standard flute fingering — resonance problem. He had died and there were articles in the papers about his flute collection in which he had a number of solid platinum William S. Haynes flutes. They told me that they were flooded with queries about platinum flutes. They said they hated platinum flutes because it's such a difficult metal to machine. I don't think anybody would consider it now. They had one man repairing flutes; they weren't making any flutes then.

### Monday Night Lectures

Bryant:

You spoke of the Monday evening colloquia. Was attendance expected of the staff?

Pound:

I wasn't aware that there was any pressure to attend it. But they were of interest to most people, and a lot of the programs were such that the people just wanted to hear it.

Bryant:

Do you have a feel for what percentage of staff attended?

Pound:

Most of the time they met in room number 6-120, which probably has no more than two or three hundred seats. They went over to 10-250 on some of the bigger ones, the later ones. Since there were close to a thousand staff members, I have a feeling that certainly not more than half of them went as a rule.

Bryant:

That would have been one separation between technicians and other personnel?

Pound:

Technicians as a rule didn't go, but there were some talks that were more generally interesting. I always remember the one that was given by a Scot in kilts who came back after being a prisoner of war in Germany. He was in the raid at St. Nazaire. He told a fancy story about going up the river. You know about the St. Nazaire Raid? One of the fifty destroyers that the U.S. lend-leased — they were really old tubs from World War I — was loaded with a very large amount of high explosives; and they took it over some flats to get into the river at St. Nazaire, where there was main submarine dry dock. They went up river, under fire from the German batteries, and smashed it into the gates of the dry dock. Then the commandoes went ashore. This Scot was one of the commandoes. They went ashore to occupy the defense troops. Meanwhile, their captain was captured, and the Germans wanted to know what they were doing with this thing. They wanted to go in and inspect the ship. So they all went aboard the ship and they were all in it when it blew up; that is, the British captain and the German defense force.

Bryant:

Must have been timed to go off.

Pound:

It was timed to go off, yes, and the British captain knew what he was doing. I read again about that not long ago, that it really put that port out of action for quite a stretch. But few of the Brits got out. There were PT boats that were supposed to be able to get them off and get the commandoes back. But only about a quarter of them ever got back. A lot of them were shot there. The Scot was wounded, but managed not to move whilst they were going around finishing off the others. He was finally taken in by a French family that nursed him back to some health. But then the Germans found him. He was in a prisoner-of-war camp in Germany for some time but repatriated. He was exchanged for a German prisoner also judged not capable of further action. So they put him into this public relations operation, talking about this expedition. He said some of his friends had managed to walk from St. Nazaire to Spain and got back that way. But that was a colloquium that anybody might have been fascinated to hear. He said, when he got off the ship with his kilts, he heard the girls saying "Wonder what he has underneath?" The old story.

Bryant:

Continuing joke.

Pound:

Yes.

Bryant:

There was a steering committee and then there was also a coordination committee. I see that Purcell was on the coordination committee, but you're not.

Pound:

No, I was never on any of those.

Bryant:

He couldn't recognize what the coordination committee means.

Pound:

No, I can't quite, either.

Bryant:

Do you have a copy of this?

Pound:

I don't think I do. I know that I had a copy of a book that told what many people did.

Bryant:

It includes short biographies.

### Publications and Patents

Pound:

Yes, I remember seeing that once a couple years ago. Does it say I did something here? Author of the technical series, microwave frequency. Oh, that's right, I was going to say how the frequency control on the radars functioned, which had nothing to do with this thing I developed. In fact, there is a chapter in my microwave mixers book by Eric Durand about frequency control. What was used had a sweep from one side. They had a frequency discriminator on the IF that came from that other mixer, and when the frequency crossed over it triggered a pulse that kicked it back a little, so it kept sweeping up and back. It's a one-way drift kind of frequency control. Since the bandwidth of the radar was large, and there was no coherence in the transmitter, you didn't have to worry that it swept back and forth by a hundred KHz or so. The bandwidth was a couple megahertz, so there was no need for having that tight kind of frequency control. Jules Halpern and I got a patent — I think I shared with him — which was on another kind of frequency control in which a cavity is given a frequency modulation as a way of developing an error signal.

Bryant:

What did you modulate it with?

Pound:

A diaphragm, a mechanical diaphragm. A sixty hertz or something, buzzer type of thing. Perhaps a 60 Hz solenoid.

### Postwar Career

Bryant:

Pound:

A lot, I would say. Among other things, it's in my life, it substituted for ever going to graduate school. And of course not only the experience of doing something professional, but the contact with such a large proportion of the active professional physicists of the world, ranging from the Rabi's to my friends in Oxford. There was a lot of exchange. We had a visit in our group in order to put the 2K33 klystron into production.

Bryant:

That was K-band?

Pound:

A K-band klystron, which was the only one that was manufacturable and got used, and that was put in production at Raytheon. In the course of doing that, Brebis Bleaney, Arthur Cook and Douglas Roaf at different times came from Oxford to spend time in our group. Originally, Zacharias discovered, on a visit to Oxford, that there was this tube which would solve the need for a K-band local oscillator that worked. He came back and he kept calling it the Bleaney tube. Then when they sent the liaison person over to start putting it into production, it wasn't Bleaney but Douglas Roaf that came first. We renamed it the Oxford tube. Roaf was a nuclear physicist at Oxford whose name didn't get very much known until later. He was the most senior of that group, I guess. Arthur Cook was very well known as the man who did experiments in paramagnetism. He became warden of New College, Oxford. The last time I spent time in Oxford I was his guest there for a dinner or so.

Bryant:

Did you take any overseas trips to Britain to visit labs?

Pound:

Not during the war, but since. I almost did. I had all the shots, I had a passport, a "special" passport as an official government representative. I was going to go to help build — to translate — Oboe to ten centimeters. Oboe was a longer wave system, much used for bombing in the Ruhr. But, instead, it was decided to establish BBRL, and people would go over for longer terms. In the end I never did, but this was in the fall or spring of 1943. I always remember having all these typhoid, typhus and other shots, which was kind of a drag. I don't think England was so bad that one needed them, especially Great Malvern, which was a very civilized place where TRE was based. I visited there in the summer of 1948. I spent a year in Oxford in 1950-51, and another term in 1980.

### Jerold Zacharias and Guy Stever

Bryant:

If we could switch just a minute to what you were talking about, Zacharias, PSSC, the Physical Science Study Committee, I believe it was called, and some of the efforts to revise physics curricula. There must have been more than one such effort.

Pound:

Well, there was. Zacharias always had strong ideas about trying to get physics to be appreciated as a sort of everyday experience. He wanted to have people be able to do experiments in their college dorms with little kits that they would take home, and various other things of that sort. I always remember, for example, at one stage he got all excited about somebody from Bermuda that he had met who had invented — had a development which he called solder glass. It was a method of making glass seals without having to use high temperatures.

Bryant:

Glass frit or something?

Pound:

Something, yes. You could do that with a Bunsen burner in your room and so forth. So he was having people make diodes for Edison effect thermionic emission experiments and things like that in their rooms. That must have been in the middle-to-later 1950s. Then he put together this study group at MIT that brought out these books for high schools. That was supposed to be the thing that prepared people for college, physics. I had one graduate student named Siphonanda Ketudat who did his Ph.D. thesis with me. He was a Thai. After he finished that he got a job for a year as a post-doc with the PSSC at MIT. I found out later that what he did was to translate the PSSC textbook into Thai. His calligraphy with Thai characters was elegant, which explained why the equations in his thesis were so pretty.

Bryant:

This is Guyford Stever?

Pound:

No, this is Louis Ridenour and connects with Stever. I was telling Guy Stever this story that when Louis came back, I had him measuring with a standing wave detector the impedance of a whole batch of crystal detectors, showing how the distribution would be and so forth. I remember that Bob Beringer came along to go out to lunch, and he couldn't believe that I put Louis Ridenour, a former Associate Director of the lab, on a job like this. But it was for his learning, actually, because he was setting up the group to develop the narrow-band microwave communications system for airport traffic control.