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Oral History Transcript — Sir James Chadwick

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Interview with Sir James Chadwick
By Dr. Charles Weiner
At Cambridge, England
April 15, 1969

Listen to Chadwick talk about Ernest Rutherford and Niels Bohr and not understanding consequences of new ideas.

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James Chadwick; April 15, 1969

ABSTRACT: Chadwick describes his life and work from his boyhood years to his retirement. He details his discovery of the neutron in 1932 and nuclear physics work at the Cavendish Laboratory from 1919-1936, when he left Cambridge for Liverpool. Among the important events in this narrative are the following: Chadwickís first meeting with Rutherford at the University of Manchester; his graduate work with Hans Geiger (1913-14) in Berlin, where he was interned for four years as an enemy alien; his return, upon release to Manchester, where he teamed up with Rutherford when the latter moved to direct the Cavendish Laboratory in 1919; his functions as Assistant Director of Research at the Cavendish from 1923-36; his role in building a working cyclotron at Liverpool. More briefly, he describes his relation to the US atomic bomb project, his admiration for General Groves; and his final return to Cambridge where, after the war, he served as Master of his College until retirement in 1959.

Transcript

Session I | Session II | Session III | Session IV

Weiner:

This is an interview with Sir James Chadwick in Cambridge, and Charles Weiner is asking some questions. Todayís date is April 15, 1969. Iíd like to pick up where we started to discuss things yesterday. We agreed that it would be good to fill in some background prior to your coming to the University of Manchester. It is not at all clear to me when you moved to Manchester; I know that you werenít born there.

Chadwick:

No, I wasnít. I was born in the country. My parents were country people. I donít really know very much about this. Itís all very vague. I know that my father went to Manchester to run a laundry. He couldnít have bought it himself, he hadnít the money. It must have been bought by relatives, probably of my motherís, and I stayed then with my grandmother in the country, near Michelsfield, in Cheshire. And I remember very little as a boy. There are some things that I remember as a very small child but I donít tell them to anybody. But I remember as a boy climbing trees, and sitting on the top of a tree and enjoying myself. I went to the village school, of course, and my great friend was the headmasterís son. We didnít take school very seriously. I remember we took a day off to go bird-nesting, and I have quite a vivid memory of being caned very severely for it. Thatís all I remember except one or two other trivial things. I donít remember very much from those days.

Weiner:

Did you have brothers or sisters?

Chadwick:

I had two brothers, and later one sister was born, who died young.

Weiner:

Were the brothers older?

Chadwick:

Younger than I. One is dead, and one was a few years ago in business in Manchester — at a small cotton business which I hope has worked out all right — but Iíve not heard from him for five or six years. We have lost contact. Iím afraid I donít have a great family feeling.

Weiner:

In terms of your fatherís occupation, generally youíd say then that he was in business; you mentioned that he came to Manchester to open a new business.

Chadwick:

Oh yes, he came for that very purpose, and he failed. He didnít make a success of it. It wasnít the kind of thing he could do. He had to take a job on the railway as a storekeeper in a small way. We were very poor. Well, poor anyhow. So that I got to the University on a scholarship which was given by the Manchester Education Committee. Manchester then, as now, is a very progressive city indeed. I went to school at what is now called the Manchester High School for Boys (I think that is the name). I think the school is still run by the Manchester Education Committee. There was only one other school which had a very good reputation and still has — the Manchester Grammar School. Some of my friends went there. Although the fees were quite low, they were rather more than my parents thought they could afford. I may have been slightly unfortunate but actually the teaching at this school was extremely good. Iíve very often wondered how they managed to get such good masters. They were, almost without exception, extremely good. And it was also a very general education. I suppose not so unusual in those days, but not usual. For the first years, you had to cover every subject in the curriculum. There was no specialization until you got into — whether it was the fifth or the sixth form, I canít remember — but we had to cover everything. An unfortunate thing which I have always regretted and I have often felt the need of — no teaching in Greek, only Latin. And I think that was unfortunate, but there it was. But everybody in the first four or five years had to take science, mathematics. It was a natural thing. It didnít strike us as anything out of the ordinary, and it was only in my later years — that is, the later years in school (I was still very young) — that I got a real interest in mathematics and physics, not in chemistry. And I then was put in for a scholarship examination -ó I think two — I canít be certain. The main one was the scholarship supported by the Education Committee of the City, and the other, if I tried for it (Iím very vague about this now) was the University Scholarship. And I think mathematics only. I certainly won the more valuable one — the Education Committeeís Scholarship (or one of them) — and I think also the other, but was not allowed to hold them both. So I had to sacrifice. But I am very unclear about this.

Weiner:

I guess it could be determined from the records of the institutions.

Chadwick:

I donít think it is of importance anyhow. You see I was only 16 at the time. I was very immature indeed, and very shy, and I realized that I wasnít ready to go to a university. I didnít want to go at that age, but my schoolmaster said that I must. There was nothing more that I could do there without being in a kind of class of my own, which would be wrong from the school point of view. And it might be bad for me. So I had to go. And, as I think I told you yesterday, I intended to read mathematics at the University. I had no intention whatever of reading physics, but one had to go up for an interview before the term started, and many of them were held in a large hall, which I think must have been the Whitworth(?) Hall. (Itís still there.) There werenít separate rooms. It was just one big hail where I think the University ceremonies are still held. They used to be in my time. And it was divided of f into kind of cubicles, if youíd like to call them such, not by walls or partitions, but by low benches. And it so happened that, as one might expect, that mathematics and physics were close together. I sat on the wrong bench. When I started talking to the lecturer or rather answering his questions on what Iíd done and so forth, I found at the end that he was a lecturer from the physics department and I was entered for physics. He was such a nice fellow — I got to know him quite well later on — he was so understanding, sympathetic if you like (I canít find the right word). He didnít speak to me as though I were a very small boy, as I was, but he was obviously trying to find out what was the best thing for me to do. But he never asked me what I wanted to do as far as I know, and I was too shy to tell him that this wasnít what I wanted to do. So there I was. I regretted it during my first year, but not later, because by that time, I had made one friendship in the physics department, and I had begun to get an interest in what was happening there — a very mild distant one, of course, but still some kind of interest. I was going to say Iíve never told this story before. Thatís not quite true. I did, in some little preface that I had to write six or seven years ago for some volume of some kind of — it wasnít quite an encyclopedia — but some general articles about science, and I for some reason told it then.

Weiner:

I had a question about your high school period. What was it that made you decide that you wanted to go to the University to read math?

Chadwick:

Because I was interested, I was quite good at mathematics. I found mathematics extremely interesting, especially what is called applied mathematics in this country. For my age, I was quite good for those times. One reason I was telling this story was that I was pointing out that what a boy is expected to know now when he enters the university was far beyond my attainments when I entered. Things have changed enormously in the last whatever it is — fifty or sixty years. And there was some quotation I remembered from Benjamin Franklin, which I have now forgotten, that I think started my Preface off. It was one of the aspects I wanted to bring out that is that things had changed enormously, not merely since Benjamin Franklinís day, but even in my own day. I remember quoting — I ended up more or less with Samuel Johnsonís remark about knowledge is of two kinds. There are things you know yourself, and things that you can find out from books, you know where to find the knowledge. And that was another point of the Preface, you see, that there were very many more books available for young people than there ever were in my day. I suppose that was the chief point.

Weiner:

How far had you gone in mathematics?

Chadwick:

I canít tell you.

Weiner:

Generally, itís far less than what one would expect of an entering college student today.

Chadwick:

Not today, no. I think I said in this Preface that I, at that time, should not have qualified for admission to a university at present.

Weiner:

But yet, at that time, you had done so well in comparison to the generally accepted standard — for example, well enough to win a scholarship.

Chadwick:

Oh yes. I found that in the courses I had to take in mathematics during my first year I was rather revising what I had done, not then doing very much new. But they were good lectures in mathematics. They had some very very good people. The professor of mathematics was Horace Lamb, who perhaps is still known, and he was very good.

Weiner:

How about the lecturers in physics during the first year?

Chadwick:

I think I prefer not to speak about them. They werenít good. As far as I remember, we had three lectures a week in physics. It was the beginning of the honors course. It was a very large class indeed, because it was not composed only of those who were going to read physics to the honors standard, but a great mixture of people and a lot of engineers. Now, I may be a little bit wrong about that, but at any rate, there were a lot of people, and there were a lot of noisy people. There must have been close to somewhere between 50 and 100 — more than 50 certainly — and with a large number not caring two hoots whether they heard what was happening or not and deliberately trying to upset the lecturer. So that one got very little from lectures. There were some good teachers in the department, but we didnít come across them in our first year. But I really ought not to be saying this because although those people are dead they must still have relations alive who might guess who I was talking about. The only lectures that I found stimulating were in my second year — that was entirely, I think, men reading honors physics. It was a smallish class. There may have been a few other people of a general interest, and one of our lecturers who was quite good left Manchester for London and a stopgap had to be found. And the stopgap was Rutherford. The course happened to be electricity and magnetism and he told us about his early experiments in New Zealand. He managed to drag them in to illustrate some of the points. Although they were not lectures bearing directly, say, on the prescribed course, they were the first stimulating lectures I had ever had in physics. And it unfortunately didnít last more than a few weeks. And then, you see, I had a half education in physics. There were whole aspects of physics that I knew little about. I read about them, of course, but I must confess I knew little about them, and certainly, did not really understand them until I had to lecture in Liverpool.

Weiner:

That was about twenty or thirty years later. During the intervening period, you had no opportunity really to fill in those gaps in a very general way?

Chadwick:

Well, I am perhaps exaggerating a little, but essentially, what I said is true. I did fill in some gaps as the occasion arose, when one wanted to know something or I had occasion to make use of it in some experiment. But it is a fact that education in Manchester at that time was not very good. Rutherfordís interest was then almost entirely in the research. He had done very little teaching in McGill. He was research professor. I suppose he gave some lectures but it would have been very few. And his interest was quite naturally on the research side. He did give some lectures, but elementary lectures, the kind of thing you would expect a man to know before he came to the University. They were the lectures to the engineers. They were a rowdy lot and Rutherford could keep them under control. There was perhaps only one other man in the department who could have done it, and he (Rutherford?) enjoyed them because he was able to show them the very interesting experiments one can perform in elementary courses. But at the end of our second year we had to choose between courses in electrical engineering — Iím not sure that is the precise word I should use but there was a department of electrical engineering in the physics laboratory — complemented by a few other lectures, and starting on research.

Weiner:

The second year?

Chadwick:

At the end of the second year, and I wasnít eighteen. As far as I was concerned there was no difficulty about the choice whatever, and as far as I remember, we had no lectures in physics. But I wouldnít be certain about that — certainly very few. But I did attend some lectures in mathematics which interested me. My formal teaching was very sparse, and you were expected to read, of course. There was a library in the physics department which was mainly occupied by journals. Books, of course, werenít as expensive then as they are now, but I couldnít afford to buy all the books that I really needed. Only a few of them. It was a very difficult time in some ways. I admit to you that for three years I had no lunch. I couldnít afford it. After that, in some way or other — I donít remember how — things got a little bit easier and I did have lunch. I used to spend the time reading and, occasionally, playing chess.

Weiner:

You lived at home during this period?

Chadwick:

Yes. Of course, all the day I was in the university. My home was about 4 miles away, or maybe more.

Weiner:

Among the reading materials, was there a standard textbook in physics that would be the most important central book?

Chadwick:

Yes, up to a point. Itís very difficult for me to remember. I can remember some, for example, one on optics by Drude. And Schusterís Optics which is from a different aspect altogether, a much more physical aspect. And I donít remember whether R. W. Woodís book had been published at that time. If it had, I couldnít afford to buy it. I donít recall when that was published. I think it must have been later. (R.W. Wood, Physical Optics, 1st edition, 1905.) And then electricity and magnetism were very largely to me, at that time, mathematics. There was very little physics about it. The first time I began to appreciate some of the physical ideas was from Rutherfordís lectures

Weiner:

From those few weeks of lectures?

Chadwick:

Yes. Itís often been said to me that Rutherford was a bad lecturer. I never heard such nonsense. It is quite true that on occasion he would be a bit dull, a bit mixed up, but that was only on very rare occasions. There were other occasions when he was really most stimulating. There was a tremendous enthusiasm about him. I donít know if youíve ever read the early papers that we published in New Zealand.

Weiner:

Iíve never studied them in a serious way.

Chadwick:

True, he said there were good teachers in New Zealand, but what he showed there was imagination from the beginning, and not merely imagination, but determination to try it out. Remember the skin effect where high-frequency magnetic forces did leave a steel needle with the residual magnetization — if itís there, take the skin off and see if the magnetism is gone. [1] Thatís what he did. But he could talk about those things as if the whole thing was alive, and that is a faculty that few people have. I donít say he showed it every time he lectured, but quite often, and it makes me quite agitated when Iím told that Rutherford was a bad lecturer. From those few weeks, I gained a lot.

Weiner:

That was the basis of your decision, then, to choose research?

Chadwick:

I think so, yes.

Weiner:

What did you do the third year when you got involved in research?

Chadwick:

There had been some meeting, I donít know what one now, I canít remember, at which it had been decided that better methods of the measurements of the amount of radium should be found, and the task of doing this was allocated to Madame Curie and to Rutherford. I donít know whether Pierre Curie was alive then. That would be 1910, I suppose. (The date of Pierre Curieís death is April 19, 1906.) She naturally used the quartz piezometer electric method, and Rutherford decided to use a very simple thing — to balance the ionization produced by the gamma rays against a constant ionization source that had been produced in the little ionization chamber by the alpha and beta particles of uranium oxide. I was given that job — perfectly simple. I saw a few snags about it quite early. Iíd seen a perfectly obvious little snag in the arrangement that Rutherford had suggested as soon as I began to work, but I was so afraid of him that I darenít mention it. Of course, when I showed him some of the measurements he saw at once what the trouble was, and I think he was rather disappointed in me that I hadnít pointed it out. I had seen it, but I was so afraid of him that I thought he must have seen it himself and there must be some reason why he wanted it this way. In those days it was not merely because I was young — as I said, I started when I was just 18 — but he was very different from what he became later on. After coming here, you see, he mellowed very much indeed. In those early days in Manchester the only thing that mattered was getting on with the experiments that he was doing — the things he was particularly interested in himself and in other people to a slighter degree. And he was a pretty hard taskmaster. I was very definitely afraid of him, and I was quite immature.

Weiner:

Did the work that you described continue for very long, or did you go on to other projects?

Chadwick:

Well, I used it for other purposes. I really find it very difficult to remember. I certainly used it in the first place to show that this was a method by which the amount of radium could be pretty accurately determined. That was the whole point of the thing. And then I used it to measure some of the radium sources, one in particular which Rutherford had brought with him from Montreal, and on which he had based some of the constants of radioactivity. And, of course, Stefan Meyer sent over some tubes, two or three, I forget which now, in which he had put weighed amounts of radium of the highest purity that he could make, and these — I think one of these — was made one of the standards. And another one made by Madame Curie in Paris was made one of the standards. They agreed together. But Iím getting out of order, you see, I really havenít thought about these things for many many years. Then I measured particularly one source of radium on which he based many of his measurements and it was about 5% out — something quite large — but it wasnít in the form in which a radium source ought to be, really at all. But that was that. And then J. A. Gray, who was then working in the laboratory — so that must have been reasonably early, 1911, or was it 1912 — found for the first time what many people had looked for and what one really expected: that the impact of beta rays on materials produced gamma rays, just as electrons produced X-rays. But he was the first to observe it. And I could then confirm it if he wanted confirmation and could observe it quite easily with the apparatus that I had, and measure it. It was a trivial thing but I measured the amount of gamma radiation produced in different materials by the source of beta rays being great in emanation, that is, they acted upon it. Of course, it was all very general. I suppose it was useful.

It was certainly very useful practice for me. I did one or two other things. I did one thing that I have never understood. I donít believe it can be right, but I observed it — gamma rays produced by alpha rays. And then, I thought we ought to have a look at the radioactive bodies which emitted alpha rays — we knew they did not emit beta rays — for gamma radiation, associated with the alpha rays. And there was a good chemist, A. S. Russell, in the department — heís still alive, heís in Oxford now, I heard from him the other day — and we joined forces. And it was at the time when he and other people proposed rules about the change in place in the periodic table of the radioactive substances with the emission of alpha and beta rays. That, of course, must have been 1911, late in 1911, and 1912, because it was after the nuclear theory that Rutherford put forward, definitely after that. And Russell couldnít get any interest in it. Then, I remember — this is gossip — he did hear that somebody was going to publish, so he wrote a note and I made some tables. He was in a great hurry as Rutherford had agreed to communicate it to the Chemical News, I think it was called, and he made a few mistakes, rather stupid, but they were really mistakes due to the hurry of the occasion. Of course it became quite general and Fajans certainly published. Soddy published, and Iím not sure about Hevesy. I am sure that he had the idea in mind. Iíve talked to Niels Bohr about this and he said, well, it was quite obvious to me. But it was very largely based on experiments by a man called Fleck in Soddyís laboratory. He had done the bulk of observing the chemical reactions of different radioactive bodies. Russell was a former student of Soddyís. His home was in Glasgow, and so, he knew all about Fleckís experiments. I suppose perhaps other people did too, I donít know. But it was certainly very largely based on Fleckís experiments. Fleck later went into industrial life and was chairman of ICI. He died a year or two ago.

Weiner:

I had wondered where I had had a later association with the name. Now I understand.

Chadwick:

Yes, he was a very able man. And a very good chemist. You see he wrote a paper on the chemistry of various radioactive substances, and he had been unable to separate one from another, in two or three instances, where the things appeared to have exactly the same chemical properties, certainly as far as he could tell. It was refused publication.

Weiner:

Where had he submitted it for publication?

Chadwick:

I canít remember properly — I wouldnít like to say. He may perhaps have used the wrong words, what I mean really, is to have been rather more definite than the editor, or the reviewer liked. He may have said, for example, that the two things are inseparable, instead of inseparable as far as my experiments go. They didnít like it, but, of course, he was right.

Weiner:

Some of this work you are describing in this period goes beyond your honors degree, doesnít it, which was in 1911?

Chadwick:

Yes, I canít remember much about that, you know. I only remember one thing we had to do. I didnít know, and it must have been my own stupidity, because it must have been told, but I didnít know that we had to have a practical examination. I had done all the papers — one or two perhaps reasonably well, others pretty badly. I suddenly found out we had to have a practical examination, and the external examiner was J. J. Thomson. I was terrified. It was not anything that he did. He came around to talk to me and I could hardly say a word. He was a kind of legend, you see. I still remember that. I was in a complete pickle. I just couldnít do anything. That didnít come to my rescue, but it came to the rescue of one man, whose name I wonít mention, when I was the examiner here. And he couldnít do the simplest experiment. Everything he touched came to pieces in his hands. Everybody knew he was extremely good. He wasnít a first (rate) experimenter, by any means, his interests were more on the theoretical side, but he was reasonable enough. This time he couldnít do the littlest thing. Everything was beyond him. I realized this, and I remembered what had happened to me. And the other examiners agreed we would just wipe it out, we would take note of what he had done during his courses in practical laboratory, and forget about the actual examination, because there was nothing to show.

Weiner:

Was someone similarly understanding in your case?

Chadwick:

I have no idea.

Weiner:

But you did get a degree?

Chadwick:

I did get the degree, but I donít know any more than that. It may have been bad. Perhaps that is why I have forgotten. But I was taken on.

Weiner:

By taken on, you mean as an advanced research student?

Chadwick:

Yes.

Weiner:

By the way, when J. J. Thomson came to you, was it then your responsibility to demonstrate a particular experiment?

Chadwick:

No, I was given some experiment to do. It was something quite simple. I donít remember properly what it was, but it was something reasonably simple with hardly more than a little arithmetic connected with it. And I had to explain to him what I intended to do and how I intended to get the results that were expected of me. I couldnít do anything. It was dreadful. Thatís the chief thing that I remember about the whole examination.

Weiner:

But somehow, perhaps because of your earlier work, you were accepted as a research student. Was there a change then in the kinds of things you were doing in the laboratory?

Chadwick:

I donít know. I suppose it must have been about that time that I joined with A. S. Russell to separate out various alpha ray bodies and examine their gamma activity, if any. And it was then that I learned a little chemistry. I was supposed to have learned something in my courses, but I didnít. I did learn something from the lectures which were quite good, but the practical class to me was a complete waste of time and I often didnít go. I donít know what you do in practical chemistry nowadays but what we were expected to do was so dull and so uninteresting that, as I said, I often didnít go to the classes at all. Except for the first one or two afternoons, it was a waste of time, in my opinion. It wasnít chemistry. And I learned something from A. S. Russell and then I got a reputation with Rutherford as a chemist in some mysterious way. Well, I wonít say as a chemist, but he thought that I did know a good deal about the chemical properties. It was partly true. Then I did, as a matter of fact, some work when I was interned during the war. I was in Germany. I was able to do some chemical work there of a very elementary kind, but still it taught me something.

Weiner:

Iíd like to probe the war experiences a little later. But, in particular, when you had established in Rutherfordís eyes the reputation of being someone familiar with chemistry, did he then put you to work in that capacity?

Chadwick:

No, what it helped me do, and what other things helped to do, was change Rutherfordís opinion of me. I think thatís rather a crude way of saying it, but I think it is essentially true. I think in the early days he regarded me as not showing very much promise. Perhaps that is not quite right, but I was very very young, and very shy, and afraid of him, and so, I didnít really talk to him in the first year or two, or even later, if it came to that. But it got better. And I suppose I improved, and what with one thing and another, he began to have a good opinion of me, not a bad opinion. Well, I wonít say he had a bad opinion, but it certainly wasnít a very good opinion at the beginning. But then later he did have a good opinion, and I was awardedÖ

Weiner:

The 1851 Exhibition Scholarship?

Chadwick:

Yes, but before that, I was awarded some university scholarship, I donít remember what the name was, but I remember that I was awarded at least one, as that was what enabled me to keep going. But then, somewhat to my surprise, perhaps, I was awarded an 1851 Exhibition, which meant Rutherford must have recommended me quite strongly. So that is why I say his opinion must have changed quite considerably. And of course I had developed. I was two or three years older.

Weiner:

An important period of growth. By this time you were in your early twenties, and two or three years makes quite a difference.

Chadwick:

Yes, I was growing up, and I was slow at growing up. He obviously was really very kind to me, because otherwise I would never have gotten it. In those days it was a great distinction to get an 1851 and I never would have got it unless he had recommended me quite strongly.

Weiner:

Had you worked directly with him during those years?

Chadwick:

No, not really. The first work that I mentioned — the measurement of quantities of radium — was published as Rutherford and Chadwick. [2] It was his idea and under his supervision. It was his job to produce a method. But I canít say it was working with him. He would come and see me about it, and see how things were getting on. But I canít say that I had very much help from him. It was a simple thing and I suppose it wasnít necessary. I have no doubt I got advice when I needed it. I donít remember any particular difficulties except one very early one which was very obvious and which I knew the answer to myself, but which I was afraid to mention. It was, in a sense, an interesting time because there were such a number of people from outside. I find it difficult to remember their names now because I suppose theyíre nearly all dead. The chief one was Geiger, of course, but he left in 1912. But he was, of course, very helpful, if one was in trouble. I personally didnít have any help from him. He took some classes in German. Rutherford thought we ought to know enough German — not that he knew very much — but he very rightly thought we ought to know enough German to read the German theory articles. And so Geiger ran a class for that purpose. That was the main contact I had with him, but he was always available if one wanted anything.

Weiner:

Were you aware of the work that he and Marsden were doing?

Chadwick:

Oh yes, in a vague kind of way. The first public announcement of the nuclear theory by Rutherford was made at a meeting of the Manchester Literary and Philosophical Society, and he invited us young boys to go to the meeting. He said heíd got some interesting things to say and he thought weíd like to hear them. We didnít know what it was about at that time. The older people in the laboratory did, of course Geiger and Marsden knew because they were already doing the experiments. In fact, unless they had done some which were sufficient to be decisive, Rutherford never mentioned it publicly. And, of course, Darwin knew about it much earlier. But that must have been early in 1911, and we went to the meeting and he told us. And he mentioned then that there was some experimental evidence which had been obtained by Geiger and Marsden. He did not, as far as I remember, say more about the results than that they were quite decisive. And, as I said before, he would never have made a public announcement of that kind if he hadnít had good evidence. And that is one of the characteristics that runs through all Rutherfordís work, particularly all his work up to the end of the Manchester period. If you look at some of his papers in the early days — I call McGill the early days — he was quite convinced that the alpha particles were atoms of helium, but he never said that in those words. He always said they were either atoms of helium or molecules of hydrogen or perhaps he may have said something else of that weight. It was quite characteristic of him that he would never say a thing was so unless he had experimental evidence for it that really satisfied him.

Weiner:

Other than the student group, who was present at the meeting of the Manchester Literary and Philosophical Society? How large a group, and did they understand what was going on?

Chadwick:

Oh, any of them wouldnít. The Manchester Literary and Philosophical Society is an old society, largely of the general public, but it was a very small section of the general public — people interested in literary and philosophical ideas, largely business people. On this occasion, if I remember rightly, the first item contributed to the meeting was a statement by a fruit importer that he had found a rare snake in a consignment of bananas. Now I may have got part of the story not quite right, but Iím pretty sure that was what was said. Whether he exhibited the snake, I donít know. That I canít remember, but that was the first item. And it must have been of some interest to somebody. There was another item — I mentioned it in some paper I wrote, it must have been in my Rutherford lecture — that the second item was the communication by Eliot Smith. He was a professor in the University, also a great friend of Rutherfordís. He might have been an Australian, and might have been a professor of anatomy. And he produced a model of a skull. The cheek part went back to early man, but what it was I donít remember any more. It must be in the Proceedings at the Manchester Literary and Philosophical Society. There was a piece of bone and the rest was Plaster of Paris. But he gave a very interesting account and I remember that later on — one of my chief friends amongst the young physicists in those days was Harold Robertson, who is now dead — I remember that we had a little talk about it afterwards. We decided that Eliot Smithís talk was extremely interesting but in our opinion it was a mixture of Plaster of Paris and imagination. And then came Rutherford about the nuclear theory. In a sense, (it was) a most shattering performance to us, young boys that we were, because we realized immediately, I think, not all the consequences. Of course, nobody did except Niels, but we realized this was obviously the truth, this was it.

Weiner:

Did he express it with complete conviction?

Chadwick:

Yes, I think so. You couldnít escape from it. The experimental evidence which he only mentioned very briefly was so conclusive that there was no escape.

Weiner:

Did he read from notes, or have a prepared talk with illustrative material of any kind, any drawing that he had made?

Chadwick:

That I canít remember. It wasnít a long talk. He must have had a slide or a drawing, probably a slide showing the hyperbola and so forth. He must have produced the little bit of mathematics that would have been absolutely essential. I donít remember much more than that, you see, because I remember the impression that it produced among us.

Weiner:

Was there a discussion at the meeting?

Chadwick:

Very little, I think. I donít really remember, but I donít think there could have been much discussion. It was to most people there, you see, something quite new, and of such consequence that one wanted time to think it over, while at the same time recognizing that a completely new idea had come in which was going to make things quite different. Even though we were very young and just beginners, we saw that. But you see there was another thing which is extremely odd, some of the important consequences were not seen for quite a time. And you will find very few references indeed in the literature to the nuclear theory of the atom for about two years after the publication. It is a most extraordinary thing.

Weiner:

One final question and then weíd better take a break. Do you recall the size of the meeting itself? Was it a large group?

Chadwick:

There were a dozen of us from the university physics department, and no doubt, there would be one or two of Eliot Smithís colleagues there, There were certainly I should say, a dozen with a much more general interest, that is, people from the city. I wouldnít like to say, but there were certainly 50 or 60 people present on that occasion because I remember being at the back. It wasnít a large room. That was 1911. I went once or twice to the Manchester Literary and Philosophical Society later. The last time must have been, I think, in the early days of the last War. So it couldnít have changed in between. And I remember on that occasion — I gave some lecture there — it struck me how small the rooms were. As I remembered from the first occasion when I was there, it was a fairly large room.

Weiner:

And you were in the same room?

Chadwick:

I suppose so.

Weiner:

Weíre resuming now after a break of a few hours. And the point you were just making to me was the influence of the form master on your decision to go into the university.

Chadwick:

No, it was that he kindled an interest, a real interest in mathematics and physics. I suppose by that time I must have migrated to the science side, because, as I mentioned before, I had no Greek. If there had been, I might very well have become a classicist. It sounds nonsense, but it would have been quite easy. But I came under his influence, and there was no Greek. He was our form master when I was in the sixth form, and he had a very genuine interest in mathematics, more perhaps than in physics, but in both. And he was encouraging as well. I learned a lot from him. I owed him a very great deal.

Weiner:

What was his full name?

Chadwick:

I only remember that his name was Woolfenden. What his Christian names were I never knew. I might have known his initials, and no doubt if I had kept the letters from his son, I would have known his full name. But Iím quite sure I burnt them with many other things I had to get rid of and had no room for, and they werenít of real interest to anybody else.

Weiner:

That does fill in some very important information for the earlier period. When we left off before, we were talking about Manchester.

Chadwick:

Yes, you asked me to mention some of the people there. There were some of them here.

Weiner:

This is a photograph taken in 1911?

Chadwick:

I think it must be 1911. It just depends on what time of the year it was taken. Itís just possible it could have been 1912 but I donít think so because J. A. Gray is there — I canít remember when he left Manchester, but about that time. Geiger left in 1912 but at what time of the year I donít know. This would have been taken in the summer. Thereís another man here whose name Iíve forgotten at the moment who was a lecturer, but he also left Manchester about that time.

Weiner:

Was Kovarik in the picture?

Chadwick:

No, he was not. He might have been a little bit later because I got to know him. You see in 1911 I would know some of these people but not all of them. That is wrong, I did know all of them but not well. I just knew their faces but not much more, the way I knew Moseley at that time. He came to Manchester in 1910, I think. And Hevesy isnít there. He often appeared and stayed for quite a time, but then heíd be off a time and then come back. Sometimes Paneth came. That must have been 1912 when they were both there. I remember particularly, it must have been about 1912, when I wanted to do something on the electrochemical side — I canít remember what it was — but I used to ask Hevesy how to do it and he would tell me. And then if I saw Paneth Iíd ask him and he would tell me something else. So I just had to try everything in sight. I donít think I was very successful anyhow. But they were both very interesting people. Of course, I got to know them quite well later on, particularly Paneth, who, of course, came to this country about 1933, when things began to happen.

Weiner:

How about Moseley? Did you have any personal contact with him?

Chadwick:

Very little. In those early days, the first year or two years, he was working next door, but his habit was to come in about teatime. There was always a kind of communal tea in the laboratory which one was expected to go to and talk about anything under the sun but you met each other. And then after that, Moseley would start work and then work right through the night. He damaged his health. I remember that. Particularly Rutherford was concerned. If I remember rightly, I was told that Moseleyís father had done the same thing. He died at an early age. It seemed to be the family habit. And Rutherford couldnít stop him, but he did advise him not to do it so much. He did try not to do it so much, but he still did do some. Then, of course, he began to work with Charles Darwin on the X-ray side and moved to a different part of the laboratory, and to some extent, reformed. But yes, Kovarik was there for a year, I suppose. Boyle was a Canadian; R. W. Boyle; Fajans; and there was Schrader. He was the Prussian I mentioned who went into business later on. At least when I met him in Berlin in 1913 or early 1914, I remember him inviting me to dinner with Geiger and other people. He was definitely in business at that time, but he must have had some interest in physics because I met him in Muenster in 1932 at a meeting of the Bunsengesellschaft, I think it was.

Rutherford and I went there, and we had a very happy time there for a few days, because there were some old friends about. Stefan Meyer for example, who was an old friend of Rutherfordís, who I knew too. He was a very dear friend, a lovable character really. And, of course, he had been very helpful to Rutherford in the early days. Rutherford got a loan of something like 200 milligrams of radium from the Austrian government. Otherwise he wouldnít have been able to do the work in Manchester that he did. And the whole story of that is undoubtedly in Eveís book — I wonít say the whole story, but some of it — because the first lot was commandeered by Ramsey, and I think an account of the correspondence between Ramsay and Rutherford about the use of this radium must be in Eveís book. It was quite obvious that Ramsay was going to stick to it as hard as he could, and it was through Stefan Meyer that Rutherford got an extra quantity for himself. And naturally Rutherford was very grateful to Stefan Meyer. That radium came in very useful after the War because Austria was in a very poor state. It was reduced to Vienna and a few rocks, practically nothing more. They had no money to run the Radium Institute. Rutherford arranged for either the government or the university when he came here, to buy this radium and to pay the money to Stefan Meyer, and it was on that that he was able to run the laboratory for a few years anyhow. I canít remember the names of all the people. An incredible number used to come for a few months to Manchester in those days.

Weiner:

You mentioned some in your obituary of Rutherford in Nature. Let us see if there are any that you have not mentioned. You mentioned Boltwood and Hevesy and Fajans and Gray Boyle, Kovarik, Darwin who was there, Russ Ö

Chadwick:

He was the lecturer who left and whom Rutherford replaced as a temporary lecturer. But he came to London and went into the medical side of the uses of radium and x-rays. He was a very able man.

Weiner:

That was fortunate for you. To continue, there was Makower Ö

Chadwick:

Yes, Makower was another lecturer. I believe his title was also Director of the Department, that is, he was next to Rutherford. The difference in stipends, however, was pretty considerable.

Weiner:

Rutherfordís title was Director of the Laboratory?

Chadwick:

I think Makowerís title was Lecturer in Physics and Director of the Laboratory, but I may be wrong about it. There must be something in it or I shouldnít have remembered it. I wonít mention figures, because I may be wrong in any case, but there was a big difference indeed, a factor of something like four. But Makower was quite a rich man, really. He was a Jew, an extremely nice man to have about. He published a book with Geiger, a practical book on exercises in radioactivity or something of that kind, and he did some quite interesting work in radioactivity. He was a very good musician too.

Weiner:

That book became a standard training book, didnít it? Did you use it there or was it published later?

Chadwick:

It must have been published at that time, I think. Iím quite certain it was though I canít remember the exact date. I donít suppose I have it now. You see Iíve thrown so many things away. I may have given it away, but I donít have it any longer. There are so many things Iíve had to get rid of from time to time, particularly coming here, Iíve gotten rid of thousands of books. (Makower & Geiger, Practical Measurements in Radio-activity, London, 1912.)

Weiner:

Among the visitors, I guess the most famous at that time was Bohr?

Chadwick:

He wasnít exactly a visitor. I remember him very well. He must have come in 1912 but at what time in 1912 I donít remember.

Weiner:

I am sure it must be in the Bohr biography. (Bohr was at Manchester from March through July 1912.)

Chadwick:

Yes, it must be there. He started some experimental work. What it was I donít remember now, but I do remember his room. I didnít have much speech with him. He wasnít there very long, and I was very junior. But I did know him. And he was very difficult to understand. He always was, but particularly in those days. Most people would say even in his later life he was very difficult to understand.

Weiner:

In terms of his diction or in terms of the content?

Chadwick:

In terms of his diction, not so much his pronunciation, but it must have been a bit more than his diction because Iím told he was also difficult to understand in Danish.

Weiner:

By diction, I meant not only that, but how one uses his voice, whether one mumbles, or swallows his words.

Chadwick:

Well, he didnít speak fast. He used to not talk about his experiments. I donít think he was very interested in them, and I think he gave them up fairly soon, and you see he became interested in the passage of alpha particles and beta particles through matter. I do remember something about that. Darwin had written something. I do just vaguely remember that Bohr thought the physical ideas were not right, and so he wrote from a different aspect. I think his chief friend was von Hevesy, who was there at that time. Then, of course, he left Ö I donít know when. But thatís all in the books. He got married. I remember seeing him and his wife for the first time when I came back to Manchester on a visit from Berlin, which must have been probably early in 1914, but by that time, I think he had been made Reader in Theoretical Physics in Manchester, a post which had been established by Schuster out of his own pocket. Later the University may have taken it over. I donít know what it was in Bohrís time, but in the earlier days, it was a personal matter on Schusterís part. Of course Schuster was a wealthy man.

Weiner:

Do you recall the subsequent developments of the nuclear theory? When we broke off earlier today, we had just discussed the meeting at the Manchester Literary and Philosophical Society where the paper was presented, and you mentioned the impact that the paper had on the people from the physics laboratory who were present. Perhaps we should pick up that thread.

Chadwick:

mp3I think that is very difficult. You see, at that time, one realized that in a way it was opening up a new world, but certainly very few people realized even some of the simple consequences. I certainly didn't at the time. I'm also quite sure that some of the simple consequences weren't realized by Rutherford, for instance, the displacement theory, or whatever it was called at the time. I've talked about these things with other people, particularly with Niels Bohr, and my feeling is that there was only one man who did understand it. And that was Niels Bohr, who really saw that things were going to be quite quite different, and that some things were completely simple. In fact, he would say they're so simple they weren't worth mentioning.
Talking about these matters with Niels was a long time after the event, but if you look through the publications at that period, you find very little mention indeed of the nuclear theory of the atom. I mean in the immediate years. It was really, I think, Bohr's papers — I can't remember when they were published.

Weiner:

1913.

Chadwick:

Were they published in 1913? Yes, I forget years. You have all that correspondence with Rutherford about the papers. They were written in Copenhagen, and there was a whole series of letters.

Weiner:

I have seen them either here in the university library or in Copenhagen. But at the laboratory in Manchester, was there a discussion of the nuclear theory after the presentation that Rutherford made? Was it the subject of much conversation?

Chadwick:

I donít think so. I donít remember, but I donít think there was very much. Of course, it was accepted. Some of the simpler consequences were not grasped. I was telling you about the publication of a paper by A. S. Russell on the position of the radioactive elements in the periodic table. The obvious explanation and a much simpler one than using the periodic table as he did, and as I think some others did, was simply the change in charge of the nucleus on the emission of an alpha particle and a beta particle. Now, he certainly didnít put it that way, and I donít think that anybody else did at that time. But at least Niels Bohr told me years afterward that it was perfectly plain to him, and if he says so, I believe him. He was always quite open about such matters. If he hadnít thought about it, he would have said so. But it seemed to him a perfectly natural inevitable consequence. It wasnít put like that.

Weiner:

By this time that weíre talking about now, around 1913, you received your Master of Science degree, and apparently, on Rutherfordís recommendation, you received the 1851 Exhibition Scholarship.

Chadwick:

It was certainly on Rutherfordís recommendation. It had to be recommended from your university and there is no doubt whatever about it.

Weiner:

And that enabled you to go to Berlin and study with Geiger.

Chadwick:

It was the obvious thing to do. You had to go somewhere else. You couldnít hold it in the same place. The obvious thing for me to do was to go to Geiger if he would have me. And I wrote to him and he accepted me.

Weiner:

Let me ask the question: why was it the obvious thing to do? There were many places in the world where you could have gone.

Chadwick:

There was no other place where I could have continued on the radioactive side except Paris. I canít think of anywhere else.

Weiner:

Had you considered Paris?

Chadwick:

No, Madame Curieís interests were largely on the chemical side, not on the physics side. And I had one or two things in mind to do in which I thought Geiger would be interested and in which I thought he could give me advice. The one thing I did try to do was to observe the scattering of beta particles, making use of what was then supposed to be a fact, that the beta particles from the active deposit of radium consisted of homogeneous groups of different velocities, quite strong and well separated homogeneous groups. And I bent them around in the usual way in a magnetic field and bombarded a thin metal foil and observed the scattered particles by using the point counter which Geiger had developed, I think, after he got back to Germany. I canít remember itís ever being used in Manchester. That was also one reason for going there. Well, then I found, of course, that I couldnít observe the damned things properly, and then I found that while these homogeneous groups were there, they were only peaks on a general continuous distribution of beta particles, and that the photographic registration of the magnetic dispersion of the beta particles had given quite a wrong impression. I quite easily showed that a group with say 5% higher than the background could be made to appear as if it were a line on nothing, just one homogeneous group, which was merely a trick in the way in which you did the photographic plate. And so I had to give that up. I ought to mention that was the occasion on which I first met Einstein in Berlin. He came round to the laboratory.

Geigerís laboratory was quite a small thing which had been in the middle of the garden of the Reichsanstalt. It was called the Magnetische Haus. It has been used presumably for magnetic measurements in the old days. It was quite a small little place but very convenient. One day Einstein came around. Whether it was to see Geiger or whether it was just making a round of the whole place, I donít remember. He came around and talked to me about what I was doing, and I told him what Iíd found out, that the beta ray emission from the radioactive deposit had a continuous range of energy practically from zero up to a certain limit on which was superimposed these peaks. And I didnít know the answer. And I remember Einstein saying to me: ďI can explain either of these things, but I canít explain them both at the same time.Ē Thatís all that I remember. I donít think very much else took place. One used to see him occasionally at meetings of the Rubens Colloquium, which I donít remember now was either every week or every fortnight. There would be very informal meetings in Rubensí Laboratory, in quite a small room packed with people, and somebody would be given an account of something that had been published. Not an account of his own work, except by a visitor on occasion. But the general thing was an account of something that had been published and then people would make comments on it. There were some very interesting occasions for me because I saw numbers of people whose names Iíd heard of but knew no more about than that. I suppose I met Lise Meitner, though not for the first time, because Geiger took me to Dahlen to see Otto Hahn, who was then at Kaiser Wilhelm Institute so I met Otto Hahn and Lise Meitner there for the first time, a very long time ago, in the autumn of 1913. And theyíve only just died.

Weiner:

Yes, both in the same year.

Chadwick:

They both became good friends. I was very fond of both of them.

Weiner:

Were all of these discussions and conversations in German, your conversation with Einstein included?

Chadwick:

Yes.

Weiner:

You must have learned enough by that time through Geigerís class.

Chadwick:

No, I certainly didnít learn very much through Geigerís class. I learned a few words. I learned to be able to read, or at any rate to get some idea from a German publication, but as for speaking, no I had to pick it up there. It was just a necessity. Geiger spoke English, of course, and perhaps some of the others did, but I knew not a single Englishman then in the whole of Berlin. I was in the middle of Germans, so it was my business. I can remember meeting an American once or perhaps twice, who must have been working with Rubens, or perhaps Nernst. His name was Tate. Does that mean anything to you?

Weiner:

John Tate was a physicist who was at Minnesota.

Chadwick:

I donít know. He died some years ago.

Weiner:

He was the editor of Physical Review. He was at Minnesota and worked on ionization and things in that area.

Chadwick:

I donít know what he was working on in Berlin because, as I say, I met him perhaps once or twice. That was all, and we had very little to say to one another. It was just in passing. And, you see, the Reichsanstalt was in Charlottensburg, two or three miles from the University and Rubens Institute.

Weiner:

What were the main sorts of questions that seemed to be on peopleís minds in these discussions? I imagine that if they were reporting on different journal articles, they didnít report on every article, but they picked out the ones that seemed to them to be of most interest.

Chadwick:

Yes, certainly.

Weiner:

Do you recall whether there were any themes of special interest in this period?

Chadwick:

No, I donít. When I said I never met an Englishman that is strictly true. But one Englishman did appear occasionally at Ruben Colloquium. That was Lindemann, later Cherwell. He had worked with Nerst and he had done some very good work with Nernst in the old days. But he used to appear occasionally, only perhaps (once every) two or three months, and I donít think that I ever spoke to him. I do remember his being at one or two of these meetings, and I remember his making some very critical observations on one paper, perhaps on more than one occasion, which was his, I might say, habit. He was very quick — I heard him later in this country — very quick to seize on what he thought was any discrepancy, and he could calculate very quickly in his head, or appear to do so, and he was very quick. He wasnít always right when you thought about it afterwards. I donít think that I ever had occasion to speak to him. He was merely there, and I never had occasion to take part in these discussions. There was always some discussion and it didnít seem to me that I have any part to play except to listen. There were other occasions on which the Colloquium would consist of an account by a visitor of his own work. I remember one occasion Iím quite sure of was when Stark came and talked about the Stark Effect. And I think another — Iím not quite clear — was Kamerlingh-Onnes talking about his work, but Iím not absolutely certain about that because I donít trust my memory completely.

Weiner:

In the course of your own work during the year, you communicated directly with Geiger, and he was essentially supervising your work. Or were you more or less independent?

Chadwick:

In one sense he was supervising my work. If I needed any help he would have been very ready to give it. But I donít remember an occasion on which I did need any special help. Yet he provided me with all the facilities — he was extremely good in that way. He was good in every way.

Weiner:

Was the availability of apparatus and resources different in any way from Manchester?

Chadwick:

In some ways, it was. It was a very large institution with a great number of different departments and some things were localized, such as the workshops. Now in Manchester, there wasnít much of a workshop. One could go and do oneís own jobs or you could get some instruction from Kay or one of the other people, but in the Reichsanstalt, you had to put in an order, or a request, if you like, and that had to take its turn. You might have to wait two or three weeks, depending upon what was happening. That didnít happen very often because I didnít need very much, and if there was any urgency, Geiger would try to do something. I couldnít do anything at all. It was completely impossible. I remember on one occasion a very trivial matter. For some reason I wanted to make an ordinary simple electroscope — I canít remember why I wanted it — but a tin box was all I wanted. I had to go to the tinsmith and give him written instructions. He was busy on making a seat for the lavatory of the — I donít remember his title — but this was a director under the head of the Reichsanstalt, a very important man. And so I couldnít get my electroscope until heíd made this lavatory seat through which warm water could be circulated in the winter. This story spread around the place and we were all interested what would happen when it was first used, and it was almost a disaster because it was too hot for Frau Herr Direktor. So I finally got my electroscope. It took three or four weeks for a simple job that in Manchester would have taken a half hour. I could have done it myself, but you had to go through the steps.

Weiner:

Was that because it was a state institution?

Chadwick:

Yes, but it was also because it was a big place. You couldnít have people popping in and out. There were very big workshops, and, in fact, there was a professor, not of machinery — Iíve forgotten his exact title — but he designed machines in big institutions. I mean the centralization of work shop facilities is quite usual and necessary in a big institution, but, at the same time, I think it is also necessary to have some small facilities which are available for the research worker himself so he can go and use it and get on with the job instead of waiting for three or four weeks. I had an argument about that during the war. There was a professor of — say, machine design — I suppose we may have some now, you almost certainly have, but that was something quite new to me. He was very good indeed, but of course I didnít need anything of that kind. If some people wanted gratings ruled in a particular way, he used to make something to do it. But weíve got off the point.

Weiner:

I was pursuing differences in the atmosphere and style of work and in the types of problems in Berlin and in Manchester, and this was one.

Chadwick:

That was quite small. Essentially there was very little difference, because I was working with Geiger. I was often the only one there. He had an assistant — I donít know what his title would be — who sometimes but not always worked in the Magnetische Haus. The first I remember was a man called Kolhorster. He was one of the first people to go up in balloons to measure cosmic radiation. Not the first, because Iíve forgotten his name.

Weiner:

Hess?

Chadwick:

Hess, yes, but Kolhorster followed very quickly. What happened to him Iíve forgotten. Later there was Bothe. Probably there werenít any more in my time because I was only there one year.

Weiner:

How would you characterize that year in terms of the effect it had on you and the role it played in your subsequent development?

Chadwick:

It was a very interesting year in some ways. I got to know people who were working on quite different things in the Reichsanstalt — completely different things — some on the engineering side, some on the optical side, and so forth. And I found them extremely friendly indeed, surprisingly so. It was a very good atmosphere. They adopted me. I was much younger than most of them, of course. There were about half a dozen or so of us who used to lunch together practically every working day. The hours for the scientific staff were nine to three — we didnít have any break for lunch. Geiger would usually bring in bars of chocolate, and I got in the habit of occasionally bringing in bars of chocolate too to stay me until three oíclock. But then at three oíclock, down tools, and six, seven or eight of us would have lunch together. For most of them, that was the end of the day, but for some of us — certainly for Geiger and me, as a rule — it wasnít. We went back to the laboratory and went on with whatever we were doing. But sometimes if it were a particularly nice day and we felt like it, three or four of us would go for a walk in the country, and come back and perhaps have dinner together or not, depending upon the state of our pockets.

Weiner:

You mentioned that for three years you went without lunches in Manchester. How did the situation change during this period. Was the scholarship adequate?

Chadwick:

In Berlin, yes, indeed. Living was very cheap in those days. Although the scholarship by modern standards would mean very little. It was 150 pounds a year. But that was more than the stipend of a demonstrator in the laboratory who began at 120 pounds a year, so 150 was adequate. There was nothing to spare. No riotous living was possible on it, but one could manage quite well.

Weiner:

When did you get back from Berlin? Was it in the summer? You were there the academic year 1913-1914.

Chadwick:

I was interned. I was a prisoner.

Weiner:

I was confused. I knew that you were interned, but I didnít know it was at this time.

Chadwick:

I was a civil prisoner. Things happened very quickly. It was then I found how kind my German friends were to me. Geiger was in the reserve and he had disappeared before the Declaration of War. He was called up and he had to go down south to report. And he advised me to go home. Everybody else said no, youíll only get into a muddle, youíll get mixed up with the troop transports which had been taking place for a long time. One of our group of friends lived in East Prussia. Heíd been home for a visit, and, on coming back — it was about a month before the war started — he told us that troop trains had been passing through during the night regularly, blacked-out. And the others didnít believe him. I never saw any English papers. There was very little in the German papers and things happened very very quickly. I tried to take Geigerís advice, particularly after I had been in a great big meeting at the Schlossplatz. Somehow or other I happened to be in the middle of Berlin I donít know why, and I saw there was a lot of excitement. I went along to the Schlossplatz there, and it was full of people. They were waiting for the Kaiser to come out and say something to them. So he did. He stepped out on to the balcony with what one would call military precision and delivered a few words most appropriate to the occasion, only quite few, and stepped back again. And all was over. I got home. On the next day — it was a Saturday morning — I went down to Cookís to see if I could book a ticket to Holland and then home. They said, no, we canít do it that way, but we think we could get you through Switzerland. That seemed to me to be taking far too big a risk. I hadnít got much money. As a matter of fact, before Geiger left, he gave me a check for 200 marks in case I was short of money and had to spend more than I expected to get home. When I told my friends what had happened at Cookís, they agreed and said, youíre bound to get into trouble if you try to go to Switzerland. Then youíll have to go through France, and if things do happen, you will be in a mess. The worst thing that can happen here is that youíll have to stay for a month or two and then youíll be pushed out. Everybody said as soon as the troop movements are concluded you will be able to go. In fact, you will be asked to go. So, I took their advice. And it wasnít until Monday night, or Tuesday night — Monday, I think — came the Declaration of War, and the British Ambassador handed in his papers. And it so happened that four or five of us dined together that night because we thought weíd go into the city and find out what news there was, if there was any fresh news. We got down there and found a howling mob. The British Ambassador had handed in his papers. The crowds were out, As I was told, or as perhaps was reported in the newspapers the next day — I donít remember exactly — some servant in the British Embassy had thrown some grossing (?) amongst the crowd assembled outside who so far had done nothing but break the windows of the Russian Embassy. And then they lost their temper, quite naturally, and mounted police were brought out to keep the crowd in order. And one of the officers said something which exasperated the crowd and made them angrier still, so they went for the police. My friends said, oh, this is no place for you, and they took me off across the river to a place Iíd never been to before to be out of trouble. And the next day they insisted upon taking me to a police station to get a permit to say that I could stay in Berlin until I was able to leave. Now that was written on a small sheet of papers that very nearly got me into trouble later. But nobody could have been kinder than they were. They looked after me. It made no difference whatsoever after the Declaration of War.

There were others in the laboratory who went out of their way to be kind to me whom Iíd hardly ever seen before. That didnít prevent me from getting into trouble as it happened, of course. A couple of weeks later I was arrested in the middle of Berlin with a German friend. We were both arrested at the same time for having said something we hadnít said, and taken off to a police station. Fortunately for me, it was a Sunday evening, and the police station was full of police officers. Otherwise, it might have been a bit more difficult. But, after lengthy questioning separately, we were told we were to be taken to prison, and if we liked, we could pay for a carriage to take us there. So we said, yes, we didnít want to walk handcuffed to a police officer through the crowds with the chance of probably getting into trouble, probably getting beaten up indeed. We went in a kind of landau. We were on opposite sides, each with a policeman at his side gripping us, and the policeman on the opposite side holding his revolver. And when we got there, I was shoved into a cell. My friend was shoved into some other cell, making expostulations that he was a German citizen, a civil servant, and this that and the other. And a couple of hours later, I heard what I thought to be his letting out. It was. They let him out after a couple hours more examination, looking at his papers. And, of course, he went to the head of the Reichsanstalt and told him the story. But I was there for about ten days.

Weiner:

What was the specific charge?

Chadwick:

Iíd said something.

Weiner:

But they arrested you while you were walking on the street. Did they claim to have overheard you say it?

Chadwick:

Yes, I think a woman and her daughter claimed to have heard one of us say: ďDie Saubande hat gesiegt.Ē What we were doing, weíd been out in the country as we often did together, and we had dinner in Berlin, We thought weíd like — before we got on the underground to go home — to hear the latest news, which was posted up on a cylindrical pillar. While we were walking there, we were arrested, and this remark was supposed to refer to the taking of Liege, which had just been put up on the pillar. Of course, it was nonsense, but unfortunate for me.

Weiner:

You were saying that the women denounced you.

Chadwick:

Well, fortunately for me, they said it wasnít my voice they had heard, but it didnít make any difference. I was there for ten days with nothing to do. After a few days, I was told that there was a prison library and that I could get a book. I think I did get a book but I was also told that I could buy some. On the very day that I was going to be let out, I was told that I could buy some food. What we had was a metal bowl in which was poured some coffee for breakfast — it was drinkable which was all you could say for it — and a piece of bread, which was all moldy, because it had been stored for about thirty or forty years. I was told this by German friends who went into the Army.

Weiner:

When the laboratory obtained your release, did you return to normal status?

Chadwick:

I did for some little time. But it was quite wrong. I ought to have known it was wrong to go on working in a country at war in a German Government laboratory.

[1]Magnetization of Iron by High-frequency Discharges, by E. Rutherford, Transactions of the New Zealand Institute, 1894, vol. XXVII, pp. 481-513.

[2]A Balance Method for Comparison of Quantities of Radium and Some of Its Applications, by Ernest Rutherford and James Chadwick, Proc. of Phys. Soc., XXIV, 1912, pp. 141-151.

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