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In footnotes or endnotes please cite AIP interviews like this:
Interview of William Lawrence Bragg by David Edge on 1969 June 20,
Niels Bohr Library & Archives, American Institute of Physics,
College Park, MD USA,
For multiple citations, "AIP" is the preferred abbreviation for the location.
This interview begins with recollections of Bragg's family members, and a discussion of his family's influence on his social development and early interest in science. Bragg then goes into detail about his early works, before discussing his x-ray research projects with his father, William Henry Bragg, and their shared Nobel Prize in 1915. The final portions of the interview focus on his undergraduate years at the University of Cambridge, his role as a part of J. J. Thomson's research group, and his relationship with C. T. R. Wilson. Other topics and affiliations discussed include: Niels Bohr, Norman Campbell; Ernest Rutherford; Cavendish Laboratory; and x-ray crystallography, among others.
Sir Lawrence, I'm going to ask you some questions about your family life and about the dominant figures. Who was the most dominant figure in the family?
I can't say who was the most dominant but I can think of four people whom I might talk about in that connection: my father's old Uncle William, my grandfather Sir Charles Todd, and my father and mother what sort of people they were and how they influenced us, and an aunt who was very dear to me because she was very much the youngest of my mother's family and more my own age and she used to do all sorts of things with me when I was young.
Could I just take up the Uncle William one first? What kind of a dominance or kind of an influence was he on you?
As far as I was concerned it was a secondary one through my father, for he, I think, determined very largely what sort of person my father was. My father had a curious boyhood. His mother died when he was very young. He came from a farming family in Cumberland. His father had been in the merchant navy and then went on to farm in Cumberland and Uncle William was a very dominant sort of person. He really went down and just took my father away from his family thinking he could look after him better in Market Harborough than his brother could with such a large family on his hands. And so my father grew up under old Uncle William who was a bachelor of bachelors. He had no idea of social life of any kind whatever. And Uncle William was tremendously proud of him because my father did so well, first at school, and then got this scholarship to Cambridge. He was really one of my Uncle William's main interests, I think, in making (?) this young boy.
Uncle William had intellectual interests then?
He had no intellectual interests whatever as far as I can make out. He merely was a chemist. He had a chemist's shop, a pharmacy. He founded it and he also built up quite a fortune doing that and owned various other things — brick works and so on — and quite a lot of property in Market Harborough. He was probably one of the leading citizens in Market Harborough. Among other things he got the little grammar school in the Market Square set up again — a curious little grammar school on posts, a minute school — and my father was one of the first pupils in this new school again. And then my father went to King William's College and then he got this scholarship and went to Trinity.
Could I ask a bit more about Uncle William? He did also, did he not, have a hand in local history societies?
I think so. He had many other interests. Yes.
Wouldn't this in some way predispose intellectual … it isn't intellectual in the formal sense but in a general curiosity.
— quite likely, yes. Perhaps I was going too far when I said he was not intellectual at all. I meant he had no learning. I don't think he had gone to any sort of an advanced school. In fact, I'm sure he hadn't. When the family broke up at my father's mother's death, it was Uncle William who saved it by going to work hard and supporting his brothers. He was a man of great character and power and so on, but no academic knowledge or tradition. It was quite a new idea for anybody, say, to go to the University in the family. It was my Uncle William who had the sense to see that this young boy was that type and to see that my father got this chance.
Now, Uncle William, I imagine, was talked about a lot in the family. What kind of impression did you get? I mean, it must have created a sort of myth of him.
Well, I knew him. We lived with him for six months. When I was seven years old we came to England in order that we might be shown off to Uncle William, who was my father's patron. He had created him, as it were. It was a great grief to Uncle William that my father got this post in Adelaide. I think it was a mortal blow almost because he set so much store by him. And he was very proud of him, of course, so after my father started a family there we all trekked back to England for a year.
And did you find that the reality matched up to what you had expected?
I was too young to have any ideas about him but I was very impressed by Uncle William. And he was amazed at us. He had never thought of children with imagination and playing games and so on. I know we were a perpetual surprise to him. We were very afraid of him but he was very kind to us.
Now, I get the impression from what I have read about Uncle William chat he was very rigid and puritanical, and if you say that the influence on your family through your father because he created effectively your father…
My father had no social life as a boy at all. And when he went up to Cambridge he really had no friends. He hadn't been taught how to have friends, if I can put it that way. And it was a wonderful thing for him to come out to Adelaide to the free life (?) there with quite a good position as a professor in the University. The family had very few social traditions at all.
I take it that one of Uncle William's characteristics was disciplinary. He was a stern disciplinarian and his views on religion were somewhat rigid, I gather?
And in both these things your father presumably imbibed this and took it with him through Cambridge.
Yes, in fact, he went through a very bad time at the end of his school life as he mentions in his own autobiography when some revivalist got hold of him and some of the boys and they spent all their time thinking they were going to hell. That had a big influence on him. But I should say that in Adelaide he was a church warden and went to church constantly but I don't think he ever talked to us about religion. I can't remember that in any way. We weren't rigidly brought up except we were taught that it was very very much the right thing to do to go to church.
So effectively, going to Adelaide, he's reacting against or allowing himself to become social.
Yes, it's his first breath of any kind of social life, seeing people who weren't in the family.
And also, although presumably he appreciated the discipline his Uncle William had given him, he clearly also didn't want to impose that kind of discipline on you.
No, my father could never bear to be stern with anybody. It was not in his nature. For instance, when I was a boy, because of this family tradition of close links with the church, I taught in Sunday School. It was the most awful ordeal I'd ever been through. I was not at all good at it. The wretched little boys and girls played up with me and I used to dread Sunday coming around when I had to trek around and teach there, particularly as my views were already rather of the free-thinking kind.
Could we come back to that a little later. I would like to ask you about one or two of the other figures.
Of course I had a tremendous figure in my grandfather who was one of the great men of South Australia, who had gone out there in 1855, who had gone out in a curious way as Astronomer Royal, and Director of the Telegraph, because when he was at Greenwich he used to have to arrange for the time signal at Portsmouth. As an expert on the telegraph lines, which was something quite new then, he was sent out to look after the telegraph in South Australia. He started by putting up a telegraph line at Fort Adelaide, then put one across to Melbourne, and then his final enormous feat, he put one from Adelaide to Darwin across the continent. He was also quite a good astronomer, made a Fellow of the Royal Society, for instance, for some of his work, and he was really the center of our life. We used to go there in a horse cab every Sunday and have a formal Sunday dinner with Grandfather and Grandmother, and Grandfather used to take us round because he read all the instruments on Sundays. We admired him enormously. He was a great influence in the family.
You saw a lot of him then?
A lot of him. He never talked to us about his work. He was a very silent man.
But what kind of a person was he? Was he a dominating man?
No, he was not, quite the reverse. He was the kind of man who was rather vague and I think at bottom a really good organizer, but who brought out the most extraordinary loyalty under the people he worked under. I realize now thinking back on the way people spoke to him and talked to him, that was the main characteristic.
Yes, and you felt in the regular contacts you had with him, he was effectively a family man?
He dandled you on his knee, and so on?
Yes, oh he was very kind to us children and we didn't repay him properly. I remember one of the things in the observatory was the evaporation tank, which of course was very important in Australia, with a guard ring round it and a tank inside. Grandfather, every Sunday, would measure how much water had evaporated, little knowing how many tadpoles we had put in that tank. But a great thing, too, about it was that at the Observatory we got all mixed up with — he became Postmaster General as well after putting up this line — an enormous amount of government stores were kept there: delightful things like copper wire and copper sulphate and old batteries and what not, which, of course, we boys discovered and raided and used as the material for many of our early scientific experiments. I think that had quite a lot to do with my playing with science in the early days.
How old were you when you last had any direct contact with him?
When we left England. He died shortly after we left England and that was when I was eighteen years old.
When you left Australia?
Oh yes, when we left Australia.
So would you say he had an intellectual influence on you, if he didn't talk about his work and so on?
No, he told us stories about his adventures sometimes.
But he was always sort of a character in those stories?
A character, yes, but I think we were impressed by the meticulous accuracy with which he read all the readings, and seeing him do it so well.
What about the women in the family? You mentioned an aunt?
My mother's youngest sister, Aunt Lorna, was very much younger. My mother was only 18 when I was born but Lorna was, I suppose, ten years younger, so she and I were not very different in age. She was a delightful aunt who used to allow me to do all the things that the family didn't allow me to do like reading at breakfast and so on when I was staying with her. And we played all sorts of games together. She used to read to me a lot when I was a small boy, Grimm's fairy tales and so on, so I had a very special relation to her. And later on when I was older we had French lessons together.
But once again, the last you saw of her was when?
She only died recently and when I went over to Australia a few years ago she was still alive and I saw a lot of her.
What about your mother?
Now, my father and mother were about as different as you can possibly imagine. My mother had grown up in a very ramshackle family with an extremely vague mother of hers. My grandmother was the vaguest person you could possibly imagine. She'd never had much education, partly because the family circumstances were very straightened at the time and none of them got very much, and partly because she was allergic to being educated to an extraordinary extent. And she was one of the vaguest people I've ever known. She didn't know any bit of knowledge exactly of any kind whatever, I think. Everybody loved her dearly because she was so kind and always so keen that they should have a good time. She was extraordinarily clever with her fingers. She could make almost anything and she was a very accomplished artist. I think she might have done anything with painting — she would have been first rate. She could never bear anything ever to be wrong. We could never say that "so-and-so was not good" or something of that kind. Mother worked and worked on us until we said, "Yes, he was after all." So it was rather an unreal life when we were children. My father could never bear to talk about anything except ordinary everyday happenings. He couldn't bring himself ever to talk about anything emotional or go into emotional problems. He just liked everybody around him to be quiet and look happy. My mother was unreal a bit because nothing could ever be wrong. With her it must be all white and never black. And so I think we lost out a good deal, as boys, from emotional repression, not being able to say what we thought.
Would you say that this characteristic of your father went with a very great difficulty in tolerating strife with other people, differences?
Yes, he couldn't bear to be at variance with anyone. He couldn't bear it. I never heard him row anybody in my life. And also because of his curious cut-off education he hadn't mixed with people, so his contacts with other people were on a very undeveloped plane, if I can put it in that way. He was never a man amongst men, and I grew up the same way. I always found that side of life very difficult indeed.
So, in this respect, you've actually acquired from your father effectively the same …
I'm sure I did because I never had boys I played with naturally when I was young. The family hardly ever had anybody else in from outside and I was bad at games, which, of course, is one of the great things which makes one become a mixer. I have felt that very much all my life.
Yes, but your father was good at games?
My father was good at games. That is one thing that helped him very much when he was a boy. He really was good. He was captain at cricket, I think, at his school. He was a first-rate tennis player. He introduced lacrosse to South Australia — brought it from Cambridge. It caught on and became one of the greatest Australian games.
And yet he was reserved?
Yes, very reserved. I don't think he had any close men friends.
Would you yourself say that you share this characteristic?
I broke through it to a certain extent, being very fortunate at Cambridge in meeting other young men there whom I made deep friends with, and that took me out of myself for the first time. I never got that until really after I graduated at Cambridge and had close contacts with some of the postgraduate people there.
Yes, but it's still possible having done that, not to really be able to tolerate dissonance with other people. Have you gotten to the state where you enjoy a row?
I loathe a row. I feel awful afterwards, but I do have them. I get worked up to a terrible state sometimes of indignation and boil over after having kept it under the safety valve for too long.
Your father wouldn't approve of that?
No, no. My sister felt that trouble at home very much. I always remember her saying to me: "Sometimes when you come home and have one of these outbursts, Willie, it's like somebody in the family's opened all the windows."
Your father, if there was a row in the family, how would he react?
He hated it. He'd try to run away. If you tried to talk about anything personal to him, he'd take refuge in talking about how the V~c were getting on.
But if he came across you and your brother having a shindig of some kind?
We sometimes had rows. He sometimes got exasperated and boxed my ears, but not often, though.
Would he withdraw a lot?
Yes, yes, withdraw.
So who operated the control in the family?
My mother working on our sense of responsibility and remorse, as it were. She entirely did it through our feelings, tried to explain to us we really had been bad to do so and so.
And your father was a person who never talked of any person's feelings so your mother, as it were, was exploiting — not in the evaluative sense — but exploiting, in the emotional sense?
Doing it emotionally and not by knocking us about.
Now, you did mention about your aunt that when you went to stay with her you were allowed to do the things that the family didn't allow you to do like reading at breakfast. That implies there were things that the family didn't allow you to do. There was in fact, some pattern laid down. There were rules in some way established and in some way mediated. There was a pattern; there was a form set out in the family; there were things you did and things you didn't. Could you locate who did this? Was it your father's idea or your mother's?
It was far more my mother, I think, and doing it in her own way which she'd entirely learned herself, because she'd married very young and so soon been cut off from her own family, which anyhow was a very vague one. As I say, all sorts of queer things happened in the Todd family. And so she entirely built up her own pattern of what life should be like and I think we conformed to it because we realized we would hurt her so much if we didn't.
I imagine it was a fairly loose pattern, was it? It wasn't rigidly set?
No, it wasn't rigidly set. I don't quite know what you're thinking about.
I mean times of getting up and going to bed.
Oh yes, and not talking in bed, and not reading at breakfast.
Not talking in bed and not reading at breakfast. What other things can you remember of a sort of family pattern? Going to church every Sunday twice?
No, we only went once on a Sunday. My dear mother was always late and it always had to be acknowledged openly in the family that it wasn't she who was late. That is a small incident that occurs to me, like the thing in the family that my mother could never drink a whole glass of beer, only two three-quarter glasses.
I get the impression of a largely self-contained family here — isolated.
Very very isolated.
Living on its own resources, which were fairly substantial.
Yes. We had delightful summer holidays. We all used to call it the "family summer," the summer holidays. Of course, in Australia you could have a wonderful holiday.
But although you went to day school, and presumably had acquaintances at school, you weren't really knock-aboutly friendly with them?
No, no, I found that very hard.
Your knock-about friendship was with your brother?
My brother and I did a lot together, but most of my interests I got from hobbies. I was very keen on collecting shells, for instance. I really did build up a very fine collection, and found quite some new ones. For a boy this was rather unusual. I even got as far as having a new one named after me — that kind of thing. But it was all done on my own.
And a favorite Christmas present would be a book of shells?
Yes, I did a lot of reading, and reading science. My father had quite a collection of old books on science. I used to read those voraciously. Just merely reading about physics interested me.
So it was a family that was isolated in which your father by and large rather willed you to be a happy family in the sense that you knew you would be offending him if you said anything, and your mother operating in the distance so that it all went nicely.
Yes, he wanted us to be happy and quiet. And any criticism of any person hurt him very much.
Now your contact with your father — apart from talking about the weather and the crocuses?
Well, he used to talk with me and fascinate me, talking about science, and, of course, I learnt a great deal through his being a Professor at the University because he would bring bits and pieces back from the University from which we could make batteries, and we made a telephone. We made a bell that rang; we made two motors — my father and I together — with these bits and pieces. We had — he gave us — a workshop with tools and so on. In that material way I had a lot of contact with him, and it was fascinating to see the way his mind worked and the way his fingers worked, because he was a very neat man.
Did he have a laboratory at home?
No, he didn't have a laboratory at home but he made lots of things at home. He wanted to make a greenhouse for instance. He made a railway for us with wooden rails, I remember, with points and all —he taught us how to make it — which we used to run.
I imagine he had a study at home?
He had a study, yes.
Was it completely sacrosanct? Could you creep in?
We could go in there. We often sat there in the evenings. And my father and mother were keen on music. Music was so different in those days because there was no public way of getting it of any kind whatever. All the music we ever heard was when the brass band came round. My father and mother though did play and sing, and my father had a flute, in a very amateur way. But that was one of their great interests.
Your father talked science to you. Did he actually talk about his research?
Yes, he did. My first memory of my father talking about science was when I was seven, when the bedtime story I always asked him to tell was about atoms — what was oxygen, and what was hydrogen, and so on. I don't know why I was fascinated but I was. But then later on he talked about research, when he began to think about it, because, you see, I was fairly old before he started thinking in any way about research. He was always interested. one of the things I remember very vividly is my father and my grandfather together experimenting with Marconi's system of radio, to see how that worked. And they put it up two miles and seven miles apart and sent the first messages to each other in South Australia. We were allowed to help even with that, of course, and go down and see it happening.
How old were you then?
Fourteen — thirteen or fourteen. And then he got — at my grandfather's he probably observed a seismograph — so we made a seismograph which recorded us walking around the room and so on. I really had that kind of background which made my brother and myself do a great deal of what you'd call practical physics.
In a little note you published in The New Scientist about your father you said that when he started his x-ray experiments, the first ones, that you were used was I think the phrase you used was "scientific confidant,” you were able, as it were, to talk with him.
Yes, he didn't start with x-rays, you see. He started with alpha rays.
Yes, I beg your pardon.
He had to give an address as President to the Physical Society of the Australian Association for the Advancement of Science, and decided to describe these very new results of Rutherford's. That made him interested. There was a kind of half-baked way of explaining alpha ray ranges at the time. My father didn't follow this, and managed to get hold of about seven pounds worth of radium and worked out the ranges of the alpha particles with his own grids and so on. That was his first start in research, and he wrote to J.J. about it. But J.J., I think, didn't realize what it was all about at all and never replied and my father was very worried about that. And so he wrote to Rutherford and Rutherford was thrilled. And a tremendous correspondence passed between my father and Rutherford about it. And my father used to talk to me then, you see, about his results. And then he realized — he was practically one of the first to realize, because these ideas were flitting around at that time — he realized that all the energy of gamma rays and x-rays was being put into certain direct hits on atoms and you see secondary beta rays as they called them in those days. He did the most ingenious experiments to prove that, and that convinced him they must be particles. It was the other side of the shield in the great quantum dispute. Is light particles or waves?
Your father was interested in the nature of these rays?
He was fascinated with the basic nature of that. He had a great controversy with Barkla which gave him great pain, before he came to England and after he came to England. And then, of course, that is why he was so interested in live experiments.
Now when your father started this research for this reason that he was invited to give an address, he didn't know Rutherford or J. J. Thomson?
No, he didn't know Rutherford. I don't think he knew Rutherford. He certainly knew J.J. Although he didn't do physics at Cambridge, he knew J.J. I can't get the dates quite right, but about that time, Soddy came out with a specimen of radium and showed the fluorescence — I remember seeing it through quite a thick steel tape caused by the gamma rays — and that some excited my father very much. My father then gave some popular lectures which I can remember quite well, saying that rays from radium broke down resistance in the air and discharged a charged body. He was awfully good at popular lecturing. And, at what stage after that — I think it was after Soddy and after he started these popular lectures that he became so unconvinced of the current explanation of the tracks of alpha rays and started his experiments and got the ranges.
Now he knew J.J. before and he wrote to JJ but JJ didn't take up that special correspondence. He wrote to Rutherford out of the blue, as it were.
Out of the blue.
Did he correspond with anyone else? With Von Laue?
No, no, no. I don't think he ever corresponded with Von Laue. But when we started doing the crystal work together, of course, there was quite a body of correspondence, which I won't go into, between people who were fascinated by this new insight into that.
I think we'll stay in the early stage when your father was at Adelaide.
Rutherford was his confidante, and I found in the Cavendish amongst Rutherford's papers these letters that my father had written, many of them twenty pages long. In fact, he wrote papers to Rutherford, as they did in those days. It was still in the days when a few scientists wrote letters to each other instead of publishing their results.
Now, could I ask about your relationship with your brother, because your brother having shared this same environment… He was what, a year younger than you?
He was a year and a half or two years younger than me. Anyhow, we did a great deal together, though he was very different from me. He was good at games, a much more practically minded person, very much a mixer, very popular, terribly outgoing. He, of course, got into all the clubs and rode and all the rest of it, but we were thrown together a great deal. We did a great deal together, made all sorts of things together, all kinds of games we played together.
He did science at Cambridge too?
No, he did engineering. He was young enough to go to school when we came to England, down to Horondell(?) and then afterwards to start engineering. Then he was killed at Berippeley(?) after he'd only been to Cambridge a year.
You said that you and your brother were very different. When you were together in the family at Adelaide, presumably your brother was as much involved in the family, and only in the family, as you were. Or had he gotten some contacts outside?
Not very much, I think, no, the whole tendency in the family was to keep the family together. I was trying to remember. Yes, I think he was more of a mixer than I was. He had various friends who he used to do things with. There were other boys in the town we used to play cricket with, and went to parties with them and so on. It wasn't entirely...
Were you aware of him being different? Did you argue really different points of view with each other over important matters?
Well, I was trying to think. Eighteen and fifteen — I think we did -but we were both too young really to argue very much at that stage. He used to get very impatient with my vagueness sometimes. But he was an absolute (?) — terribly admiring when later on at Cambridge I followed this research on my own. I always remember that — terribly admiring.
Your father not talking about matters emotional, presumably he didn't talk in the family about politics?
No, I never heard him mention politics. Only it was very very hard if you went to him with some troubles or emotional problem, he would do almost anything to avoid talking about it. He couldn't bear to talk about it. He'd write sometimes the wisest letters afterwards about it but he just couldn't bear to talk.
And he didn't talk religion, didn't talk theology at all? You didn't have to really pray?
No, he did write about it.
Yes, he wrote eventually the Riddell? Lectures. Now, did these come as a surprise to you. They were late — in 1941, they were published.
1941, yes. No, I don't think they did quite because one got an idea that my father inside thought very deeply about these things because sometimes when I had a problem he was not inclined to talk about it but he would write afterwards going quite deep into some fundamental matter.
Did he read a lot of religious material? Did he read the Bible?
Yes, with deep interest. He’d had… even I got a tremendous Bible education. We knew the Bible from cover to cover in a way that children never learn it now.
But this didn't impose itself on the family. You didn't have Bible readings or family prayers?
He had a great reaction from that bad time at school when some religious revivalist got hold of some of the senior boys and almost drove them mad. They were thinking all the time whether they were probably going to hellfire forever if they didn't do this or that. When he came round after it, he had a tremendous feeling against that type of emotional religion. But he liked thinking of the relation of religion to science.
Now the effect on you of this family background, I mean his upbringing with Uncle William made him see religion as essential and important, and then he had this reaction against it though it still remained important to him have you the same feeling about matters religious, because as I get the impression you had the regular Sunday church-going which was somewhat of a formal obligation? Did it link with the pattern of life in a meaningful way so that you entered into it?
You mean later on in my own life, my own inclination?
I've never been so regular a church-goer. I do go. We always … the family have had regular… being a family man and because my own convictions are so deep.
But have you acquired from your father, in this rather curious non-communicative way, the sense that religious problems are deep and important?
Certainly, yes, yes. I'm very interested in the relation of science to religion and what that side means. I very much like reading books like Teillard de Chardin.
You do read quite a bit in this area? It does give you pleasure?
Yes, I'm always interested — with a very open mind.
You did say earlier on a free-thinking turn of mind. So you would be low-church Anglican?
I never thought whether I was low or high. I just go to church with my wife. Sometimes you see I could be in the garden instead, but feeling there is a sort of discipline in a way that it would be very wrong to give up.
Political views — your father didn't talk about this? Was he essentially a conservative?
I don't think so. I think he was a-political, and I think I am a-political too.
You presumably both vote?
We generally voted… did we always vote Conservative… perhaps we always have. I'm not sure. Anyhow, my wife is always in sympathy — she has a lot of public life — in being a-political in it, and I sympathize with her very much.
You don't see in any way any relationship between your scientific work and discipline and the values that are involved in that and political …
Certainly not. I see great relationship between scientific ways of thinking and religion, I think. I always tried to think it out the best I could.
Now, you left Adelaide with the family and a degree to go to Cambridge?
I went to the university very young — at 15 actually — and got my degree at 18, in mathematics.
And when you were 18 and you had just gotten your degree, your father went to Leeds as professor.
He was invited to go to Leeds. He had made a reputation with his research work and become a Fellow of the Royal Society and got this invitation to come to Leeds.
And you then were registered at Trinity, was it, at Cambridge, as an undergraduate, and at the end of the first year, you got a scholarship?
That's right. I got a scholarship with a temperature of 104. I always remember that. I was having very bad flu, and it was rather tough. But I was allowed to take it though I was feeling queer, as a matter of fact, and I remember the Master, Butler, insisted on reading all the essays. He was very struck with mine; he said: “It shows a fertile wild imagination,” but I think it was the temperature more than anything else.
Now you did Math, Part I, and Part II Physics in two years? And then went on with a Studentship?
Yes, I got some kind of — yes, I suppose it was a Studentship — I forget what it was called. It was one of these student ships that was given to the University as a whole, not just to Trinity.
Now, before we go on to your work with J. J. Thomson actually at the Cavendish, during your undergraduate career, did you make close friends and confidants?
One or two very close friends. I started a friendship with the one who was my greatest friend afterwards, my wife's cousin actually, a young man called Cecil Hopkinson. And I had a wonderful time with him because he introduced me to all the exciting things which our family never dreamt of doing, like sailing, skiing, climbing, long walks — all those rather sporting things — and it was like water to a thirsty man. It was wonderful.
So you went with him on a lot of this, and you struck up a close social and personal relationship too?
Yes, a very close personal relationship. Yes, we were as different as possible because he was so very very good at all these things and I was such a rabbit. On the other hand, he rather liked my intellectual in interests, I think, which were not very strong in his family, and he had them.
He was killed during the war, wasn't he?
He was killed in the war, yes, quite early in the war.
What was his intellectual interest? What was he supposed to be reading?
He was an engineer and I think he would have made a good one. He was a very practical boy and had tremendous character, a lot of character.
Did he have strong views on things that influenced you?
He rather had his family views which I enjoyed very much tilting at, and he enjoyed my tilting at them. Their ideas on art, for instance, were entirely The Stag at Eve, and so on. I remember my saying once that I thought (?) was the ugliest thing that one could imagine — His family worshipped (?) That was the great thing about him. He really enjoyed a good old argument and having his ideas turned upside down. That's what I gave him. He gave me all the excitement of life.
He also gave you the chance of having arguments.
Yes, we worked in wonderfully.
He was an undergraduate at Trinity, wasn't he?
He was an undergraduate at Trinity and afterwards we were allowed to keep rooms together. It wasn't supposed to be done in those days but I had a very large room with two bedrooms, and we each had a bedroom.
Did you have any other close friends as an undergraduate?
Yes, I had a group which influenced me a great deal. I always tell students this when I talk to them about starting science. We had a small body which used to meet and give each other papers, and really it was very good — very good both to have to give the paper and very good to hear about things that you didn't hear about in the normal way. And I think that was partly responsible for my starting crystallography because some man gave a paper on the theory of crystals at this little group. We used to have dinner together and then go on arguing until about two or three in the morning.
How big was this group?
Six–eight — something like that.
And this was an inter-faculty group? Who would it include?
All Trinity people who were great friends.
That includes historians?
There was one classicist, one historian, and the rest of us were mathematicians or scientists.
Now, the paper on crystals — when would you have heard that?
About 1912, 1 think, when I was just starting research. Before Laue's paper came out, I had that as background to think about Laue's paper — the sort of way atoms might be arranged. Pope and Barlow — Pope was a professor of chemistry at Cambridge—Pope and Barlow had deduced a theory of the structure of crystals in which they thought that atoms have a volume proportional to their valency, and on that worked out a lot of structures. It was quite wrong — the theory — but a wrong theory is always so much better than no theory at all, and it gave ideas, you see, about the way things might be arranged in a regular pattern.
Is it true that up until that time when you heard that paper on crystals that you really hadn't given a thought to crystal structure?
Nobody had. Only people who did mineralogy ever had crystals mentioned to them. It wasn't part of physics at all, and it was quite a new field. It was the first time I realized that atoms in crystals were arranged in planes, I think, not because it wasn't obvious but because I never thought of it.
These discussions in this small group were related to papers which presumably were the papers on people's special interests. I mean the classicist would give a paper on classics, I assume. Did the discussion become very much more general and go into the implications of things?
Yes indeed, and we always got off on to the universe at the end, and discussed the universe. Yes, I remember that Townsend was one of our group and we did a joint paper on Minkowski and we brought out his ideas about relativity. Our title was: "Some Hitherto Little Understood Ideas," I remember. Townsend started, and all the things we had painfully worked out he said, and then said: "Now you go on." I always remember that. I had nothing else to say.
The idea is like the Einstein ideas and so on. They permeated Cambridge.
Yes, you see Cambridge was very queer at that time. It really hadn't yet developed out of being classical physics. I remember Searle in his lectures on heat spending several lectures on the alteration of the zero of the vases made of Vienna glass. That was the kind of thing, you see, that was physics — or the field around an ellipsoid, that had to be worked out with some horrible integrals (I've forgotten them now) — and there was that. The optical instrument was treated in an extraordinarily mathematical way. If actual nature didn't lend itself to the mathematics, you imagined a different kind of nature that did. That was the important thing. There was just a breath of life there. C.T.R. was very exciting about optics. It was classical but it was his way of looking at it that was so good. J.J., of course, was interesting in his funny way, and Jeans. Jeans had begun to catch on to the new mechanics, And I always remember there was a young fellow at Jeans’ lectures who used to take me on one side in the corridor afterwards and pin me in the corner and talk to me for half an hour on where Jeans was wrong. I remember that so well, and this young man was Bohr.
It was who?
Bohr, who had come to Cambridge to learn physics and then realized that the great home for physics in England was Manchester, and he only stayed in Cambridge for a few months, and then went off to Manchester. And there, of course, he developed his theory of the atom.
The Townsend, you mentioned?
Not the Townsend, not the physicist Townsend, no. He was a mathematician friend of mine who went into civil service afterwards.
Were there any other members of this group you recall particularly?
The classicist was great fun because he had that point of view which we lacked as scientists — a real artistry of words, I always remember that. Hyam, the historian became one of the leaders in Longman’s afterwards. Michael Gosling went into General Electric. But Townsend was the most interesting character of the lot.
You said, of the group, he was the one most interesting. What kind of a person was he, apart from his mathematics?
Very precise and meticulous with an elegant way of thinking about things, about everything. He was very interested in new ideas of any kind. He was great fun.
But insisting on precise discussion of them?
Yes, and I was so vague.
Were t here any other undergraduate societies and groups?
I don't know. This really was just after graduation. Oh yes, there was one very important one — the Natural Science Club. That was all Cambridge, and to be elected to that was rather like being elected to the Royal Society, and, in fact, nearly everybody who was ever elected to that became a Fellow of the Royal Society later. It was most interesting. And there we met regularly. There was a host who provided the food for the evening and I think the host also gave the paper at that evening, and we covered all sciences. That was, I suppose, the most forward thing at that time.
How big was this group at that time?
If I remember rightly, it was limited to twelve.
And this was undergraduates or postgraduates?
You could not be a Ph.D. -– anything under your doctorate. I think it was mostly postgraduate, but there were undergraduates as well.
There's this recent French sociological study on the social patterns of undergraduates that worked out that the average French undergraduate knew — 19, knew well enough to talk to quite a lot — 8, and the names of and winked at knew intimately — 3 other undergraduates. This is a social scale, as it were, of modern French universities. Would you have put the social scale of the Cambridge you were in in this kind of …
I should think so for most people, it was. Of course, there were some organizers who ran clubs and things of that kind who would know more.
But you yourself, apart from these two groups you have mentioned?
I had two very great friends and half a dozen quite close friends, and other people that I knew because I played hockey with them and that sort of thing.
Now, you went on to research and you joined J.J. Thomson?
J. J. Thomson in the Cavendish, yes, to do research.
Was he effectively the only research director?
He was effectively the only research director. C.T.R. Wilson was there, and, of course, C. T. R. Wilson is unique — really, a genius. But C.T.R. was a lone worker. He did have one or two people at odd times to work with him, but, on the whole, he worked entirely alone. He ran the Part II let us class and he inspired us tremendously. He wouldn't, as it were, let us get through keeping us at experiments. He made each of us do a little research and would insist on it keeping us at it until we got the most out of it. Oh, he was good. Anyhow, he was doing his cloud chamber. I remember that cloud chamber so well. I remember his coming dawn to a Part II class the first time he got an expansion with alpha rays and saying to me: "They're as fine as little hairs." He didn't expect to get clouds like that, you see, and I went up to the Royal Society with him to set it up while he showed it off to everybody. Well, anyhow, he was doing very fine research but making all his own apparatus. J.J. had Aston working with him. Aston was good, but there again, making all the apparatus. But none of the rest of us, and there were a lot of us, could get anything made in the workshop. We had access to the workshop. We were given a box of tools and unlimited odd bits of wood and tin cans and if we wangled it out of the head steward we could get insulated wire, but it was always a difficult fight to get it. And we had to do the best we could with that. And really we weren't doing useful research because even in those days you must have properly made apparatus before you can get results in even the meanest things. So I was really anguished my first year there.
Now, C.T.R. Wilson had no research student directly working with him?
He did have one or two. Dee worked with him for a while and there were one or two others who did. But he hadn't any research students with him when I was there. He just patiently made the cloud chamber, and when he was asked: "Is that the first model?" he always gave the same reply: "I only made but the one." Wilson worked away at every detail of that and I was just told the other day by somebody who had done a lot of work of that kind that nobody has been able to exceed his results. Nobody has got a cloud chamber to work as well as he did, and they can see now in his photographs some cosmic ray effects. Of course, he didn't realize it but the cosmic rays are there.
Now, you went to lectures by C.T.R. Wilson which you have described as having the best content and the worst delivery?
That's just about right.
You had personal contact with him too, did you quite?
Oh yes, and when I came to do research he was very kind. There were two people in Cambridge who really furthered my research. And it was C.T.R. when, I described my ideas to him who was pretty excited because it had largely come from his lectures on optics, and encouraged me to go on and try experimenting with diffraction directly. He really put me on to that. And the other person was Hutchinson who was the lecturer in the mineralogical department, which was run by Lewis, who was very old. Professors didn't retire in those days. And Lewis had given strict orders that nothing was ever to leave the collection of minerals in the mineralogical laboratory, and under the counter Hutchinson used to sneak them out of their cases and give them to me to make experiments with.
Now, how were these contacts arranged? Was it a matter of J.J. Thomson's seeing that you ought to meet these people or did you on your own initiative?
No, no, it was entirely on my own. C.T.R. and then Hutchinson hearing of me, I think, and then having me to have a talk, and then being very excited at this revealing of the crystal structure.
This was after 1912?
This was after 1912 when I had started on the X-ray work. J.J. was very hard to see. He came round the laboratory generally at half-past one when most of us were at lunch and just looked in and went off again.
So he didn't give you research supervision?
No, he didn't give us research supervision. You can't say he did.
And it sounds almost as if he was responsible in his approach to taking on research students?
I don't know. He was so pressed. His reputation, of course, was so high. And he did have us all to tea, and we would talk about things in general at tea-time.
But there was nobody else in the place really — I always feel the magic number is five, that one man can look after and communicate and share ideas with five other people. That's the maximum. Andin a place that size one got five or six subsidiary research leaders each with their own little group, not everybody under J.J.. It was too much for him. I had grown without his realizing really.
When did you first make the move to see C.T.R. Wilson, to go and talk to him? Had you met him then formally somewhere?
Immediately. I had enjoyed his lectures so much. I think he was rather fond of me and had chosen me as a young student to take this cloud chamber up to London and things like that. We really were pretty close.
So it was through the Part II class?
Yes, through the Part II class, exactly.
Now, what about Pope?
Well, I liked old Pope. He was a fierce old boy but he was very kind to me. He also was thrilled with my first X-ray results, because in the crystal Laue had used, the zinc blende, I had found evidence of a face-centered cubic structure. And part of Pope's theory was that elements ought to crystallize in a face-centered cubic way, and in rock salt, the alkaline halides ought to do it too. And Pope, when he heard of my results, he promptly got specimens of alkaline halides for me so I could take their pictures. That's how I did my first real crystal, sodium chloride.
Now, had you had contact with Pope before?
No, I don't think so. He just heard — well, you see, they would hear about my paper because it was given at the Cambridge Philosophical Society and Pope was fascinated at once and sent for me, and was another of my (not to such an extent) patrons, as it were.
So that paper to the Cambridge Philosophical Society had several contacts made as a result of it?
Yes. I think that's when Hutchinson first realized what I was after and when Pope realized what I was after.
Now, what about this group of 40 research students which J.J. Thomson had? To what extent did they share ideas and pass ideas around amongst themselves?
I don't think they really did very much. We used to meet at tea. J. J. always had us for tea. There was no regular colloquium of any kind that I can remember.
No discussion of papers?
No discussion of papers between them. They did talk to each other of course. We did because there were two or three of us in a room together.
Did you ask any of this sort of: "Have you seen the latest reference in so-and-so to so-and so?"
I can't remember any of that at all.
And were their problems in any way related? Was it possible for them to talk to each other about their own problems because they were essentially in the same thing?
I am trying to remember what they were. I think most of them were like myself trying something far too hard for us, where we really ought to work with somebody else for a while to begin with to learn how to do research with fine apparatus. You see we were all rather struggling to make bricks without straw.
So you have no impression that among this group of getting ideas from them or in any way sharpening up your ideas or your experimental technique?
No, I don't remember it. C.T.R. Wilson was my great friend.
I imagine the morale of this group must have been very low.
I think it was low at that time. There were several people despairing. I remember it was always very hard to get a hold of a pump. I think there was only one in the place, and I remember once passing a poor young lady struggling along and at last she had managed to get hold of the pump. She went out to lunch leaving her door open and I passed and saw the pump inside and I dashed in and got it. It happened that later I passed her room and saw her bowed over her desk in tears, I remember.
So it is surprising that these forty research students stayed if this was the case.
Well, you see, it was the first and practically/only research school then. What others were there in England?
Yes, that was starting out, and, of course, people were starting to other go there. Bohr went there and quite a lot of other Cambridge people did.
What about the European centers?
Going over to Germany? I don't know whether many people did. I think some did at that time. There was a great tradition among the chemists, wasn't there, to go to Germany?
So it was a case then that anyone who wanted to make a real professional career of research physics had virtually to stay in this rather curious disorganized and demoralized group?
Yes, I think really the posts were largely supplied by men at the Cavendish at that time. It had such a tremendous reputation. It wasn't J.J.'s fault really. It was just the way things had gone. It had grown far too fast because he had done such wonderful work.
Now let's talk a little bit about this summer of 1912 when the Von Laue paper was published. You heard about this early in the summer?
Yes, my father and I were on our holiday and my father talked to me about it. He had the paper and we looked at the results in July and August of that summer.
Yes, now the paper was published in the Bavarian Academy in June 1912.
It may well have been, yes.
And your father got a special copy sent or something?
I think Von Laue sent him a copy because my father, you see, was such a great protagonist of the particle theory of X-rays, the particle nature of X-rays.
I wouldn't have thought — I mean, it was brought up after the Second World War in the Cavendish — that the Royal Bavarian Academy, Proceedings of, would have been one of the journals that people looked at very often.
Oh no, heavens no, no one had seen it, I think. I don't think anybody ever looked at it, but of course, when Von Laue's paper came out, it reached a few of the people that realized what it meant, among them my father. And we talked about it, and then I, of course, was very keen to see if there wasn't any way of proving that they were particles, that is why it involved looking at it. I even tried an experiment when we got back to Leeds after the summer holidays of seeing whether his spots in their symmetrical patterns they were made by rays shooting down avenues in the crystal. And there was some indication they might have been because the geometrical relationships in a crystal rather fit in with that, but then, when I got back to Cambridge, I realized looking at all his results, no, this is real diffraction. It must be.
Could I just go back to what journals you were likely to have looked at because you didn't have in your group any sort of journal search? When I did research at the Cavendish there was a formal thing every Saturday morning in which somebody/ploughed through all the journals and we discussed papers.
No, no, it wasn't organized at all.
So you had to do it on your awn?
I can't say I looked at any, you know. I just took over this, you see.
Did you read Nature regularly?
Did we? I think we were just given an experiment like a Part II student might have been given a practical experiment in lab to do, and we plugged away at it. I can't quite remember. No, I think it was more under my father's influence that I started hearing about journals since the Bohr theory. Bohr was which — was it 1911 or 1912 — or was it later that he put forward his theory of the atom? There at least, we did hear all about that, because that very energetic fellow, Norman Campbell — he was very much in on those early days in that curious period when the classical was beginning to give way to the new physics, and he always talked about anything exciting and new that was coming out. He was a very live spirit.
So, in effect, the life of the research student at the Cavendish involved very little library work?
Very little library work.
And by that time you had exhausted all the text books and so there really was really virtually nothing to do to read in your subject?
I mustn't generalize too much. Probably some of the other people there did read journals connected with their work. But what I was doing was just straight Cavendish, you see. It was going on with Langevin and Langevin — well, it's a tradition — the difference of velocities of positive and negative ions. That's the sort of thing I had to do.
And J.J. Thomson never said to you: "You ought to read this, you know."
No, no. I don't remember anything.
Hoe extraordinary. Now, you had this summer when you discussed Von Laue's results with your father and then you went back to Cambridge, and you have recounted several times with some vividness how it all worked in your mind. It must have been a fairly exciting couple of months before you wrote your paper with things working very quickly.
Oh very, yes, I was terribly excited about it, and I was rooming with Cecil Hopkinson at that time and he was thrilled too at seeing these things. I found him so awfully decent. He tried to work out for himself how it worked. I remember him grunting in the corner of the room pouring over my results.
He was the one person you'd been talking to about it? Was there anybody else you went to at this time?
Yes, I think I said something about it to our little gang — the other people of this group — when we met regularly. And they were interested and excited.
Did you go to C.T.R. Wilson or J.J.?
Of course I showed the first results on reflection to J.J. He was excited. He really was thrilled.
This was after your paper?
This was after my paper. He really was thrilled but he didn't get any further. He didn't mention it to me again.
Did he go to hear your paper? Did he know of your paper before you gave it?
I don't think he did.
Did you show him a draft of your paper?
I showed him the paper of course.
Before you gave it?
Before I gave it, yes.
Did he comment on it?
No, unless I don't remember.
The meeting itself?
The formal reading — I've quite forgotten that, except I have a vague memory of how frightfully bad I was at explaining anything. It is incredible how bad one is to start with.
There was discussion of it though, wasn't there?
I don't think so because it was a general kind of crowd with people of all sorts of other interests and so many of them had never thought of a crystal before in their lives. I had more fun talking to the Mineralogical Society about it.