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Oral History Transcript — Robert V. Pound

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Interview with Robert V. Pound
By Katherine Sopka
At Harvard, Massachusetts
November 30, 1976

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Robert Pound; November 30, 1976

ABSTRACT: In this interview Robert Pound discusses topics such as: family background and childhood; Harvard University department of physics; undergraduate work at the University of Buffalo; Submarine Signal Company; microwave radar; Radiation Laboratory at the Massachusetts Institute of Technology (MIT) during World War II; Henry Torrey; Ed Purcell; Ewen Fletcher; Emory Chaffee; Nicolaas Bloembergen; nuclear magnetic resonance; quadrupole moments; crystal fields; I. I. Rabi; ionic crystals; George Watkins; Christopher Dean; Mossbauer effect; E. Bright Wilson; Zeeman effect; K. T. Bainbridge; Office of Naval Research; National Science Foundation (NSF); Edwin H. Land.

Transcript

Sopka:

This is Katherine Sopka speaking. I am visiting today, November 30th, 1976 with Professor Robert Pound in his office in the Lyman Laboratory of Physics. In 1975 Professor Pound became Director of this laboratory, having previously served as Chairman of the Physics Department from 1968 until 1972. In the interest of compiling a history of the Physics Department in recent decades, Professor Pound has kindly consented to share with me today his recollections of developments in Physics at Harvard since he joined the University as a Junior Fellow in 1945. Professor Pound, perhaps we can begin by asking you to comment upon your prior educational and research experience and upon the circumstances surrounding your coming to Harvard.

Pound:

All right. Well as far as my early education and research background are concerned, I attended the University of Buffalo before the Second World War. Actually, I was an undergraduate there, a member of the class of 1941. And the war was getting more of a shadow on the horizon, if you like. In the fall of 1940, Selective Service began and all of us began thinking about what the future held and how best to use our special talents, if any, in connection with what was coming. So that when an opportunity came along in December of 1940 to become involved in warconnected research and development, I followed that up and came down to Boston in January 1941. There I became a physicist at the Submarine Signal Company which had a project in microwave radar related to the newly started Radiation Lab at MIT. I found very soon that this small company was not what I wanted to be with for the longer stretch and so after the summer of 1941, when I spent part of that summer at the MIT Radiation Lab, as an industrial visitor, I began making efforts to transfer. Because of the effect of the Selective Service, it was not easy to resign one position and get another warconnected position. So it took quite a while to maneuver it. It wasn't until March 1942 that I actually made that final transfer into the Radiation Lab, although I had fairly close connections with what was going on there from the beginning. So I spent then the rest of the war years from 1942 till, in fact, July 1946 as a member of the staff of the Radiation Lab. In the spring of 1945 I was made a candidate for the Society of Fellows at Harvard as the way to go back to physics after the war. I had, in fact, received the BA degree from the University of Buffalo by advancing my credits sufficiently to get the degree after three and a half years. When I left in January of Ď41, I wasn't actually due to graduate until June of that year. And that's the end of my formal schooling, as a matter of fact. I came to the Society of Fellows in principle in July of '45, but was on leave until July of '46 while for most of that time, I participated in the Office of Publications, writing for the Radiation Laboratory Series. In fact, most of volume sixteen of the Radiation Lab Series was the result of my effort. In the fall of 1945, while we were worrying about the writing projects mostly at the MIT Radiation Lab, we (Henry Torey and myself and Ed Purcell) had the happy experience of getting involved together in the project which developed into the discovery of nuclear magnetic resonance. That came about because Torey and I who shared an office in the writing project, often went out to lunch together, walking to Central Square, and we invited Ed to go along one day. On route Ed asked Henry Torey, "Why couldn't one do the Rabi type of proton resonance in solids?" Torey, who had done his thesis work with Rabi in the middle thirties, said initially that there used to be some talk about that around Columbia and he was trying to resurrect what the problems were. That developed into more and more thought over the next few days, and in fact developed into the project which we undertook as a moonlight operation which had its fruition in early December of that year in the first observation of nuclear magnetic resonance of protons in solids. Well, so that's my education. I came to Harvard as a member of the Society of Fellows in fact in July of '46. One of the initial problems was that the Selective Service thought it would be a good idea to draft all those who had exemptions during the war. President Conant had announced that draft deferment requests were fine during wartime, but any officer of Harvard University was forbidden to request the deferment of any other member of Harvard University during peacetime. So I was called up for a physical exam and managed with some care, to come out of it with a 4F rating, although I had come out of it with a 1A during the war years.

Sopka:

What was your ailment?

Pound:

My ailment was having sweaty palms and some other evidence of psychiatric instability, I guess, such as a dislike of subways. I'd rather drive and a few other things like that. It was probably one that would not have stuck if the situation had been more difficult. I thought it was a little anticlimactic to have spent six years involved in activities relating to the war, having an award of a Certificate of Appreciation for the War Department for these things, and then being part of the occupation in Germany. Well, the classification meant that I was going to be able to stick around and carry out some of these things that I was interested in as a member of the Society of Fellows. The thing that I had discussed with the Senior Fellows in my interview was an idea of developing atomic clocks. The reason being that I thought that they would be the ultimate reference to try to test for relativistic proposition about the relationship between atomic time scales and gravitational time scales  a question which hasn't yet been answered completely, but a question about which I thought I was in the position to develop something that might make possible some measurements. I never did get around to doing that though, because, in a few months time, I had gotten involved in the start of the nuclearmagnetic resonance program. That occupied my interest for quite a few years. I was also concerned with the development of atomic clocks because it related to what I had been doing at MIT, rather on the side. It wasn't a part of my actual responsibility, but I developed the technique known as frequency stabilization of microwave oscillators. I always thought that the thing to stabilize them on was an atomic reference line, the ammonia line from molecular ammonia, for example. The ammonia inversion spectrum was the one in mind. Well, a project was undertaken here in that direction, with me as sort of a consultant and that was done by Ewen Fletcher as a thesis project in what has become the Division; it was the Electronics Research Lab and part of what was then called the Engineering Science and Applied Physics Departments indirectly under Professor Chaffee. It didn't go very strongly in the direction of trying to develop the atomic clock, because Fletcher spent a lot of his time trying to see how stable an oscillator could be made without stabilizing it by removing all the perturbations. He made very elegant power supplies and other things. I was a little disappointed that he didn't pursue the issue of the fundamental frequencies standards as rapidly as I would have liked him to. But anyway, I got into the nuclear magnetic resonance business with Purcell. Bloembergen became the first student here to work with that project and I worked rather actively with him during the spring of 1946 and then summer and through the fall. In 1947 I started another project on my own which was an effort to detect nuclear magnetic resonance in zero magnetic fields where the energy spacings were caused by the electric quadrupole interaction, the interaction of nuclear electric quadrupole moments with crystal fields. I was inspired into that by hearing a lecture by Rabi who described some low field experiments in molecular beams where it was zero field splitting which could be observed in molecules. The idea of contributing to nuclear physics was the interesting thing to me, and molecules had electric field gradients dreadfully difficult to evaluate because they involved a lot of electrons to make up the total electronic wave function. Therefore nothing much very quantitative about the nuclear properties could come out of those experiments in molecules. But I thought, for some naive reason, that if we could do the same sort of thing in ionic crystals, the charges could all be treated as point charges, situated on a simple lattice and one could calculate straightforwardly the electric field gradient at one of them due to the others. That turned out to be an extremely naive picture. Such a calculation is involved but the effect of the electric field gradient on the ion containing the nucleus in question turns out to be just about as complicated as is the molecular problem, and for the same reasons. There are an awful lot of electrons whose polarizations and quadrupolarizations have to be included. But anyway, I naively thought this was going to make a great subject and I set out to try to do that experiment in ionic solids. Well it didn't work, I couldn't, it was too hard to predict where to look for a nuclear magnetic resonance line of that sort, you couldn't move it around in the field, and one just had to find it. I tried to do some calculations, particularly for mercuric sulfide and I thought I knew about where to look, In retrospect, we still haven't found that line in mercuric sulfide although an associate of mine worked rather hard a couple of years ago, just to find it, just for completeness. It's probably about a hundred times different in frequency from the frequency we were expecting it to be, based on my simple calculations back then. The lines in mercuric chloride have been found, you see and they are about a hundred times different, 300 megahertz instead 300 kilohertz — a thousand times larger. So instead of trying to do that, I realized after a few months that that particular thing would be very hard to find. I wasn't interested in looking for the case of a molecular solid. One could predict the frequencies to look for in molecular solids by knowing quadrupole couplings in the gas phase. This had been observed in many cases, like chlorine, and iodine and others, in microwave spectroscopy of gases. So I thought, well that's the same problem. You don't solve the problem about the field gradient; you're looking at the same material. So I didn't look at that. Instead I decided to look for fine structure in ionic crystals. And that's what I in fact, found. And so my independent contribution besides measuring values of certain nuclear magnetic moments was finding the first examples of fine structure in nuclear magnetic resonance lines in a strong magnetic field, the fine structure being due to the electric quadrupole interaction. That became my main interest for a while. Meanwhile Dehmelt & Krueger in Germany did discover the zero field quadrupole resonance, which I had looked for a couple of years earlier by looking at molecular crystals containing chlorine. I had returned to look for it again, when I realized there was a virtue in a very high frequency version of it. Namely, I had published in 1949 the proposition that a crystalline solid with a sufficiently large electric quadrupole interaction, if put at a very low temperature, would have oriented nucleii — nucleii aligned in space, that is space measured by the directions with respect to crystal axes. I became interested again from that point of view as a way of studying the directional properties of nuclear decay radiations and crosssections and so forth. I set out to show that such high frequency couplings did exist. And in this case, I was interested in the molecular examples and started to explore them. Just before finding any, the Dehmelt & Grueger results on chlorine came out. I began looking for the high frequency cases for iodine and others, which were expected to correspond to temperatures of the orders of tenths of a degree and therefore they would give significant nuclear alignment at reasonably easy to achieve temperatures.

Sopka:

May I interrupt just to ask you about your educational background? I'm curious to know whether your undergraduate training at the University of Buffalo was sufficiently sophisticated to allow you to then take off and be self-taught so far as doing the normal graduate course work that a student does before embarking on independent research.

Pound:

Yes. Well my educational experience there was rather special. Actually, I grew up in a family with my father a Ph.D. physicist in 1913 at the University of Toronto. I knew that I was going to become a physicist from the time I was ten or less. So the answer to the question when did you decide to be a physicist is simple in my case. I never thought of being anything else. Not because I emulated by father especially, but somehow I did think that that was what I was interested in, from that young an age when I didn't really know what it was. My father had ceased being a physicist before I was born. When he returned to academic life in 1922, after five years out of it he became a mathematician instead. And taught mathematical physics at the University of Buffalo. In fact, in that college experience it became such that I couldn't even avoid being a student in my father's classes, because he was the only person who taught advanced theoretical mechanics, and vector and tensor analysis and such courses. They did switch around the courses so I could avoid him in some of the other cases, but there wasn't anyone else who taught the advanced mathematical physics.

Sopka:

But you did have those as an undergraduate.

Pound:

I had those as an undergraduate, definitely, yes. And complex variables from Ellis Ott who was a professor in the math department as well. But I wouldn't say they were terribly sophisticated compared with what our undergraduates get now.

Sopka:

No, but compared with what the undergraduates for 1940's would have had.

Pound:

And another virtue of the University of Buffalo at that era was that it had no distribution requirements and it had patterned itself on the Eliot and Lowell model of education, in that it had adopted a completely elective system but had a strong concentration and tutorial requirement. And as a matter of fact, because of my special preparation I think, (I had been a radio ham from the age of thirteen and I was pretty prepared to be an experimental physicist in some way) I began doing independent projects as a sophomore under Professor Hector, who was perhaps the most research oriented member of the physics department there. In fact, I served as his assistant, not only in research, but also in his outside consulting activities while I was at the University. He did a number of things, particularly in the area of acoustics and among the things I did as a tutorial student were the development of a reverberation timemeter which we used in his consulting activities, going around measuring the acoustical property of the new Kleinhans Music Hall in the city which was designed by Sharinen and which we found to be much too dead compared with what it was supposed to be. That turned out be because some women of Buffalo had contributed carpeting to the floor, which wasn't part of the acoustical plan. A high school in Kenmore, New York which was being built with acoustical plaster ceilings. The school department began to wonder whether they were getting their money's worth for the extra price of the acoustical plaster and we found with my machine that they were being short-changed, that the acoustical plaster was not absorbing in the manner that it was supposed to be and the contractor had to do over the whole high school ceiling. By this indirect method it was discovered that he only had about half of the thickness of the acoustical plaster that was required. So I did things like that. In the last year that I was there I took over the research project which had been the basis of the award of several master's degrees — they didn't have a Ph.D. program then. This was a project that Hector had followed ever since his graduate days at Columbia, on the electric susceptibility of gases and in order to carry it out I developed some new instrumentation, including a frequency standard, which related to some things that I did later. So I had a hundred percent of my time in the last couple years devoted to concentration subjects in formal education and I had a lot of involvement in experimental research or developing gadgetry of one kind and another. So that was a rather special undergraduate education. But I think that my real education came about during my Radiation Lab days when I became relatively professional, in the era between 1942 and 1946. I suppose I reached a kind of technical maturity even if not in physics. There I was, however, working with fifty percent of the distinguished physicists in the country even though there wasn't really any fundamental physics going on there. The approach and the point of view was always that of physicist and I was a fullfledged participant in all that. I have a feeling that I'm a kind of maverick. My graduate education was one of the sacrifices of the war. In a way, I never expected to avoid it as I did. I always assumed, (and that's something that I've had a problem about ever since) that I was waiting for something before I got started on my proper career. I assumed I was going to Columbia as a graduate student because that was what my mentor's first choice would have been, since he came from Columbia. But in the end, I never did. I didn't expect that, so I put off everything during the war thinking I was going to be a graduate student for some years after the war. Instead I ended up joining the faculty in 1948. So I only spent two years in the Society of Fellows, which is normally a threeyear term. Because of the first year I spent on leave I probably could have easily gotten my third year as an extension of the end of the technical term, but I was invited to become an Assistant Professor of Physics instead.

Sopka:

So then you had teaching responsibilities.

Pound:

Yes, I certainly did. In fact, I think I was the last socalled fulltime assistant professor. All of our assistant professors now are half or quarter time and therefore, my first term I had two courses to teach, not one. There just began to be the appointment of people at halftime and they had the advantage of being otherwise paid from research grants and contracts, and having a source of research support in that way, plus being only required to teach at half the rate that I was. So I found it a little hard to understand what my advantages were, because I was a fulltime assistant professor. The first term, I taught what was called Physics 10. Physics 10 was a course which, when added to one, equaled eleven. A course we don't have any longer. In some ways I suppose it most resembled of the present courses the newly created Physics 5. It was a oneterm course, with the idea that the concentrator's introductory course differed in sophistication mostly, not in subject matter. So Physics 10 was supposed to cover all of the subjects of Physics 1 and bring the sophistication up to the level of Physics 11, which meant using calculus and so forth. The theory was that there were a lot of students who discovered they were interested in Physics and wanted to go further, and therefore would have to have the introductory course 11. The practice was that there were a number of people in other fields like Chemistry and Biology whose departments preferred them to have credit for 11 rather than 1, but they didn't feel up to taking 11 in one fell swoop. Therefore, they were trying to do it the slower way, and the talents of the students were not so high as you might expect on the first thesis. And you also found out that the students that you had didn't seem to have retained very much from Physics 1. So you sort of had the problem of teaching to them all of Physics 11 in one term, instead of a whole year. That was the problem I felt I was faced with. That wasn't the first course that I taught at Harvard though. I did teach a course as a Junior Fellow. In those days, Junior Fellows were encouraged to teach a course at their own instigation. I gave a course numbered in the Division — or what was then the Engineering and Science Applied Physics Department — on the fundamental limits to amplification and fundamental noise. This was a subject to which I was particularly close because of my Radiation Lab background.

Sopka:

What level students were there taking it?

Pound:

Well, it was basically a graduate level course. I guess they were all graduate students, yes. In fact, one student who came to it, mistakenly so, was Dave Middleton who became, had already become I guess, a very prolific contributor to the mathematical theory of noise. He's been in the field ever since as far as I know. He works as a private consultant but he publishes great stacks of things. His concern with the theory of noise was a bit different from mine. Mine was a more pragmatic and experimental one. Middleton had worked with Van Vleck during the war on the theory of the detection signals in noise. So the other course that I took over teaching was one that Purcell had given the year before. Basically, the three courses I taught that first year were what became Physics 231 and 131 and 10. 131 was the intermediate electricity and magnetism 231 was the graduate level electron physics course which I taught, off and on, for several years. It finally moved over to the Division and has died now, I think. I don't think they have such a course anymore. I think Chaffee had taught it before the war and that Purcell taught it for a year or two. And then I did.

Sopka:

I took it with Purcell — it was called 28.

Pound:

That's right; it was called 28 when I first taught it. Then I taught in the Summer School in the summer of '49 for the first and, I discovered, the last time. I taught 131 again in the summer school of '49 and I taught a course for the Engineering and Applied Sciences Department called Applied Math 102 which was something close to what Math 105b is now. It was a second halfcourse supposedly dealing with series and Laplace transforms and differential equations. It was completely new to me. My first graduate students were two of about the same phase. I think they started working with me in '48 or '49. George Watkins and Christopher Dean. They were both working on NMR problems. I think they both got their degrees in '52. George Watkins has had a career at the General Electric Research Labs, and he became a very distinguished contributor to the study of solids by methods of electron spin resonance and others. He left there just a year ago and has become a faculty member at Lehigh. Christopher Dean went first to the Lincoln Lab and then to the University of Pittsburgh where he had a tenured position. Then he decided to get out of academic work, came back to this area working first at American Science and Engineering and then at Remington Rand Research Lab. He decided he preferred academic work after all and is back in academic work at the University of New Mexico in Albuquerque. I have had about twentyfive odd students over the years. So far, I've not run large groups. My students have generally tended to have rather independent projects and so worked individually and, more or less, directly with me. Often there has been relatively little continuity from one student to the next. That meant the students had pretty much to build up their own experiments as well as to carry out their application.

Sopka:

You then provided a setting for a student who would not feel at home in the large project kind of group research. With you he could work on a more independent basis.

Pound:

Well, that's not by design but that seems to be the way things have worked. I've tended to do things that haven't required a big investment in machinery that committed one to continue in a certain kind of activity for a very long time. Right now I probably have more such commitment than I've had before, in the form of our high field magnet. We have a fairly extravagant superconducting magnet and cryogenic system with a dilution refrigerator. The student who has been working with that for the last three years, Harold Vinegar has finished. He finished this fall and that apparatus is now inactive. With the kind of time I have, I can't do experiments with it alone because it takes continuous attendance in the course of an experiment which may last for a couple of weeks, and I just can't make that kind of commitment. So until a student or a postdoctoral person that I could afford, appears, I don't know what's going to become of it.

Sopka:

You mentioned one other day when we were talking about the fact that what constitutes physics has changed over the years and particularly the development of the Division of Applied Physics and so I thought that you might want to say something about that on the tape.

Pound:

Well I don't know as there is any easy way to say that. In this department we have tended to emphasize high energy particle physics. But that's not really to a very great degree. The physics that one can do as an individual project gets less and less in a way, because everywhere people have more sophisticated apparatus available. One may have many computers or be tied into big computers even in order to do simple things like nuclear magnetic resonance or Mössbauer effect studies. It's not easy to run an experimental program that just carries individual projects in the old way anymore. If a good project comes along, you can't generate the kind of sophisticated instrumentation it takes to solve it, just overnight in order to do that project. So it has become harder to move from one subfield to another. Having the machinery going and then if something interesting comes along to do, you can do it. In some sense we were in that position when the Mössbauer effect came along because we were actually studying the directional correlation of gamma rays for the purpose of observing the effects of internal fields. And we had the equipment to do gamma ray research. Therefore that aspect of the problem was not novel for us. We could convert our interest into that particular form that was required for the Mössbauer effect. Perhaps some people acquire skills in a technique and tend to use that technique to let it lead them into subjects to which it can be applied. Nuclear magnetic resonance is an example. One easily moves into the kind of physics that nuclear magnetic resonance leads to. I've been involved in several fields that have ended up being of great interest to materials scientists and chemists. I've not pursued them for all their worth in that respect. Nuclear magnetic resonance is an example. It now is such an important tool for chemists that it's almost their subject. Relatively few aspects are often employed in physics laboratories now. Some of the very low temperature studies, like the studies of helium3, are still interesting as applications of nuclear magnetic resonance to learn new physics. The directional correlation of gamma rays turns out to be a subject that chemists employ, and are interested in. Before nuclear magnetic resonance, microwave spectroscopy, which I might have thought of entering after the Radiation Lab days, became a chemists' field. In fact, I helped Professor E. Bright Wilson and the chemists here get started in that field, when I was still down at Radiation Lab. Bright Wilson sent his postdoctoral assistant, Ben Dailey, down to my laboratories where he started building up their first microwave spectrosgraph. I mistakenly advised them to use cavity resonators. We were devising a cavity resonator into which could be introduced a Stark field to modulate the absorption in a manner parallel to what we were doing in nuclear magnetic resonance by modulating the Zeeman effect. I had, in fact, asked Wilson if there wasn't a way of modulating with electric fields and wouldn't the Stark effect provide the similar modulation so you'd get much increased sensitivity. That's how they came to get into Stark Modulation, Microwave Spectroscopy. It turned out that using a resonant cavity sample container was a bad idea for microwave spectroscopy because the RF field strength easily saturates and broadens the microwave lines since they are electric dipole transitions. The cavity didn't work out too well, so they ended up with absorption cells made in a non-resonant wave guide. That was harder to introduce Stark fields into, but they did it that way. I don't know what else about the evolution of physics that you might want to talk about. Here we have that accident of funding that led to a division between the Division of Engineering and Applied Physics and the Physics Department for the support of some kinds of physics — the solid state area particularly. It would not necessarily be separated out in that way if the institution didn't have the accident of a different form of support for the Division than for the Physics Department. It made it possible to add people in that sort of applied physics area under the aegis of Gordon McKay endowment, and thus to increase the total strength of physics at Harvard without doing it through the Physics Department.

Sopka:

About what date would that have been?

Pound:

It was '69-'70 or '68-'69...I think it was '69-'70. In fact, it was very sudden. We were, as usual, asked to submit our budget request in December 1969 and in March, 1970 the ONR suddenly said, instead of what they had said earlier that our contract would go on as expected, they were going to have to terminate it as of, originally, the end of March. After an appeal, they extended the contract through June. We had that much time to go look for new funds. The cyclotron had already closed down as far as the ONR was concerned. Involved were the continuing projects, which included Norman Ramsey's, mine and Bainbridge's. Those three I think were the only remaining active ones. Ramsey had already begun to get additional support from the NSF, so that he was able to transfer the loading and the NSF increased his funding. The ONR support had the quality of what we call, nowadays, an umbrella contract and we could work relatively flexibly within it, once it was set up, and we didn't have to put up a project as a detailed proposal to be compared to all other proposals in the country each year and decide that it was going to be a new grant. Rather we had a kind of continuing security. The NSF individual grants are commitments for twoyears at a time. That means that one never feels that he can be confident about the future. I've rarely felt that I had the security to say that I should try to hire postdoctoral people because I must fight for those to be covered in the grant enough ahead of time to have it available at the time that they're there. One gets locked into a style of operation and once you're into it, itís hard to get into a different form. Some groups have always had large scale grants with several postdoctoral people. That's because they got into that mode early on and it's sort of expected from year to year when they ask for the grant that they will continue in that level. It's not easy to change from the one to the other if you want to have larger group activity. You were asking about the gravitational red shift experiment which we carried out and that's one of the most intensive periods of my professional experience, because I shared a considerable excitement about the possibility of doing the experiment when we realized that the new Mössbauer effect could be developed or might be developable to produce resolution sufficient to detect this predicted effect in the laboratory. This began in the fall of 1959. We became aware of the existence of the Mössbauer effect through two letters that were published in the Physical Review Letters by a group at the Los Alamos Laboratory and at the Argonne Lab in the same issue of Physical Review Letters. They both repeated Mössbauer's experiment and added a little bit to it. But otherwise this pretty much just let us know what Mössbauer had discovered a few months before, in fact about a year before. It was only after a few weeks of thinking, "gosh, couldn't this be used in some way to measure gravitational red shift," that a certain letter in the Physical Review Letters by a local person names Husein Yilmaz that discussed tests on the earth of the principle of equivalence, which is a way of putting the gravitational red shift. I read that letter in the Physical Review one morning before I came in, and I came in and talked to Glenn saying, gosh, I think there must be a way of doing this principle equivalence with the Mössbauer. So in the course of that morning, it became clear that it was, in fact, enormously simple. All one had to do was to separate vertically the source from the absorber, in a conventional Mössbauer experiment, and try to detect the energy shift associated with a vertical separation. So that night we started exploring the tables of isotopes, to see if there was an isotope that should be exploitable and have a resolution on the level that we needed for doing such an experiment. And we came up with two examples: iron 57 and zinc 67. We decided to try to have a go and see if we could produce this new effect with those. We tried rather hard for several weeks to make iron 57 (actually the parent, cobalt 57). We made radioactive cobalt 57 which has a halflife of 270 days. Our first efforts to do that involved using the cyclotron at MIT. We found a mess which emitted all kinds of gamma rays and I don't think we actually even really could distinguish the 14 kilovolt gamma ray of iron 57, which was the one for absorption we were going to look. I was greatly aided in pursuing this problem by a conversation with Lee Grodzins, I think it was, at MIT to whom I mentioned that I was trying to find Cobalt 57. I found that the source of Cobalt 57 in the literature, which had been used to study the gamma ray spectrum published, was done at Oxford by Grace (I think it was) and they had used some material that had been made in the Cyclotron three years earlier. Therefore the shorter lived activities which contaminated our material made in the MIT cyclotron, had been allowed to die out. It wasn't easy to do an experiment on our time scale and wait three years. I was told, however, that Cobalt 57 is used as a calibration source for scintillation spectrometers in the radioisotopes business for the medical research. And therefore Lee Grodzins suggested we could probably get it from the New England Nuclear Company in Boston. I called them up and I said "Do you have any Cobalt 57?" And they said "Sure". So that was as simple as driving down into Boston to buy a millicurie of Cobalt 57 and then we started making successful sources, learned how to electroplate it on iron and to diffuse it in. We became the first to observe the Mössbauer resonance and the hyperfine structure of Iron 57 which has become the mainstay of Mossbauer reward. Then we knew that we had something in hand that we could exploit to try to do a gravitational red shift experiment. This was about three weeks after we started. And so we then put a large part of our efforts into that. Well, three weeks after we submitted the paper to the Physical Review of Letters on the absorption spectrum of Iron 57, we started to become aware that there was at least one other group in the world that was onto similar experiments. I guess I didn't really learn that until close to December when the Physical Review was about in publication. I was told by the person who called me up from Physical Review Office and asked if he could discuss our results, which he'd seen in our manuscript at the Physical Review Office, when we was to present a paper at the meeting of the American Physical Society in Cleveland in November. He said there was an interesting letter from England there also. I said "Oh, really?" and he said it was pretty much on the same subject as yours. I said "Oh". But he couldn't tell me from whom it was or what it said. I told him it was alright to tell to the Physical Society Meeting what we had found in our manuscript. So that came out before that was all published.

Sopka:

Did he also tell at that meeting what the other group had done?

Pound:

That I don't know. He didn't have a direct access to ask their approval, I guess unless he telephoned England, which I doubt. So maybe he just said there is also a group in England doing this. I'm not sure. But I became aware of what was going on in England only through the reply of my letter to Walter Marshall who was the one person to whom I had sent a preprint of the paper we had submitted to the Physical Review on the Iron 57Mössbauer results. Because Walter Marshall, I knew, was particularly interested in calculating the internal fields in ferromagnets and therefore he might be the one most interested to know our first details of the hyperfine structure situation. It turned out that he was busily helping the experimental group at Harwell do a similar thing. But, in fact, they did not have a spectrometer, and did not observe the hyperfine structure directly. They only inferred there was hyperfine structure, from the strength of the absorption. So anyway, we worked very hard and I think I had less sleep in that year than I've ever had in any other stretch of time in my life, before or since. Actually I was able to participate actively as an experimental physicist during that term because my teaching commitment for the fall sort of fell through because there were very few students registered in 247 in which I was working with K. T. Bainbridge. Instead of having double staff, we decided I would not teach that fall. Street, who was acting chairman that year, said that didn't mean that I would have to do something extra in the spring. Actually, what did turn out was that the experiment got very hectic, just about the time of the end of the first term and our problems of solving why it wasn't working properly and also getting the results fell into the spring term, during which time I did end up teaching double rate. So, as I say, that was a more hectic term that I've spent in my life. I taught Physics 12b, the first time for me, that spring.

Sopka:

That's not an easy assignment under any circumstances.

Pound:

I had never taught Physics 12 before. I had 200 and some students. I also taught 247 in the spring term. We ran it both terms that year, so I sort of had a double teaching duty, one of which was the full, the big course as well, you see. Sometimes in the old days we used to consider the management of the big course to be worth double teaching duty. When we used to have to teach two courses one term and one the other, the two courses could in fact be substituted for by management of the big introductory course. We didn't have as many assistants as now. Now the big courses usually have one or two junior level faculty members associated with them, as well as the teaching fellow staff. I had Joe Palmieri as my assistant in 12b, that year. Anyway, we went on to make the experiment work after discovering certain troubles, particularly the trouble with temperature stability. Our experiment was carried out in the old tower of the Jefferson Physical Laboratory the socalled enclosed tower. It wasn't an isolated tower, anymore, by the time we got to use it, because back in 1953 there were certain building renovations done and the question of not doing anything that would violate the isolation of the tower from the rest of the building came up, and we decided then that nobody was interested in that isolation and therefore some of the isolation was bridged by the stairway, up in the attic area. But it was a rather amusing site to have available because it sounded as if it was special to that subject but I think the fact that it was an isolated tower never really helped very much.

Sopka:

Was that put into the building design in anticipation of specific use?

Pound:

Well, I think its original purpose was to provide a backing for the mounting of sensitive instruments in the several rooms that surrounded the tower. There used to be a kind of window shaped aperture on the inside wall of the rooms surrounding the tower — the optics lab and so forth. So you could mount your galvanometer against that remote wall and have it isolated from the walking on the floors. None of the corridor floors or any of the other floors were supported from that tower, you see. The separation is about a foot between the two masonry walls, one of which supports the building rooms and the other is the tower. But that gap is closed down just to a mortar strip in the corridors where you can see it in the arches. It's not really isolated completely, the mortar is not supposed to carry the major vibrations through that small area. Anyway, there was an earlier experiment that had been carried out in that tower. The only one I had ever discovered was one the E. H. Hall had done in 1902, and its reprint is in the first issue of the Contributions from the Jefferson Physical Laboratory — series of articles under the title "Do objects fall South?" He had a device that released balls which dropped through the tower and landed in some modeling clay at the bottom. He compared where they landed to where his plumb bob showed was the vertical and he tried to detect the scattering, to find out whether there was a mean deflection toward the South. I don't know quite why the question was the South. It's a secondary Coriolis force, but he never seems to have analyzed it in those terms. Anyway, the conclusion was that the scatter was far bigger than any measurable southerly component. Department Chairmanship days — that was 1968 to '72 — I think I should remark that those were rather difficult days at Harvard. That was through the period of student upheaval, the occupation of University Hall and all the emergency committee meetings and things that went on as an aspect of the whole unrest that was alive in the country. I remember having to go make speeches in the main faculty meetings which met almost weekly. They were meeting in the Loeb Drama theatre to have a large enough meeting space, where these issues about the creation of a department of AfroAmerican studies came up. There were factions, there were liberal and conservative caucuses of the faculty which had teams that would take stands at the faculty meeting pro and con on certain issues. And I was required to make statements on behalf of the students and the faculty of the Department of Physics. How they stood with respect to proposed legislation.

Sopka:

Can you recall briefly what those stands were?

Pound:

I was trying to remember that. I would have to think that one out.

Sopka:

In general, was there a consensus within the department?

Pound:

Yes, yes I think that there was a pretty strong consensus in the department. But I cannot quite remember. There wasn't a very strong element of extremism here.

Sopka:

Did it seem as though the Physics Department had a characteristic stand which differentiated it from other departments, either scientific or social sciences?

Pound:

No, I don't. I think that the Physics Department and the science departments generally were more concerned with keeping their activity going and with interest in their subjects than were some of the other departments. The main activities, the strikes, and the efforts to get some voice in the decision making in the University came mainly from other, from the social science people — the students. I remember there were some efforts to get the physical sciences people involved in SDS activities. There were meetings, mostly held in the old lecture room in Pierce Hall I remember, that had tried to get a statement endorsed to do with "military research" as they called it. You see, there was an issue. It was easy to say, "get the University out of military research". Those of us who did research with sponsorship from, say, the ONR, (the Office of Naval Research) knew perfectly well that we were not doing military research. And what researchers looked to be that or have that sort of title were not military but the sources were the Department of Defense. It was a rather odd situation; because you were on the one hand put in the position of pointing out that the fact that it was sponsored by the Navy was purely incidental and it had nothing to do with the Navy's objectives. But then in another year or so, the Mansfield amendment ended it. In the beginning the only sense in which these things had to do with the Navy's objective was that a strong scientific community was regarded by some in the Navy as an important part of the country's defense. They had learned in the Second World War that the flexibility to call upon that community when the chips were down was something that they valued very highly. They hadn't had it when they went into the Second World War, when the United States military establishment was abysmally poor in technology, and that's an important factor which some people don't realize. I think the Europeans, say the British, were far ahead of us in the technology in their military establishment. Less so, in the Royal Navy than in the RAF. After all, that's mainly where radar came from. And as I've understood it, the only communication radios in the United States Air Force at the beginning of the Second World War weren't even superheterodynes. They didn't, you know, have modern equipment. And of course everyone knows that the aerodynamic and fighting qualities of the Air Force equipment at the beginning of the Second World War were far inferior to those of the RAF or the Luftwaffe. I remember, A. J. Liebling writing about how it was almost criminal to send out American pilots in P40's to fight in North Africa, where they had to engage with firstclass German fighter planes, but we didn't have anything else. Apparently the main problem was that they were quite vulnerable to enemy fire and they also had rather poor firepower compared with the European planes at the time. But anyway, the Navy got its baptism in working with the scientific community during the war and there were people continuing in the Navy who thought a close relationship was really a great asset. They designed the ONR to be able to continue it. Originally it was called the Office of Research and Inventions. The Navy was the only military establishment that had a structure that allowed it to make contracts like that. So they got started, just after the war, in using some of their money to finance academic research — like the Harvard Cyclotron. Mansfield was probably quite right that they were using their monies to promote objectives that were hard to connect with their role, if you took a narrow view of it, especially after the NSF was founded. Then there was an alternative. But it was a long, long time to get an NSF started. And the people who first staffed the NSF were the people who built up the ONR. Allan Waterman, Randall Roberts and Manny Piore. Those people who put the Navy in the business of funding fundamental science translated their experience into the NSF to get it going. Well, some argued that the ONR ought to continue anyway in that field because it's good to have flexibility. It's good to have competition, more than one agency to which to look for a given kind of funding. I think that's a reasonable argument so long as there are human organizations they are subject to frailties as they are, get locked in to a situation If you get rejected in looking for funding from one agency it's nice to think there are others you might try. There really are not now. For most fundamental things the NSF's the only one. In some fields ERDA is an alternative. In some fields NASA is an alternative. But the only one that really covers all is the NSF, now that the various Defense Department agencies have been taken out of fundamental research.

Sopka:

All the others, I suppose, would be subject to the same restriction from the naval research in the sense that they would have to show some relevance to their main mission.

Pound:

Yes. For example, I might argue about experiments in relativity. We have argued that NASA should be willing to support groundbased activities that are complementary to what they might have to fund to do spacebased experiments. The development of frequency standards, of Clocks for example. Eventually these things will be of great importance to establish the metrication of the solar system to higher levels of precision than so far. So one argues that NASA should be in that business. They resist it rather strongly. Most NASA budgeting likes to be very closely connected with true space exploration.

Sopka:

As of the moment.

Pound:

Yes. That's right.

Sopka:

Well, were the students reasonably wellconvinced that the Physics department had not sold out to the military?

Pound:

The ones in the department...oh, yes. There was a rare case of a student inside that had the wrong idea. One of the problems that I had a bit later was the interference with Ed Land of Polaroid who was scheduled to give a colloquium talk on what he calls the Retinex Theory of color vision. He had been harassed by a companybased group of blacks, particularly, who were called the Polaroid Workers Union and who were trying to force Polaroid to take a different stand with respect to their relationship to South Africa. They threatened to interfere with his talk and this group came and occupied Jeff. 256 to hold a meeting to decide what to do about the scheduled lecture in 250 which Land would start in the next hour. We talked to Land who was here and he didn't want to have his lecture interfered with on that basis, partly because he felt that if any of that crept into the talk, what people would take away from that talk was recollection of that incident and not really a technical understanding or concern with the subject that he wanted to deal with. He had already had such an experience at the New York Physical Society Meeting where the Chairman of the meeting had talked him into answering questions before he started his talk and that was rather a disaster from his point of view. Well, it turned out it was a graduate student in the Division who had informed the Polaroid Workers people that this thing was going to happen here and encouraged them to come and do this. He later got his Ph.D. in the Division, I think, with Harvey Brooks. But he remained a protagonist of this position of harassment about Land in particular.

Sopka:

How did you resolve the dilemma on that particular day?

Pound:

On that particular day, as the time approached we were told by some of my students who attended their meeting that they'd taken a vote to force the talk for at least twenty minutes into their channel. We decided just to cancel the lecture and made the announcement that the lecture was cancelled because under this climate it did not seem possible to have a talk without interference. This became a cause celebre in the University. There was discussion in the Faculty Council. All kinds of people saw fit to make their comments, thinking that we were negligent or derelict in our duties in not holding an official function of the University, just because we were faced with a disciplinary problem. And this was the cause of considerable argument in defense and in opposition to our position. In the Faculty Council there was proposed a resolution by Roger Rosenblatt, who was one of the leaders in its formation, which suggested that it was improper ever to call off a university function which had been officially scheduled. It was hard to get everyone to understand that this was not interference because of any University issue. The interference was between the President of Polaroid Corporation and people who would change his corporate activities, most of whom had some relationship to the corporation itself. Now perhaps it was our duty to get enough police to keep them off our premises. But on the other hand it had been the tradition that our colloquia were listed as free and open to the public.

Sopka:

There was not specific criticism then within the University student body of the fact that the Physics Department was honoring, by inviting to a colloquium, Land who was under criticism on racial grounds?

Pound:

I didn't know anyone in the Physics Department who sympathized with that crew, but this young man, a graduate student in the Division, who had participated in the New York Physical Society interference with Land, and then promoted this particular one, certainly did take that position. And he would advertise that Polaroid was participating in the apartheid situation by (he claimed) making the identification badges. The antagonists fabricated ones that had, as the signature of the officer, Edwin H. Land. You see, they tried to make Polaroid's involvement completely obvious. Polaroid itself sent a commission to South Africa to investigate the situation, including a black administrator in Polaroid. And they came back recommending not ceasing to sell things through their licensed distributor there, but rather encouraging such violations of the racial regulations as was consistent with their business. And they thought they would have more effect on the racial problems there by just being strong enough not to pay them their due than they would by just not importing anything there. In the first instance they claimed that they weren't doing business directly there but only had a sales agent in the form of the subsidiary. So it was very hard for them. I know that Land felt that the lecture should be called off. But he said at the same time, he felt that this was a great warning to those of us who have very liberal leanings. That it made them very vulnerable. I think myself that the Polaroid company has been rather special in the amount of effort they have made as a community benefactor, particularly employment and other things like that. I've heard some people say that when they found people who said they had a severe employment problem, they would suggest trying Polaroid and they always came through. They had that year in their own report ceased to give their charitable contributions to the United Fund and gave it to the Black United Fund (or whatever its name was) in Roxbury. Polaroid then got publicized, I think, with the respect to the Black United Fund refusing their contribution, because they considered Polaroid monies tainted because of their involvement in South Africa. So it was a very confusing thing. I don't claim to be knowledgeable about Polaroid's business methods in any detail. But I did think that there were a lot of people who too easily subscribed to the accusations. There were people going out picketing the photographic stores, to stop you from buying Polaroid materials. I'm pretty sure that was probably wrongly directed if they wanted to choose someone to protest I think that Polaroid was far from the most worry some. So that made being Department Chairman somewhat rocky, with problems of that sort that kept coming in. That was in the days that Archibald Cox was our troubleshooter for problems of this sort. And I had him on the phone two or three times in the course of that day as we were making preparations for the colloquium.

Sopka:

When you say "our" you mean our department or the University?

Pound:

Harvard...the University. Yes, for the University. Archibald Cox had established his reputation in this area by having been the chairman of the study at Columbia which pointed out that Columbia's mistake was allowing the occupation of their building to go on too long. They should have moved suddenly and early. And that's often been blamed as the advice under which Pusey decided to move on University Hall, right away, rather than letting something like the Columbia one develop. His reputation went down the drain for that in many books. Well, I think that's an aspect of the Department Chairmanship but it's certainly not all of it. I mean, we have the usual problems with people coming and going and trying to get new people to come. During the time I was Chairman two or three new senior appointments were made including Carlo Rubbia, Arthur Jaffe, and is that all? There must be some more but I can't think of them right now. I don't think there's very much I can say about responsibilities on the laboratory directorship. That's more or less a service that I'm doing for, I hope, a finite length of time. On the side, while I continue to be a regular member of the department. Somebody has to do it. And we opted to do this on, perhaps, a rotating basis instead of appointing somebody who was just professionally an administrator.

Sopka:

This is the departure then from previous Directors for whom it was a lifetime job.

Pound:

It is. Yes. The first director of these laboratories was Professor Lyman, of course. But it was a rather different situation then. He did it more or less in the image of the European director of an institution. Also most of that time, I think he was sort of retired from being a regular professor anyway. I'm not sure about the timing on that, but he, after all, had been the prime mover that generated the funding that built the Lyman Laboratory. Then it was natural for him to be in charge of it when it was built. Nowadays you wouldn't think of being able to produce funding for a physics laboratory that way because the costs are so much bigger, and in those days I think there were more industrial friends or wealthy friends of Physics than there are now. Physics was less separated from Applied Physics for one thing and I think now that Physics has placed more emphasis on the fundamental aspects and that the exploitation of Applied Physics is an art itself, we're in a harder position with respect to finding other than government funding. Government is almost the only one that can make the very longterm investments.

Sopka:

Is the Jefferson Laboratory also in your jurisdiction?

Pound:

Yes. Jefferson and in fact, in principle, the High Energy Physics Laboratory. We have much more expense and activity which is all supported by government funds on High Energy Physics than all the rest of it put together. Namely, we have one and a half million dollars in government funds we spend that way. And all the rest of it put together is about two million including the faculty salaries and everything. The High Energy Physics establishment is now over in the building formerly housing the Cambridge Electron Accelerator. It occupies all but one floor of that building. The top floor is occupied by psychologists, as an overflow from William James. But as Director of the Physics Laboratories I think I'm supposed to know about that too. Margaret Law is the immediate supervisor over there. As Director of the Laboratories I am an agent of the Dean, as it were. I'm a budgetary officer of the faculty. I submit a budget for the expenditures of our restricted and some unrestricted funds for the maintenance of our operations in these laboratories. And in that sense I also do what is a part of the Department Chairmanship in many other places. But here we've always separated all the employees, other than teaching members, and they are administered through the Laboratory Directorship. The employment of the machinists and the technicians and the secretaries are all handled here. Those are part of the annual budget here rather than that of the Department Chairman.

Sopka:

The Physics Department then is concerned only with teaching aspects?

Pound:

Yes. The teaching aspect. The Department office also does make the appointment of research fellows. All of the professional physics people are appointed that way. But all the others...the technical help are appointed through the Director's office. I pay less attention and know less about the high energy group because they don't spend any University money. Whatever they do is funded by the ERDA contract. For that reason, essentially, the Dean had no reason to limit or otherwise control them except in the annual approval of their research contracts.

Sopka:

We're coming to the end of the tape. So I think I'll thank you for your help.

Pound:

All right...that's a good time to stop.