Interview with Paul Peter Ewald by Charles Weiner in New Milford, Connecticut 17-24 May 1968

Transcript

Weiner:

This is a tape-recorded interview with Dr. Paul P. Ewald at his home in New Milford, Connecticut, and this is Charles Weiner, about to be served coffee by Mrs. Ewald. The date is Friday, the 17th of May, 1968. In earlier interviews with Tom Kuhn and in published articles you covered pretty well the early events of your life. Beginning with your home life, your work at Munich and then the two separate intervals at Goettingen, you described the people there and the general atmosphere.

You described your thesis work and its impact, the reaction to it, and the origins of the dynamical theory and its subsequent development, up to a point. And I would like to start at the point in all of this which is most obscure to me, because I've seen very little information concerning your own recollections for the period about 1921 when you were at Munich. You made the transition in 1921 to Stuttgart, and it is not at all clear how this came about, what your expectations were, why you left-- that's what I'd like to start you on.

Ewald:

Well, let's see. After the war--I think I should start it in 1918, when there was a flood of people returning from the war--I had "habilitiert" myself during a furlough, become a lecturer in Munich, I think by the end of '17. After the armistice the University had to arrange a special summer semester, an abbreviated semester, for the people who flooded back from the army. My first job in lecturing was to give a course, alternating with Sommerfeld, on mechanics. He gave one lecture, I gave the next, and, of course, this was not always a very good lecture I gave. I remember especially making one terrible howler concerning the Carnot energy loss, though it was a good thing because later on when I had to lecture on mechanics in Belfast a good deal, and also in Stuttgart, I knew I had to be careful with the Carnot loss.

It was also during that period that in some Easter vacation I gave a series of lectures on the theory of x-ray diffraction, which of course was still relatively unknown. And rash as I was, I wrote to my friend Berliner, the editor of Naturwissenschaften, that I was giving these lectures and I thought I should write them down and would he publish them as a book? I would have the manuscript ready by about Whitsun- tide. Berliner said yes, he was very willing to publish it.

I'd written for Naturwissenschaften previously, so he knew me. I put a young student to take notes during lectures. This young student was Otto Laporte. This Otto Laporte wanted to go on a spree on one of the dates of the lectures, and so he charged someone else [with the responsibility] of taking the notes. This was Heisenberg. And so I got notes which really weren't very good, even as notes go. Of course, I was entirely wrong in my idea that I could finish up the lectures into book form within a few weeks, and it took me two or three years...Well, it finally came out in '23. This was the origin of Krystalle und Roentgenstrahlen. It took much longer, and I worked on it in Stuttgart, and I worked on it during the inflation, and I worked on it during vacations, which we took on the Isle of Ruegen together with the Schroedingers when the times were very hungry. Of course, when the book came out it was fine because I sold many copies in Sweden and abroad and got foreign currency, which I could turn into good value during the German inflation when nothing was stable.

Weiner:

Where did you meet the Schroedingers?

Ewald:

Well, I first met Schroedinger in Munich when he and his wife, a newly married couple, came through Munich and he gave a colloquium talk there. This must have been right after the war, in 1918 or 1919 [with Mrs. Ewald's confirmation]. (You see, my wife is the historian; she knows the dates. I'm all confused about dates. That's why she has to be with us.)

Weiner:

You know the dates, but you just don't know what happened on the dates.

Ewald:

All the dates, yes. Well anyway, Schroedinger was on his way, I think to Jena, where Max Wien had offered him a position. He stayed there only for a few months, then he went to Stuttgart on an Extraor- dinariat for Theoretical Physics, which had been held up to that time by Max Abraham. But Abraham, you know, was sick; he had a brain tumor, and I guess that's the reason he had to quit. In Stuttgart then, Schroedinger was his successor. At that time there was so much demand for theoretical physicists that Schroedinger didn't stay there for more than half a year, and then he was called to Breslau. And in Breslau he didn't stay for more than about half a year, and then he got a call to Zurich. And so they were really on the move. I became Schroedinger's successor in Stuttgart.

Weiner:

Why was there such a demand for theoretical physicists?

Ewald:

There weren't any, so people wanted theoretical physics; Atomic theory had grown up and developments in physics had taken place which made all of Sommerfeld's pupils go off, as the German saying is, "Wie warme Semmeln," like hot rolls.

Weiner:

"Like hot cakes." Well, this was a period when the universities were crowded, so there was a need for teachers.

Ewald:

There was a need for teachers, and it became fashionable to have extra chairs or extra Lehrauftrag for theoretical physics.

Weiner:

I see. And at Stuttgart, for example, there had been one man, and then he was replaced by another. Was it ever the custom at the smaller institutions to have a group of theoretical physicists?

Ewald:

No, except that I soon got an assistant at Stuttgart. The experimental physicist at Stuttgart was Regener. He did the cosmic ray work.

Weiner:

Before we get on to that, and I know I got you off the track, I want to get you back to the period in Munich, which you started to describe.

Ewald:

The question was why I left Munich?

Weiner:

That's right. You started to describe how you got interested in working on the book, which culminated much later than you had thought.

Ewald:

Yes. Well, I stayed on in Munich until 1921 and I gave several courses, one of which was on lattice dynamics. And there was a very intelligent young man sitting in, Wolfgang Pauli, who made a very good contribution because he found a better way of defining stress in a crystal than in Born's book. So it was really very stimulating to lecture there. Well, why I left Munich: clearly, you've heard of Privatdozentenkrankheit--everybody who is young wants to get into a position of his own, and I saw Lenz going off and Kossel being called away, and so I was waiting for my turn. And when the call to Stuttgart came, of course there was no question of my accepting it.

Weiner:

Do you know how it came about? Had Sommerfeld made the recommendation?

Ewald:

Oh, I'm sure that Sommerfeld made the recommendation. I'm sure the people knew of me through Schroedinger.Among the people who really made the policy at Stuttgart at the time, the main man was Fritz Emde. You know him from Jahnke-Emde, Funktionentafeln. Fritz Emde was the professor of electrical engineering, and he was a very interesting and very important man. I learned nearly as much from Fritz Emde as I learned from Sommerfeld.

Weiner:

In what way?

Ewald:

Well, you see Sommerfeld's lectures on Maxwell's theory, which formed one of the parts of his regular course, were beautiful and very interesting, but they were entirely from the viewpoint of a theoretical physicist. The permeability of a substance was always a constant, the dielectric constant was always a constant, and with that, of course, you could never do anything in a practical engineering application. And Emde, who I think had never been to anything more than a Technikum-- a Technikum is a medium-grade institution, not of the standard of a university--was a self-made man who worked at Siemens, in the Siemenswerke, before he was called to the chair in Stuttgart. He really tackled the problems as they came up in reality. His sense of reality was much greater than Sommerfeld's.

Weiner:

Was this typical or atypical of people in the universities, to have this contact and prior experience with industry and to apply it then to their own work in the university? In other words, you would expect that a professor of electrical engineering would know the real world. But what about in physics?

Ewald:

Not in physics. You see, one of the nice things about Sommerfeld was that he was keenly interested in Hydrodynamics and the problem of turbulence, which was not solved. I don't think it's ever been solved... Well, it may be solved now by the Prandtl theory, but at that time it was quite unknown why, when you exceed the Reynolds number, suddenly turbulent flow begins. In a little play we acted in Sommerfeld's house the saying was: "Und stimmte was nicht, behauptete Keckich, der Aether ist rein, die Materie dreckig." I'll have to write that down.

Weiner:

Give us a rough translation anyway.

Ewald:

"And if something did not fit in with the theory, then I would dare to state, that the ether is clean and matter is dirty." And that was, so to say, in a nutshell, the attitude of the theoretical physicist-- he liked to have a simple theory.

Weiner:

Did Sommerfeld actually say this, or was it just attributed to him?

Ewald:

Well, he said something similar; we modified it a bit, to put this little rhyme into verse.

Weiner:

Was this done by the students?

Ewald:

Yes, his students. You see, Sommerfeld quite regularly gave invitations to groups of students to his house, and we quite often acted and gave a little play or something. And I should credit this particular verse to the author, Ludwig Hopf (not the mathematician Hopf but the later professor of mechanics in Aachen and a great friend of Kármán and Sommerfeld--Ludwig Hopf).

Weiner:

You mentioned Fritz Emde and his particular approach. Do you think he had a say in the selection of theoretical physicists?

Ewald:

Fritz Emde? Oh, yes, surely.

Weiner:

So you think that with Schroedinger there and with Emde there and with the contact with Sommerfeld ...

Ewald:

Well, Schroedinger, you see, was an Extraordinary Professor which means that he had no say, except in a personal way, of course, in the choice of his successor, but he was not on the faculty board determining or proposing the next man.

Weiner:

Well, then, one way or another, you got the invitation and you were very pleased and ...

Ewald:

I was very pleased and I had a race with my wife, which she won. The race was that we expected our fourth child--a boy but we didn't know it would be a boy--to arrive, and I wanted to go to Stuttgart punctually on the first of April, 1921, because that was the date of my appointment, and so I took off from Munich on the 30th of March and paid a visit to Stuttgart and looked around and presented myself at the ministerium in order to draw my first salary check. I was very proud, of course, and when I came home late at night, I found a notice on the outer door of the apartment from my mother-in-law, saying, "quiet. Arnold sleeps in Father's bed." So my wife had won the race.

Weiner:

And so that delayed your permanent move to Stuttgart somewhat.

Ewald:

Well, I went over, and they couldn't come because there weren't any apartments to be had. This was a terrible time.

Mrs. Ewald:

Especially not for a family with four children.

Ewald:

And it took more than ...

Mrs. Ewald:

A year until I could come.

Ewald:

... a year until the family could move.

Weiner:

Then you commuted?

Ewald:

No, I stayed there. Luckily I had a kind of godmother or aunt in Stuttgart and I stayed with her until we found an apartment.

Weiner:

[to Mrs. Ewald] But you were in Munich?

Mrs. Ewald:

No, I was really in the country with my mother-in-law.

Weiner:

I see. But in the country near Munich?

Mrs. Ewald:

Near Munich, on the Ammersee. [brief interruption]

Weiner:

We just interrupted for a second to make sure that all contributors were represented on the tape, and we've determined that that is the case. What were your duties the first year in Stuttgart?

Ewald:

Well, I had to lecture on theoretical physics, that is to say, mechanics, thermodynamics, electricity and magnetism and optics--this was the usual division of courses. Atomic physics at that time hadn't come in yet; there was too little of it. But then quite soon afterwards I gave lectures on atomic physics, especially to the chemists.

Weiner:

At what level in physics were the students?

Ewald:

The students had all passed their "Vordiplom". The Vordiplom an examination which they had taken after at least four semesters of study, two years, and then the total range of studies was another two years. So I always got fairly mature students who had had their mathematics background and their experimental physics background and were working on their Diplomarbeit, on a mainly experimental problem for the diploma.

Weiner:

Did you at any time in the '20s in Stuttgart have any one working with you on a higher degree level on thesis problems?

Ewald:

Yes.

Weiner:

When did that start?

Ewald:

Oh, I think nearly straightaway. Quite soon. My first pupil was Ulrich Dehlinger who later became my successor in Stuttgart and did a lot of work on metals. This was very funny. You see, every year there was a kind of Rektoratsfest, an invitation by the rector of the Hochschule. to all the staff and to outside people, and there I met a rather short, stubby gentleman. I was rather new in Stuttgart; I didn't know who people were. He was introduced to me as the father of my Doktorand, Dehlinger. And we talked about his son, and I was quite patronizing, as I would be, you know--young professor--and said, "Oh, yes, your youngster is doing quite well," and so on. And only later I heard that he was the Minister of Finances, and all the money came from this man. [laughs]

Weiner:

And then shortly after you arrived, the book came out. This was 1923. You completed it then during your first years there.

Ewald:

And I am always astonished how I could manage to do so much work in those years because I had to build up my own lecture courses, and I wrote the book, which came out in '23, and quite shortly after that I began writing the article for the Handbuch.

Weiner:

Did Sommerfeld ask you to do that?

Ewald:

No. This was the Springer Handbuch der Physik, the blue one. There were two competing Handbucher at that time: the blue one and the green one. The green one, by the Akademische Verlagsgesellschaft, was more on the experimental side. And, of course, one of the main differences was that the Springer one made use of many young research people, many of them Jewish and very bright. The one of the Akademische Verlagsgesellschaft--i.e. Mr. Jacobi and Mr. Jolowicz, which is really Fock--I don't know whether you know there was a big Antiquariat in Leipzig, scientific antiquariat, a marvelous institution created by Jolowicz, who was also the driving man behind the Akademische Verlagsgesellschaft and the father-in-law of Jacobi. This green handbook was edited by Wien and Harms and is I think probably entirely Aryan.

Well, Springer offered a very good honorarium. So all the young people who needed money--and we all did after the inflation--fell in to writing articles for the Handbuch. And I wrote this article--in 1926 it appeared--and I wrote a second edition in 1933. I still think it's a very good book, but it suffered under being embedded in this Handbuch volume, and Springer wouldn't release it. Linus Pauling wrote me that he wanted to make it the textbook for his courses on x-ray diffraction, and could he translate it? So I wrote to Springer, and Springer said, "He can translate the entire volume of the Handbuch, but not your article." A mean thing to do. And so this article was hidden away in the thick volume, which was, of course extremely expensive, and nobody knew it.

Weiner:

When did Pauling make this request?

Ewald:

Well, this was, I think, after the first edition came out, that is to say, after 1926--I guess '28 or so when it became known.

Weiner:

So you have demonstrated that you were pretty busy.

Ewald:

And besides these, you see, I was asked by another publisher, Vieweg, to write for a new edition of Mueller-Pouillet. Now, I had a kind of liking for Mueller-Pouillet because it was the book from which I learned my first physics. This was the edition of 1856, I believe, which I found in my grandfather's library. I often read that book as a child, and so I had a kind of very friendly relation to Mueller-Pouillet. I wrote an article on the solid state which was then later, without my knowing it, translated into English by Blackie together with other chapters of Mueller-Pouillet by Prange and by Prandtl. I think you asked that question before.

Weiner:

I see. I wondered about that. I'm just trying to check the year.

Ewald:

Well, the Mueller-Pouillet volume appeared in 1929.

Weiner:

They took selections from there and put it into ...

Ewald:

Put it into the Physics of Solids and Fluids. And I didn't even know it. I heard of it just by chance so I made quite a row, saying this was not a way to deal with a publication, especially since I had written this article for Mueller-Pouillet, and they had kept the manuscript lying for about three years. And so, by the time it appeared, parts of it were already antiquated, and I was rather mad at them. And then two years later this translation was made and called Advances of Modern Physics or something--I don't know what the title is.

Weiner:

They have Physics of Solids and Fluids.

Ewald:

Yes, but somewhere ...

Weiner:

Probably a subtitle.

Ewald:

Yes, it's a subtitle.

Weiner:

It seems to me that there were very momentous developments during those years from '26 to '29, when they had the manuscript.

Ewald:

All the properties of metals were developed--well, not all of them; the slip was already known, and I gave a version of the research on slip in metals. Polanyi and Schmidt, and these people who worked in Dahlem, wrote articles. Well, the main people had been in England; there was Miss Elam, and, I think, Carpenter.

Weiner:

These are in the nature of review articles summing up the state of the field.

Ewald:

Yes, it was review articles but, you know, also presenting quite often details in a rather different way and in a different light. I mean, there were also quite a lot of original ideas involved; it's not pure review.

Weiner:

Well, by my definition of review article, it means surveying the literature, interpreting, criticizing, and synthesizing from it.

Ewald:

Yes, synthesizing.

Weiner:

What about your other contributions during this period in terms of your ordinary research papers? Was most of your research centered on the interpretation that went into these Handbuch articles?

Ewald:

Yes, I think you can say that.

Weiner:

There were probably other papers that you had done, a good many of them. Ewald - 8

Ewald:

You see one thing that developed out of my book Krystalle und Roentgenstrahlen was the Strukturbericht. At the end of my book of '23, I gave a list of all the structures that were then known, and this was a list covering 20 pages. And I thought it might be a good idea to keep this list up to date, so I started a kind of card index of all the structures I came across in order to present them in a second edition of the book. Well, I never wrote a second edition of the book for two related reasons: I couldn't read this book anymore; it was not terse enough, you know, and not concentrated enough; it was much too wide. Now I know that that appealed to a great many people who entered the subject at that time, because I got compliments on the book, many times years later. The Russians now and then--there's a Russian who still says he has learned all his stuff from my book of '23. It must have been translated into Russian, but I've never seen it. But to me it was overtaken by the Handbuch article, which was a condensed and much better and, of course, much more advanced presentation of those subjects, so I never wrote a second edition. But I did try to keep this card index of the known structures going and, by and large, that became too much work because the number of papers increased so rapidly, you see. And so I tried to get help.

I wrote to Laue and asked him if he couldn't give me an assistant for that, could he procure that through the Notgemeinschaft. Laue, of course, was a very important man in Notgemeinschaft, in the distribution of money. And so Laue got together with Berliner, the editor of Naturwissenschaften, and they had the special fund--now this is quite interesting--which was handled by a special Elektrophysikausschuss der Notgemeinschaft, and as far as I know the main part of this money came from G.E., the General Electric. And it was during a visit of Whitney's in Germany that he contacted his friend Berliner and asked what could he do. And thereupon Berliner arranged for this Elektrophysikausschuss to be created. Whitney did not want the Notgemeinschaft to do it. And so they made it a separate section of the Notgemeinschaft-- it was formally attached to the Notgemeinschaft but it was autonomous in its dealings. And from these funds I obtained Carl Hermann as an assistant to help me with the collection of structures.

Weiner:

Oh, he wasn't a teaching assistant; he was strictly for that special project?

Ewald:

For that special project. Now I told you this story just now about the G.E. I tried to confirm that when I wrote the "Fifty Years" book; I tried to confirm it with the people in G.E. who are still alive, especially Hull ...

Weiner:

Well, he's no longer alive.

Ewald:

he's no longer alive, but he was then.

Weiner:

I see.

Ewald:

Hull and Coolidge. I think Coolidge was still alive. I think I wrote to Coolidge and asked him if there was any trace of this gift because I felt it was really a great help at the time and very generous. And they searched the files of G.E. and couldn't find any mention, but I'm pretty certain that I'm not wrong in this statement, which I got from Laue and from Berliner.

Weiner:

There are ways of looking further. It would be interesting to check that out. Did Hull or Coolidge recall anything about it even though they weren't able to find records? Was this news to them when you told them this?

Ewald:

They had forgotten; they were of no help to me.

Weiner:

Well, even if it did occur, they might not have been aware of it at the time, And so Hermann came. What year was this?

Ewald:

'25. Hermann was a pupil of Born. He had gotten his doctor's degree with Born in Goettingen on the calculation of the optical activity of sodium chlorate. Sodium chlorate is a substance which rotates the plane of polarization of light, as a crystal, but not in solution, so you have a proof there that the rotation is caused by the arrangement of the molecules in the crystal--the molecule itself is not optically active.

And so this was a thing that you could calculate, really with the methods of my thesis, and Hermann did that calculation. Unfortunately, he got mixed up with the electrical units and left out several factors, Pi and so on, and later work in that field has been done by Hylleraas who calculated the optical activity of quartz. Well, then after his thesis, Her- mann came, I think, to Dahlem and worked with Mark, who was at the time in Dahlem, but only for half a year or so, and then he got this job with me. And he stayed with me ...

Mrs. Ewald

Five years.

Ewald:

until 1937?

Mrs. Ewald

No, '30. Five years I think he stayed with you.

Ewald:

No, he stayed until the Nazis ...

Mrs. Ewald:

No, then he was already in Ludwigshafen, at the I.G. Farben.

Ewald:

Look, he had the offer from Ecuador ...

Mrs. Ewald

But I think he surely was for five years... You can find it ...

Ewald:

Well, all right, if you say so, it's the law.

Mrs. Ewald:

Well, I think so; I wouldn't swear to it, but that's my feeling.

Ewald:

Well, I have to find out anyway quite soon because I've been asked to write a biography of Hermann, for this biographical enterprise here.

Weiner:

For the Dictionary of Scientific Biography?

Ewald:

Yes, Dictionary of Scientific Biography. And I'm planning to go to Marburg and get some dates from his wife.

Weiner:

Were his duties during this period that he stayed with you consistently on this structure catalog, or did he get involved in other things?

Ewald:

Oh, he got involved in other things, too, yes.

Weiner:

But he was paid, basically, for this task?

Ewald:

Well, he was first paid by the Elektrophysikausschutz. That went on for a year or maybe two years. And after that he was paid by the Zeitschrift für Krystallographie, that is to say, by the publishers of the Zeitschrift, for writing the Strukturbericht.

Weiner:

Had you gotten involved with the Zeitschrift as early as 1924?

Ewald:

Yes. Before I answer that, may I tell you ... You asked whether Hermann had to do other things.

Weiner:

Yes.

Ewald:

It's quite amusing. The first job I gave to Hermann was to discuss with me a method for turning the intensities of the diffracted rays into information about the structure. You see, if you had the amplitudes of these rays, including the phases, then you could just make a Fourier transform and you'd get the structure. But the complex part of the amplitudes and phases are not observable, and so you have to deal only with the absolute values of the amplitudes squared, which are more or less proportional to the intensity. And I worked that out and found what is now known as the Patterson diagram, Patterson method, and tried to resolve the Patterson diagram but didn't get anywhere. And so when Hermann came, who was a very good mathematician, we both tried hard to do it and didn't succeed. It hasn't been done even today, in a proper way, not in a straightforward way as we tried to do it.

So I never published anything about it, but this was the Patterson method long before Patterson's paper--I think it appeared about six years later--but he never published it. But one thing came out of it, that is, that Hermann brought in the idea of symmetry. I don't like symmetry myself and I always want to do things in the general case without much appeal to Symmetry, but Hermann was a man who saw relations of symmetry naturally; he never looked up coordinates of atoms in a crystal structure but he wrote them down by inspection just as quick as looking at the tables. He was phenomenal in that. So Hermann brought in this idea of Symmetry, and that led to his introducing what he called "Kennvektoren", which was a term he coined. This led to the nomenclature which is now used all over the world in crystal structure determination, the so-called Hermann-Mauguin symbolism.

Mauguin in Paris had invented something very similar. So, instead of the Patterson method, which I should have published, this came out of it at least. The reason I didn't publish anything at the time was that the whole idea of applying Fourier methods to the crystal structure determination had not yet been mentioned. You see, this really goes back to a paper by Sir William Bragg, but it became a practical proposition only with the advent of the Taylor-Lipson strips, which was a convenient method for summing Fourier series and a very important one in the history of crystal structure determination. It enabled people to do Fouriers in a reasonable time, whereas formerly if you wanted to look up your log tables and look up all the cosines and so on it would take you years. But here the values were printed on strips which you laid in a certain order beneath one another, and you could just sum the figures standing in the columns, and that gave you the Fourier sum.

Weiner:

Now, did you say that when you had done this work, there did not seem to be enough in the Fourier work to publish it? You felt that you knew enough about it, didn't you?

Ewald:

No, no. I probably wasn't aware of it, although in 1921 I wrote a Paper in Zeitschrift fur Krystallographie on the reciprocal lattice, and if I had been more practically minded, I think I might have turned that into the Fourier method.

Weiner:

I see. but as of this time when you were working with Hermann, you hadn't?

Ewald:

I had not.

Weiner:

Wasn't this discussion on intensities and the general problem of intensities the thing that led you into convening the conference?

Ewald:

Oh, the conference was later than the 1921-paper; the conference was in '25 or '26.

Weiner:

'25.

Ewald:

'25. That came later.

Weiner:

When did Hermann come?

Ewald:

Also in '25, but he came in the fall, and this conference was in the summer.

Ewald:

Hermann came only after the conference?

Mrs. Ewald:

That's my feeling.

Ewald:

No, but he was at the conference from the very beginning. Yes, surely.

Weiner:

You listed somewhere the people who you recalled were at the conference and he is not listed here.

Ewald:

He's not listed?

Weiner:

But you said who those present were, and you emphasized Laue and Mark, Ott, Herzfeld and yourself from Germany.

Ewald:

Oh, there were more. Well, Darwin must be among them.

Weiner:

I just mentioned the ones from Germany. There were Bragg, Darwin, Wyckoff and James, Brillouin...

Ewald:

Brillouin, Fokker.

Weiner:

Right. And Waller.

Ewald:

But I think that Hermann was there. I have a slide where I can prove it.

Weiner:

Good. That's evidence.

Mrs. Ewald:

If you can find it.

Ewald:

Yes, that of course is a different matter.

Weiner:

The reason I brought it up is to get into that other subject of the concern with intensities. Now the way you described it in this article, way , you said it was a problem and that you used the occasion of Wyckoff's visit to Europe to call together this group. It seems quite spontaneous and quite bold to call a conference, and I just wondered if you had ...

Ewald:

It was. [laughter]

Mrs. Ewald:

You just got letters that the people would come to Germany at this time, all single.

Ewald:

No. Not all single. I mean, Wyckoff was to come over and I don't know of anyone else who would have come to Germany.

Mrs. Ewald:

I thought there were some more.

Ewald:

No, no. You see, crystal structure really was at a dead end. To a certain extent you can determine a structure by geometrical means only, by measuring the angles of diffraction, because that gives you the size of the cell. And therefore you know the number of molecules and of atoms which are in the cell and quite often these atoms have to be placed on symmetry elements, because otherwise there would be too many. If you place an atom on a symmetry element of course, it's not duplicated by the symmetry, whereas if you place it next to it, it would be multiplied. The number of atoms restricts the positions of the atoms on symmetry elements, but that is possible only with rather simple structures. And now as structures became more and more complicated, you had to take the intensities into account for determining the position of the atoms. But there was no theory for reducing, or for making use of the intensities.

Bragg's method was to make every crystal, perfect as it might come into his hands, into a Darwin type mosaic crystal by grinding it up until it was an ideally imperfect crystal and then to apply Darwin's theory for the imperfect crystal and to discuss the intensities in that way. But, first of all, this was a very crude way of doing it and, secondly, it was not a very reliable way either. And so the whole structure determinations had reached a dead end. You could deal with structures where there was only one parameter, or two parameters or even three parameters to determine, but that limits the range of structures you can investigate very heavily, and the ideal was to get on to structures with eight or ten parameters, and this seemed quite hopeless. So when I heard that Wyckoff was coming I thought this is a good moment to discuss it because Wyckoff was really the leading man here in America and he did excellent work of high precision.

The Braggs work was much more inspired; they saw things in three dimensions. Old Sir William Bragg didn't want to know anything of group theory, of space groups or so; he wanted to see things before him. He spoke of the halving of planes by other atoms, and so on, and he constructed each case on its own merits, and that's the beauty of his work. There's hardly a more beautiful book than the presentation the two braggs gave in their early book, X-Rays and Crystal Structure, which is really a summary of the papers they had published mainly in the Proceedings of the Royal Society. The argument is so simple and direct and straightforward that it's a lovely book to read. But it doesn't lead very far, if you get to more complicated things. And so I thought we must do something about it. Besides, there was the hiatus between the predictions concerning intensity given by the dynamical theory and by the theory of imperfect crystals, which were miles apart, the intensity formulae, while the actual crystals gave something in between.

Weiner:

Did the other people in the field seem to identify this as the one important problem?

Ewald:

I think they all felt this was the important problem, and so I wrote to Bragg and asked him if he wouldn't come over and have a discussion with Wyckoff, and with Mark, who at that time was very active in Dahlem on structure determinations, and a few more people.

Weiner:

Any funds involved, any sponsorship?

Ewald:

Nothing. No. I suggested they meet on the Ammersee in my mother's house. My mother was a painter and she had a big studio, and I thought that would be quite a good place to meet. We certainly wouldn't be disturbed. It was during or after the inflation, so there was very little money.

Mrs. Ewald:

Someone gave you money for the conference.

Ewald:

Oh, yes, I got some money, but that was a trifle only.

Mrs. Ewald:

It was a trifle, but one didn't offer money in those times.

Ewald:

I think the Gesellschaft der Freunde der Technischen Hochschule.

Mrs. Ewald:

Just a trifle to give some coffee and cake or something like that.

Weiner:

Nothing for transportation or anything like that?

Ewald:

Oh, no, they had to do that themselves. And I think we fed them.

Mrs. Ewald:

No, only the in-betweens.

Ewald:

Wasn't the main meal quite often given by Mother? Well, anyway, you see there was one inn in this place, and I lodged them there. And there was a school in the nearby village, Utting, and I borrowed a blackboard from there--my mother had easels so that was not difficult to put up. And I wrote to bremen and got two boxes of cigars sent, and that was about it.

Mrs. Ewald:

And I remember you planned with your mother what kind of cake you would give them--there was quite a good Konditorei [pastry shop] in Utting, and that was about all that was given to the people for the coffee break.

Ewald:

And you shouldn't forget the show that was performed, which Bragg remembered; I didn't remember it.

Mrs. Ewald:

By the children, yes, a little play.

Ewald:

By this girl [pointing to a picture], Rose Bethe and this boy ...

Mrs. Ewald:

But at that time she was Rose Ewald. And the oldest was eleven, the youngest was four, so it was really a trifle.

Weiner:

But it was the spirit of the time.

Ewald:

They all were really more or less personal friends. I did not know Bragg,but I knew his Father. And I did not know James, but I knew Fokker and Brillouin and Mark, of course, and Laue and Ott.

Mrs. Ewald:

Had you met Darwin? He was at this conference?

Ewald:

I think I knew Darwin; yes, I knew Darwin.

Weiner:

When you say know, do you mean to know personally? Had you met him?

Ewald:

yes, I met him. You see, when we were newly married, my whole desire was--this was in 1913--to see southern France, and so I had planned a nice honeymoon trip to southern France on the border of Spain, San Juan de Luce. And then I saw a number of Nature, and they gave the program for the British Association assembly in Birmingham, and there was Professor William Bragg, W.H. Bragg, to talk on the structure of diamonds. All plans for France were cancelled, and we went to England to the British Association, and there I met all these people. I made the acquaintance of Sir William Bragg, who was not yet Sir at the time. Young Bragg was not there, but Darwin was there and Bohr was there and Moseley was there. So it was quite a rewarding experience. Marie Curie was there; she got an honorary degree and the newspapers said that she had come over just for the ceremony, and after receiving the degree, "the silent woman rushed off to France"--that was the newspaper [description].

Weiner:

It was making a mystery of her. In later years, in 1925, when you convened this group, had you been in touch with them before by letter?

Ewald:

I had been in touch with them before by letter. I corresponded with Bragg, even during the War. I received a postcard from Bragg with great delay by the censors, but it finally came through, and he told me, "I'm now on the structure of pyrites (FeS2), but it is terribly complicated."

Weiner:

Then, anyway.

Ewald:

yes, this is one of the quite simple crystals but one with a parameter, and it was the first one he came across where--you know all cubic crystals have four trigonal axes, the cube diagonals are trigonal axes in all cubic space groups--and this was the first one where they don't meet at the center of the cube but they go past one another, and so he had to invent that.

Weiner:

Complicated system, in that period.

Ewald:

Yes.

Weiner:

How about Wyckoff--had you corresponded with him?

Ewald:

Yes, I corresponded with Wyckoff. You see, as editor of the Zeitschrift, I had a lot of correspondence with Pauling and Wyckoff and other Americans, and altogether an international correspondence with authors.

Weiner:

This is a hard question to answer, but how large a group was it, do you think, who were concerned, either as their main research interest or as one of their major research interests, with crystal structure?

Ewald:

At what time?

Weiner:

At the time of this conference in 1925?

Ewald:

'25? I would guess about a hundred, if that many.

Weiner:

Throughout the world?

Ewald:

Throughout the world.

Weiner:

And this is based on your experience with the Zeitschrift, as well as your own reading?

Ewald:

Yes.

Weiner:

Then the group that was there represented a good proportion of the total group. They were pretty much among the leaders, weren't they?

Ewald:

Yes, they were the leaders, certainly; they were the people who wanted to make something exact out of x-ray diffraction. But the greater number of people of these hundred I quoted--the actual number might be only 70 or so--the majority of these took powder diagrams. They were chemists or physical chemists and investigated reactions and took powder diagrams to compare whether substances were the same or not.

Weiner:

Their motivations then were different. Would you say that this group was primarily concerned with the theme that seems to have guided your work of the interaction of radiation with matter?

Ewald:

Yes, that is quite true.

Weiner:

In the physics sense of it.

Ewald:

In the physics of it.

Weiner:

And so the people concerned with the intensities would have represented that group. It's not necessarily so, because you can be concerned with intensities without having this broader interest in the ...

Ewald:

In the structure determination.

Weiner:

Yes.

Ewald:

No, but they were mainly ... You see among the people I had got hold of ... Brillouin was not interested in structure determination; he was interested in the optics. And Fokker was not interested; he was interested in optics. Debye was there; he was not particularly interested; ne came only for a day or two. There were a number of people who came just for a short period, actually people whom I had not invited because I didn't think they could contribute very much. Debye I probably had invited.

Weiner:

How did the ones that weren't invited know where to come to the conference?

Ewald:

Oh, well, if they came to Munich they heard by word of mouth where these people were on the Ammersee so they just flocked out to see - their friends or colleagues.

Mrs. Ewald:

But who else came just for a day? I can't remember ...

Ewald:

Well, Herzfeld wasn't there for the whole time.

Weiner:

Fajans, too.

Ewald:

Fajans, yes. Well, Fajans had nothing to contribute to that.

Weiner:

You have him listed as "an occasional visitor."

Ewald:

Occasional visitor--that's probably correct.

Weiner:

About how many would you say were in the total group? We can add up these names but it may be incomplete.

Ewald:

The real gang were perhaps ten.

Mrs. Ewald:

Let me count them on my fingers.

Weiner:

You have eleven and yourself--twelve--as regular plus a couple of occasional visitors.

Ewald:

Yes.

Weiner:

Was there a regular procedure of someone making a presentation?

Ewald:

Yes.

Weiner:

but not a prepared paper, was it?

Ewald:

No, not a prepared paper. But, you see, we were worried about Darwin's papers. Darwin's papers were done quite early, before the first World War in 1913 and '14, and really they were very beautiful papers where he got the gist of the physics in a marvelous way and in a very simple way, so that even now people prefer to deal with Darwin's theory. Warren is just writing a book and he prefers elaborating Darwin's theory rather than the farther-going dynamical theory. On the other hand, there were contradictions in Darwin's papers which we didn't understand and so we asked Darwin to present his paper. Well, he took a reprint, I think, and more or less went along the lines he had there. And when we asked him questions, he got entirely confused and didn't know how to answer; he hadn't looked them up, and his standard answer was, "Oh,yes, yes, this I only wrote down, you know, for the print; I did it in a different way." And I don't know where it is that Bragg says--I think in this Festschrift contribution--that he was so annoyed.

Weiner:

In the Acta Crystallographica in '68, he said, " To our consternation we found that Darwin had typically omitted to refresh his memory of his own theories and was unable to explain them when he got up to make his contribution."

Ewald:

I don't know what his expression was, something from sports, that their main champion failed. ["I felt we were bringing along the British seeded player to represent our country at the meeting."]

Weiner:

I see. So he was called on spontaneously to explain ...

Ewald:

Yes. Then I gave a presentation of my dynamical theory, and, well, there were lively discussions all the time. It was absolutely informal.

Weiner:

How long did this go on? Did you have a morning session, and an afternoon session?

Ewald:

Yes, morning and afternoon sessions.

Weiner:

And evening as well?

Ewald:

This I don't remember. I don't know what else we would have done in the evening, so we probably still discussed in the evening.

Weiner:

You had a play one night, and ...

Ewald:

Well, but that was quite short.

Weiner:

And this lasted for, what, five days?

Ewald:

I should say for about four or five days.

Weiner:

I see. Then the people just dispersed and went on their ways?

Ewald:

Then some of the people went away and with some of the people we made an excursion through the beautiful woods in the hinterland of the Ammersee; we went to ... oh, what's the name of the oldest German monu ment .. I must ask Ella ... there's an old monastery, hidden away in the woods, and then to the Peissenberg which is a nice mountain in front of the main range of the Bavarian apls, and it was very dramatic because it turned out that we were a bit late. We had to catch a little train that went, at say five o'clock in the afternoon, and at four o'clock we were still up on the Peissenberg. And Darwin got very nervous and said he had to catch the train because if he didn't make that train, he couldn't get back to Munich and he couldn't get back to his steamer, his boat from Harwich and get back to England. And he didn't tell us that the next day was his wedding! So he very nearly missed his own wedding. But then at the top he and Bragg said, "Well, let's run it," and they began chasing down the mountainside, and the others followed at a bit slower rate.

Weiner:

And they made it?

Ewald:

We all made it, finally, yes.

Weiner:

Were any notes taken at the conference?

Ewald:

No. But as a result of the conference Bragg and James and Darwin overhauled the whole theory and they published a paper, I guess in Phil. Mag. And then Bragg got hold of Waller, who was one of the people at the conference, and he got Waller to come to Manchester, and they worked on the theory together. And so it really had a great effect on ... [Mrs. Ewald returns; he addresses her] Ella, Wie heisst das Kloster? Das alte Kloster ... Wessobrunn. The oldest German literary monument is the Wessobrunner Gebet ... that's the monastery there.

Mrs. Ewald:

There's only a stone.

Ewald:

Yes, there's only a stone, and the monastery is no longer existing.

Weiner:

But you went to that spot.

Ewald:

It's very beautiful.

Weiner:

You mentioned the outcome of the conference. Was there another outcome in terms of the feeling that this was a good thing and that perhaps it should be continued--the idea of meeting together?

Ewald:

Well, I don't know. No. We met on this problem, which was a problem we had in common, and I don't think we thought of any further meeting. But, as a consequence of this, Mark and Ehrenberg and I started work on the intensity of diamond. This work was being done in Dahlem where Mark was in Herzog's Kaiser Wilhelm Institute, and that is an outcome of the conference.

Weiner:

Was there any precedent for this kind of a meeting? Had a group with this special interest--not necessarily the special problem but the overall interest--ever convened before? You mentioned a British Association meeting, but that was not specialized.

Ewald:

Oh, well, that was a very big meeting. No, I don't think so.

Weiner:

This was the first specialized group.

Ewald:

This was the first.

Weiner:

Well, certainly it was international. Was there any group that met on that subject within Germany, prior to that time? By that, I mean, you know, exclusively German.

Ewald:

No, not on x-ray diffraction certainly. You see, that's the queer thing about this whole x-ray diffraction: by far the main part of the work was done in England, all the successful work of structure determination was done in England. The original work was Laue, and if you look at the various methods which are used for x-ray diffraction, let's say the Laue method, the rotation diagrams, the oscillation diagrams, the Weissenberg diagrams, then several other wide-angle diagrams--they were all German inventions, but no structure work. All the really successful work was done in England, in the two schools of father and son Bragg.

And the only other work in competition with that was Wyckoff's work here-- Wyckoff and a few other people. It started out in Pasadena with dickinson, and Pauling, and I don't know who else--all that is in the "Fifty Years." Hendricks, for instance, who's in Washington, was one of the early people.

Weiner:

Was Epstein interested in this at all? Paul Epstein.

Ewald:

No, except that Epstein rigged up quantum theory of x-ray diffraction , with momentum transfer to the crystal. Epstein and--who was the other man who worked on that?--I've forgotten just now. [Ehrenfest ?]

Weiner:

What was the relation of this to studies of the solid state? You use this word--or someone uses it--in the title of something you published in the late '20s, but is there any concept of this being a separate kind of physics concerned with separate problems?

Ewald:

No. Well, of course, an entirely new world was opened up by the possibility of finding the locations of the atoms in a solid, and so one was keen to apply that to calculation of physical properties. And, of course, in the same period Born developed his dynamics of crystal lattices, and he showed in a formal way how the various properties of crystals, i.e. of solid matter, could be put in relation to the structure. The first of these properties was the specific heat.

That was Debye's work, who, however, smeared out the crystal to a continuum and so was lmt very much in this same line. Whereas Born and Kärmän started the work, and Born continued the work, by assuming the real crystal with a periodic base of atoms periodically repeated in each cell. And so in a formal way the various physical properties were explained. The main properties of thermal conductivity and electrical conductivity were those which couldn't be explained at the time. Also thermal expansion was not explained, although everybody seemed to be aware of the fact that you had to introduce non-linear terms in the forces in order to do it. But how to do it was quite difficult.

Then the other application of the new knowledge came in the theory of atomic radii, which Bragg was one of the first to establish and to use for the determination of structures. It really came out of the ideas of Cambridge chemists Barlow and Pope. Pope, I think, was the professor of chemistry who had this concept of atoms packed together like spheres, spheres of various sizes, and this was taken over by Bragg and proved to be very successful. Then in Germany it was Kossel who also took up this idea and llnked it to the Bohr atomic model. He and Fajans, both in Munich, and often in collaboration, followed up this idea of atomic radii and of completed shells, which are similar to those of the inert gases and which lead to the chemical bonding.

Weiner:

And these developments that you've been describing occurred over how long a time?

Ewald:

Well, Kossel's work is quite early. That was, let's say, 1919 to, I don't know, '23. And Fajans introduced the concept of deformed ions, and this always seemed to me a very vague concept.

Weiner:

Let me get back for a minute to the general activities at Stuttgart. We talked about the conference. What about visitors in the normal course of things? I know, for example, Warren came over. I am sure there were others.

Ewald:

Oh, we had a good number of visitors.

Weiner:

Would they come on a fellowship or on a tour or for some specific purpose?

Ewald:

M ainly they were visiting laboratories in Germany and came to Stuttgart as one of them. And then there were a few who settled and worked in Stuttgart for longer periods, such as Warren and Nitta, the Japanese, and where they worked d either with me or with Glocker in Stuttgart. Also Konoboyevsky, a Russian, who I think is still quite active in metals, and I don't know whether it was Uspensky also who was there. Well, I mean there were a number who were there.

Weiner:

This is the '20s you're talking about.

Ewald:

This is the '20s. This was actually after I had gotten my little institute.

Weiner:

The institute was 1930, I thought.

Ewald:

That may be. These people may be earlier.

Weiner:

When did you meet Lonsdale?

Ewald:

Kathleen Lonsdale? Oh, I came over to England quite often and each time I visited Sir William Bragg. Sometimes I was invited to stay with him, and Kathleen Lonsdale was one of Bragg's co-workers. So were Astbury and Bernal.

Weiner:

I know Bernal visited Stuttgart on one occasion.

Ewald:

Yes.

Weiner:

I know you said you went to England often. Did you make other trips to other places in Europe?

Ewald:

If I went to England, I also usually, or several times, went to Paris.

Weiner:

What was the attraction there, other than the life of the city?

Ewald:

Oh, it was Mauguin. You see, Mauguin's and my book were the first books, except for the Braggs', which was really a resume of their own papers. But both Mauguin and I tried to give a balanced account of the whole field, and the two books appeared about the same time. I think mine may have been a bit earlier than Mauguin's or it may have been the other way around--I don't know. We didn't know one another, or of one another, at the time, but then soon after I took an occasion to go to Paris and to meet him. The first who went to Paris on an explorer's trip, so to say, was Mark and a group of his co-workers in Dahlem, a very jolly group. Herman Mark and his wife Mimi and an Indian, Bose, who worked with Mark. Let me see, is this the "Einstein" Bose or not?

Weiner:

I was going to ask you that.

Ewald:

I think it is the "Einstein" Bose; I'm pretty sure. And there was an Englishman, Green-something [probably Greenwood]; I think he was at the British Museum--Francis Bitter was with them and then Ehrenberg. And you see, this was one of the very, very nice parts of Mark. Ehrenberg was a cripple; he had had infantile paralysis and could walk only in a very limited way. But they took him along on this trip to Paris, to go sightseeing in Paris, and visiting the people, especially de Broglie-- that was not Louis de Broglie but Maurice de Broglie, the elder brother-- who had his laboratory in his own private hôtel, in the Rue Lord Byron, and they visited Mauguin, of course. And on the way back they made a stop in Stuttgart and all stayed overnight with us.

Some of them came on the way back, and I was, of course, very keen to hear all about Paris--I hadn't been to postwar Paris at that time; this must have been in '25, shortly before the conference--we could find out from our guest book the exact date--and so the description I got from Mark of the laboratory of the Duc de Broglie (yes ,Duke, the younger one is the Prince) was, "Oh, it's wonderful. It's a big hôtel with high rooms and there are Gobelins everywhere on the walls of the rooms. And two rooms are there for the x-ray equipment--they have the diffraction thing and the x-ray tube in one room, and they have the high-tension in the other room, and then they have cut a hole in the Gobelin and in the wall and have the high-tension lead passing through the wall." And the people who did the work at the time were Thibault and Trillat and it was very interesting work.

And then I 'asked him, "What kind of a chap is Mauguin?" And Mark said, "Look, how shall I describe him? He looks like a bricklayer." You see, Mauguin lived in the country outside Paris and was one of the most charming figures I ever met, ruddy-faced with a moustache somehow, and a very straightforward little French beard--a charming personality. He was very unfortunate because his wife became blind and for the last ten years at least, or fifteen years, he mostly had to live for the care of his wife. He put her in order in the morning, then he came into the lab in Paris, and then he went out in the early afternoon back to his wife because she needed him then and he looked after her.

Weiner:

Now, did you visit Munich often? Did you ever go back and participate in the Sommerfeld seminars?

Ewald:

Oh, yes. I visited Munich quite often. You see, since my mother lived not far from Munich, of course, many of our vacations were spent there on the Ammersee.

Weiner:

Did you go to Sommerfeld's seminars at all?

Ewald:

Well, I was in Bavaria mainly during the academic vacations. Oh, I went to visit Sommerfeld, or the Sommerfelds came out to visit us.

Weiner:

But the people who subsequently went different ways. into different branches of theoretical physics--did you have the sense that you were separated from them in a way?

Ewald:

Looking back on my own life I am really astonished how one-sided and strictly limited my work has been. I always thought I was fairly interested in a wide field, and indeed I think I was. But it doesn't come out in any of my work. What I've been doing is working on my thesis all my life. I'm still at it. I mean, this latest work in Acta '68 is really a continuation of my thesis work. It's a problem which has held me.

Weiner:

A theme.

Ewald:

A theme. And I don't think it's finished yet. I see another part I would so like to achieve, but it's very hard to do, so I'm not certain that I shall. I've tried it now repeatedly these last years and never gotten anywhere. It's the problem of how big an optical activity there is for x-rays, and I'd like still to do that. Then my life's work would really be fairly completed, but I doubt that I'll have the force to do it.

Weiner:

Well, if you solve that, you'd find another problem of equal interest.

Ewald:

But you see I became interested in this whole subject really through a sense of duty, collecting all these structures. And that at times took really all the force I had besides my professional duties, and then the editing of all these papers, that took a lot of my work.

Weiner:

Well, I was amazed in looking over these descriptions of these major pieces of work, the Handbuch and the 1923 book and the chapters that were subsequently reprinted, that also you still have a group of individual research papers that you seem to have published every year.

Ewald:

Well, that should be the case, and other people have done much more in that respect.

Weiner:

No, but I'm saying besides the teaching, and the keeping up of the structure work, you have papers--starting in 1921--on Bragg's reflection law, on the reflection formula for x-rays, the reciprocal lattice in 1921; optical-electrical lattice potential, and "News from the Field of x-Rays,"--that last is an interesting title.

Ewald:

Well, I mean, this is sheer ...

Weiner:

... a note, probably a note.

Ewald:

This is a resume of something. I don't know. You know, this list of papers contains good and bad stuff. You may have noticed that I started with some articles I wrote when I was in high school, for the local newspaper, so this is just as complete a list as I could put together. It doesn't tell anything about the quality of the work.

Weiner:

It shows that you were productive. There are a number of things that go on through the period. So let me ask you how you would characterize this part of the work since these papers are reports intended for rapid publication, which implies that they are new findings. How would you characterize this work in the '20s?

Ewald:

You mean papers with the character of abstracts? Like those you have now for the APS meetings?

Weiner:

Right. Many of these I'm sure are in that category.

Ewald:

No, I don't think so.

Weiner:

I see. Then I'm talking about these. I meant these.

Ewald:

No. You see in the early days I had a wonderful key to all the problems; I saw clearer than most people how to deal with these problems because the construction in reciprocal space was so close to my heart, and so many of these papers deal with constructions which are not really very difficult, results which could be obtained fairly easily from a knowledge of the dynamical theory and of the what we nowadays call the Fourier transform technique.

Weiner:

So it was the application of these things which you had developed, it was the application of these techniques and these approaches in turn, to one problem after another. But was your main interest in trying to develop the dynamical theory, let's say, and then finding out that in doing this you had run into some problems along the way, and that you had to solve these problems in order to refine the theory further? Or was it the other way around: you felt that you had the theory and were looking for applications for the theory?

Ewald:

Well, at first there were no applications whatsoever. Then, if I remember correctly, the first application came when the high precision people in Siegbahn's laboratory in Uppsala measuring x-ray spectra found that they got deviations in the wave lengths according to whether they took first or second or third or fourth order reflections. That was easily explained by the dynamical theory. Actually, it's simpler to explain it; you don't need all the dynamical theory for that, but just the idea of a refractive index would do. Then the next group of confirmations came from the work of Bergen Davis at Columbia University. Now Bergen Davis is someone you should try to get into your system of notes because he really did very excellent and quite important work. Bergen Davis and von Nardroff published together. Some years ago I wrote to von Nardroff and asked him if he couldn't give me some details or write something about Bergen Davis. I never got an answer from him. Now I think he died.

Weiner:

Yes, von Nardroff died; about a year ago. I think.

Ewald:

About a year ago, yes, and it's a great pity that he died without giving any information about this work with Bergen Davis and about Bergen Davis' personality, etc. On my first visit to America in '36, I tried to visit Bergen Davis and I think I may have seen him, but he was a very sick man at the time and I have not much recollection other than just having been there.

Well, he published some things which I could discuss on the dynamical theory, and that turned out fine. Then the next were so-called Aufhellungslinien, that is to say, white lines crossing x-ray spectra or rather background, between the line spectra of x-rays. There were white lines--I would now in English call them deficiency lines--and I explained that at once. This was quite dramatic because Siegbahn had come for a visit to Munich (we were still living in Munich; it must have been before 1921) and he was one of the first foreign visitors we had in Munich after the war. Sommerfeld gave a dinner for Siegbahn at his home and invited the people who were doing x-ray work.

Among them there was Ernst Wagner, the assistant of Roentgen who was a very good experimentalist and his theoretical understanding was quite deep but his formal mathematics didn't go beyond cos and sin; I think that tan (tangent) was already too difficult for his understanding; he had to decompose it into cos and sin. And Ernst Wagner showed Siegbahn--he was a man, like all the Roentgen people, of great secrecy; this was traditional in Roentgen's institute, no one was to know what the other one did--the films he had taken with the deficiency lines in them. And Siegbahn saw them and, well, he didn't speak very much anyway and didn't say anything.

I happened to look into this group of people standing together and I saw these and I said, "Why, of course, this is when there's a third reflection occurring, which takes away the intensity." Wagner, at first, did not want to believe this, but finally he came round, he made further experiments and finally he was convinced that this was the case. So that was something which would not have been explainable by Laue's kinematic theory because that doesn't take account of intensity. So, by and by, but very slowly, some things accumulated which showed that this theory was perhaps quite useful.

Weiner:

Now, during the '20s you were developing the theory, applying it where it could be applied, and at the same time reviewing the whole state of the field. What about the developments in quantum mechanics, the new approaches--did this make much of a rumble in Stuttgart?

Ewald:

Well, did it make much of a rumble? My assistants worked in that field. The assistant were, first, Fues, and then [to Mrs. Ewald] Ella, could you help out, what was the sequence of assistants? Fues ...

Mrs. Ewald:

Fues. London.

Ewald:

Then Bethe ...

Mrs. Ewald:

Fues was there from '21 onwards. From '25 to '27 he went to Schroedinger, then to Bohr. And then in the meantime Hermann had arrived. I remember now definitely that Hermann is on the picture of the conference in the atelier. And in the fall of '25 there was this changeover from Fues to London, and Fritz London came to Stuttgart as Paul's assistant, for two years. And in '27 Fues came back from Copenhagen and Zurich, and London went to Berlin with Schroedinger. Schroedinger had in the meantime, in '28 or '27 accepted to go from Zurich to Berlin as the successor of Planck, who had reached the age limit of 70. And so Fues was with Paul until '28 when he was made--'28 or '29--professor of the Technische Hochschule in Hannover. And then Renninger came ...

Ewald:

No, Hönl.

Mrs. Ewald:

Then Hönl came.

Ewald:

As theoretical assistant. By that time I had two assistants.

Mrs. Ewald:

Yes, Hönl came as theoretical and then soon after, then you got your institute after '28, you know, you had the call to Hannover and you got your institute built. In '29 or '30 the son, you know, of our friend from England came ...

Ewald:

Ruhemann?

Mrs. Ewald:

Yes, Ruhemann came to be your experimental assistant.

Ewald:

And after him, Renninger.

Mrs. Ewald:

Ruhemann was the first, and then when he went to Charkov, Renninger came, in `32, I think.

Ewald:

Yes.

Mrs. Ewald:

I think that was the sequence, and Hönl was with you until you left.

Weiner:

Well, good. Thank you. That sets the background.

Ewald:

Fues worked on wave mechanics. You see, he came to Zurich just in the year when Schroedinger formulated the wave mechanics, so he worked on wave mechanics. And London worked on quantum theory in general, quantum mechanics, really, at the time.

Weiner:

Now by this time ... The original assistant you had was paid for by the special fund from the Notgemeinschaft, and was concerned with the structure catalog. But these other assistants were more in the nature of the traditional type of assistants.

Ewald:

They were paid by the Hochschule.

Weiner:

And so they had teaching responsibilities?

Ewald:

Not necessarily, but they could become, and they did become Privatdozenten.

Weiner:

I see.

Ewald:

I don't think that London became Privatdozent with me. I don't know whether Renninger ever did.

Weiner:

If London and Fues were working on the new developments in quantum mechanics, were either of them teaching it at Stuttgart? Did they introduce any courses in it?

Ewald:

Well, Fues was "habilitiert" and was teaching. You see, you couldn't teach if you weren't habilitiert.

Weiner:

But did he teach that? I was curious to know if he introduced the new quantum mechanics into the curriculum.

Ewald:

Oh, surely. The system of German universities was this: You had the so-called Kursus vorlesung, the regular course which consisted either of four or six sections, each lasting one semester. In Munich it consisted of six, which were mechanics, thermodynamics, electrodynamics, optics, and then mechanics of continua, and mathematical methods.

But these last two I don't think we had in Stuttgart because at a Technische Hochschule the course of studies is more regulated, and the regular course was only for four semesters after the first diploma, the Vordiplom. But then there were small special lectures, which were on quantum mechanics and wave mechanics and so on.

It wasn't taken into the big course, but it was additional material which was presented. For instance, I didn't give these courses; I gave courses on geometrical optics or on the physics of surfaces--one or more actual layers--or I don't know what. And then there was, as I told you before, the big course on atomic theory, which at that time meant that you discussed spectra and then term values and hydrogen-like atoms--that's as far as you could go--and the chemical implications--this kind of thing.

Weiner:

That course would have been taught somewhat differently after 1926, I would think, than before 1926.

Ewald:

Yes. You see, after ... Well, I guess after 1930 I really hadn't too much time because I was, first, head of the department, Abteilungs- vorstand, and then I became Rector of the Hochschule.

Weiner:

Oh, I see.

Ewald:

You know that this rotates; this is changing. And at that time nobody wanted to take over the rectorship because of the Nazis, and so I said I wasn't afraid of them and took over. And had a very interesting time in 1932-33, just during the revolution, der "Umbruch". But, of course, it kept me away from my institute quite a bit.

Weiner:

I want to talk about that, but let's go back to the institute. How did that get established?

Ewald:

Well, the German system for promotions is that you get a call from another university; then you go to your Ministry of Education and tell them, "I have this call to the other university and I'm much in favor of accepting it and I've made a date to visit the university, and the place; I've then to go (in my case, to the Prussian Kult-Minister) and to discuss conditions with him." Well, then the people in Wuerttemberg would say, "Well, you go ahead. You just discuss it but don't tie yourself down. We'll see what we can do for you." And so I had to call to Hannover ... [bell sounds].

Weiner:

The ringing of the telephone also served as the dinner bell, and we've since been to luncheon and are resuming now after a long, pleasant interval. At the time you were talking about the general procedure for getting a promotion.

Ewald:

Well, in my case I had a call to the Technische Hochschule in Hannover, and so I inspected the place. It was in a big castle in Hannover, and they showed me the basements where I was to establish an institute, all cluttered with hot water and steam pipes for the heating-- and it wasn't attractive at all, but of course I didn't tell them. And I went to the Minister in Berlin and told him, "We'll, I don't know. What is it that you would give me to run the institute, etc., etc." And he made me an offer, and I said, "Well, let me consider it." And I went back and told the offer to the Wuerttemberg minister, and he said, Well, we can build an institute here, if you like, and if you stay here, I think you won't be sorry." So I said, "Fine, then I'll write off Hannover."

Now as to this institute, I really had the idea that I didn't want to have much space. I wanted perhaps two rooms to work in, just to set up the few tables and do some experiments and maybe a very small workshop, but I didn't want to have any institute which was comparable to the big physics institute of Regener, very well equipped, in Stuttgart, or the very well equipped x-ray institute of Glocker, also in Stuttgart.

And so "Well, said, Well, we need perhaps two or three rooms for office work, for my assistants, and then two or three experimental rooms." So they made a plan accordingly. And the workmen began to excavate, and the people from the Bauabteilung, or Bau ... what was it? Well, you see, all this is under the state, of course--who did the digging came and said "Now Now look here, why not dig out the whole institute to have all that floor space instead of digging out only one of the rooms?" ( I had made it a condition to have one room in the ground so that it had a constant temperature.)

"We might just as well dig out the whole thing--it doesn't cost much more and then we have room to put in central heating, and we can have room for storing the fuel for the central heating, the coke, and so on." Well , as it turned-out finally, I had a lovely little institute with four rooms in the basement and about six rooms on the ground floor and a lovely workshop, and it was really a joy to work in it. And from then on I had quite a series of experimental research going on.

The first thing we did--I did with Martin Ruhemann as my assistant; Martin Ruhemann had been trained by Franz Simon, (later Sir Francis Simon at Oxford) so he knew low temperature work--we investigated the structure of solid nitrogen, trying to grow single crystals of solid nitrogen.

We didn't believe in a structure which Vegard in Oslo had proposed for nitrogen. That had been done on powder diagrams, and we thought it was not very good work so we tried to grow single crystals and were successful in that we filled the capillary tube with two crystals, growing side by side, so you could disentangle the diagrams. And later there were Dr. Achille Papapetrou who worked on crystal growth and Renninger--who was Ruhemann's successor--who discovered the influence of multiple or simultaneous reflection of the intensity measurements of x-rays and did other very good work which he is still pursuing in Marburg; and Kochendörfer who was the only man thus far, or up to nearly this year, who investigated the slip properties of an organic crystal; he grew naphthalene single crystals. We built a special apparatus for testing them for slip, and we found that the laws of slip are quite similar to the laws in metals. This was an astonishing thing because, after all, a metal consists of single metal crystals, built up from single atoms, whereas a naphthalene crystal is built up of large molecules.

You would expect that the glide and slide, slip properties of these large molecules are different from those of atoms. Well, there are still a number of smaller papers which were published, and altogether I was quite satisfied with the output of the institute, especially since I had very little time to look after it, being lnvolved in the Rektorat of the Hochschule.

Weiner:

When did that start?

Ewald:

Well, first came the Abteilungsleiter, which is a kind of preparatory and lasted usually for two years, but I had made it a condition that it be cut down to one year only. And after that one year I became the rector, in 1932, at a time when there were student demonstrations and great difficulties in keeping the students down in most German universities. I never had very great difficulties. On one occasion I had to become quite energetic and tell the students that I just would not do what they demanded; on other occasions I thought, well, a demand, for instance of hoisting a red Nazi flag on the Technische Hochschule, that really isn't worth quarreling about. And so I had quite a jolly time as a rector. And it gave me much insight into the ways the Nazis took over. And when the laws against the Jewish professors came out, there was a conference of all the rectors of all the German universities, called, I think, in Wiesbaden, and the Nazi Minister of Culture and Education just treated us in a most dirty way, not giving us sufficient information to really appreciate what the law was about. And when I came back, I wrote a letter to the Minister that I could no longer perform the duties of a rector, and didn't want to continue.

Weiner:

You wrote to Rust?

Ewald:

No, I wrote to the local Wuerttemberg man, and he, of course, had to report to Rust. And so they accepted that.

Weiner:

It would be interesting to know how this was presented to a group of rectors, and academic people. Wasn't this a new role for the state in general? Wasn't this an extraordinary thing, to call people together on a national basis?

Ewald:

He didn't call it, no. There was a regular Rektorenkonferenz every year, and we had had one already in Danzig. And then these laws hadn't appeared yet in print, though one knew that they were being prepared, and so a second Rektorenkonferenz, an emergency conference, was called at Wiesbaden. The opening of that conference was delayed because we expected the appearance of the Rector of Berlin University, who was Professor Kohlrausch of the Law Faculty, and when he appeared, quite haggard-looking, he explained that he had been in the antechamber of the Minister for I think four or five or six hours, whereas all these young Nazi-dressed-up people had access to the minister. Finally he was called in and was given a few details about this law but not much more. And so we debated what we knew about it and came to the conclusion that this was unacceptable.

The Berlin rector himself said, "Why, in my own Faculty of Law in Berlin the most prominent people and my very best personal friends are Jewish, and I just can't dismiss them. This is impossible." But he said in private afterwards, "What can I do? I have five children and I have to live and I can't break with the Nazis." And the difficulty for us to rig up any protest against the laws lay in the fact that among the rectors there were perhaps five or six who were Nazi Party members and who, of course, said, "Well, if you protest, we shall report to the minister." And in that case the consequence would have been that before we returned to our respective universities, we would have been deposed and some Nazi put in instead. So it finally ended that we did not do anything, but each of us went home, very sad at heart, except for the young Nazis. I think the Goettingen rector was one of them who was very vociferous for the Nazi rule.

The consequence of not protesting and not being turned out by the minister himself, as far as Stuttgart is concerned, was that in Stuttgart we managed to get a successor to me who, of course, was a strongly conservative German nationalist--that was inevitable--but a very decent man and at heart very anti-Nazi. He belonged to the Department of Architecture and he had a little dog, a fox terrier, and when I paid him visits in his Rektorat room, he would close the door carefully, call his dog Hexe, and tell her, "Hexe, Mach 'Sieg-Heil.'" And Hexe would sit up on her hind quarters and have one paw hanging down and the other one lifted up.

Weiner:

Which was a caricature ...

Ewald:

This rector Wentzel was rector for another year and a half, and then a successor had to be chosen. And as a successor we managed to get an historian, Goering, and this Goering was a man who had been imposed on the Hochschule; the faculty had not chosen him, had not even proposed him among the three names which usually were forwarded to the ministry for the choice of the ministry; but the minister, Bazille, had insisted on putting him in a few years earlier against the wish of the faculty. Well, now it came in very handy because Goering was a cousin of the big Goering in Berlin, Hermann Goering. At heart he was not a Nazi, and in private, he told you, "Well, I know very well what a scoundrel my cousin is." And so when there was any political difficulty threatened for the Hochschule, Goering would just slip in a word and say, "Well, I must discuss that with my cousin. I am going to Berlin next week and we'll wait; I would like to see what my cousin says to that." So he had a very beneficial influence on the Hochschule, and that means that the entire Hochschule stayed without serious external interference for two and a half or three years longer.

Weiner:

When was your term as rector up? It started in '32.

Ewald:

It started in '32 and I guess in the early spring of '33 was this conference in Wiesbaden, and then after that I stepped down in April. But I retained my professorship.

Weiner:

And you still had your institute?

Ewald:

I still had my institute, yes.

Weiner:

What happened at the university as a consequence of the new laws? Did this, in fact, decimate the faculty somewhat?

Ewald:

It decimated the faculties, yes, and it gave much heartbreak to a great many people on both sides, both the passive and the active side, but vou couldn't do anything.

Weiner:

Was there any reaction in the German professional societies of scientists?

Ewald:

It was all entirely dominated by the Hitler gang. You see I had hoped that my, of course carefully worded,letter to the minister would be published in the press, and |'m pretty sure that several others of the rectors assembled at that conference resigned. Not a word of it came into the press.

Weiner:

This is the time when Einstein, for example, resigned from the Prussian Academy and, I was never clear whether he resigned or was expelled from the Bavarian Academy, but either way it was the same. Do you remember if this was a public event, if people were aware of it?

Ewald:

I can tell you where to find out about whether he resigned or not, and that's in the Correspondence: Einstein-Sommerfeld, a copy of which I have upstairs if you are interested in it. From the Sommerfeld-Einstein correspondence I gather that the Bavarian Academy (Secretary at the time v. Dyck) asked Einstein in 1933 to declare his resignation as a member of the Academy. Sommerfeld can't establish the exact wording, as the files are burnt but he read a translation of the letter in 1937 (in Geneva) in Einsteins booklet "Comme Je Vois la Vie." Einstein refused to resume the Fellowship.

Weiner:

Oh, yes, I would like to see that because there is a letter-- I've seen the published version--that he wrote to the Bavarian Academy in response to their letter asking him, in view of his recent actions in regard to the Prussian Academy, what did he think his relationship should be to the Bavarian Academy. And in his letter he essentially explains that he couldn't be part of any group that stood by. But yet his biographer, Phillip Frank, said that he was expelled from the Bavarian Academy, so I'm not clear--that's all.

Ewald:

Well, I can't tell you but I have the Proceedings of the Bavarian Academy here and I've got this part of the correspondence of Einstein and Sommerfeld--there may be something in it.

Weiner:

Now, where did that Einstein-Sommerfeld correspondence come from?

Ewald:

From the Einstein Institute and partly from Ernest Sommerfeld.

Weiner:

Do you have copies of it?

Ewald:

Yes, xerox.

Weiner:

Well, that would be important to see. What about the effect on the student population--was there a great deal of instability in terms of political upheaval in the classes themselves?

Ewald:

No, not in the classes. No. The only way it made itself felt was in the student assemblies, Allgemeine Studenten Versammlung. And you see the students had a governing board, the so-called Asta, Allgemeiner Studenten Auschuss, and there I think .... The only difficulties I had was that in one of these student assemblies they had proposed to vote or to demonstrate against the presence of the librarian of the Technische Hochschule, Professor Marx who was also an historian and Jewish. And I told them that they were not to demonstrate against Marx, who had great merits for the Technische Hochschule because he had really done a wonderful job in getting all the foreign journals during the inflation. Since Marx had great assets for the library, I told the students that if they made any demonstration against Marx, I would not stand it. I do not know how I could have resisted; this was really a dramatic moment where I confronted some 2,000 students, I guess--most of them in their student uniforms, their fraternity, their corps uniforms and others in their Nazi uniforms--and told them I would not stand any demonstrations against Marx. They finally gave in. It was quite a fight and quite exciting.

Weiner:

Was this '33?

Ewald:

It was maybe '33--I don't know.

Weiner:

Right. But it was before you stepped down as rector?

Ewald:

Yes, before I stepped down.

Weiner:

Then what about the effect on the number of students entering the university? Did enrollments in this period decrease? Did you not any change? I think there was a general decrease.

Ewald:

Well, already at high school marks didn't play any role What played a role was whether the student was good in gymnastics and good in sports and good in party membership.

Weiner:

This is even before Hitler, before 1933?

Ewald:

Before 1933 when my children went to school.

Weiner:

If you can, when would you date the beginnings of that change? How far back? Would it go into the '20s?

Ewald:

This question I can't answer. You see, I've no historical min [Ella says it started only after the take-over of 1933.]

Weiner:

What I'm trying to get at is the general state of science and of learning and university life in Germany from the late '20s on, even before Hitler, because this would be interesting.

Ewald:

Well, I can tell you of two experiences of my children at school One was that of my daughter, now in London, who was at the Maedchen Gymnasium and took Greek. The girls performed a play--I don't remember which--in Greek, and she should have played the leading role according to her classmates, but then the Ministry of Education found it impossiple that she, not being pure Aryan, should play this role. So somebody else had to play it. That was one experience. The other experience is quite funny. It was what my eldest son experienced in the Real Gymnasium.

In all classes they had to give lec- tures on human races, and the teachers had certain books, prescribed books, and they taught according to these books. The teacher in my son's class explained that "mixed races were very bad and you saw that in the fact that it is well known that mixed people are not fertile."

And so my son after a while asked quite timidly, "Oh, what about Brazil? I've always read that the main part of the population in Brazil is a mixture of Portuguese and Indians and Negroes and so on. Are they all infertile?" So the teacher blushed a bit and said he couldn't answer that; he hadn't the latest edition of this book at hand so he would have to look it up.

Weiner:

That is already in the Nazi period, beyond the '20s?

Ewald:

That is in the Nazi period, yes, so you can imagine that the boys who came to the Technische Hochschule were not well prepared.

Weiner:

Now you mention that your daughter was denied the part in this play...

Ewald:

I think Antigone but I'm not sure.

Ewald:

Well, my wife is Jewish and I am half.

Weiner:

Oh, I didn't know that. Did that complicate your situation as rector? After all, you were chosen as rector in '32.

Ewald:

No, it didn't. Officially I was a quarter Jewish. You see, my wife and my mother came from the same family, although they hardly knew one another, but it's the same family. And my grandfather, the father of my mother, was Jewish. I think he was baptized later on but he was born a Jew, and so I was a quarter Jewish.

Weiner:

By Nazi definition.

Ewald:

Yes, by Nazi definition.

Weiner:

I see. Now, under the laws, though, that was enough.

Ewald:

Yes, they wouldn't harm me--in the first period. Later on they would have. If we had stayed in Germany, I'm sure we would have ended in a gas chamber. [Slight pause.] But it was not really the anti- Jewish attitude that drove me out of Germany; it was more the fear, or the certainty, really, the expectation that Germany would get into a war with England and other countries and that if I were caught in Germany I would have to work for Hitler. And that idea was too much.

Weiner:

Well, what about science in Germany prior to the time you left? Was there any noticeable change in the pressure on physics and its relationship to the state, for example?

Ewald:

Well, of course, there was a strong party of physicists in Germany who were Nazis. Lenard and Stark were definitely Nazis. Lenard with his Deutsche Physik--I don't know whether you've ever seen that?

Weiner:

I've just finished going though it very carefully, different editions of it, too, as a matter of fact.

Ewald:

And you know that Lenard at the entrance of his institute had a notice that members of the German Physical Society were not admitted, because he had broken with the Deutsche Physikalische Gesellschaft because this Gesellschaft was not strongly national or Nazi enough.

Weiner:

But did this affect the teaching of physics at the University Was there any interference in the curriculum or ...

Ewald:

No, it would affect more the arts, history teaching, for instance

Weiner:

And biology, of course, as well.

Ewald:

Biology--maybe literature. As a matter of fact the last time went to a meeting of what we called Senate, the whole professional teaching staff of the Hochschule, I met the professor of literature, Pongs; we had been very friendly; I had been quite essential in getting him to Stuttgart. And I said, "Well, Herr Pongs, how are you? I hay seen you for a long time "Well", he said, " how should I be? Who course," he says, "we have to relearn our entire field. We have to look upon everything "unter dem voelkischen Gesichtspunkt."(under the racial or voelkische point of view). So I said, "I really pity you."

Weiner:

What about the students coming into physics--was there a decline? Well, first of all, you said that in general students were ill prepared. Did you find this at the higher levels in physics?

Ewald:

I couldn't tell you. You see I had no contact with the stu- dents. I lectured to them, but they didn't come to me and there was hardly any contact these last years. There had been before.

Weiner:

Did you have any Doktorands then?

Ewald:

Yes, I had Doktorands. I had Schmid and Bausch who finished in 1935.

Weiner:

But their work would be pretty much the same; they would work on specific problems.

Ewald:

That didn't ... You see, they were all not Nazis. None of the people with whom I was in contact was a Nazi.

Weiner:

Yes. Just a few more things I want to get to fill in this picture. What about colleagues in German science--did you know of many cases of people and of their difficulties in getting new positions or getting out, or anything going on in an organized way to assist them?

Ewald:

Yes. I think there was a large group of people helping those scientists who had to leave Germany to get positions somewhere else.

Weiner:

No, I mean within Germany. Was there any way that this could be...

Ewald:

Within Germany there was the possibility of going into industry, of leaving the academic positions and going into industry, which would have done no good in the long run. But a number of people did it. You see, the nasty thing was you had been friendly with your colleagues; I always was on very good terms with practically all of my colleagues and I knew practically all because I'd been rector so I had to have contacts with most of them. And then it became the official demand that you shouldn't say "Good day," you should say "Heil, Hitler." And on the street if you met them, you shouldn't take off your hat but you should lift your hand, heil Hitler. And you saw how these colleagues first ridiculed these things the first few weeks and then gradually they began making a very sloppy Hitler salute, and gradually it became more and more formal. And then when you met on the same side of the street or were about to meet, you saw that they crossed over to the other side and they avoided you, and it was really a shameful experience.

Weiner:

You must have felt increasing isolation then from the rest of the community.

Ewald:

Yes. Of course, there were exceptions. For instance, a new professor of electrical engineering was appointed to Stuttgart, a man called Feldkeller, and as far as I know Emde had told me that he had been one of the earliest party members of the Nazis. And after his appointment he came to pay me a visit in my institute, and I must say I found that ... I don't think I met him; I happened not to be in, but I thought very highly of this act which few others would have done.

Weiner:

During this time were there any scientific meetings that you attended or was this somewhat curtailed? You mentioned that you used to move pretty freely to Paris and to England and that there'd be scientific meetings that you'd attend here and there.

Ewald:

For these scientific meetings, of course it was now necessary to belong to a German delegation. And the delegation was headed by a Fuehrer, appointed by the Reichscultsminister, and they had to act unisono. And my only experience in that respect was that in 1936 I got my first invitation to come to the United States for the summer school in Ann Arbor. And just before I was about to leave, I got an invitation from Harvard to attend the Harvard Tercentenary meeting. Now you see I was in a queer position. Of course I wanted to go there but on the other hand I had to return to Germany. And so I wrote a letter to the Reichs- Kultminister, telling him I obtained this invitation and asking him for permission to attend the meeting. I thought that was more prudent to do. I didn't get an answer while in Germany, but many weeks after I arrived in Ann Arbor--it was actually toward the end of the term there end near the beginning of the Harvard Tercentenary--there came a letter from the Reichskultministerium not permitting me to attend the Harvard meeting. So when I went to the Harvard meeting I stayed a bit incognito. And if anyone had questioned me, from the German delegation, for instance, then " I would have said, "Well I'm visiting M.I.T."

Weiner:

Did you request permission to go to Ann Arbor or did you feel that that was not necessary?

Ewald:

Oh, yes, I had to ... Oh, that is quite amusing. You see, the year before, in 1935, I had an invitation to lecture in Madrid, and I'd gone there, lectured for one month or two months in Madrid and really hoped to get a job in Madrid, but it was very lucky I didn't because the revolution broke out quite soon, the civil war. And so I had to go to the rector in Stuttgart. He was the first Nazi rector-and the stupidest and dullest of the colleagues far and wide, but he had been nominated by the Reichskultminister to become rector. The faculty had told the Reichskultminister, "According to our statutes this is not possible. This man is not a full professor; he is an assistant professor." So he was made full professor the next day and became rector. Well, I came to him and told him I had an invitation to Ann Arbor and would like to go. So he looked very puzzled and important and finally he said, "Well, isn't it right that you've already been to Spain last year?" And I said, "Yes." Then he thought again for a long while. "Well, it might be even more disadvantageous for Germany to prevent you from going. You go."

Weiner:

That's a nice approach.

Ewald:

Isn't it nice.

Weiner:

Who invited you? Do you know how the Ann Arbor invitation came about? Ewald - 35

Ewald:

Oh, I don't know the details, but there was Laporte whom I knew quite well, and he may have had a hand in it.

Weiner:

Who paid you to get there? You, or did they provide funds?

Ewald:

I really don't remember. I got a salary there. I got paid in Ann Arbor.

Weiner:

You were one of the lecturers?

Ewald:

I was one of the lecturers, yes.

Weiner:

Before we get on to that, I want to get back, because that is a little story in itself, to the period in 1929 when you went to the Faraday conference in London. We also left something else out, too, and that is that one of your assistants was Hans Bethe, and I wanted to get your version of how that came about and what your impression was of him, if that was your first meeting.

Ewald:

Hans Bethe, well ... You see, Sommerfeld took his first trip to America in--oh, here my wife should come in again for what year it was. [in 1929]

Weiner:

Bethe's first trip to America?

Ewald:

Sommerfeld's first trip to America. And Sommerfeld had just hired Bethe as an assistant--or maybe Bethe had already been there for one semester--but anyway Bethe was free, and I had lost Fues who had received a call to Hannover, so I asked Sommerfeld if I could have Bethe. And that's how Bethe came to me. [Apart from a colloquium on his theory which he gave in Stuttgart on my invitation a year before.]

Weiner:

Had you heard of him by reputation?

Ewald:

Well, not only had I heard of him but you see his thesis is very very close to my work. This was really a translation of my theory of x-ray diffraction into the theory of electron diffraction. So from the point of view of interest we were very close. And besides, Hans Bethe's father was a great friend and formerly the assistant of an uncle of mine who was professor of Physiology in Strassburg.

Weiner:

His father was a physiologist.

Ewald:

Yes, his father was a physiologist and he was assistant and friend of Onkel Richard, my uncle Richard, so it was an old family relation, which we had cultivated; I did not know Bethe before he came, but we grew friendly very quickly. His father has written the nicest and most intimate obituary of my uncle. And his father was described to me, by the way, by Walter Gerlach who was professor in Frankfurt and therefore a colleague of Albrecht Bethe, as one of the most "geist- voll" --spirited--people he ever met. And Gerlach met a good many quite spirited people.

Weiner:

And so when Bethe came in '29, you put him to work on a related problem?

Ewald:

I put him to work on a related problem, yes, and the problem was really a very good one. It is so good--or, rather the paper which Hans made of it--that a few years ago it was translated and reprinted here in America, and this was the question I put to him: in atomic theory we deal with the influence of an electric field on an atom, which is called the Stark effect. Now we always assume the atom put into a homogeneous field. If an atom is in a crystal, it is not in a homogeneous field but the field has the symmetry of the particular position in the crystal and is quite anisotropic. What is the Stark effect? And instead of answering this question in a modest and straightforward way as I had expected, Bethe made a group theoretical study of it. And this is still today the foundation of the splitting of energy levels in crystals which chemists and spectroscopists and all use, so this was really a very beautiful paper. And Hans always says that this was one of the best times of his production, in Stuttgart, which I am very glad he appreciates.

Weiner:

He said that was a very happy time for him. That's when he first met your daughter, on that trip.

Ewald:

Yes, but with no great interest.

Weiner:

But he was close by later on, though, when he was in Tuebingen in '33.

Ewald:

yes, but I don't think they ever thought of falling in love or the like at that time.

Weiner:

It's hard for a father to say.

Ewald:

And it's not my business either. As a matter of fact, I think I tried quite hard to get him interested in looking up Rose when we were together in Ann Arbor in '36 and Rose was with the Courants in New Rochelle. And Hans went back to Europe, and I told him, "Won't you look up Rose?" but he had other interests at that time.

Weiner:

Well, then a little later, in '29, there was the Faraday conference in London, and it was there apparently that the idea of further international development in the field of crystallography got started.

Ewald:

Yes, I went to several Faraday conferences. I can't quite remember in what years. One was certainly in 1931 because that was the big centenary celebration of Faradays's discovery of electromagnetic induction. That was beautifully arranged by Professor William Bragg. And there was a conference following in Cambridge which was probably one of the "Unclear conferences on nuclear physics, which was misprinted as Unclear Physics" on the program.

Weiner:

The same year? Was that '31?

Ewald:

Yes, just a few days after. I think just the weekend separated the two conferences. Well, I should tell you systematically because that's a story in itself of my experiences with the international unions, but maybe we should leave it until later.

Weiner:

yes, that perhaps is a full story for next time. Do you want to go on any more today, or do you think this is a good time to break? I can tell you the other things that I had wanted to talk about, and we can decide whether it's better for next time. The reason that I asked about the Faraday conference is that it is the beginning of the story that leads to the international involvement. Then I wanted to ask about the 1934 conference in London, the conference on theoretical physics. You had a paper on the program, in the solid state section--there were two sections: one was nuclear physics, one was solid state--

Ewald:

That was '31.

Weiner:

No, there was one in '34.

Ewald:

'34? What paper is that?

Weiner:

I'll tell you ...

Ewald:

Is it the one on optical activity?

Weiner:

No, "Optical Activity" was 1930; that was the Faraday thing. Here, "Mosaic Texture of Rock Salt" with Renninger.

Ewald:

Oh, yes.

Weiner:

That was the 1934 meeting. I wanted to ask you about that and then to start with the trip to the U. S. in '36, talk about Ann Arbor, about Harvard, about other experiences and impressions of this country; and then from there to take you back to Germany and to the transition from there to Cambridge, and so forth; and then, of course,the rest of the story. So, we can stop now and then pick it up at that point. This little review will serve as a reminder to me, too. ****

Weiner:

This is Friday, May 24, and we are resuming the interview with Dr. Ewald. Mrs. Ewald is joining us, and this is Charles Weiner again, asking some questions.

Ewald:

Well, you wanted to hear about the 1936 trip to Ann Arbor, my first trip to the United States. I don't know from whom the invitation originally came. I have a hunch that it may have been Laporte whom of course I knew very well from Munich. Anyway, I remember that it was on Peter and Paul's Day in 1936, that is, the 29th of June, that I started out from Stuttgart, skipping the last few days or even weeks, of the semester, and bearing in mind that I would show these American physicists what real physics are--all the high-headedness of a German full professor in me. And so I took the boat over and landed in New York, and the arrival in New York was very spectacular because at the pier were my daughter Rose and Nina Courant, who came to pick me up.

Mrs. Ewald:

Rose, 19 years old ...

Ewald:

Rose had come to America a few weeks before me and the day before she met me at the pier she had passed her driving exam and got her license. And it was a new car the Courants had bought, and Mrs. Courant was in the back. And the boat arrived at five o'clock in the afternoon, and I said, "I must first go to the Cunard Line office, which is in downtown Manhattan." And so she had to take me through the heaviest traffic of the day, and I didn't know at that time what I did to her. But we arrived with only one little bump, safely in new Rochelle at the Courants. I spent the night there and the next day I took the train to Ann Arbor, and I remember that I was very disappointed because the scenery didn't match at all to what I had imagined America to be.

I had thought of primeval forests with thick trees and beautiful landscapes. And instead the only things you saw was fifth or sixth growth with very miserable little trees. In Ann Arbor, however, I spent some six weeks, I should say, during the summer school, and I lost all the haughtiness of a German professor. I found that the level was extremely high; that sitting in on other people's lectures I sometimes had great difficulty in following at all; and my own talk mainly on Fourier methods of discussing x-ray diffraction was, well, not really of as much interest as I would have thought, compared to the other talks which were on the recent developments in wave mechanics and atomic physics. The people who lectured there were Bethe and Breit, Condon, I think Segrè or maybe Amaldi-- I'm not quite sure--and then late in the summer school, the so-called "Italian team" arrived and were feted. There was a nice Bierstube in Ann Arbor at the time ...

Mrs. Ewald:

Rabi was there.

Ewald:

Oh, yes Rabi was there, too, of course. As a matter of fact I lived next to Rabi--the rooms were adjacent in one of the fraternities. It was terribly hot. This is where I met Mrs. Slater--now Mrs. Slater, then Rose Mooney. We usually had breakfast together in a cafeteria before the lectures began. I remember that I did not suffer very much under the heat; I even played tennis from two to three o'clock in the afternoon, because it was the only time we could get the courts--I don't remember with whom-- but at the very end it was a terribly sultry day and I wanted to ... I bought a car for $30, a Hupmobile, which was picked out in a physics seminar by the physicisits who understood something of the cars, mainly the two brothers Slawsky (I think that's correct, isn't it? One of them is now in Washington at the NBS, National Bureau of Standards?) Well, this is a story by itself, the experience with the car. I wanted to visit all the Eastern universities and try to find a position somewhere,but that plan broke down pretty soon--in Pittsburgh.

Weiner:

The car broke down?

Ewald:

No, not the car, but the chauffeur broke down; I couldn't stand it. You see, I'd never driven a car in Germany; it was new to me, and driving these long stretches alone just got on my nerves and all night long I dreamt about railroads and crossings and flattened-out skunks on the highway, and so on--it was no good; it took my mind entirely off the purpose of my trip, so I gave up the car.

Weiner:

These gentlemen helped you pick out the car. Was it in a physics seminar?

Ewald:

Well, I mean, I brought the car from the second-hand car dealer to the curb of the Physics Institute, and they came down and then they listened to the motor, and they had very good ears for that, some of them. And then Sam Goudsmit came, seeing us all bent over the open hood, and patted me on the shoulder and said, "You should never know what is under the hood of a car." That was his attitude.

Weiner:

Well, about the seminar itself: do you remember the atmosphere-- were the discussions continued in the informal social activities?

Ewald:

It was not so much seminars; it was more lectures. Actually there may have been seminars, but I have no clear recollection of them. It was very nice to meet all these people. There were the Dennisons, and one of the teachers of the summer school was Lawrence. He was helping-- oh, his name begins with a C-- [It was Crane]

Weiner:

Colby?

Ewald:

No, not Colby; Colby was there, too ... construct the cyclotron.

Weiner:

At Michigan?

Ewald:

At Michigan, yes. And cyclotrons at that time were still a new venture, and you really needed an expert to help you do it. Once Hans and I made an excursion, towards the end of the summer school, to Purdue University at the invitation of Lark-Horovitz, and gave lectures there. And there was Yearian constructing his cyclotron, and I still remember what an impression I had of the work this involved, buying these thick copper rods and bending them and getting railroad equipment secondhand somehow for doing it cheap. It really impressed me, this combination of physicist and engineer, which was quite new. I came more from the period of string and sealing wax.

Weiner:

Would you say that the difference was due to the difference in the period or the difference in the geographical and cultural ...

Ewald:

I think the difference in the geographical and cultural attitude. These people were not afraid of tackling problems for which in Germany you would have had a special mechanic and, I don't know what, to do it; it would have been high-polished copper wire instead of just an ordinary copper rod. It was definitely a different attitude. And then, of course, the whole spirit of such a summer school was new to me. I'd never been to such an institution before. I don't think there were any in Germany, or none worth mentioning;

Mrs. Ewald:

Not at that time; that was Hitler.

Ewald:

No, not at that time, and I don't think before that either. And this whole spirit was such a nice spirit, you know, everybody friendly and open and working together--the team spirit was something that was entirely new. And I think that made a lot of difference to the development of physics. This is really the main contribution of the Americans to physics, introducing the teamwork.

Weiner:

This also implies that there were very few boundaries between graduate students and faculty. Was that the case at the summer school? Was there more social contact than in Europe?

Ewald:

I think it was all much more informal. The mere fact that everybody sat there in his shirt sleeves was new to me. And that the lecturers took off their coats before they went up to the blackboard-- all that was very new. I enjoyed that school immensely.

Weiner:

That was a six-week period. The trip to Purdue was an excursion within the six weeks, was that it?

Ewald:

I think so, yes.

Weiner:

Then you mentioned that you wanted to visit American universities to see if you could line up a job. This means that you had already come to a decision. It implies several things to me: that you had already come to a decision that you wanted to leave Germany and that you were at least willing to seek a job in the United States.

Ewald:

Yes, that's right. I was very keen to leave Germany. The year before, in 1935 I'd had an invitation to lecture in Madrid, and there I tried to obtain a Job. But luckily it turned out that the minister was thrown out the day when he would have had to decide upon it. Bias Cabrera, that is, the father of the present Cabrera who is now in Charlottesville, had invited me. He was the great man at the time, an important man for work on magnetism, and he had very good connections with the Liberal minister. But then all this was thrown over, the Socialists took over, and very soon there was the beginning of the Civil War.

Mrs. Ewald:

Next year.

Ewald:

Next year, yes. So I was happy not to have had any permanent appointment in Madrid. But, well, I visited Land in Columbus, and the next stop was Pittsburgh, and then I had this invitation to Harvard. I think we spoke last time of that.

Weiner:

Yes, a little bit.

Ewald:

About the tercentenary. On the way there I looked in at Rochester and ...

Weiner:

Who was there at the time?

Ewald:

Rochester? They were building a cyclotron at the time, like everybody else.

Weiner:

Well, Weisskopf wasn't there yet, but DuBridge was there.

Ewald:

I think it was probably DuBridge, yes.

Mrs. Ewald:

Wasn't that the man who drove you in the car?

Ewald:

The man who drove me in the car, that was Herzberger, the Kodak man, the optics man, geometrical optics. And he nearly wrecked us; he was quite new at driving. He drove me to Ithaca from Rochester, and when we came down the hills in the park--I don't remember the name-- he nearly lost control of the car. It was quite exciting. In Ithaca I met Parratt and ...

Mrs. Ewald:

Krauss?

Ewald:

No, I didn't meet Krauss, but I met Parratt and Bacher.

Weiner:

Well, of course, Hans Bethe was there.

Ewald:

I think he had gone off to Europe; he was not there.

Weiner:

Oh, yes, this was summer.

Ewald:

Yes. I think I stayed with Bacher and his mother; they were living together in Ithaca. Well, I guess that's about all. Then from Harvard I drove back--Karl Herzfeld drove me back--via Providence, if I remember correctly, but we didn't stop there very long. And that was quite a dramatic drive, because Herzfeld became very tired toward the end. We stayed overnight somewhere, but he got very tired toward the end as we were approaching New York, and there was a rain storm so that you couldn't see anything. I remember that we took shelter under one of the overpasses on one of the driveways. And somehow or other we suddenly found that we were driving on a highway straight away from New York. So that didn't add to our amusement. After having done that for some time, we got aware of it and had to drive back. So then I guess I came back to Stuttgart ...

Weiner:

Before you do, I want to review the places you visited: You were at Michigan, you visited Purdue, you visited Landé in Columbus at Ohio State, you visited Rochester, and Ithaca ...

Ewald:

No, Pittsburgh first.

Weiner:

Pittsburgh, Rochester, Ithaca.

Mrs. Ewald:

Duke.

Weiner:

Harvard, of course, and Duke?

Mrs. Ewald:

I think you went to a symposium at Duke.

Ewald:

Yes, I guess that was afterwards. I didn't go home straight, but I went South because my daughter meanwhile had landed at Duke as a kind of household assistant to Hertha Sponer ...

Mrs. Ewald:

And student at the same time.

Ewald:

And studying, yes. And so I went to Charlottesville and visited the Beams. The visit to Beams I shall never forget. First of all, the loveliness of the campus at Charlottesville; and secondly, the impression I had of the physics laboratory at Charlottesville, which was, I think, in an old gymnasium, a big, big hall. And it had a very ramshackle old floor. And Beams was trying to build probably one of the first linear accelerators at the time. And wherever you stepped, the floor gave way. And the alignment of this linear accelerator was something which I just couldn't imagine as possible under these circumstances. But I think he achieved it eventually. And so from Charlottesville I went to Duke and saw Fritz London, who was then in Duke as assistant to ...

Mrs. Ewald:

I'm sorry, that's a mistake, for I saw London still in '37 in Paris. You saw him later, when you came again with Arnold in '50. I am quite sure he was still in Paris when I passed it in '37.

Ewald:

Yes, that is probably true. Well, perhaps this whole tour to the South was in '38?

Mrs. Ewald:

No, Paul. We have photos from Rose and Hertha Sponer and Debye while you were there.

Weiner:

Debye? Was he there?

Ewald:

No, I think that the photo was taken at Harvard.

Mrs. Ewald:

But Rose was on the photo and Sponer; then perhaps Debye wasn't on it.

Ewald:

Well, somebody took a photo of Laporte, Ella, and Rose--isn't that the photo you're thinking of?

Weiner:

We'll ask your daughter and get another point of verification.

Ewald:

Well, it's not important anyway.

Mrs. Ewald:

No, it's not important.

Ewald:

No, quite true; I think Ella is right. In Duke I also tried to get a job, and there was this very enterprising chemist--I think Gross was his name--who later on got hold of Fritz London. And he was looking for someone and he was quite willing to accept me there and had prepared it already with the president. And I went up to the president and had a talk with him, and I found the president such an awful man with so little understanding of what I needed and what the department needed. The whole place was still like a high school and not like a university. I think that changed a year or so later or maybe even longer, later, but at the time the only really live man seemed to be Gross, and chemistry, of course, was not just my strong point, and I was not too much interested. Nordheim was there, as far as I remember, and there was a German couple whom I visited who came from Hamburg. He was a great educator.

Mrs. Ewald:

Cohn?

Ewald:

William Cohn. That's quite probable. And they were very, very unhappy. He had been a highly recognized teacher and specialist on education in Germany, and here he was just giving an elementary course, and nobody recognized him at all, and they were living in a little attic and were thoroughly unhappy. So I had no very favorable impression of Duke at the time.

Mrs. Ewald:

And he was a man about 15 years older than you.

Weiner:

What was his field?

Ewald:

I think psychology and education.

Weiner:

This experience at Duke seems to be quite a contrast with experience at other universities. Not that you're comparing the universities on the same basis, but at least at the University of Virginia and at Purdue and at Michigan and the other places you mentioned there was a lot of activity going on in physics. It all seemed to be, from what you described, nuclear physics, and it all seemed to be something to do with accelerators, because you mention that there was one being ...

Ewald:

Well, at Ann Arbor it was not just nuclear physics. There was, for instance, the beautiful laboratory of Randall for infrared, which impressed me tremendously. I don't quite remember what else impressed me at Ann Arbor. Oh, the whole layout of the university, the engineering part, etc.--all this together. No, I always make the statement that Ann Arbor is my hometown in America. And you see I think I was very fortunate in just passing through New York and the next day finding myself in Ann Arbor and meeting America in the interior and not on the not very characteristic coastline.

Weiner:

Not on the extremes. Now what about Harvard? When you went there, you saw Bridgman. What was your impression of Bridgman?

Ewald:

I had a short visit with Bridgman in his laboratory. He was rushed, and I was rushed, because you see it was the days of the tercentenary and the whole place was flooded with visitors from abroad and from America. Well, I mean we just had some personal contact, and I don't remember too much about his equipment and his work at the time. I knew his work because we had always exchanged reprints, and so I was aware of what he was doing and was of course very much interested in it, since it was solid state physics.

Weiner:

Did you meet anyone else, either from MIT or from Harvard while you were in the Cambridge area?

Ewald:

I guess I met Van Vleck at the time. No, I don't remember and as I told you last time, I tried not to appear too much publicly because I was really not allowed to be there.

Weiner:

Do you remember the sessions themselves--the focal point of the meeting and the things most interesting?

Ewald:

No; I think I was there for only two or three days, only a short while.

Weiner:

Oh, I see. I remember one thing from the meeting: they were concerned with questions like penetrating radiation and cosmic rays and this was exciting to people like Oppenheimer. One thing about the seeking of a job: Had you prepared the way by writing in advance, or did you just show up?

Ewald:

No, I couldn't have done that. I didn't want to have anything written about it for fear that if it came into the hands ... We all lived under the threat of the Nazis, and you had to be very careful in what you said about the Nazis, because if this, by inadvertence or so, came to the ears of the consulate, they would send word back. And you had to be afraid that the Nazis would lead you into trouble and ,..

Weiner:

You mean even in this country?

Ewald:

Even in this country, oh, yes. For instance, I don't know if you've spoken to Russian refugees at the time--they have to be very careful in what they say. All refugees have. So I spoke quite openly to people like Rabi and others whom I knew well and on whose discretion I could rely, but otherwise one had to be careful.

Weiner:

How did you come to know Rabi, for example?

Ewald:

Well, we lived together in this fraternity ...

Weiner:

Oh, but you hadn't known him before that?

Ewald:

No, I didn't know him before.

Weiner:

And Wyckoff was a student of yours for a brief period in Stuttgart. Did you ...

Ewald:

Never, not Wyckoff, no. Warren.

Weiner:

Warren. Wyckoff, of course, was a different generation.

Ewald:

No, he was not a different generation, but ...

Weiner:

I got the impression ...

Mrs. Ewald:

Oh, yes, Paul, in a way.

Weiner:

Well, he was older than Warren, I would think.

Ewald:

Well, he was a few years older but I mean he was the leading man at the time for crystal structure determination. I visited him in New York at the Rockefeller Institute. He was there.

Weiner:

I see. That was on the way ...?

Ewald:

Probably on the way back, yes. It couldn't have been on the way there.

Mrs. Ewald:

I think Wyckoff was born about 1896.

Ewald:

Well, then he's between Warren and me.

Mrs. Ewald:

Yes. Well, Warren is 65 now. Yes, just in between.

Weiner:

I had meant Warren in that statement but I really meant to ask about Wyckoff because I was surprised that you didn't visit him. Now you tell me that you did see him. What kind of set-up did he have at Rockefeller? Was he the only one concerned with this field?

Ewald:

Well, Wyckoff usually has been rather a one-man researcher. I don't think he has ever had very many pupils. Wyckoff is a man of very strict principles and I think he found it sometimes--or other people sometimes found it quite difficult to handle him. He had been for a couple of years, I believe ... He had changed quite a lot his positions, and at the time when I saw him he was at the Rockefeller Institute, just opposite the cathedral-like hospital with a beautiful view from his window. He was doing x-ray work, and I think he had already begun work on the centrifuge, of which he saw the potentialities. And there was a change in the directorship of the Rockefeller Institute, and I think with the new directors he didn't see eye to eye, and so he left and in '38 we visited him in Pearl River. He was with the Lederle Laboratories. And I must tell you of that.

I don't quite know how we got out there. I think we took a train and he picked us up or something of the sort. Anyway, we arrived at the laboratory, and he took us to his shed. Now the laboratory was a place with big acreage where they had all their animals, their cows and their horses and all the animals they used for their investigation. And we finally came to a shed, which was Wyckoff's laboratory at the time and were led to his room, which was a little cubbyhole which was filled from floor to ceiling with boxes of eggs. And the boxes of eggs had inun- dated the whole space of this cubbyhole, and Wyckoff had to sit on one of the boxes of eggs while we talked. I think there were chairs for us.

And the fact was that he had managed to grow a virus for equine encephalitis, which was a terrible pest in the whole West and killed all the horses there. And it was known that it was a virus disease, and Wyckoff had managed to grow the virus on the inner skin of the eggs. So all these eggs had a little hole bored in and had been inoculated and, I think he told us, 80% of the protein or something within the egg was turned into virus by the time they were opened up.

Mrs. Ewald:

Were they not in a kind of incubator?

Ewald:

Yes. There was another room with incubators. And then before the eggs hatched, they were ground up and they extracted the virus, and that gave a vaccine against the horse encephalitis. I think it was a very important contribution. Wyckoff was very proud, being a precision man as he is, and he said, "This is the only biological product that is being regularly tested for its efficiency." I think that was a beauti- ful job he did, very important job.

Weiner:

That was in '38?

Ewald:

This was '38.

Weiner:

I was going to get you back to one other question about the results of this trip. Was the answer no or uncertain with regard to a possible position in each case, in each university?

Ewald:

Well, you see, my position was difficult. I was still spoiled. I had a family of four children and possibly a mother whom I wanted to bring out, so we were at least six people to be provided for. And well, I think the maximum offer I obtained was one for $3,000 a year, and I did not think that I could come on that little money. So, of course, later on in Cambridge we had even less, but then that was a year and a half later and ...

Mrs. Ewald:

I still think that $3,000 in America was less than the little sum we got in Cambridge.

Ewald:

Yes, probably.

Weiner:

Do you recall where those offers came from?

Ewald:

Oh, they came from all over. Hugh Wolfe, for instance, was trying to be very helpful.

Weiner:

Was he at Cooper Union at the time?

Ewald:

He was at Cooper Union. And, oh, a number of people. Gross, for instance, at Duke University, tried to get me, but the president there offered me probably even less than the $3,000, and I thought I couldn't do that. And I wouldn't do it. You see, I got a very good salary in Stuttgart, so I was quite spoiled. [Interruption in taping caused by telephone]

Weiner:

So then by the time you completed your tour, things weren't satisfactory, and you went directly back to Stuttgart. You didn't stop anywhere else, in England or anywhere?

Ewald:

Oh, Ella should be here to check ... I probably went to see my old friend Sir William Bragg in London. And I think it was on this occasion that I told him I wanted to leave Germany, that I had not been successful in America. And he finally gave me the advice, "Stick to it as long as you can." Those were his words, meaning the job in Stuttgart. And so this was my order by which I went, my marching order, to stick to it as long as I could. I had great trust in Sir William Bragg. He was really a fatherly friend and a word of his like that had more weight than any written agreement or so.

So I stuck to it but not for very long because soon after I returned to Germany I found that things had been taken over by the Nazis more than before. The university had been free up to that time before I left, but now there were Nazi agents everywhere. Many of the people--I guess my mechanic, for instance-- belonged to some of the Nazi formations, so you had the feeling of being surrounded by spies. In every university they had appointed a Dozentenschaftsfuehrer, leader for all the faculty, and this Dozentenschaftsfuehrer had great power. He could convene the whole faculty at any time and lecture to them on the new regulations and edicts of the Reichskult-minister, Rust. And in the case of Stuttgart this was a young man... Now, excuse me, did I tell you this whole story before?

Weiner:

No. I think when you talked with Young and Warren, you'd gotten into it, but I'd like to have it in context.

Ewald:

Well, all right. The Dozentenschaftsfuehrer was an assistant in the electrical engineering department, and he convened a Pflict versammlung of the Dozentenschaft sometime after I'd returned and lec tured to them on the new views of the Reichskultminister regarding the fact that there was no such thing as objective science. Science was an outcome of national feeling and of nationality somehow, and objective science did not exist. And so I thought it wasn't necessary for me to be lectured to on things this young man certainly didn't understand, so I stood up and went out of this assembly--to the horror of all my neighbors and of all the other professors--and actually went to the American Consul General to discuss with him what we could do for the librarian of the Hochschule in Stuttgart who was Jewish and wanted--well, had--to leave Germany. And then nothing happened, to my great amazement, until after, oh, perhaps a month.

I received a letter from the rector, who by that time was the first Nazi rector we had had in Stuttgart, a very stupid chap, asking me whether I'd left the assembly as a demonstration or for personal reasons. So I thought it was better to explain to him that it was for personal reasons, but on the other hand that I disapproved very highly of what this Dozentenschaftsfuehrer had been trying to put across to us. And then again nothing happened for several weeks, and finally he called me to his office and asked me why didn't I go to live in Berlin where the government had established a special cultural area for Jews, including their own schools and theatre and a special high Party administrator, a friend of his, to look after their well-being. Alternatively, since I was so well known abroad, I might prefer living there.

At any rate it would be better if I left the Hochschule. So I said, "I'll be delighted." And from that moment on I was put on the pension, no longer full salary. And I went to my mother's house on the Ammersee where I'd had the conference in '26, and settled down and wrote one paper in the series of papers which were really started with my thesis. And I was quite happy to have succeeded in solving a problem which involved some fairly intricate algebra.

Weiner:

Was this at the end of the winter term in '37? You got back sometime in the fall of '36.

Ewald:

No, I think it was probably in the spring term of '37, or maybe in the winter term of '36-'37. Yes, I think that is more likely. I think it was still winter in Holzhausen. But then I got an invitation from Herman Mark to come and visit him in Vienna, and I took the occasion of going to Geneva first where there was Weigle. Do you know Weigle? He is working on genetics. He turned away from physics. He was professor of physics in Geneva but left physics and took up genetics and is now in California with Delbrück and these people. And Weigle had done some very interesting and excellent work on the dynamical theory, and this was at the time still when there were very few people who had done any work on that. And so I went and talked with him and gave a couple of lectures. And then from there I went to Vienna and stayed with Mark for about a month and then I returned. In Mark's laboratory all the people were leaving. There was his assistant Guth, who later was in Notre Dame, ...

Weiner:

This is Eugene Guth?

Ewald:

Eugene Guth who worked there and others--most of them now are dispersed somewhere.

Weiner:

If you stayed there a month, were you on some kind of fellowship or any kind of support?

Ewald:

Oh, I don't know. Mark always had means somehow to pay for visitors. One interesting man I met in Vienna was Przibram who is an old hand in luminescence and radioactivity and did very good work there.

Weiner:

How does he spell his name?

Ewald:

P r z i b r a m. He looked quite different from what I'd expected. He looked like a cavalry officer. He is still alive; he must be nearing his nineties. And he and Lise Meitner were at the Radium Institute in Vienna and did their early work there.

Weiner:

What sort of feeling was there in Vienna at that time? Were people expecting the worst to happen?

Ewald:

I think they were more concerned with Grinzing, the new wine, and leading a jolly life. I really don't know. I had not very much contact.

Weiner:

How about the university people. Some of them were, as you explained--Guth and others--on their way out.

Ewald:

Oh, well, this was quite clear. They were more or less all on their way out, but all the people I met were always anti-Nazi, I don't know how strong the Nazi group in other laboratories may have been. Certainly not in the physics laboratory, which was still Ehrenhaft. Oh, at the end of my stay in Vienna, Laue and Lise Meitner arrived, and Frau von Laue, and we had a lovely excursion--they came in their car, Laue's car--and we had a lovely excursion to some old places on the Danube, and finally we all went to Gratz. Schroedinger was in Gratz at the time and Kohlrausch, so we all had a very jolly time in Gratz,too, for a few days. Well, then I went back, I guess, to my mother's house. Where did I go from Vienna? No, I came back to Stuttgart, I'm sure.

Mrs. Ewald:

To Stuttgart.

Ewald:

Yes, but when did I get the letter from Peter Wooster?

Mrs. Ewald:

Just about sometime that summer. You spent the summer ...

Ewald:

I got that in Holzhausen, Ella.

Mrs. Ewald:

Maybe. You spent some weeks with your mother in Holzhausen and did some work there.

Ewald:

You see, I wasn't tied down to Stuttgart except through the family, but the quieter place to work was always at my mother's, so I commuted quite a bit. And one day I received a letter from our friends the Woosters in Cambridge, saying that they had heard via America that I had lost my job in Stuttgart and would I come to visit them in Cambridge. So I wrote back, saying that I had been outside Germany already in '35 and '36 and I couldn't leave again except permanently.

Mrs. Ewald:

Could you write that in direct language?

Ewald:

I wrote that in direct language. Very often these messages were camouflaged you know, but I think this time it was direct.

Weiner:

You meant in this case that you didn't think it wise to ask permission for another temporary trip.

Ewald:

Right. You see, when I came to the rector to ask for permission to go to Ann Arbor, he looked very important, up and down, and finally said, "Well, you have already been to Spain last year, and now you want to go to the United States. Well," he thought for a good while and finally he said, "it might be even worse for Germany not to allow you to go." On that condition I got the permission to leave Germany. But I didn't want to repeat that. And so I said, "I can come but if I come, it must be permanent." And three days after that I got the invitation. I'd been given a fellowship to come to Cambridge for one or two years, I don't remember, one year probably.

Mrs. Ewald:

Two years. I think two years.

Ewald:

Or two years for £400 a year.

Weiner:

Who supplied the fellowship, do you know?

Ewald:

Well, this was the Society for the Protection of Science and Learning, which had been founded under the chairmanship of Lord Rutherford. And I think that Lord Rutherford was one of the quite essential people in this society.

Weiner:

Yes, he was the president.

Ewald:

President. And as far as I know the funds came largely from voluntary contributions of a great many of the British professors who donated lO% of their income to this society, which really is something that should be better known.

Weiner:

It will be in September, when my article on this is published. There's a good deal of it in there.

Ewald:

Well, so I left my family. You see, the family was in a rather difficult position in Stuttgart. We had moved out of our apartment into another house in 1937--that was not so difficult--but my younger daughter Linde, who is a doctor now in Essex in England, had been run over by an automobile.

Mrs. Ewald:

Paul, excuse me. That was many years ago; that was in '33.

Ewald:

Oh, that was '33, yes. But in the next years we were tied down to Stuttgart by the fact that her whole leg had been shorn of the skin and substrate, and it was a long hospital job to get the skin to grow again and so on--it was touch and go. But now she went to school again, and we wanted her to finish her school so that she had her Abitur, which meant quite a lot.

Mrs. Ewald:

It meant an entrance to every university all over the world, at that time still, I mean, the respect for the German Abitur was still there.

Ewald:

Well, this Abitur took place when?

Mrs. Ewald:

In '38 in the spring.

Ewald:

In the spring of '38. And now we were in the fall of '37 when I got the offer to go to Cambridge. So in October '37, I guess, I went to Cambridge alone, leaving the family in Stuttgart.

Weiner:

You mentioned Wooster, was he from Cambridge? Where did you know him?

Ewald:

Oh, we were old friends. Where do we know the Woosters from?

Mrs. Ewald:

You must have met them in Cambridge early because they were in our house already in '25 or before that. They visited us in Stuttgart. They were really good friends.

Weiner:

And then you went in October by yourself.

Ewald:

I went there. And after arriving I looked for lodgings and as soon as I was settled, I went to Lord Rutherford to present myself there. And of course I asked him could he give me any money because I had to leave Germany with, probably, less than £ 5.0.0 in my pocket. It was limited. And Rutherford in his gruff voice looked at me and said, "You know how to handle money?" So I looked a bit funny, and he said, "How much do you want?" So I said, "Well, say, £50." " £ 50 pounds? That's a lot of money." But he was already signing the check, and so with that condition he gave me the check.

And then a few days later Niels Bohr came to Cambridge, on his way probably from Paris to Copenhagen, and he wanted to see Rutherford and I think he came also very much worried about the condition of refugees from Germany. That I take from Bohr's biography, where by the way I think this particular trip to Cambridge is not mentioned. But Rutherford of course invited him to give a colloquium, and he gave a colloquium talk on some recent development of nuclear physics. And after the colloquium Rutherford invited a few people to his office for a cup of tea and I was amongst them. Now Rutherford's office, which had been J. J. Thomson's office before and probably Maxwell's before, was an office no secretary would look at nowadays.

It was quite small because the philosophy was that the space of the building should not be taken up by offices but by experimental work. And we were crowded in. There was the big desk behind which Rutherford sat, and I think he moved one chair also behind the desk so that a second man could be placed, and the others were, one or two seated and the others standing before the desk. There was Fowler and Niels Bohr and I guess Darwin and Dirac and myself. This was very nice, and it was the only chance I had to see Rutherford at that time because a week later, or quite soon after, he was dead.

Weiner:

That was 37?

Ewald:

'37.

Weiner:

This occurred just a few days after your arrival?

Ewald:

A few days after my arrival, and quite soon after, he died.

Weiner:

Was he in good health when you ...

Ewald:

He was. He seemed in good health and all right. He died quite unexpectedly. I was told at the time that he died of a hernia which had been neglected. He was in the hands of a chiropractor or something-- not a real doctor. He didn't like to go to doctors, so this hernia got worse and broke through. But I see there is a different version of his death, connected to a fall which he had either in his garden or somewhere.

Mrs. Ewald:

But that might have been the cause of a hernia.

Ewald:

That might have been the origin of the hernia.

Weiner:

Right. What was the impact on his laboratory, other than the shock of it?

Ewald:

Oh, I think it was a great shock mainly. And then of course later, well, there were also a great many people who knew him intimately and who were grieved as his friends--Cockcroft and Walton and ...

Weiner:

But, I'm sort of jumping ahead of the story, was there any feeling of lack of direction in the laboratory? He was such a strong personality, and the laboratory had been built around him.

Ewald:

Yes, I think very much so, You see, the question arose as always with the succession in the Cavendish Laboratory--who was going to head it? But the difficulty was that among the nuclear physicists--I think there was a strong feeling among the nuclear people--that it should be run again on the lines of nuclear physics. And the trouble was that there were Appleton and Cockcroft and other associates of Rutherford who were all more or less of the same age and rank, and so it was finally decided--I think it took quite a long time to find a successor--Bragg was offered the position and became the successor, much to the disgust of the nuclear people. The cystallographic laboratory had been a kind of separate institution up to that time which had been headed by Bernal, later for a short while by Wooster, and there were very good people working there. Perutz was one of the members and Wells another one, a man called Knott was one, and ...

Mrs. Ewald:

Fankuchen was there.

Ewald:

Fankuchen was there.

Weiner:

As a visitor.

Ewald:

As a visitor. So it was a well-knit group and working actively. I was there as a visitor; I was attached to that laboratory.

Weiner:

Do you remember when Bragg came in?

Ewald:

No. It took quite a while. And the uncertainty, you know, maimed the whole laboratory a bit. The same is happening now with the Fritz Haber Institute in Berlin where Brill is going to leave and all these people are wondering what is going to become of the Institute.

Weiner:

Yes. Well, also this was the period when things were so unsettled in Europe in general that it wasn't at all clear ... No, maybe that's not fair to say; perhaps that wasn't the feeling in England. Perhaps they didn't see ...

Ewald:

Oh, of course, politics took a lot of our time and attention, at least of the refugees' time and attention who were perhaps more closely attuned to the events in Germany than the British. My family came over in April '38. You see, I had saved some of the money in order to give us a good start and so we found a house in Guest Road and ...

Mrs. Ewald:

First we lived a few months with relatives who had a house, and that saved money again.

Weiner:

Relatives in Cambridge?

Mrs. Ewald:

In Cambridge, who were refugees, too. And they shared a house in a very modest way but ...

Ewald:

On the outskirts of Cambridge.

Mrs. Ewald:

Then we went to America in the summer of '38.

Ewald:

Yes, that was a break in the Cambridge ... Before we got Guest Road?

Mrs. Ewald:

Yes.

Ewald:

Yes, I had an invitation to go to Columbia University, to summer school there, and give a course on electromagnetic theory.

Weiner:

Who extended that invitation? Rabi?

Ewald:

Oh, I guess Rabi. And, as you know, I came with the idea of the Ann Arbor summer school and tried to get all the nicest things with complex integration and so on which I'd learned from Sommerfeld into a nice course, building up something which really was for gourmets. And when I came there, I found the lecture room full of people and when I started, soon after I started, I found out that they didn't know anything. These were all teachers, and their only interest was--I found that out only at the end of the term--that I had to give an exam and give them a good mark because then they would get an increase in their salaries. Oh, this was the worst experience I ever had.

Weiner:

Was this at a graduate level then?

Ewald:

Well, it should have been at the graduate level, but the students weren't prepared for it.

Weiner:

No, but I mean the idea of getting extra credit, meaning extra salary increment, implied ...

Ewald:

Well, in the school system I think they got this provided they took a course for retraining or I don't know what they call it.

Weiner:

This is still true.

Ewald:

This is still true? Yes. It was just devastating because they couldn't answer the simplest things to my mind at least, about ... Well, I'd tuned down the level of the course to quite an elementary, intro- ductory course, but even so they couldn't follow. And then at the end of the term, this idea of an exam suddenly sprung on me, and I wasn't prepared for that in the least and I hadn't given the course with the idea of an exam at the end. And I had at that time no technique in setting up exams, so this was really quite bad. I remember that several of the people,--two or three--came afterwards: one had a dying grandmother in a nursing home and he couldn't get the money except if he was passed here; and the other had bought a new car or a new house, and they came and complained because I had failed them, which they deserved. And so I had to change that somehow, and this was so terribly different from the kind of summer school they had in Ann Arbor which was pitched to research.

Weiner:

What else was going on at Columbia at the time? Did you get involved in any research or any discussions? Anything of a theoretical nature?

Ewald:

No. I did not get ... I remember meeting Patterson whom I didn't know. But he was in a rush, I was in a rush; we just happened to find out who we were as we were going up in an elevator--that's about all I had from Patterson.

Weiner:

Was Rabi around that summer?

Ewald:

Rabi was around and Pegram, of course, and Dunning.

Mrs. Ewald:

Pegram was very kind.

Ewald:

Pegram was very kind as always. Yes, and I remember an invitation at the Dunnings where the Pegrams were. Isn't Pegram the father-in-law of Dunning?

Weiner:

I didn't know that.

Mrs. Ewald:

Yes, I think so. Does he live still?

Weiner:

Pegram? No.

Ewald:

And then we went to see a cinema, a film on wild life in Africa. Well, then Darrow was there, of course.

Weiner:

How long did you stay that summer?

Mrs. Ewald:

Altogether two months.

Ewald:

We lived in the Kurrelmeyer's apartment ...

Mrs. Ewald:

May I remind you that first you went to Ann Arbor again. We all were in Ann Arbor again in '38 before you started the summer school. There was some meeting or something.

Weiner:

Well, summer school went on every year at Ann Arbor so it may have been ...

Mrs. Ewald:

Yes, that was a short stay of about one or two weeks. We were there with Rose.

Ewald:

I think much less, Ella.

Mrs. Ewald:

Even less. You had to take the train to reach there immediately from New York. And Rose and I drove with Kurrelmeyer to Ann Arbor.

Ewald:

Yes, that's right.

Mrs. Ewald:

After that was the summer school in New York, The Kurrelmeyers had offered their apartment.

Ewald:

On that occasion, you see, I also went to Princeton and saw Ladenburg and Weyl. And then somehow --- Einstein had left Princeton and was vacationing on Long island, quite at the tip, very end of Long Island somewhere, and we went out with Rose and the man who is now in Poland, what's his name?

Weiner:

Infeld.

Mrs. Ewald:

Infeld, yes.

Ewald:

Went out with Infeld to visit Einstein. And that was quite characteristic of Einstein. It was a visit of a few hours. At the end I told him, "I'm going back to England and shall probably go for a few days to Germany. Is there anything I can convey, greetings or so?" And Einstein thought a minute and said, "Gruessen Sie Laue." (Give my regards, or greetings, to Laue) I said, "What about Planck, Sommerfeld?" Einstein repeated, "Gruessen Sie Laue." I think It's very characteris- tic--it shows the very high esteem he had for Laue.

Weiner:

That's interesting about that part of it, but about the negative part of it, too.

Ewald:

The negative part I think is very important.

Weiner:

Because it is not at all clear in my reading of this what the relationship was with Planck because when he was head of the Prussian Academy, you know, the ...

Ewald:

Yes. Well, you see personally I didn't know Planck very well. At a Physical Society meeting once in Stuttgart, he came to see us and had supper with us and told us of the beginnings of his theory, of the quantum theory, and that was very nice.

But before that, I think it was on the occasion of the opening of the Kaiser Wilhelm Institute of Metals in Stuttgart, and Planck as president of the Kaiser Wilhelm Gesellschaft came to the opening. And he had to give the talk, and this must have been in '34, and we were all staring at Planck, waiting to see what he would do at the opening, because at that time it was prescribed officially that you had to open such addresses with Heil Hitler. Well, Planck stood on the rostrum and lifted his hand half high, and let it sink again. He did it a second time. Then finally the hand came up, and he said, "Heil Hitler." I was terribly disappointed, and I think this may have been the same reason why Einstein didn't do anything. Looking back, now, it was the only thing you could do if you didn't want to jeopardize the whole Kaiser Wilhelm Gesellschaft.

Weiner:

On Einstein--what did you discuss earlier that afternoon when you spent two or three hours?

Ewald:

I don't remember.

Mrs. Ewald:

It wasn't a long visit.

Weiner:

Was it your first meeting with him?

Ewald:

Probably, yes. I may have just exchanged greetings with Einstein on previous occasions. My first impression of Einstein was at the Naturforscher Versammlung, or Physiker Versammlung, I don't remember which, in Bad Nauheim at the time when Lenard and Stark originated their drive against Einstein. And I must say I didn't like Einstein. I thought: the man who was the center of all this discussion and controversy I didn't like to see him looking more or less like, what are the longhaired people called?

Mrs. Ewald:

Hippies?

Ewald:

Like a hippie. With his hair unkempt and his suit not very clean and tidy--I was just too formal to take a great liking for Einstein and so I was again a bit shocked when I visited him on Long Island because he ...

Mrs. Ewald:

Oh, but we heard he was very much dressed up for the occasion.

Ewald:

Well, he was dressed up, that is to say, he was in bathing trunks and a shirt. I think normally he went about in bathing trunks without the shirt, but for Ella's sake ...

Mrs. Ewald:

Yes, I think in my honor he had ...

Ewald:

He had put on a shirt. But I wasn't used to this kind of great informality.

Mrs.Ewald:

I didn't feel that at all when I saw him.

Weiner:

This was your first trip to the United States?

Mrs. Ewald:

My first trip to the United States and the only time I saw Einstein. No, I had seen him giving a talk in Berlin once in '31, but I had never talked to him and I was very glad that I have had this opportunity.

Ewald:

Yes, I don't remember anything about our conversation with Einstein and I don't think it was of any importance.

Mrs. Ewald:

I remember that I dared to say that I am so unhappy that in Germany before Hitler came to power the people didn't dare to do more against him. And he said, "Well, that is the spirit of liberalism and democracy, and that is inseparable." That was very characteristic for him again to give me that answer.

Weiner:

In line with his pacifist convictions?

Mrs. Ewald:

No, in the line that principles are followed. I mean that if these liberals and democrats are for freedom, they cannot on the other side do things to keep themselves in power. I mean, that's what he gave me as an explanation because I felt that ...

Weiner:

I see. That's interesting. Now, on this trip, '38, you made visits to Princeton, and we digressed on this visit to Einstein. Did you visit any other universities and did you make attempts to find a permanent position once again?

Ewald:

Oh, yes, certainly. And I think on that occasion again Hugh Wolfe tried quite hard to get me to N.Y.U. or Cooper Union, I don't know which, but nothing came out of it. So I returned to England, and you see our position was ... Oh, yes, I stayed a few days in England; we rented a house that belonged to one of the colleges--a very small, miserable little house, but it had plenty of rooms so that all of the family could be placed and have their bedrooms.

And now we still had our apart ment in Stuttgart with all our furniture and belongings, library and everything, pictures, and this, of course, was weighing heavily on me and I wanted to get rid of it. It couldn't continue that way. My eldest son also, who is now living here close to us, was still in Stuttgart. He was with the firm of Bosch, doing magneto and motor work. So Lux, this son, took a small apartment, a two room apartment in Stuttgart somewhere, and I had to go to Stuttgart and get rid of our furniture, either pack it and send it over to England or do something about it and get rid of the rent which we had to pay. But I didn't dare go to Germany because of the threat of war at the time we came back to England. But then it seemed that Chamberlain would go to see Hitler. He had been once before to see Hitler and it was the second visit that was being planned. And I thought that as long as Chamberlain was staying in Germany with Hitler, war would not break out, so I went to Basel where we had friends and stayed with them until I heard the news that Chamberlain was actually on his way to Bonn. Then I took the next train to Stuttgart and tried to organize the sale of our furniture and our library and everything. Nobody wanted to pay anything for any furniture or books or anything.

I told the people from the Antiquariats, "Well, come and have a look at the books. There are valuable books among them." They wanted to pick out one book and another and wouldn't look at the rest. I told them, "No. You have to take either the whole lot or nothing." And so finally I separated the books into two heaps. Finally I got someone to cart off the one heap, the other Lux took into his new lodgings and stacked them there. And he very soon sent them out to Belfast. As soon as I had the position at Belfast they could be sent there.

But that took some time, so at first he had to store them in his little apartment. And he stored a lot of our furniture there, too. And the rest I tried to get rid of, but it was very, very difficult. But finally I managed to get it carted away. And all the while there was going on a meeting of the German Physical Society in Stuttgart. And when I did my errands in Stuttgart--you see, I didn't want to stay long and I still had to go to Holzhausen to my mother's house. My mother was with us in Cambridge by now, but her house was in the keeping of her cook, so there wasn't really very much to look after at the house but there were some pistols and revolvers which were remnants and which I had to take out and get rid of. So I had to rush to Holzhausen. On my way through Stuttgart I met the physicists coming back from lunch. I met in particular Gerlach and Debye. Well, I stood with my face against a shop because I wanted to let them pass and not be held up, although they were of course

quite old friends, but I didn't want to be seen. But Gerlach detected me, and we had a few nice words, and then Debye came and spoke to me. Well, this conversation with Debye was quite characteristic of the times because I think he came along with me, and we went a few blocks back together. I told him, " I see that you have arranged a special issue of Annalen der Physik in honor of Sommerfeld's birthday (I don't know which one, 70 probably. '68 he was born and this was '38-- no, 60th birthday) but you never asked me. After all, I'm one of Sommer- feld's pupils.

I should have been in that group." "Oh," said Debye, "this would not have been possible. We had such difficulties already in persuading the publisher to bring out an extra number in honor of Sommerfeld. "You know that Sommerfeld went through the papers as one of the white Jews, so-called white Jews. Heisenberg also at the time I think. "Oh, this would have been quite impossible." I said, "Well, pity that you have not that much influence on your publishers. In the Zeitschrift für Krystallographie we would not have allowed It."

"Oh, no" Debye said, "but you must understand that. It would have been impossible." Well, anyway, I went to Holzhausen and picked up those weapons and then went back clandestinely to my institute and (I don't know how I got into the institute at the time) took out the numbers on the grinder so that the weapons couldn't be identified, you see. And then I dropped them piecemeal on the train, throwing them either out of the window or ... Oh, one lived in a terrible fear at the time.

Weiner:

What would have happened ... You had gone to England. You had emigrated. You had asked for permission to go ...

Ewald:

Oh, I was officially in England and I got my pension.

Weiner:

So there was no real, no legal problem of your being in Germany at this time.

Ewald:

No, there was no legal problem at all. But on the other hand, you see the S A and S S did what they liked or what they were told to do illegally, so you never felt sure. Well, on the Bahnhofsplatz, before the station in Stuttgart there was an enormous bomb standing up, made of colored glass and illuminated at night so that everybody saw what was really in store, the bomb threat of the war. And everywhere you heard military tunes, columns of people marching through the street-it was all a very warlike spirit.

Weiner:

This was still '38?

Ewald:

This was while Chamberlain was, I think, either in Godesberg or up in Bertesgarden--I don't remember which, but it was the last meeting, when he came back with "Peace for our times." Well, I came back to Cambridge unscathed, and in Cambridge the next day--it was before we moved into the Guest Road house, the little house; we were still staying with our friends, Professor Hutton, the metallurgist in Cambridge--and the next day there was an announcement that gas masks would be distributed to the population and this would take place in the Corn Exchange, a big hall in Cambridge that was used

for auctions, and all the things in the Corn Exchange had to be auctioned off. So we went there and bought furniture for our house. And we bought a magnificent table for 10 shillings or so. And I remember a big, life- size mirror for one shilling. And I was so tempted to buy two big Chinese vases, beautiful things, you know the pale blue and white and about 4 feet high, and nobody wanted them and I could have had them for a shilling each. But we had neither the money nor the room. So we bought most of our equipment for the new house at that auction.

And the next day when the hall had been cleared, we went there and received apas mask. And you know, the contrast between the war music in the streets of Stuttgart and the tense atmosphere everywhere, the unfriendliness, the enmity you felt everywhere, and then in Cambridge the quiet university town and the people distributing gas masks even to the enemy aliens. It was incredible. These were really interesting times.

Then we settled in our house and Professor Hutton, who was already retired, came with a table they didn't use, and people whom we hardly knew brought in rugs and things. And then Hutton came with an enormous wardrobe; he had a little carrier at the back of his car, and he came with that and put it up himself in my room. It didn't fit in anywhere except in the main room downstairs, which I occupied as my study, and there we had space enough to put it up, and that was the mainstay of all our order. And Ella's linen was in there and my ... You see, it was so friendly; it was incredible. And at that time one of our main occupations was to hear the radio, three or four times every day to follow the developments. And to write innumerable letters helping other people, partly the family and partly other people. For instance, Przibram, to get away, to get out of Germany.

Weiner:

Who was with you then of your own family?

Ewald:

Of my own family, all of us except my eldest son who was still in Stuttgart in his little apartment.

Weiner:

And your daughter Rose, who was ...

Ewald:

Oh, she was in America; she was safe.

Weiner:

And how old were the others?

Ewald:

The other girl went to an English school, I think for a term. And then my youngest boy, who is now in Australia, went to the Perse school.

Weiner:

How old were they at the time?

Ewald:

Well, Linda was born in 1919, and this was 1938, so she would have been 19. And the younger boy is two years younger so he was 17 and went to the Perse school in order to be able to go to a British university.

Weiner:

And what about the life in the laboratory itself during this period after Rutherford's death?

Ewald:

Well, you see, I didn't get involved much in the real physics part because we were in a different courtyard in the crystallographic lab, and of course I went there mainly. There was no real colloquium in Cambridge. You see, at a German university there would have been a real official colloquium. But there was no such thing.

There were little societies in Cambridge. The mathematicians had a society called, I think, The Delta Club, and Cockcroft, who had his room in one of the towers at the entrance to St. John's, had a Physics Club in his rooms. And this was all there was. The technique seemed so very alien to me. Instead of having a well presented lecture in a good lecture room with a good blackboard, which would have been the case in Ann Arbor, as well as in Germany, the Cambridge pattern was to crowd into a private room with all the belongings of the fellow, carpets and knickknacks, and have a wee cup of coffee, crouching there on the floor or on as many sitting possibilities as there were. And then listen to someone's

stamering talk, which was quite usual in Cambridge--you weren't really a high-powered research man if you didn't have a good stammer--and there was a wee little blackboard, on which he could just write one formula and then he had to erase it, and then he could write the next formula, and you never saw the whole story before you. But they gave the argument, "No, if you have a big blackboard, people are likely to present calculations, and we don't want that; we just want to hear of the physics." It was an entirely different attitude.

Weiner:

That's very interesting. I can see a theme on a comparison using the size of the blackboard as a symbol of the atmosphere at different institutions. Did you go to the Physics Club? There was nothing specifically for people interested in x-ray diffraction and crystal structure?

Ewald:

No, not in x-ray diffraction. This was wave mechanics and nuclear physics. Goldhaber, for example, was one of the participants.

Weiner:

Right. He would still have been there in '38.

Ewald:

Yes, he was in Magdalen College. You see, I had a characteristic conversation with Rutherford on a previous occasion; I think this was perhaps in 1931 or 1934 when he had invited me to have supper or dinner with him in Trinity, where I guess Rutherford was. Well, I didn't know him very well, but at that time there had been some attempt to create a chair for crystallography. You see, crystallography wasn't a subject in its own right; it went with mineralogy and often even petrology. And in Cambridge I think there was Tilly already--or was it this predecessor of Tilly who had left and Tilly became the professor then. There was an attempt to create a special chair for crystallography, and I'd even been asked if I would take that chair.

So it may be for that reason that Rutherford invited me to dinner. And as we were eating the soup, I told him I'd been visiting the crystallographers and said some flattering words about the crystallographers Bernal and Wooster and Henry and these people. And Rutherford didn't react at all but ladled his soup. And then at the end of my talk he said, "I'm not interested in crystallography." So after my next spoon of soup, I said, "Why not?" Rutherford, after his next spoon of soup said, "It's not fundamental." Well, then I said, "It's true; it's not as fundamental as nuclear physics and the interior of the atom, but after all, it's fundamental and interest-ing for all the physical properties of solid state, of matter, of solid state matter." Well, we left it at that. But this was his attitude; he was not fundamentally interested in the x-ray stuff; we were, so there was quite a gap.

Weiner:

Yet after he died the choice of a successor was in that field, in solid state.

Ewald:

Oh, but that was a matter of personality. There was nobody of the stature of Bragg who could have taken over.

Weiner:

I see. Who else in this period, in '37 and '38, were refugees in the lab? You mentioned Goldhaber; he had been there from about 1930 and had gotten stuck there, as I remember.

Ewald:

Who else? Well, I don't remember really very many. There was Peierls, but I think he was no longer in Cambridge; he may have already been in Manchester. But we saw quite a lot of Peierls and of Ginia, his wife. Then there was a mathematician Rogosinski who was there.

Weiner:

Where was he from?

Ewald:

I don't know where he came from in Germany, but he interested me because he had worked on Fourier Theory and conversions problems of Fourier Theory, and he wrote a nice little book on Fourier series and Fourier methods. But I didn't get very much out of him. Oh, then for a while there was Jehle who turned up everywhere. Herbert Jehle, yes. But that was not permanent.

Weiner:

We were talking about other refugees at the Cavendish, and you had mentioned a few names. When you did work with the crystallography group during the rest of this period, did this lead to any collaboration? I have noticed in most of your papers and from what you've told me that you work pretty much on your own, occasionally with students or assistants working with you. What about in Cambridge--was there any collaboration with others then?

Ewald:

Oh, there was collaboration. First of all, we started a regular colloquium on crystal methods, which had not, I believe, been held before, and then I was interested in the work in general. The only outcome of it, I think, was some ... I don't quite remember whether it was remarks only or ... There was a man Knott who worked on some structure, and I told him of the method of Fourier transform of molecules and how the crystal picks out from that transform the values at certain points, the points of the reciprocal lattice.

And he incorporated that idea ... No, he worked out the Fourier transform of a benzene molecule or something of the kind. This idea of molecular Fourier transforms really came to me after a man, whose name I've now forgotten, a German, wrote a paper. [A. Hettich, also see below] He was a pupil of Groth, and Groth couldn't get the hang of his ideas, and so Groth turned him over to me. And at the time he wrote his thesis I think he was in Dahlem and later on he went to Palestine, to Israel, but I've forgotten his name at present. He actually was the first I know of who made use of the Fourier transform of molecules. And I added a short note to his paper in Zeitschrift fur Kristallographie, explaining what he was doing because his presentation was hardly to be understood.

Weiner:

Do you think in the 50 years' volume there might be a reference to his name?

Ewald:

Yes, there is a reference certainly among the list of my papers which I gave you. [The paper is not on the list. Its reference is Zs. f. Kristallogr. 1935 90 493/4.] ---

Weiner:

Okay, well I'll check that now while we're talking. What year would this have been?

Ewald:

Let me have a look at the list if you have it there. The man's name was Hettich.

Weiner:

Yes, I see, that was the one you inserted there, as a matter of fact. And this was earlier.

Ewald:

Oh, that was much earlier, yes. But this idea of Fourier transforms of molecules, you see, was quite alive in me. And I think about this time there must have been the conference in Bristol where I gave a talk on the Fourier transform method, and that has been quoted a good deal. I was not aware at the time that it would have so much appeal. [Pause - looking over list] Well, that appeared in the only paper of the Proceedings of the Physical Society. Yes, here it is, "X-Ray Diffraction by Finite and Imperfect Crystal Lattices."

Weiner:

That was published in 1940.

Ewald:

It was published in 1940, and the conference in Bristol was pro- bably '39 then. '39--that was already during the war, wasn't it? No, I think the conference was just before the war; I was still in Cambridge.

Weiner:

I see. Well, I notice that it turns out to be the last prewar paper that you published. The next one was in '44. That's interesting for later on. How long were you in Cambridge all told, on this temporary fellowship?

Ewald:

I think one and a half years. Then I had two offers which came nearly simultaneously. A chair was to be created in Belfast for theoretical physics, and I applied for that. And at the same time I had an offer to go to Laval University in Canada, where I would have had to teach in French, though that wouldn't have been very difficult, but I did not go there finally. It was quite a difficult decision, whether to leave Europe, --that would have been the advantage of Laval--or to stay in Europe. But seeing that we had close ties in England, I mean old family ties, many friends, and we had hardly any personal connections in Canada especially, I finally decided to apply for the Belfast job. Then it was quite interesting ... You see, in Germany it would have cut me out entirely if I had applied for any academic job; you had to wait until you received a call, and any application was considered absolutely outrageous. So this was new to me, and I went over to Belfast on the invitation of the Council to be vetted, as they called it.

And this was very funny, especially the situation when there was no Vice Chancellor at the time--he had just left and the new one had not yet arrived--and so there was a professor of philosophy, I think, who headed the Board, and 1 was asked questions. There was a big, U-shaped table at which the faculty sat, and I was somewhere at the end of one of the limbs of the U, and I was asked questions by the various members, who were not only faculty but also from the Council. 1 know that Judge Megaw, for instance, was one of the members. And when one of the people asked, "Can you hold discipline in a class?" this really struck me as being very funny after I'd been rector of the Technische Hochschule in this stormy period, but I kept my face straight and said, "Oh, I think so; I've never had any difficulties."

Weiner:

Oh, I guess it was necessary to go through those formalities.

Ewald:

Well, I finally got the job. There were two other candidates who were being interviewed; we all came on the same boat, and I think I had happened to speak to one of them beforehand on the boat, coming over to Belfast. And, of course, they were a bit disappointed to find me there and that they weren't the strongest candidates.

Weiner:

Do you recall who they were?

Ewald:

I don't know who they were, no. They were young people.

Weiner:

But in terms of their relative position in physics, you were certainly more well known.

Ewald:

Yes. And I remember that Judge Megaw showed a letter which I saw from afar to be from the Royal Institution, from Sir William Bragg, evidently a letter recommending me. And I think I heard later on that in that letter Bragg said that of all the German refugees I was the most English. And so that must have been a good recommendation.

Weiner:

Why at that time did they decide to create a chair in theoretical physics?

Ewald:

Well, I think they had all good reason to do that. There was only a chair for physics, and that meant experimental physics. And then there was a chair for mathematics, but this was the usual arrangement of chairs. And you know that the English system is to have only one professor for each subject, so I mean the fact that there was a physicist heading the big institute for experimental physics meant that theoretical physics would always be in a very minor position. And actually, when I applied, it was not for a chair; it was for a lectureship, and I was given to understand, however, that they had decided that the next chair to be created would be the one raising the lectureship into a full professorship. Now, this never happened to me, except at the end of the war, for with the beginning of the war all promotions were stopped and the appointments were frozen in, so to say. And 1 remained a lecturer on a £600 salary for the duration of the war. And only, I think, in the last year of the war, was I promoted to a readership. Then after the end of the war there came a visit from the University Grants Committee to review the whole situation in Belfast, and it made the recommendation that this should be raised to a professorship. For the last four years or so of my stay in Belfast I was finally a professor, and had a good salary, but before that I was on a rather meager salary. But it was sufficient to keep us.

Weiner:

What were things like during the war years? First, it would be good to find out when in 1939 you went to Belfast?

Ewald:

Well, I guess I went to Belfast in the spring semester of '39. This was a very nice arrangement they had made. I must say that my predecessor in Belfast was Massie, now Sir Harry Massie, a first rate man, excellent man, Australian. And he was also working in quite close contact with the experimental physicist Emelius who was working on plasma, or what we nowadays call plasma--discharge in tubes. And this was close to Massie's interests who worked on atomic collisions and the theory of plasma. So Emelius was very happy. Now, when I came, unfortuantely I was not able to take much part in his problems because I knew nothing of it. The same, by the way, was the case with Regener,who also worked on these discharge problems. And I never could get interested in it; they weren't clean enough for me; it wasn't simple enough.

Weiner:

Regener was in Stuttgart?

Ewald:

In Stuttgart. So in that way I was unlucky in not having too much contact with the experimental side of the physics in the places I was at. Well, the nice arrangement they had in Belfast was to leave Mass 's assistant, S. F. Boys, and a German refugee, Paul Weiss, in charge of the department after having appointed me, so that I could just be in the department and see how they handled it and what was going on and prepare. This was really a very wise and good idea. Paul Weiss is now here in the United States, I think with G.E. or anyway in Syracuse or thereabouts. He was a very good mathematician and physicist. And this man Boys was also very good; he is now the head of the computer department in Cambridge. Very self-made man.

Well, so I was there during the spring term and lived in the Queens Chambers, which was very nice because I came in contact with a number of my colleagues there, while the family was still in Cambridge. And then I managed to find a nice house just at the back of the university and facing the Botanic Garden. And in August, I guess, we moved over, which was a problem. You see, we hadn't the money to pay for the moving of our furniture so we had to leave part of the furniture--well, much of it was borrowed anyway and other parts we had to get rid of--hoping to get furniture at similar rates, used furniture, in Belfast. This turned out not to be the case. But on the other hand people from all sides came and offered us furniture they didn't use, through the Refugee Committee. Again we found this incredible amount of goodwill and help, this neighborhood feeling. It made us feel at home in Belfast from the first few weeks on.

Weiner:

You say Refugee Committee. Was this part of the Academic [Assistance Council]?

Ewald:

No, that was the general refugee committee, not an academic one. We are still very good friends with many of these people in the Refugee Well, as we were on the boat, crossing over, we heard over the radio that Hitler and Stalin had just concluded a pact. [Brief interruption]

Weiner:

We're resuming recording now. We messed up a small portion of the tape. We had just established that that pact was August 22, 1939, and after we established that, we took a break for a delicious luncheon and a walk in the pasture. And you were describing the boat trip from England to Belfast. On this occasion there were three of you; your son was with you.

Ewald:

You see my mother had come to join us in Cambridge when she was 79. She celebrated her 80th birthday quite soon with us in Belfast. And she had come over from Bavaria on a return flight ticket so as not to be suspicious by trying to get out of Germany. And in fact she wanted to return. She paid a visit to her friends in London and then came to us with her little folding easel and her box of paints and a little suitcase, and that was all. And then she stayed. I didn't let her return to Holzhausen because the burning down of the synagogues and all the other horrors took place in Germany and I didn't want her to be left alone in Germany when were in England, seeing the threat of war. So she was my prisoner, and we took her over to Belfast; that is to say, she came after the three others, brought over by my daughter Rose who was then on vacation in England. Rose didn't stay very long because she got a cable from Hans Bethe to take the next boat over to the States and to marry him.

Mrs. Ewald:

I mean, that was agreed before, that they would marry. But in coming over ... you see, one overlooks the situation better from America than from England, the seriousness.

Ewald:

Well, anyway she had a quite adventurous journey from Belfast to the States but arrived safely. And my son Lux got a guarantee from Hans and got his visa in time, a year later, so that he was not interned after Dunkirk, when all enemy aliens were being rounded up throughout Great Britain and being interned on the Isle of Man or overseas. And our youngest son was interned and after three months or so we heard that he had been transported to Australia, which is how he came to live in Australia. I should have been interned and I went to the Vice Chancellor of Queens (College) and asked him, "Well, what shall I do?" And he said, "Well, if they want to intern you, why don't you go and be interned, if His Majesty's Government wants it." So that was not very helpful. But Ella didn't allow my being interned, and the girls of the Refugee Committee were very worried about my being interned. I personally didn't mind the idea at all because I was pretty certain I would be returned very soon, which probably was the wrong idea.

Mrs. Ewald:

Yes, you took it too easy.

Ewald:

Yes, I would have found myself either back in Canada or Australia or sunk to the bottom of the sea, by the torpedoes.

Mrs. Ewald:

It was a very depressing state of affairs. You remember how Weissenberg suffered.

Ewald:

Well, anyway, they cooked up the excuse that I was instructing ... They said, "Theoretical physics--that's no good; nobody knows what theoretical physics is." And then Ella got the bright idea that I was instructing about 100 civil engineers and that engineers were very much needed for the war effort, and so that's how I came not to be interned. The police in Belfast were extremely helpful; they knew exactly ...

Mrs. Ewald:

And the government, too; they informed London and then it was arranged.

Ewald:

They could distinguish between refugees from Hitler and spies, whereas the British Government on the whole said, "We haven't time to bother about that; intern them all and then we're on the safe side."

Weiner:

Were many of your colleagues interned?

Ewald:

Oh, yes, many of my colleagues were interned. One of the main men who then became a kind of leader of the refugees on the Isle of Man was Weissenberg, Karl Weissenberg. You know that one of the x-ray methods is the Weissenberg goniometer.

Mrs. Ewald:

Does it matter that it really was not the Isle of Man but in this place near Liverpool?

Ewald:

Oh, it was in Hayes? In Liverpool?

Mrs. Ewald:

Yes.

Ewald:

Well, I don't know. They first were brought to Liverpool and to Hayes and then they were transported to the Isle of Man.

Weiner:

What about German scientist refugees who became involved in the war effort? When was it that ...

Ewald:

Well, you see, in order to get involved in the war effort, you had to have British nationality really. And people like Peierls and, who else was there?

Mrs. Ewald:

Born.

Ewald:

Born. Well, Born was never involved in the war effort; I think he would have refused. But Peierls was quite essential for the atomic bomb. He had acquired British nationality. But as soon as war broke out, this was stopped, and so during the whole time in Belfast we were enemy aliens. And it was only at the end of the war that I received British nationality. But this is a story which I'll tell you later in connection with the International Unions.

Weiner:

Yes. Well, then as far as your teaching duties in Belfast, you mentioned that because of your particular research interests that, although there was experimental work going on in Belfast, it wasn't the kind that you could have a close tie with. So you were relatively isolated in your field. That's fair to say, isn't it?

Ewald:

That is true, and there was no x-ray work going on. There was later a small x-ray laboratory in the Department of Chemistry. That was after Ubbelohde had become professor of chemistry in Belfast, and there was a Miss Woodward who had worked with Sir William Bragg, I believe, and who took charge of the x-ray department, but it never developed very much.

Weiner:

What about the teaching duties? Was it mostly at the undergraduate level?

Ewald:

The teaching duties were mainly at the undergraduate level--that's right. There isn't really this distinction between undergraduate and graduate level. I mean, you give special courses ... You see, the difficulty with the provincial university like Belfast is that all the good students you have get scholarships to go to Cambridge, in science. As soon as they are ready to become really useful members of a scientific society, they are taken away on their scholarship jobs to one of the big places, mainly Cambridge. And you even have to advise the students in their own interest to go to Cambridge because the provincial universities at that time--I think this may have changed by now--were really starved of the best people.

Weiner:

In terms of faculty...

Ewald:

Yes, and of graduate students and of people who wanted to obtain a higher degree and so on--postgraduate students. No, what I had to learn in Belfast, which I'd never done before, were several things: first of all, mechanics plays such a role in the education of an English physicist that I had to learn a lot of mechanics. I did that by reading these wonderful books of Horace Lamb and Ramsey--classics, really, which contain in very simple language very deep-going understanding of mechanics, dynamics mainly. Secondly, I had to learn to talk to engineers on a scale I'd not done before. And sometimes I had over 100 students in my class, and I had to learn to give them more work to practice on than is usual in Germany.

In Germany the course is mainly a course giving the lectures and showing the elegant ways of doing things, but not requiring the student to work out simple problems by himself, except in the seminar, which is at a slightly higher stage, where he really has to get down and study for himself and develop his own ideas. But in England, like here in America, too, the teaching is much more on the scale where you give many more exercises. And so I had to do that. And finally, I had to learn to set exams. This was quite new to me. Personally I'd never passed any exam, except my final school-leaving exam. It so happened that my doctoral examination was very limited; it was mainly a friendly conversation with the professors who knew me, except in mathematics where the professor knew me very well, Pringsheim, and where I would have failed according to all rules and regulations; but he came out of the room where they consulted and looked up to me and said, "Well, you know what you have done was really very poor, but if somebody has had so many suppers in my house, I don't spoil his marks."

I'd failed entirely, although I'd listened to him with the greatest of interest and greatest of joy; in fact, I'd gone to Munich in order to hear Pringsheim, and yet his method was such, so formal, that nothing stuck in me. So that was the doctoral examination. And then since I obtained the summa cum laude in my doctor's work for the thesis, I was dispensed from any further examination when I wanted to become lecturer. So actually the leaving-school examination was the only formal examination I ever sat. And now I had to give all these students these many examinations and very well-graded examinations.

Weiner:

You had an introduction with your Columbia summer experience.

Ewald:

Yes, I had that, but that was not very helpful and I didn't learn very much. No, but you see, the system in England was that you had an external examiner who was really supposed to set the exam. Then you and he marked the papers. He came over for that purpose, and they were quite helpful. Actually I usually set half the questions and he set half the questions, which I think is fairer to the student, especially if the subject of the course varies from year to year. And my external examiners were very good. The first was Sidney Chapman. It was wonderful to meet him and to work with him. And then after that I got as my external examiner, Ramsey from Magdalene College in Cambridge, who had written one of these famous textbooks, so I quite enjoyed that.

Weiner:

Now, what was the effect of the war on life in Belfast as you knew it. You mentioned there was always the threat of internment and the idea of being considered an enemy alien. What about the total picture, though, in terms of the university?

Ewald:

No, there was no feeling against us in the university whatsoever. We had very good friends in Belfast, made very good friends, and even now, on our last visit to Belfast in '59 or so, I was still greeted on the street and people held me up and asked me, "Well, how come you're here, and where did you come from?" and so on. They still recognized me and knew me, and it was really a very warm atmosphere all through. We lived in one house with a big terrace, that is to say, houses under one roof, with the entrance on Rugby Road and the back garden next to the Botanical Garden so that we saw nothing but green out of the back windows. And my mother had her little walks in the Botanical Garden in easy reach, and we had very good neighbors. In fact, several professors lived on the same terrace, and we grew very friendly, not only with the professors but also with other neighbors.

Weiner:

What about the effect of war in general on the university and on life in the city?

Ewald:

Well, of course, we were a bit cut off. There was the censorship between Belfast and the British Isles proper. The philosophy of that was that it would be impossible to draw up a tight cordon about Northern Ireland, which of course went with England, de-limiting Northern Ireland from Eire, and therefore they included Northern Ireland and Eire in the censorship for all the mail which went over to England, and there was no travel across the Irish sea, except for special missions. Towards the end of the war, I became a consultant to the Admiralty, although I was not yet naturalized, but this was very nice. It was John Todd, the mathematician, who is now in Pasadena, who arranged that--he's a Belfast man--and I went over several times and of course enjoyed that each time, especially meeting my old friends in England. I don't think I did very useful work for the Admiralty. I tried to, but they wouldn't give me their real problems, because they probably wouldn't let me look sufficiently into the problems they had. But it was a good excuse to get over and, for instance, this lecture which I gave in Oxford was given on one such occasion when I went over because of the work with the Admiralty.

Weiner:

That's the 1944 lecture ...

Ewald:

Which started the Union.

Weiner:

Right. We'll get into that very soon. What about other people in Ireland, other scientists--did you have any contact with Schroedinger?

Ewald:

Oh, yes, we had quite a lot of contact with Schroedinger. We had no difficulty in getting to Eire, just because of the censorship encompassing the whole of Ireland. And Schroedinger had several summer schools in his Institute for Advanced Physics, and these were very attractive and stimulating. Dirac came, and Heitler was there, and who else was there?

Mrs. Ewald:

Kathleen.

Ewald:

Kathleen Lonsdale and Born. And the main difficulty in one of the summer schools at least was that the food in Dublin was so much richer that they all got sick. They were starved for fats in England, and in Dublin you could get whipped cream and other things which of course they liked very much, and they all got sick on it, nearly the whole summer school.

Weiner:

Did the summer school start with Schroedinger?

Ewald:

Yes, it was his creation. The whole Institute for Advanced Studies was really formed around Schroedinger by DeValera. I see that DeValera is the latest honorary fellow of the Royal Society, which is nice. You know that he is a mathematician by training, a school master.

Weiner:

So at least in Schroedinger's case there was the development of a school of theoretical physics there. Was it because apparently they had made this kind of a commitment at Dublin. Do you know anything about the past history of it there? What led to that?

Ewald:

What led to the formation of the Institute for Advanced Studies?

Mrs. Ewald:

Should I say what I know about it?

Ewald:

Yes, you tell the story; you probably know it better.

Mrs. Ewald:

I think Annie Schroedinger said that DeValera wondered what he could do once he was no longer Prime Minister of Eire. And then he thought he could work at the Institute of Advanced Studies--that was one of the ideas.

Ewald:

No, but you see Schroedinger made a quite dramatic escape from Austria. After having been in Oxford, Schroedinger went to accept the position of professor in Graz in Austria, although we warned him that it was foolish to do it. But he did. Well, that worked quite well for one or two years. And then he was called to Vienna on some pretext, or he visited Vienna and the Minister, and mentioned that he was going somewhere abroad. And the minister said, "What? You still have your passport?' And from that Schroedinger concluded that his passport would be taken away and then he would be captive, of course, of the Nazis in Vienna. And so he rushed back to Graz, and they packed and fled over the frontier to Italy.

Mrs. Ewald:

As tourists.

Ewald:

As tourists, yes. And they arrived ... I think they had taken a ticket to Rome. Now this is a wonderful story. They arrived in Rome and didn't have a penny.

Mrs. Ewald:

But they had booked a hotel, no?

Ewald:

No, I don't think so. They couldn't, Ella, because they didn't want to make it public that they were leaving, you see.

Mrs. Ewald:

oh, yes.

Ewald:

So the first trouble arrived when the porter wanted to get money for carrying their luggage. So they had taken a taxi and told the taxi man to pay the porter. Then they took the taxi and that delivered them at the hotel where they had been living before when Schroedinger had been made a member of the Papal Academy. And so the hotel porter knew them, and they told the porter to pay the taxi. Then they asked for a room, and the hotel porter asked them, well, did they want a room with or without full board. And so they said, "Oh, yes, we want it with full board" because in that case they would get a weekly invoice. So they went up and had their room and could brush up and heave a sigh that they were out of Germany and Austria. And then they contacted Fermi, probably, I don't know. Yes, Fermi, I think. Anyway Fermi was already in the Academy and was His Excellency, the youngest in the Academy, Su 'Excellenza. And so Fermi then gave them money.

Mrs. Ewald:

And they were already in contact with DeValera.

Ewald:

And they were in contact with DeValera and they sent a telegram to DeValera, who I think was in Geneva. You know that he had two eye operations in Geneva; he had a loose retina. And then DeValera told them to come to Dublin. And somehow he had arranged this instiute already.

Mrs. Ewald:

And then, fortunately, he got the Nobel Prize so he could buy a house.

Weiner:

With the money.

Mrs. Ewald:

Yes. He said, "Never has a Nobel Prize come at a more opportune moment."

Weiner:

Oh, that's wonderful.

Ewald:

And the money from the Nobel Prize they left to the largest extent in Sweden, and that accumulated and was very useful and was mainly invested in Guinness Brewery, and they went up during the war.

Weiner:

That's a good investment. Now let me ask you how you know this?

Ewald:

Oh, from Schroedinger and from Annie, yes.

Weiner:

Did I tell you that since I saw you I found a letter in California in the Millikan Papers, Schroedinger's letter to Tolman in Cal-tech, just at the time he arrived in Dublin, telling him the situation. And I asked for a copy of it when I was in Caltech, and last week the letter came. I have a copy of that letter now. I should have brought it, and it would have been good to refer to it for some other things, but anyway it gives his reaction at the moment of arriving there. What happened as far as possible internment? Was he faced ...

Ewald:

Oh, he was in Eire; he wasn't in England. Eire was neutral.

Weiner:

Oh, that's right. You were in Northern Ireland, I see; that makes an important difference. And so your physics circle then would have been centered around him and others who had visited there. Was that the extent of it, pretty much, during that period?

Ewald:

Yes. I had a very nice assistant soon. You see Boys left and Paul Weiss stayed on for a while; but then he left--I don't know where he went. And I got a very nice assistant, James Hamilton, who is now I think back in London, but he was in Copenhagen for a while. He was in Cambridge later and he wrote a big book on nuclear structure or something. I had several quite interesting assistants in Belfast. Another one was Joe Moyal, who is in Chicago, at Argonne now.

Weiner:

Where had he come from?

Ewald:

Oh, he had come from France; by birth he's a Palestinian. He had studied in France at the école d'Electricité. I don't know how he came to England. There was another man, Mautner, who also was my assistant for a while, and he had come back from Australia from internment ...

Mrs. Ewald:

I think he was an Austrian by birth.

Ewald:

And he was a chap who was bent on group theory and really knew just group theory and nothing much else, I think. And I couldn't do very much with him. You see, if I set my questions for the students and they delivered their problems back, and if I asked him, "Well, is this solution right?" he would say, "Well, it might be right. The value would be somewhere between 3/4 and 5/8. Yes. Yes." That's about all the information I could get from him when I wanted the third decimals, so finally I sent him to Schroedinger. And he worked with Schroedinger, who I thought might be interested in this logician ... Mautner's idea was to apply group theory to logics. And after having been with Schroedinger for a year or so, he came over to America somehow.

Mrs. Ewald:

Annie said at the time that Schroedinger was enchanted and interested in the working of Mautner's mind.

Ewald:

Oh, yes, I'm sure. I mean I recognize that this was a specific ... Begabung?

Mrs. Ewald:

Gift.

Ewald:

Gift, yes. But somehow it was beyond me to advance him and to get something out of him. And besides the Vice Chancellor objected very much to his being on the campus because he always had dirty shoes and didn't cut his hair properly. Now you know that I didn't like the Vice Chancellor, but I thought that Mautner would probably have a better future if I sent him to Schroedinger, who appreciated him very much more and Schroedinger sent him to Princeton. And I've lost track of him. I think he married in America and got his shoes brushed and his hair cut and ...

Mrs. Ewald:

Already in Dublin.

Ewald:

We knew it already in Dublin, yes; Annie told us about it.

Mrs. Ewald:

You don't know about it?

Weiner:

No, I don't. How do you spell his name?

Ewald:

M a u t n e r. I think | heard once that he was at MIT, but I never checked on it. [Note: Mautner is a professor of mathematics at Johns Hopkins and teaches graduate courses in "analysis, group representations, and operator theory" there.]

Weiner:

I'll have to look that up. I think that we covered a lot of ground on Belfast, except that you were given a chair in 1946, the chair that was originally ...

Ewald:

Finally. I guess it was 1946. When was the University Grants Committee there?

Weiner:

Well, this I got from your letter to Fankuchen where you said ...

Mrs. Ewald:

I think Christmas '46. Is that possible? Christmas '45 or '46.

Ewald:

Well, you see the University Grants Committee came to visit Belfast and to give their verdict on what should be done, and one of the members of the Grants Committee was my old friend Darwin, so of course he knew who I was and I was pretty sure that that would settle the matter.

Weiner:

I'm checking here this letter you wrote from 37 Rugby Road, Belfast, on the 22 of March, 1946--this is to Fankuchen--and you made the point here that: "They have now created a chair for me, which approaches to doubling my previous pay. And they have appointed a special lecturer in the Department of Mathematics for teaching the engineering students, who formed the bulk of my large classes. As soon as I can get someone, I shall have a lecturer instead of an assistant in my department, and I shall then be in a position to enjoy life again, that is, to concentrate on my own problems and to follow up my own ideas, a thing I found impossible all these years when I had to think of the next course as soon as I had finished a lecture." Does that summarize fairly what the situation had been? That's an interesting letter.

Ewald:

Yes, I am quite interested in hearing the letter.

Weiner:

Apparently he had made an inquiry about whether you would consider moving to the U.S.

Mrs. Ewald:

Was that '47?

Weiner:

No, this is '46; this is an initial attempt, and then he renewed the attempt later. And you said in your letter--here, I'll read it because it's interesting: "You understand from this that I am looking forward to a fairly idyllic future, aware, alas, all the time that this dream may be ended by some political catastrophe. But this, I am afraid, is a thought now common to everyone everywhere. No country enjoys preference in this respect. To this country I feel strongly attached through the common experience of the war years. In the States I would have to begin over again in many respects.

I would have been only too glad to go to the States in 1936 and 1938, and it would have had the great advantage for me of having become a full-fledged and helpful citizen during the war, whereas I am here still waiting for naturalization in spite of kind attempts to get it through. However, '36 and '38 are gone and I am not really tempted to go to the States as such."

Mrs. Ewald:

And what is the date of this letter?

Weiner:

March 22, 1946.

Mrs. Ewald:

So then he got it at Christmas '46.

Ewald:

Yes, I was naturalized ...

Weiner:

But you got the chair prior ...

Mrs. Ewald:

The chair was, as far as I remember, the summer of '45.

Ewald:

It was as a result of the visit of the University Grants Committee. I must add a word that we enjoyed living in Belfast, which was wonderful as a country. It's beautiful, the green Irish hills and a penny-ha'penny ride on the tramway brought us right to the midst of beautiful hiking country. And of course we rode on our bicycles. And as soon as we were free to move about, we went to the Mourne Mountains, and I to the Sperrin Mountains and other places. It's a lovely country to live in. But we were not free to move to the coast except by special police permit--you see, as enemy aliens we were not allowed to approach the coast nearer than 14 or 15 miles, I think. And so the most beautiful parts like the Mourne Mountains were excluded from our territory except by a special permit which we once managed to get. But we had no difficulty in getting to Eire, so we took our vacation in Donegal.

Weiner:

I was going to ask you about meetings during the period in other places, but that just leads into the other story. Let's just take this now, if you think we have covered Belfast, to the point that I really introduced with this letter, that is, the transition to the United States. Now this letter represents an inquiry that he apparently had made in early 1946. And yet it wasn't until '49 that you came. But you were here on a trip. Your next trip to the U.S. was in '48, and that was probably for the International Congress at Harvard.

Mrs. Ewald:

Yes, that was the first meeting ...

Ewald:

When did my mother die?

Mrs. Ewald:

In '48 in January.

Ewald:

Yes. You see, we had my mother living, and as long as she lived, I didn't want to go away.

Mrs. Ewald:

She was very happy; she had become very much at home in Ireland.

Ewald:

Oh, yes. She had many friends. After coming to Cambridge at the age of just 79, and before her death at 88 years old, she painted 70 portraits, first in Cambridge, then in Belfast. For instance, here in the attic is probably a life-size portrait of Dirac as a young man.

Weiner:

Oh, really?

Ewald:

But probably it's all cracked and no longer in a state which can be seen.

Weiner:

I'd love to look at it.

Ewald:

Well, the trouble was that it was painted in Cambridge and with colors that were not familiar to my mother, and it has turned much yellower than it was originally. It was fairly yellow because Dirac had a kind of, what do you call that complexion?

Mrs. Ewald:

Sallow. Is sallow the word?

Weiner:

Yes. Sallow complexion, yes.

Ewald:

Sallow complexion, and it turned really yellow in the course of time--probably a restorer could replace it--and he was not very happy, and his wife didn't like the portrait so it was never given away.

Weiner:

Who were the subjects of the other portraits?

Ewald:

Oh, a lot of the professors in Belfast. I mean, the people whom Mother knew. Sometimes she picked up someone in the park whom she liked to look at and painted their portrait. My mother couldn't stand being idle, and so if she felt a bit low at her age, after a day or two she said, "Oh, I must get down to some work," and then she began painting someone. She painted quite a number, and she sold quite a large number of portraits.

Mrs. Ewald:

In Cambridge are several of her portraits. I don't know whether you know Seeley? ?

Ewald:

Sir John Seeley, the historian. What was it, Greater England, I think was one of his famous essays ... That was a generation before.

Mrs. Ewald:

That was when Paul was still a boy that she painted these. They are hanging in Cambridge colleges. [Note: St. Johns College, Christs College, Trinity Hall]

Ewald:

Yes, that's quite out of the course of this ..

Mrs. Ewald:

And she has painted Rupert Brooke, and that is hanging in one college. [Note: Kings College]

Weiner:

And she died in the early part of '48.

Ewald:

She died in '48, and that set me free in the summer of '48 to go to a meeting in Amsterdam, I think on metals, and from there to continue to Harvard to the founding meeting of the Union of Crystallography.

Weiner:

And it was on that trip--this is the part I want to cover now-- that you visited Purdue?

Ewald:

No, I came back to Belfast and then later in the year, the second or third offer of Lark-Horovitz came, to come to Purdue. And I was on the point of accepting that when a letter arrived from Fankuchen, telling me of an offer from Brooklyn.

Weiner:

Those letters are here.

Ewald:

I see. So I said I have to go and look at the places to decide. And I looked at Purdue, and it was a wonderful campus and a big institute and a very good set-up with a very potent Fuehrer heading it, Lark-Horo-witz, and very good and interesting people like Yearin and Meissner Akeley, and oh, I don't remember who. I think young Keesom was there already. And he offered me, I think, three rooms and secretaries and I don't know what, but the corridors were so wide I felt giddy, and altogether I felt I was entirely superfluous at this place, whereas Polytechnic Institute of Brooklyn was in a ramshackle old building on Livingston Street with the corridors sloping down because the building was sagging, and not an inch of room anywhere and nobody to head the Department of Physics, and they really needed someone, and so I decided on Polytechnic.

Weiner:

Also, you knew Herman Mark.

Ewald:

I knew Mark and I knew Fankuchen, although I didn't know him very well, and I at once made friends with John Dropkin who impressed me very much by his personality. And also Weber who was then head of the Electrical Engineering Department I came to know and like.

Weiner:

How do you account for the change? You were near retirement age in Belfast. The transition, I would think, would be a great one at that time. Also, it wasn't exactly a retirement position you were taking because it was the chairmanship of the department, and it wasn't quite clear that things would be easy; you'd probably have to fight for space, fight for a budget, and take on a lot of administrative chores.

Ewald:

I think I was as innocent as a new born babe. I'd never had to fight in my life, and I'd never been in an institution heading a large group of people. And when I spoke to the president, Rogers--Prexy, as he was called--I told him, "Well, you know, I've never had any experience in heading a department or in administration or so, so I don't know whether I am the right man for you." And he patted me on the shoulder and told me, "We'll give you one of these American-trained secretaries, and she'll do all the work for you. You just come along." And, of course, the great lure was that he said, "Now, look at old Reissner. He's going to be 80 next year, and he's still active here." No age limitation or anything, whereas in Belfast I would have been turned out automatically and entirely severed from the university at 65, and I didn't feel like that. So, actually I stayed active in Poly until I was 72, I believe.

Mrs. Ewald:

71, yes. And you see in England the prospect for Paul to earn any money was very small.

Ewald:

No consulting, no ...

Mrs. Ewald:

And as he was a bit on the sideline in Belfast, not in the center so much, he wouldn't be in many committees, etc. Besides he wasn't English born, so he felt there wouldn't be very much to be done except his own work and no money to be earned.

Weiner:

You feel that there were limitations on getting involved in the professional life of science in England because of a more rigid structure and more limitations on so-called outsiders?

Ewald:

Well, I think so, yes. There were strong ...

Mrs. Ewald:

Simon and Born and Peierls are very involved, of course. Simon was.

Ewald:

yes, they are of an order higher than I am in science. No, I think it is quite difficult to get into the British-born gang, on any committee or so.

Weiner:

As a matter of fact, Peierls' entry was through wartime involvement, through a specific project.

Ewald:

Yes. And Simon took the same course.

Weiner:

And Simon especially.

Ewald:

And in my particular field there was the very strong school of the two Braggs. And, well, I think even now in England nobody cares for dynamical theory, for my own creation. They are all bent on getting results and not so much on the method. It wasn't quite my style.

Weiner:

Well, that's an interesting point. Was there more of the sympathy or predilection for your type of approach in this country? Now this has do with individuals, probably, but was there more of a clustering of such individuals here than in England?

Ewald:

Well, this is hard to tell. Of course a place like the Cavendish under Bragg or the Royal Institution or Birkbeck College--or University College with Mrs. Lonsdale--they are all centers of very intense research and really are schools, and there wasn't that much here in this country. On the other hand, they were very friendly here. Soon after I came I was made president of the American Crystallographic Association--one or two years later, after a very short interval--and I had to organize a summer meeting in Tamiment then. Fan, of course, had to help me a lot. But the whole atmosphere in the Polytechnic Institute was so extremely friendly. And besides in a way it was like coming home, coming to America, because there were so many refugees, and people we knew. And I thought that New York would be a much better place for Ella to live in than Lafayette, Indiana.

Weiner:

Because of getting adjusted in the community and ...

Ewald:

Well, you see we were just standing, as Fan used to say or Mark used to say, we were placed just behind the immigration officer. Anybody who comes from Europe first visits Brooklyn Poly. We can get hold of them very easily. It is usually said Brooklyn doesn't belong to America but it's an island half way between America and Europe; in a way it's true.

Mrs. Ewald:

I personally had the good fortune to have a school friend in New York; one of my very good friends lived there.

Weiner:

Well, that must have helped. And also I guess it helped to have a daughter and son-in-law on the East Coast or close enough ...

Mrs. Ewald:

And a son in New York at that time.

Weiner:

Oh, when did he get to New York?

Ewald:

Oh, he got to New York during the war.

Mrs. Ewald:

In '40.

Weiner:

This is not Lux?

Mrs. Ewald:

This is Lux. He lived in New York at that time.

Weiner:

Who was interned?

Ewald:

The youngest.

Weiner:

Who is now in Australia, I see. Well, before we get on to the other story about the development of the international aspects, maybe it would be good to ask you to try to characterize this period at Brooklyn Poly. You had certain expectations and certain misconceptions of what it would be like when you came. How would you characterize the whole period from the time of arrival until the time of retirement?

Ewald:

Well, the first thing was that I was trying to write a book. In fact, I've been trying to do that ever since 1936, since I gave the lec- tures in Ann Arbor, and I'm still at it. I think the third edition or fourth edition is now lying in my drawer. I've never finished the book-- on Fourier transform methods in x-ray diffraction. I think I may have mentioned that I was given a secretary and that was most confusing. You see at that time there was very little room in Poly, and so I think Mark offered me hospitality in his own office. And I sat there, and the secretary was there and wanted work, and I had nothing to give her. And this upset me quite a bit. That was my first impression. But I soon overcame that, and later on I had a very nice secretary, a German-born woman, Gustava Bütow, daughter of a Prussian officer.

Well, Brooklyn Poly, I would say is an ant heap, with everything crowded together and heaps of ants crawling about, and you can't really follow the path of each one because there are too many. So in the narrow, narrow corridors of the old Poly building on Livingston Street and across Livingston Street on the other side where Fan's Lab was and Mark, it was all compressed and you never quite knew what was going on. I was lucky in that there was a strongly formed and well established undergraduate department, which was under Housman and Slack, the two authors of the famous textbook in, I don't know, its 20th edition or something. Housman I think had been professor up to my arrival and had just been made dean. No, in the first years I think Housman was still head of this whole department, and I told them, "For heavens sake, keep your department and I won't interfere at all, and do just as you like."

Mrs. Ewald:

You mean the undergraduate ...?

Ewald:

The undergraduate department. So I had no trouble there.

Weiner:

But what was your chairmanship of then?

Ewald:

Physics.

Mrs. Ewald:

The graduate school was there, too.

Weiner:

I see, but it also included ...

Ewald:

It included the undergraduate department.

Weiner:

But you left the structure intact.

Ewald:

I left the structure intact; it would have been impossible to change anything with Housman and Slack there and, well, things weren't entirely satisfactory but they couldn't be changed. Although my main aim during my active time at Poly was to reform the undergraduate teaching, I've entirely failed in that. It was so firmly set, first with Housman, then with Slack, and later with Schleuning--and it is still with Schleuning--that nothing much could be changed. I had the strong impression that it was not perfect, especially for the reason that there was no demonstration lecture for experimental physics.

Now I must add that in Germany the scheme is that there is one big lecture for experimental physics on which students who have to take physics are started. The aim of this lecture is to show all the important phenomena of physics thoroughly to the students, to demonstrate them, and to make simple measurements during the lecture; to arrange the demonstrations so that they come as close as possible to really making meaningful measurements in the demonstration lecture. Now these lectures require a big lecture room of the amphi-theatre type, so that the students can see things, and they require a lecture room which is entirely at the disposal of the professor who gives these lectures. And they require an anteroom in which the demonstrations can be prepared, and then they are brought in and built up in the auditorium.

In Germany they usually have a special mechanic attached to this service. So this is a big show. And then it depends on the professor how much he wants to extend the show and how much he wants to go into the depth and do some theory, but always very simple theory which doesn't go beyond quite simple calculus in its application. And that's the foundation in Germany, and then later on come the lectures on theoretical physics, more theoretical. But here the system was such that there was no such lecture, there were hardly any demonstrations and those which there were were quite poor and antiquated. And after one such demonstration lecture a week or even once a fortnight, the class was then split up into little sections which were handled by quite inexperienced young teachers, teaching assistants in part. And I thought that was a very, very bad system, and I still think so. But on the other hand, when I talked this over with the president or other people, there was always the difficulty, "We are hemmed in; we have no space; we can't build a lecture room."

And even when Poly moved from Livingston Street to its present location, it was not possible. We discussed that at great length, but the engineers said it is not possible to create a lecture room going through two floors so that you can have an amphitheatre and have a really good lecture room. And if you go to Poly today, you find there is not a single lecture room which fulfills the requirements. And I think they have just extended their realm to two new buildings on Johnson Street, and I asked Scheleuing whether he now had such a lecture room and he said, "No", but the room is no longer so long; it's now wide." It's a very inadequate way of dealing with physics to my mind, but I gave up this fight because it seemed quite hopeless.

Weiner:

What about the research work there? It seems to me that at Poly you were surrounded by more people in the same field than you had ever had before.

Ewald:

Yes. Well, I think this was one of the ideas in Poly, to stress certain limited fields and to really excel in these, rather than try to get an all-round physics department for which the money wouldn't have been there, nor the means.

Weiner:

You had Fankuchen and Mark and who else in the related work?

Ewald:

Well, Fankuchen, Mark, myself, Brill, Harker, Ben Post--this was really a very strong gang.

Weiner:

Did you at that period work in a collaborative way or did you still keep on with your pursuits and they with theirs but somehow it got together?

Ewald:

It got together. Well, Mark went out of this field, or had already left it. I don't think there was any significant x-ray work being done. However, Banks, for instance, in the chemistry department, did some very interesting and good work on bronzes. No, the focal point really was the physics colloquium and the special colloquium on x-ray diffraction methods. We had called the colloquium I'd inaugurated at the Cavendish Laboratory, the Space Group, and so since we had no space at Poly, Fan suggested we call our colloquium the Point Group, and this is a name under which it still goes.

Weiner:

This is characteristic of his personality to come up with that approach.

Ewald:

Do you know that Fan and I started a book-selling business?

Weiner:

No, I had no idea.

Ewald:

A book store.

Weiner:

A real, commercial enterprise?

Ewald:

Well, yes. You see, there was a certain difficulty in obtaining crystallographic literature from the usual book shops who took very long, and books had to be ordered from Belgium or from Holland or from God knows where, from France. So, seeing this difficulty, Fan and I decided and Mark also joined at first--to put up some money and to start a book service. And we called it, on the suggestion of Doris Cattell, the Polycrystal Book Service. And we got subscriptions to journals of the Union, to Acta , and other publications of the Union, which were otherwise very hard to get hold of, and took all kinds of crystallographic literature concentrated at the Polycrystal Book Shop, and the ACA members were informed of that and got the list of new books, etc., and it worked very well.

Weiner:

Did you have an office for this?

Ewald:

No, it was all done on the desk of Doris, who is an excellent worker and kept everything apart and could do things very, very quickly. She is a very fast worker. And later on, I think Mark never paid in his dues or perhaps he was paid out, and then later on I wanted to get rid of it because I no longer had so very intimate contact with it, and Doris Cattell took over r my $300 worth of investment in this book service.

Weiner:

Does it still exist?

Ewald:

It still exists, but now people in Pittsburgh--I forget their name--have taken over. [Note: Mrs. W. L. Kehl] Doris wanted to get rid of it; she had done enough. But we still order our books through the Polycrystal Book Service, and you'll find the Polycrystal Book Service mentioned on the inner side of Acta as one of the places where you can subscribe.

Weiner:

That I think gets to this other story I'd like to get into now about the international aspects. Do you want to take a break first?

Ewald:

Yes, I think a break would be good. [Brief interruption]

Weiner:

We just agreed that we are refreshed and are resuming.

Ewald:

So you want me to start on my experience with international communications between scientists and especially the International Union?

Weiner:

Yes. We talked of the 1925 conference, which in a sense was the beginning of some private international efforts. Then in 1927 there was a conference involving the editors of journals in crystallography.

Ewald:

That was Niggli and Laue and Fajans and myself. Was that the conference in Constance, on the Lake of Constance?

Weiner:

Yes.

Ewald:

Well, I think it was on that occasion that I suggested we should internationalize the Zeitschrift fur Krystallographie by accepting articles in English and French, as well as in German. Up to then under Groth's regime and also in the beginning years under Niggli's regime all manuscripts which came in in English or French were translated and published in German. And I thought this was really not necessary, so I suggested this internationalization, and the other editors agreed to it very willingly. And the publisher, Jacobi, who was also at the conference, agreed to it. And then we started accepting these papers in their original languages. I think that's all I remember of that particular conference. There may have been technical details concerning the Zeitschrift but they are of no importance.

Weiner:

But then in 1929 when you attended the Faraday conference in London, you and Bernal started a project that ultimately worked out into an international undertaking with permanent repercussions.

Ewald:

Well, at this conference in London I think we had several--we formed two commissions, just private commissions. One was with the idea of creating an abstracting scheme for structural determinations which could be published running in the Zeitschrift fur Krystallographie; these abstracts were to be dealt with in a strict format so that no text was necessary. The format would be something like name of the crystal, chemi- cal formula, mode of preparation, density, etc.,

and then optical properties or what not, and then the X-ray methods which had been used and the results. Well, I worked quite intensively on that scheme, and I guess Bernal did, too, and finally it came to a manuscript which Bernal sent me shortly before some vacation, I think Easter vacation, which my family and I took in Arosa. And I remember that these vacations were more or less spoiled by working on this abstracting scheme.

Mrs. Ewald:

I don't remember that we were ever in the spring in Arosa together.

Ewald:

Well, I may be wrong in that, but anyway I remember that I spent several vacations with the Schroedingers in Arosa. Schroedinger had a kind of infection of his lungs or something and had to go up to Arosa repeatedly. I mean, from Zurich, this was a very small journey. And they quite often invited me to join them, so we were up there. Anyway we worked quite hard on this scheme and finally, in trying to apply it, I found that it was impossible, and one couldn't do it, and that's that, and I think it led to a report which is somewhere hidden in the Zeitschrift fur Krystallographie, about our work. So that's this one committee. And the other thing we achieved was the creation of the Tabellen- komité, a Tables Committee. And this was with the intention of creating international tables, what finally appeared as the International Tables for the Determination of Crystal Structures. Now this is a story by itself, which by the way I have documented more or less in ...

Weiner:

In this article.

Ewald:

No, that's an article on the structure of faults, isn't it?

Weiner:

No. This is ...

Ewald:

Well, I don't know in which. But I'm pretty sure I put that down somewhere.

Weiner:

Well, in two places, I think: at the end of the 50 Years...

Ewald:

Well, that's quite short.

Weiner:

That sort of a summary of all these developments. And then I think you covered the tables in this article in Physics Today in December of '53.

Ewald:

Well, that may well be.

Weiner:

Well, anyway, it's only about a page that you devote to it. You talk about what the different problems were in the tables and how these had to be reconciled. For example you mention a questionnaire that you and Bernal had circulated prior to the 1930 meeting.

Ewald:

No, but what I'd really like to talk about is my experiences with the Unions, and if you agree I'll get down to that. I told you before that Hermann, who was my main helper in all these things, was first paid by the Elektrophysikausschuss der Notgemein- schaft and then he was paid by the Zeitschrift publishers, and that was quite a heavy load on the Zeitschrift and made the Zeitschrift quite expensive. And since all over the world people complained about the high price of the Zeitschrift, I was very keen to get this payment off the account of the Zeitschrift. So when I was in London, I asked Sir William Bragg whether the International Union of Physics wouldn't be of some help in creating ... I think it was then already that Hermann turned mainly to the international tables. I'm not sure about that.

It might have been for the Strukturbericht also. Sir William Bragg at the time was president of the Union of Physics. Now this Union of Physics, as you may know better than I, sprang up after the First World War from the desire to continue the Conseil de Recherches of the war allies. And under the French influence, especially Poincaré, the Central Powers were excluded from the Union--no admittance of Germans. The Union of Physics didn't do anything. And Sir William Bragg explained to me, "Well, we are waiting for the Germans to enter the Union. We don't do anything as long as they are excluded." The difference between the Conseil de Recherches and the later Unions and the ICSU is that the Conseil de Recherches, springing out of a military organization, was the commanding general for the scientists. They decided what was to be done, and they gave the orders. And it was due mainly to H.A. Lorentz that this was changed very gradually into a Union where the unions were their own masters and where they were united under a head organization which was the International Council of [Scientific] Unions, ICSU.

But each Union was independent and was master and had not to accept any commands. So this happened slowly. Then there was a period of great misunderstanding between the Union of Physics in particular and the Deutsche Physikalische Gesellschaft, which represented German physics, because any time when the Union of Physics made advances to the Germans, the Deutsche Physikalische Gesellschaft and later also the brother society, Gesellschaft fuer Technische Physik, made counter demands, let's say of accepting German as an equal language. I don't know what it was in detail.

So there was a constant phase difference between the two approaches, which by the way was characteristic also in German politics at the time. Every time the general feeling in England was pro-German, let's say when the Oxford group of students debated and said: this house will not fight for King and Country--what was the exact term I don't remember--then the German students were particularly rigid in their nationalistic attitudes, and vice versa. And with France also.

It was a fatal phase difference between the countries, and this, in the case of the Unions--the Physics Union, I should say; other unions didn't fare quite so badly--worked out that finally when the Germans were willing to join and the British had arranged everything, then Hitler came up, and now the British became reluctant to admit the Germans. So this maimed the Union of Physics. The Union of Physics had never done much, but I always claim that the one thing they did was to pay for Hermann's work. And so I felt really very much in debt to the Union. After visiting Bragg, I went to the Secretary of the Union, Abraham, in Paris, and he was very kind and in this way, by personal contact, I arranged for the pay of Hermann to come from the Union for I don't know how long.

Well, now I jump to--make a big jump--1944 or '45, I guess, where I was in Belfast and I suddenly received a letter from Manne Siegbahn.

Mrs. Ewald:

I think that was in '46.

Ewald:

Well, '46, yes, quite likely '46. I received a letter from Manne Siegbahn, asking me to become the Secretary General of the Union of Physics. And, as I told you before, I was not yet a naturalized Briton; I was still an enemy alien in Britain, but I felt very proud that this was offered to me and I felt under a kind of obligation to the Union because I was, as far as I know, the only man who had really gotten something out of the Union. Oh, I should say that the 1934 conference in London probably was also one of the undertakings of the Union of Physics, this international conference which Bragg had called, so it is not quite true that Hermann's pay was the only action of the Union. Later on I heard that this letter from Siegbahn had been written after a visit which Kramers had paid to him in Stockholm, so Kramers may have been the originator of this idea, although I really didn't know Kramers very well; I knew Siegbahn better. Well, so I undertook this task, and the Union was, according to Siegbahn's description, in a state of absolute dissolution. Most of the members of the committee had either died or had been murdered by the Germans, like Abraham.

Weiner:

Did he die in a concentration camp, or what?

Ewald:

Oh, he was taken away, and I don't know what happened to him.

Weiner:

I see 1943 given as the year he died in a concentration camp.

Ewald:

Well, that's quite likely. Did I write that?

Weiner:

No, this is an article written by someone in Australia, which gives the history of it, a man by the name of Boas.

Ewald:

Oh, walter Boas.

Weiner:

And they said, "Abraham, until his death in a concentration camp in 1943 ..."

Ewald:

Well, so I thought the only thing I could o was to call for an assembly of the Union, of the executive committee of the Union, and I arranged all that, writing from Belfast, inviting the people who had either been active as members of the Union or who seemed to have taken interest in it. And we arranged to meet in Paris in the last days of December of '46. Now my personal difficulty was that I had to get a passport. The French wouldn't let me come to their country without a valid passport, and so I had to press my naturalization through, and with the help of the local authorities in Belfast this was achieved. I had to go the Foreign Office in London on Boxing Day, 1946, where there would be a special man to make me sign the passport and hand out the passport to me. And the next day I was in Paris and tried to arrange things there for this conference.

I don't quite remember where the conference took place, whether this was in the College de France or in the Sorbonne--probably in the Sorbonne. Ma - guin probably arranged for the meeting in the Sorbonne. Now on the way out or before the conference, I had a long talk with Darwin, who was the English representative. And Darwin was of the opinion that one should give up this useless Union of Physics anyway, and we would have to put the question whether there was any point in keeping the Union alive at all.

And this was the general feeling; it was very dubious whether this Union was worth keeping in existence. I don't quite know what was the status of the other unions at the time, but certainly some of them--for instance, the Union of Chemistry, and of course the Union of Astronomy--had been very active, including the Central Powers, before the war. But as I say, the Union of Physics had never become active. So the idea was it was not really much use. Well, in France it was really very exciting for me. There were heaps of old French professors - I don't remember exactly who they all were. Siegbahn, of course, was there as the president, and there was the treasurer of the Union who was a professor from the big magnet, Bellevue, and Mauguin from crystallography whom I knew well ...

Mrs. Ewald:

Was Fleury already there?

Ewald:

Fleury--I'm not sure whether he was there or not. I don't know; I have no very clear recollection of the proceedings. The only thing I remember was that Siegbahn was of very little use. He didn't speak. He is a very taciturn man, and he didn't like to take any decisions, so I had to sit next to Siegbahn all the time and prompt him whenever there was to be a vote or anything requiring a vote. And there was no interpreter, with the result that I first made an exposé in English, and then I tried to give the same material in French, but I never succeeded because I can't translate, and I gave entirely different arguments in French and in English, as far as I remember. They may not have been too different; I mean I didn't do it purposely; I just couldn't help it. There are some people who can repeat an argument beautifully, but I'm not of that type. So I invented new arguments. It was really quite amusing, and we made progress. And now at the time there was already the idea in the air that crystallographers should forma Union of Crystallography. And so I tried to get rid of being General Secretary of the Union of Physics. And somebody I guess proposed Fleury as the coming Secretary, and I was very happy to find someone who would take over, and the whole thing was handed over to Fleury.

Weiner:

You were Secretary of the Union of Physics until '48, weren't you? From '46 through '48?

Mrs. Ewald:

Yes, Paul, that's quite probable that you forgot. I feel, too, that you didn't give it up immediately.

Weiner:

See, there are two things here that were left ...

Ewald:

Of course in '48 we founded the Union of Crystallography.

Mrs. Ewald:

Then you gave up the other.

Ewald:

Didn't I give it up previously?

Mrs. Ewald:

I don't think so.

Weiner:

We are going to verify all these dates.

Ewald:

Oh, I can't keep track of these historians checking all the dates.

Weiner:

A little green book in this case. The green book has it.

Ewald:

What's the green book?

Weiner:

The green book is the International Union of Pure and Applied Physics General Information. Well, Fleury took over in '47, it says here.

Ewald:

That's more likely.

Mrs. Ewald:

Is Paul's name there at the beginning?

Weiner:

They don't have him listed at all. They have Abraham from '22 to '43, then Fleury from '47 to '63.

Ewald:

Yes, that what I always thought. They just ... It was me really who revived the whole Union.

Weiner:

But here in this article written by the physics man in Australia, he said, "The Secretary General, Professor P. P. Ewald ..." This was at a meeting in Paris in January 1947 at the General Assembly; he refers to you as Secretary General at that time. What I gather is that for at least a year, from the time you accepted it from Siegbahn in '46 until this meeting in '47 you were Secretary General.

Ewald:

Well, from let's say the summer or spring of '46. And then I went to pay Siegbahn a visit in Sweden--that was my first outing from Great Britain after the war; it was a marvelous experience, seeing shops full of goods, for instance, and seeing Stockholm for the first time, which is also an event. And then in late December after Christmas we started this meeting, and it lasted until the first days of January and then Fleury took over. I think that's the sequence. So actually I was Secretary for three-quarters of a year or so.

Mrs. Ewald:

Yes, and I think Fleury has always suppressed that ...

Ewald:

Yes, Fleury has always neglected that period before he came. Well, it was a very exciting experience, trying to get these old gents and these, you know, formal French professors, very strict and formal, and trying to deal with them. I was always afraid of them, all my life, of this formality, but I think I managed quite well, and anyway the thing got going again. And I would have quite liked to continue except for the fact that ... You see, we hadn't fully decided yet--or that was my view of it--in England. We had had this conference in '46 which prepared the International Union, and it had not been quite decided whether we wanted a separate Union or whether we wanted to become part of the Union of Physics. Whether this view is quite correct, I don't know, but this was my impression of the proceedings. And so if they had decided in England to form part of the Union of Physics, I would have remained as Secretary General of that Union. But on the other hand if it was to be a separate Union, I wanted to be free for that.

Weiner:

The point that Boas makes in this article is this: He said, "At the General Assembly in Paris in January 1947 the creation of two new international unions was discussed. One was Pure and Applied Mechanics, and the other was Crystallography. On the one hand the separation of physics, mechanics and crystallography was deplored, and a framework within the Union of Physics thought possible whereby the importance of these disciplines could be done justice. However, the Secretary General, Professor P. P. Ewald, pointed out that those disciplines also have strong bonds to other disciplines, for example, mathematics and astronomy, and their activities could easily dominate the parent Union."* And then he goes on, "And apparently this was the view that carried the day." He doesn't say that it was approved but ...

Ewald:

This was not the view in the Union of Physics, but it was the view of the crystallographers, that they had really closer--or at least as close-- ties to the Union of Chemistry than to the Union of Physics.

Weiner:

I see.

Mrs. Ewald:

What was it for astronomy?

Ewald:

Well, mathematics and astronomy go together.

Weiner:

Mechanics, anyway.

Ewald:

Mechanics and astronomy. But the Union of Physics, you see, the main feeling of these people who had grown up with the Union that the Union should be something which embodied all these different branches, so there were enormous fields: one was physics, one was chemistry, one was the entire field of biology, which by now is split up into I don't know how many, five or six, unions.

Weiner:

But you had started in 1944 with the x-ray analysis group in England, which had been established as part of the Institute of Physics, to make a plea for an international organization of crystallography. And this is the thing that you describe in your article in Physics Today.

Ewald:

Yes.

Weiner:

The plea was published in Nature in 1944. In March 1944 was the evening lecture at Oxford, the meeting of the x-ray analysis group, and it was then that you made a plea for the formation of an International Union.

Ewald:

That's right. Bragg asked me to give an historical survey, and I made the first part historical, showing some old slides and so on, for instance, of the Holzhausen conference, and the second part, making a plea and giving a program of what the Union could do. And one of the main points was that the Union should have its own journal, so that the Jour- nal of Crystallography should not be in the hands of private publishing interests.

*[Note from Dr.Ewald:

I haven't got the Boas article, but the acceptance of new Unions is up to ICSU. So probably Boas is talking of an ICSU Assembly, in that case the General Secretary would have been Stratton. Mechanics has strong bonds to Mathematics and Astronomy; Crystallography would have strongest bonds to Physics and Chemistry and some to Mathematics. The bond to Biology was still quite weak in 1948.]

Weiner:

There is another point here, too, that the result of this meeting was that Bragg took it up--I imagine it was the younger Bragg at that time, wasn't it?

Ewald:

Yes, that's right.

Weiner:

The younger Bragg took it up and arranged the International Conference of Crystallographers in ...

Ewald:

'46.

Weiner:

In '46 in London. And then you refer here to an earlier one in 1934 which the Union of Physics sponsored. That was the time we were looking for before.

Ewald:

Yes, that was the time when Bragg was president of the Union of Physics.

Weiner:

Right. And anyway the meeting in 1946 occurred in London but there was also a meeting in Paris of the International Union of Physics.

Ewald:

But at different times. The Paris meeting was quite at the end of '46, and the meeting in London was during the summer sometime, I guess, because the Americans had to come over.

Weiner:

I see. So, now I think I have the chronology straight.

Ewald:

Oh, yes, this is quite true, it was in the summer because I took a number of Americans to Kew Gardens and we had a very nice excursion and lay on the lawn, so it must have been summer.

Weiner:

And so the International Conference of the Crystallographers had decided to see about the possibility of forming an international Union of Crystallography and so by the time the International Union of Physics met, this was a request from the ...

Ewald:

This had already been discussed yes.

Weiner:

Yes, I see, and the crystallographers had agreed that they wanted a separate union?

Ewald:

My impression is that that was left open. But I'm not quite certain about it, this may have been a misunderstanding on my part.

Weiner:

I get the feeling that it was left open to see whether it would be accommodated under the umbrella of the larger Union of Physics or ...

Ewald:

You see at this meeting of the International Union of Physics in Paris there was another strong group who objected to being swallowed up by the Union of Physics. These formed the Société d'0ptique in France, of which Fleury was the main man, and so it was decided that we would have special commissions--I think we used the term "grandes commissions"-- besides the ordinary, smaller commissions. There were these grandes commissions who had a kind of autonomy and who, especially, I think, collected their own means, their own funds. And the opticians were taken into the union as one of these grandes commissions, and of course this pleased Fleury very much because he was made the secretary of the whole affair.

Weiner:

Well, why wouldn't that approach have been adequate for crystallography?

Ewald:

Because crystallography was just as much tied to chemistry, and nowadays I would even say also to biology, but in those days just to chemistry. You see, the fact is that after Laue's discovery, the x-ray diffraction work in Germany remained purely theoretical and on the physics side. And the chemists, who had no mathematical training in Germany, didn't accept the new methods at all. Whereas in England the investigation of solid state matter very soon came into the hands of chemists, and in America also, where there were chemists like Wyckoff and Pauling and Dickinson and a number of early investigators, all trained in chemistry. And there the whole thing flourished, because the chemists really knew what problems to put, whereas the German chemists couldn't be interested in it.

Weiner:

And in the post World War II period, this desire for internationalization--you've discussed this but it's not clear to me: whether this was just the postponement of something that had been in the air but had not been possible for the prior 15 years because of Hitler and because of the war, or whether something new had occurred in the state of the field where it was just absolutely necessary to do this.

Ewald:

I think that people took a warning from the example of the post-World War I years where the exclusion of the Germans was the rule, and they were keen not to fall into that same mistake again.

Weiner:

Well, how was that problem handled? Here it's 1946 and you and other people still had travel problems. Was there any resistance to including the Germans in the new international union?

Ewald:

I can't tell you about 1946 but I can ... Oh, yes, '46 of course, at this conference which Bragg called. This, you see, was on the personal initiative of Bragg. He was prompted by the x-ray analysis group, and I remember meeting several times with Bragg and this group and discussing what we were going to do regarding this conference and what program there would be and what our aims would be, etc. But then the response was excellent. There came a strong party of representatives from the United States, there came the Frenchmen, Belgians, Dutchmen, and there came Laue, who was specially invited by Bragg to come. He was the only German to come, and there was no Austrian, and I don't believe there was an Italian.

Weiner:

And the Russians came, but they came late.

Ewald:

The Russians came but they were late, yes. That was quite usual in those days.

Weiner:

Was that because of red tape at home, indecision?

Ewald:

Well, nobody knows. Finally they came. They said they'd been held up in Berlin or I don't know where. Anyway they came just in time for some after-conference conferences in Cambridge where we discussed the details of the new journal. And one quite critical moment was at the banquet where Bragg spoke, of course, and then Laue was invited by Bragg to say a few words. And Laue spoke in German, and you know that Laue was quite hard to understand in German because he had no very clear diction, but that was very good, however, on that occasion because Laue said some things which were quite innocuous and okay, but at that time you couldn't Ewald - 88 hear that. He thanked Bragg and he said Bragg had spoken in such laudatory terms about him and also about his attitude during the Hitler regime. "But I can assure you," he said in German, "beside me there were tens of thousands of Germans who deserve that praise as much." And I saw, well, how people on all sides got restless, and so I got up and broke that spell by telling a silly story.

The silly story is quite worth telling, though. The silly story is quite true, that in one of the pre-assembly meetings we had discussed ... Well, Bragg always said, "Well, couldn't we give a name to this whole piece of research of investigating solid structure with x-rays? I always feel the name of "atomic architecture" would be a good name." And so that didn't please some, so finally I went back to a name which had been given to this field by a German crystallographer, Rinne in Leipzig, who had written a number of semi-popular books on this subject, and he had called it "Leptologie." Leptos is the Greek word for "fine" and so this is, as Rinne thought, a rendering of fine structure of matter. Well, I suggested it just to see how it would be accepted, whether it would be accepted at all, not really in great seriousness. And they turned it down and said, "No, that's no word."

Then I came home to Belfast and when I came from the boat in the evening, there was a lecturer on archeology, Oliver Davies, at our home, and so I told him what I had seen and heard in London. And I finally told him that also. And Oliver Davies had a wide grin on his face and said, "Do you know what leptologia in Greek means? It means 'talking windy stuff.'" So that was a narrow escape. So I told that story and said, "Well, we should be solid statesmen, that's a better name." And that broke the spell.

But after the dinner, several people both Dutchmen and Belgians, and the French also, came to me and said that, had they only understood what Laue was saying, they would have left the place. They couldn't stand to hear that there were decent Germans, decent people among the Germans.

Weiner:

When was this? Early '46, would you say?

Ewald:

This was probably the summer of '46.

Weiner:

Oh, this was the summer crystallographers' meeting, right. Now this whole move for the internationalization, you said, was due to the feeling of trying to avoid what had happened after the First World War by leaving the Germans out. And yet you said that the sentiment here was still very much, as one would expect, anti-German. So I don't understand how that could be the sentiment and yet be the motivation for the international group--do you see what I mean?

Ewald:

Well actually, the Germans didn't play a very prominent role in the union at first. At the Harvard meeting there appeared Laue and Hermann, and both were known to have been violently anti-Nazi.

Weiner:

Was there difficulty with travel restrictions? Getting the travel visas from East Germany and so forth, or was this at a much later period that this occurred?

Ewald:

Well, they were not from East Germany. Laue came from Goettingen, and Hermann from I don't know where he was [at Mrs. Ewald's prompting] ... probably from Marburg. I don't know if he was already in Marburg. So that matter didn't come up.

Weiner:

Perhaps I'm thinking of some later travel difficulties that I heard of ...

Ewald:

Oh, that was much later, yes.

Weiner:

'50, 60s then?

Ewald:

Yes, especially after the wall went up.

Weiner:

Yes, I'm confusing the periods. It seems that the significant difference in the International Unions in the post-War II period was the foundation of UNESCO and the tie-in with UNESCO, because this provided a source of funds.

Ewald:

UNESCO provided a source of funds, yes.

Weiner:

And it seems to me that this is half the battle when you can tie in ...

Ewald:

That certainly made it easier to start the union, very much easier, and that was largely, I think, Auger, who was then the secretary of the Science Department of UNESCO.

Weiner:

We had talked about the origins of the International Union of Crystallography and your involvement as Secretary General for the period in 1946 up to about the beginning of '47. And apparently that discussion about the formation of separate groups was resolved. The actual meeting of the First International Congress of the Crystallographers Union didn't occur until '48 and that was at Harvard. And then the journal itself didn't get started until '48, but decision on the journal had been made several years before, hadn't it? I wanted to know why the delay in getting rolling.

Ewald:

Well, if you want to start a journal, it takes some time to get it started. First of all, the decision had to be brought back to America and to the other countries, and other people had to agree. Secondly, we had to get the Union of Crystallography organized and accepted, that is to say, we had to draw up statutes and we had to submit the statutes to ICSU, and ICSU had to accept them so they had to have a meeting and accept the Union.. And, as you know, some of the bigger Unions were

very reluctant to accept smaller Unions, specialized Unions. But luckily at the time the General Secretary of ICSU was still Stratton, the astronomer from Cambridge, who was an old friend of mine, and also of Robert Evans. Robert Evans in Cambridge, who is a crystallographer and x-ray man, played a large role in the setting up of the Union, and he and I together worked out the statutes, and we had much contact with Stratton. Stratton was a remarkable man, a really charming character--a good sketch of Stratton is contained in the Biographical Memoirs of the Royal Society. He did all this enormous amount of work just in writing with his little hand, and he had everything in his head; he never kept duplicates of his correspondence-- the true English way. Well, so that took some time, getting the Union acknowledged. And then it was quite difficult to find a publisher for the journal.

Oh, by the way, I should mention that we didn't decide finally to start this new journal until we had ascertained from Laue that the old Zeitschrift fuer Kristallographie was not likely to be revived in any foreseeable time. And actually this was quite true because the Zeitschrift was the property of the Akademische Verlags Gesellschaft, which had had its house in Leipzig and had first to found a branch in Frankfurt--of course they had emigrated to the States here; what was it called?--The Academic Press--and then there came a lawsuit between the two houses. You see, one was in East Germany, and the other in West Germany, and that had to be decided, and well, altogether they finally divided up their claims and came to an arrangement. But all that led to the fact that the next issue of the Zeitschrift fuer Krystallographie--which I think was the second issue of Volume 105 or something,the first one having appeared just at the out- break of the war--and the next issue in that same volume was about eight years later.

So I think Laue was quite justified in telling us that in the immediate future there was no chance of the Zeitschrift's being reinstated. On the other hand, there was the great wealth of material that had been collected during the war years and which was crying out for publication. And so we had good hopes that we would get sufficient material for the new journal. But then it was quite difficult to find a publisher. We approached many British firms and other firms, too; we wrote to Sweden and to Holland and to Denmark, to France. We got sample layouts and pages and a way to compare all these prices. Well, finally although they were not the cheapest, it seemed the most convenient and safe thing to trust the

publication to the Cambridge University Press, one of the reasons being that Evans had his office across from the press rooms--he was the British and technical editor--and could keep close contact with them and had them on the telephone every moment. Well, this went all right, so we started with the January number of '48, and by the time of the first assembly at Harvard, we had already two or three numbers out. I was very happy ... Well, I had been made the editor of the Acta; I had not been too keen on that, but there was a universal claim that I should take over the editing, and I did after some reluctance on my part, and I'm not sorry that I did it. The others were called only co-editors; I would have called all of us editors but ...

Weiner:

They were distributed internationally so that there would be representation.

Ewald:

Yes. Fankuchen was the American editor, and Wyart--Mauguin didn't want to do it--became the French editor, and who else was there? Evans was the British editor. I think that's the lot.

Weiner:

How did you handle the refereeing situation?

Ewald:

Oh, very laxly. I don't like the refereeing system, and so I accepted a great number of papers on my own, and especially the first one, which I was very happy to get. I received the manuscript about a year in advance of the publication of the first number, and it came from a man who had been more or less exiled from Spain by Franco, Garrido, who was then probably in Mexico. And I was delighted to get a paper which was anti-Franco, and I accepted it--and it's all wrong. So it opened up with a wonderful paper which was all wrong, because of my dislike of the refereeing system. It was wrong even on questions of symmetry, which I should really have seen.

Weiner:

What is your objection to the refereeing system?

Ewald:

Well, I think it gives a much more personal touch if the edit- ing is done by somebody who has a certain responsibility and doesn't shove off the responsibility on other shoulders. The editor gets the credit for the excellence of a journal, if it is so, and not the referees. The referees have to do the dirty work and don't get any kudos.

Weiner:

What if an article is in a field which is out of the specialty of the editor?

Ewald:

Well, the editor should be capable of seeing whether this article is: a) entirely mad--then he should reject it; or b) whether it is clearly presented, logical, and with sufficient explanation that one can understand it by sitting down and studying it, and that an editor can do even if he doesn't understand the subject. It's a different aspect. You see, Laue always said, "The editor is not responsible for the contents; only for the form of the paper. The contents are the author's responsibility." And I think there is very much in that. He said, "It is much worse if one good paper is refused because the editor or referee rejects it than if a bad paper is accepted now and then." That's the minor misfortune. So I'm still not terribly impressed by the refereeing system. Seeing how referees among themselves disagree on the evaluation. I was recently in Watertown and spoke to Dave Shoemaker who told me of a paper where I think he had asked five referees and had received five entirely different reports.

Weiner:

This would be especially complicated if a journal covers a number of specialties.

Ewald:

Yes.

Weiner:

It's easier I think to maintain the personality of a journal and an editorship if the field is well defined, as crystallography has been. I mean, Acta still would fit into a well defined field.

Ewald:

Yes.

Weiner:

Well , It's getting late and our half day has stretched. I have a few final, summary-type questions to ask which will not take very long, but are there also major events and developments of interest in the international aspects which we haven't touched on?

Ewald:

Let me add just a few words about the Acta. Acta grew quite quickly in volume, and the Cambridge Press had not sufficient means to publish more pages than they had agreed to. I think they made a concession in the third year of publishing about 10% more, but we were bursting out of the seams with manuscripts coming in.

And so we had to look for another publisher. And we looked all through England, but there was no publisher available who would undertake the work. The reason why the Cambridge Press couldn't publish more was not so much the lack of paper but the lack of compositors. The compositors are a very close-knit trade union, and they won't accept more than a quite limited number of apprentices each year. And the whole setting of Acta in the Cambridge University Press was done by one old master, and he was pretty occupied with it. And that's why they couldn't go any farther. I think this is very characteristic of the state of affairs in England.

And after the Stockholm assembly of the Union, I went to Denmark and asked a firm from whom we had received one of the original offers and who had made a very attractive offer, though we had preferred finally for these reasons that I gave you to have it done in Cambridge. And went to Munksgaard and found that the head of the firm was a lady who had the whole people of the firm like marionettes at her fingertips. And told her our problem, and she said, "If you want to publish more, we can publish more." And I said, "Well, we don't want the change to be visible. Can you use exactly the same type?" The Cambridge Press was always very proud of their particular type.

So she called another young man and said, "Have you got that type?" "Yes, Madam, we have that type. No difficulty." "Can you handle that and that problem, (figures and I don't know what, or half-tone figures)?" "No problem." No problem anywhere, so we gave the production to Munksgaard.

Weiner:

And that's where it remains.

Ewald:

That's where it still is. The nice and beautiful lady has left Munksgaard, was bought out. Well, she was over here in America with her husband; somehow there was some intrigue, and when she came back, somebody else took over. But it doesn't matter. And now I think I see that Acta is being handled by Munksgaard but is being printed just across the border in Germany, it seems to me but I'm not quite certain of that, but the imprint on the Acta and the stamps--I think it's sent from Germany.

Weiner:

How has the publication increased in size? The reason I ask that is to get an idea of the relative growth of the field itself.

Ewald:

Well, let's say the original volume, the first volume, was perhaps 500 pages; it grew in the next years to 800, 1200 pages; and I think now it's about 2,000. Acta has just been split into two parts, A & B, the one part dealing more with chemical problems and one part dealing more with physics problems. And we don't know yet how much material for the physics part will be received. It's now quite a formidable journal. Horrid. Like most journals, they grow too fast; you can't keep pace.

Weiner:

Well, the field itself grew.

Ewald:

And you see with the development of the computer system and the automatic gathering of data, all regulated by computers nowadays, the work grows exponentially.

Weiner:

The automation of research.

Ewald:

The automation of research. And this is a job which lends itself very well to automation, so it's not to be forecast what will happen.

*Acta 1948 Vol. I 344 pages 1957 Vol. X 866 pages 1967 Vol. XII,XIII 2076 pages 1968 Vol. XXIV A & B 2364 pages

Weiner:

Let me get you back to yourself now and ask you to think about your research work and to see if you can identify the theme of your work, whether it has been a consistant theme, and whether your approach to problems and research has been ... how you can describe your approach to physics, let us say.

Ewald:

Well, the research work that interested me and still interests me is my thesis, which I have been developing gradually into this dynamical theory of x-ray diffraction. If you see my latest papers of '68, that is still absolutely in the same style because I always feel that the problem is not yet fully worked out and solved. So, if you want to know, my only claim to posterity is to have inaugurated this dynamical theory, which then has spread to electron diffraction, to neutron diffraction and to other applications which are very closely related mathematically to the problems in x-rays.

Weiner:

How would you describe your approach to physics? There are many people who work in physics and they have different interests, different approaches to solving problems, and they're interested perhaps in different kinds of phenomena or different kinds of questions. Can you ... ?

Ewald:

My approach to physics? Well, looking back on my own life, I feel a very regrettable lack, or urge, to enter into what you should call really fundamental problems of physics, that is to say, both the philosophy of physics like, let's say, what Bridgman felt an urge to do; or the problems of my time. You see, I've followed these problems, but getting farther and farther away as my age grew. I did not take much part in the development of relativity theory or of quantum mechanics and wave mechanics--I never worked actively in these fields. I tried to follow them as far as I could, but the work in crystallography really had precedence, so in a way I'm astonished myself that I, who always thought of myself as being fairly generally educated in physics and science, actually worked on a very restricted field. My interest in science is still very much alive. But it manifests itself in reading the Scientific Ameri can, every number from cover to cover, or very nearly so.

Weiner:

And that covers a lot of fields.

Ewald:

It covers a lot of fields, but it's a kind of dilettante's approach, not that of somebody who wants to achieve results.

Weiner:

And yet, as you developed new approaches in your work, it was applicable in a number of ways to other problems in the structure of solids, and these techniques were used by people who may not have been pursuing your theme, may not have been pursuing dynamical theory but using the results, reciprocal lattices, were using the different things with the adjective Ewald-attached to them which are in the textbooks.

Ewald:

Yes, but they were so trivial. These things are really very trivial.

Weiner:

To you.

Ewald:

Well ... I think to other people.

Mrs. Ewald:

That's what he always says.

Weiner:

No, things which you've done can be seen throughout Kittel's book on solid state physics and other basic works. These things can be identified as part of the literature and the basic techniques of solid state physics.

Ewald:

The reciprocal lattice was really very simple and trivial. And I didn't even develop it in its generality; this was done by Laue.

Weiner:

We could go on down the list but this is ...

Ewald:

The so-called Ewald sphere came out direcly from my thesis. I could have told that to Laue before he made that experiment, had I been a bit brighter or quicker.

Weiner:

Well, another point is the use of the dynamical theory in the interpretation of many other things, being able to fit newly discovered effects within the theory is something that I am sure has kept you stimulated. But it also has meant something to other people who were trying to understand these new effects.

Ewald:

Yes. Well, the effect which has interested me mainly in these last years is the so-called Borrmann effect, and I think I had for a while a better understanding of that than anyone else. But I have talked so much about it that now there are quite a number of people who ... I mean, my interpretation has spread.

You see, what I am interested in observing at present is the very close analogy of the whole dynamical theory to the theory of small oscillations in mechanics, and that's what I'm probably going to talk about in Cambridge at the meeting in June, except that I've to cut it down to more practical aspects. But this talk, for instance, in Watertown a short while ago, and in Washington also at the APS meeting,

I stressed the aspect, that it's a close analogy to the theory of small oscillations. Now the trouble is that nowadays people don't know the theory of small oscillations anymore. Mechanics is not a subject which is really being taught properly; it's antiquated.

Weiner:

Well, perhaps you can revive interest in it by relating it to your own theory. Let me ask a final question and that is, in thinking back on the work you've done thus far, what has given you the most personal satisfaction, which particular time period or piece of work can you identify, if any, as the one that had most personal meaning for you?

Ewald:

Well, I would say lately certainly the Borrmann effect, and its interpretation. At the meeting in Harvard in '48, Laue gave me a manuscript in which he had calculated the Borrmann effect, and I didn't appreciate that very much. But I appreciated the whole Borrmann effect and its physical background and interpretation--that is really what interested me in these last years.

Weiner:

And it gave you satisfaction and a sense of personal ...

Ewald:

Yes, that gave me much satisfaction and altogether, I think, if I look back on my work, it's nice to see the development, the rather crude and very cumbersome methods I used in my original thesis and how this has been perfected more and more and become easier and easier to do in the course of time. And it would be quite easy, if I had ever written the book on Fourier transforms, on which I've been working now and then and which I've not yet quite given up; I would like to see that done. And it really should have been done much earlier because it would have given much better nomenclature to the whole field. And another problem which I still hope to go into--I've tried it repeatedly but so far I've had not much success-is whether there is an optical activity of crystals for x-rays.

If a crystal is constructed on a screw-axis basis, then you would expect a linear polarized x-ray to enter (without any splitting off of secondary rays) and its plane of polarization to be rotated. And this is quite difficult to calculate and has never been done. I've asked several people to make experiments, but these have always turned out negative, which is not astonishing because you have to know the order of magnitude before you can set up a sensible arrangement for measuring such a rotation, if it exists. So that would be the so to-say final stone in the crystal optics of x-rays, which I'd like to still perform.

Weiner:

In a sense you've answered the question about what is the most satisfying work by saying that the thing that you're still involved in is the most satisfying.

Ewald:

Yes, what I'm still involved in. In this whole work you know of editing so much and collecting structures and writing Handbuch articles, and all that kind of thing, it was really from a feeling not so much of research as that it was for the public benefit to do this. And it has kept me quite busy, and I also had pleasure. I mean, some people like teaching; I liked it, but now I think it's a bit strenuous and especially repeating myself so often is rather tiresome.

Weiner:

I think we've covered a lot of ground, a lot more than you thought we would, and when we look at the transcript, we'll probably think of all the things we left out.

Ewald:

Well, be thankful for everything I left out.

Weiner:

Well, I'm thankful for your patience.