|Interviewer: Robin Hughes
Recorded: January 20, 1992
This is a transcript of the complete original interview conducted for the Australian Biography project. Each transcript page covers one videotape (approximately 35 minutes). There is also QuickTime video of the full interview available. To play the video, click on the icon in the right hand column. In addition, each question in the transcript is linked to the video. Clicking on a question will play the video from that point. (Help with this feature.) Optionally, you can download the video file for offline viewing (approx. 10MB).
The interview has been left it in its original state so that you can get a sense of how the conversation developed. The repetition of some questions, or a question followed by another question, is often due to the end of a particular tape or some other interruption, and has been indicated at the appropriate place in the text. There has been minimal tidying up of the text so that the flavour of the encounter has been kept.
When you've got a moment, I'd like you to - in relation to this interview, to read this letter. This is from a woman who was my secretary for eight years.
That's her name here.
And, after she had been Secretary for eight years, there was a conference on in La Jolla in California, which they wanted me to be present at, which was the opening of the new research laboratories of General Motors.
... and ... they would be opened by Niels Bohr the great theoretical physicist, and Niels Bohr had a habit of walking all the time he was speaking, and he'd suddenly sort of disappear almost into the distance, and he mumbled under his breath, so he wasn't very easy to hear. But these people had the answer, they built a pulpit, not only did they build a pulpit, but the pulpit had a gate on it and then they arranged microphones all the way around the edge of the pulpit, so that wherever he - whichever way he was facing he was facing a microphone. But the point about it was that I had this lassie Barbara Shanahan, they asked whether I could provide any secretarial assistance, so I asked her whether she would go, and she said yes, she'd love to, you see, and so she came along to the meeting, and at the meeting I introduced her to a chap who was an expert in cosmic radiation, and I lost her.
You have to be more careful of your secretary than your wife.
They made her - they made her start at once and - and I thought she'd be coming back with me, but didn't.
(speaks over Robin & Frank - continuing story)
Are we going to do a slate, or are we going straight on?
Right. Well we're rolling now, so we'll be able to come back to pick up where we were in Cambridge, and I was going to ask you, you had been thinking, and dreaming and planning, and working towards getting to the Cavendish for so long, when you arrived was it everything that you were hoping for?
No it was - it was a remarkable experience. The Cavendish Lab was off a little lane called Freeschool Lane, that ran past St Bennett's Church and then behind Corpus Christie College and was a cobbled, an old cobbled lane - a curved lane. And there was a large door that opened onto what were known as the University Museums - all the laboratories in Cambridge in those days were known as museums - they were a big ... I suppose they started as museums and only became experimental with time ... and I walked along this lane and came to this door in which - which I'd been told led to the Cavendish Lab. The Cavendish Lab opened off the side of this way through the building, and I went up three or four steps and into a small foyer, not bigger than my kitchen, out of which there arose this - a wooden staircase up to the next floor, and also with some portraits on the wall, and also it was absolutely crammed full of bicycles. Everybody had parked their bicycle there so they wouldn't be stolen, because a bicycle left in the street was free-for-all. I mean you never - you know, I was continually going to the police station to pick out my bicycle from the hoards of bicycles that had been picked up by the police. Somebody'd borrow it and go from A to B and then just abandon the bike. But everybody, every student rode a bicycle in those days. But I went upstairs where I'd been told Rutherford's office was, to find myself going up along a corridor, which was just bare, wooden ... [INTERRUPTION]
When you arrived at the Cavendish, it must have made a bit of an impact on someone who'd been looking forward to it for so long.
Yes, it did because I discovered that it wasn't at all the sort of place that I'd expected. I'd expected you know, [a] beautiful laboratory. Instead of that it was a terribly old-fashioned building that was approached from a lane called Freeschool Lane that ran by - cobbled lane that ran past St Bennett's Church and around the back of Corpus Christie College - and the entrance to the Cavendish was off a sort of archway that went through to where most of the laboratories of the university were situated, called the Museums. Apparently University Museums historically I expect. But the Cavendish, I found, had a little foyer into which one moved, which was about the size of my kitchen here, a tiny little place with a wooden staircase going up to the next floor. A few portraits hanging on the wall, but the whole of the available floorspace, underneath the staircase and elsewhere, except the approach to the staircase and a way through was filled up with bicycles, dozens and dozens of them just jammed together. Because everybody in Cambridge in those days rode a bicycle and still does I find. When I got to the top of the staircase because I'd learnt that Rutherford's office was on the first floor, I found myself walking along a passageway with bare, wooden floors, and absolutely filthy windows, you know that old fashioned ... [INTERRUPTION]
So the Cavendish was very unprepossessing physically.
Oh it was really filthy, the passageway, and Rutherford's office I discovered was up some two or three steps, after one had gone about halfway along this passageway. But I found he had somebody with him, but his secretary next door was a man, a man named Hailes. He pronounced it Hyles or Eyles without the 'h' punch. And Hailes was a man who hated smoking, and Rutherford was an inveterate smoker, he smoked a pipe all the time, and so that after he'd finished with the person he was with, I was ushered in by Hailes into the office, and I could scarcely see Rutherford because the place was so full of smoke, from his pipe. But I sat down in front of his desk and we had chatted away about what [were] my ideas about what I'd like to do, which he was very sympathetic with, and then he said to me, 'Well now you'd better go around and make yourself familiar with the laboratory, go and talk to some of the boys'. He said, 'You'll find ...' I said, 'Which boys?' He said 'Oh you'll find J. J.' - J. J. Thompson was the discoverer of the electron, and one of those Gods that lived up there for me, - 'down in the basement, he's still working down there, and you'll find Aston next door' - Aston was the man who first measured the masses of isotopes of atoms. And then he gave me a number of other names of equally distinguished people that I was to go and see, and I was very awed by this of course, but I made my way down, and there I ...
What about Rutherford himself? What sort of an impact did he make on you?
Well I'll - I've got a lot to say about Rutherford; I'll do that in a moment. But this was as it - at the momentary contact with him at the beginning which, as I said, I found him looking more like a farmer than a great physicist. His desk was even worse than this one, his table. But J. J. was very kind to me, so was Aston and so were the other people that I'd been told to talk to, and I found - felt at home immediately with these people, I didn't feel that I was a stranger. When I did feel a stranger was when, in the Cavendish they had each week a colloquium and at which some member of the staff or one of the workers in the laboratory gave a talk about what he was doing, trying to do, or else one was addressed by a distinguished visitor like Niels Bohr or Einstein, or Max Planck or Max Born and people of that sort, Heisenberg and so on, all of whom were just textbook names to me. But when talking to other students, the other research students, those who'd been prepared, had taken their first degree at Cambridge or at a British university, they just appalled me because they knew everything as far as I could see, and I knew nothing - I felt such an ignoramus. In the end I discovered that this was very much a put-on thing that some people liked to appear very wise, wherein they really weren't and it soon wore off. I soon felt at anyrate able to hold my own with them.
Did it act as a spur to you?
Yes. But the thing that acted mostly as a spur to me, was that Rutherford had an assistant whose name was Chadwick - James Chadwick. James Chadwick had been a prisoner of war throughout (telephone rings) the First ... I said it wouldn't work - it wouldn't go. [INTERRUPTION]
You were telling us about the impact that the meeting with Chadwick had on you.
Yes Chadwick was Rutherford's offsider, he'd come from Manchester to - where Rutherford had been Professor - to the Cavendish immediately after the First World War. Now Chadwick had been a prisoner of war throughout the First World War because as a student, he'd been travelling in Germany when war broke out, and he was interned there, and this upset his internal mechanism; eating and so on was ever afterwards a bit of a strain for him, though he lived to be in his early eighties. But Chadwick was a rather a taciturn sort of person, but I liked him at once because he was so direct and honest. And I learnt that he was ... [his] actual personality was rather different from the way he expressed himself, because he used to go around the laboratory regularly every day to visit all, every research student, and find out how they were getting on and when he came to me, on the first occasion, he said to me, 'How are you getting on?' and I said, 'Well I'd rather have a high vac pump', and that's an electric motor driven vacuum pump, 'than this thing that I've got to turn a handle on, because I'm letting gas into the vacuum continuously and it's an awful chore having to turn this handle for half an hour every hour'. And he said, 'So you'd like a high vac would you?' and I said 'Yes'. He said, 'Well you just can't have one'. And I was a bit disappointed with this you see, and I went - I used to go home to lunch with my wife, and I cycled home to lunch and feeling a bit depressed went back to the Cavendish and there sitting on my table was a high vac pump.
So that was ...
And so I learnt that Caven ... that Chadwick's bite was much worse than his bark. He was about ten years older than me, but we rapidly became close friends and that lasted until his death. He was - became Master of Caius College in Cambridge, and we - I've just been to England a few weeks ago to a celebration of the 100th anniversary of Chadwick's birth, which was held in Liverpool where he was Professor for a time, and in Cambridge where he was - became Master at Gonville and Caius College. Gonville and Caius College, by the way, is the College, at the present, of that chap Hawking who writes the - wrote the book about time and so on, and who is an invalid.
So you were this young man from Adelaide, arriving in a quite extraordinary environment, in which there was tremendous stimulation, and tremendous opportunity. How did you make out in it yourself?
Well there - at first I was a bit upset by the fact that everything was so filthy. I discovered in the end that the windows were washed and the floors were washed once a year.
And you'd arrived at the wrong time of year.
I'd arrived at the wrong time. At the end of the year. They were washed as a matter of fact soon after I got there. But ...
So you were looking at a year's grime?
That's right, and there was a Virginia creeper that grew sideways over the windows you know, and there were sort of strands of Virginia creeper across windows and so on, and all - it made it all rather depressing inside. Particularly on a winter's day, and winter was rapidly advancing when I got there, because the Cambridge year begins in October, the middle of October.
But intellectually stimulating.
It was terribly stimulating intellectually. The people sharing the room with me, there were four people working in the room - large room, twice as big as this room - with me and I had one corner of it and others worked there, one of them was named Bullard. He was the son of the owner of the brewery in Norwich which made Bullard's Norwich Ales, and Bullard called across the lab one day and said to me, 'Say Mark, do alcohol and water mix?' Here was the son of a brewer!
Ah, but anyway we were all good friends, and got on so well together and there was an Australian who joined Bullard at doing some experimental work on the scattering of slow electrons, whose name was Massey. A man whose name was to become well known; later in life, he became Secretary to the Royal Society and things of that sort. Professor of Physics in London and ... Bullard you know, was measuring one of the magnetic fields which was produced by a coil of wire with a current passing through it, and this coil of wire, he didn't know how many turns there were on it, but he knew that he could measure the diameter of the wire, so he weighed it. The way he weighed it was to hang from some hooks on the ceiling, a piece of rope, put a piece of wood across, then he put Massey on one end - whose mass was known, and he put the coil of wire on the other side, and then adjusted the distances until he got a balance, and that way he weighed his coil in masseys. And ... I mean doing it. They were a wonderful group of people to work with.
So what about your work? How did you make out in this? Did you find your direction quickly? Did you get onto a line of enquiry?
Oh yes, I got on - got going very quickly thanks to this high vac pump which we'd already mentioned, which made all the difference in life to me.
And what work were you doing?
I was doing some work on the effects produced when positive ions hit a metallic surface of various kinds, and this is a process that's important in the discharge of electricity through gases which was J. J. Thompson's great specialty. So I was in good company, in those early days. But then very soon after that, in 1932 - well it's not so soon as that is it? It's three years later, four years later, when I'd been working for quite a long time on this with positive ions in various properties of positive ions, Rutherford asked me whether I'd like to work with him, and of course this was a great honor, and ...
And why do you think he'd asked you?
Well he'd asked me because he felt that he wanted to do some experiments which were like those that were being done by Cockcroft and Walton in the laboratory. Cockcroft and Walton together had for the first time produced the disintegration of an atom by artificially accelerated particles, and this was the first time that the atom had been split artificially, and this of course excited Rutherford and he wanted to do some experiments which he'd thought of in that field, and he wanted some technical - somebody technically good to help him, and he thought that I was the right person, so he asked me to work with him and that was absolute heaven working with him; actually with him. It was - because he was full of ideas all the time, and most of which, of course, were nonsense, but every now and again there was gold amongst all that dirt, and we got on famously together, and I had one or two research students working with me also. We set up an equipment in a cellar in the old Cavendish, a room which we had to use because it could be blacked out - completely blacked out, and one detected the products of the formations of the atoms that were fired out like little bullets through a mica window, a very thin mica window. They came out in the air and there they struck a zinc sulphide screen and gave a little flash of light when they - but in order to see this little flash of light, your eyes had to be dark adapted so you had to sit around for half an hour before you could begin experimenting at all while your eyes grew dark adapted, and then you looked down through this microscope at this screen and counted the number of particles that - number of flashes of light that you saw. You could only keep doing this for twenty minutes or so until your eyes got tired, and then you changed. On one occasion I was there counting with Rutherford, and with Chadwick, and Rutherford's technical assistant named Crowe and after some time, some considerable time counting these particles, Rutherford said to Crowe, 'How long have we been down here Crowe?' and Crowe said, 'Oh about an hour and a half sir'. 'Well it's time', he said, 'Lead me to that sink.' In the dark he couldn't find his own way. So - it was, you know, it was that sort of good fun. You sort of were part of a team, you worked together.
(Over Mark) Sitting in the - in the dark counting particles.
... and you call it good fun.
Oh it was, because it was so exciting. You never knew what you were going to see next, and you changed the voltage or changed the target or something and something totally different would happen. Then in the middle of these experiments, while I was working with Rutherford, in 1934 there came to the Cavendish a man from Berkeley in California, a very distinguished physical chemist whose name was Lewis, and he'd brought with him two samples - tiny little samples, only a fifth of a cubic centimetre each, sealed in a glass tube - of heavy water. He was the man who had discovered how one could extract and concentrate the heavy water, that is one part in sixty thousand or so of ordinary water is heavy water, but it's a very costly and difficult business to concentrate, that's why these samples were so small. But he handed them to Rutherford, and Rutherford, of course, handed them to me and straightaway I took the deuterium, as the heavy hydrogen is called, chemically out of the water and used it in our bombarding experiment, and straightaway a new world was opened to us, there were a new set of explosions, atomic explosions which were terrific in their intensity and in the number that took place. It was like entering a new realm of star watching as it were, when looking at these scintillations and then fortunately, there was a Welshman working in the Cavendish laboratory named Win Williams, and he had developed a technique for counting the particles electrically instead of using a - having to use the scintillation screen, and he gave us one of his earliest counting equipments which were made up in characteristic Cavendish manner. Each stage of the linear amplifier - there was six stages of it - was housed in a separate biscuit tin, and together with the batteries to operate the valve, there were old-fashioned valves in those days, no transistors at that time, and these made a pile of biscuit tins about that long you see, then one had a tube coming out of it that led to the ionisation chamber, and then at the other end, the output was put onto an oscillograph where the movements - the ionisation produced still being counted by eye was now counted by the deflections of the oscillograph. So one had a length of bromide paper, the same width as ordinary cine film that was fed through and the deflections of the oscillograph were recorded on this piece of bromide paper, which then had to be taken out and of course developed and then washed fixed and then washed, but Rutherford's so impatient that he would insist on looking at the record before it was washed you see, while it was still slimy from the fixing solution, and he usually tried to write on it and he'd drop ashes from his continuous smoking ah cigarette oh, generally a pipe, which he smoked, and in this pipe he smoked a tobacco which had been dried out in front of the fire at home, and it was like a volcano it there were ashes and sparks coming out of it all the time, and his wife was very upset because he always had holes burnt in his clothes as a result of the sparks from his pipe, but this made a mess of our lovely records, and we - it was sort of like this you see - waiting for him to allow us to put it back in the fixer and get it all properly finished; the record properly finished.
This is an amazing image we've got here of a place that with dusty windows, biscuit tins in the laboratory, and ash dropping out of the great master's pipe all over it, and yet amazingly interesting work was being done.
And your role in it was not only as a technical wiz but also you were seen as someone who was tremendously inventive and adaptive that you could always find a way around problems.
Well the problem arose, you see, of the interpretation of these things, and it was quite clear to us from the ionisation that was produced, we could distinguish between particles with one charge of electricity on them, and particles with two charges: elementary charges. And it was quite clear to us that most of the particles that we were seeing only had one electric charge on it, probably got their energies by measuring their range in air - the distance they went in air, and from our our experiments we knew, we calibrated this so that we knew what the energy was, and we found that there were two sorts of reactions taking place, one of them resulted in the production of a new sort of hydrogen, a very exciting discovery of a new sort of hydrogen of mass 3 - as we'd seen. Deuterium of mass 2 had been discovered and it was deuterium that we were using to produce this hydrogen of mass 3, but it was produced together with a particle with no electric charge, with one electric charge this hydrogen of mass 3, an ordinary proton, an ordinary hydrogen atom as it were, so we'd broken down the deuterium into hydrogen of mass 3 into - by hitting 2 plus 2 we got 3 plus 1 as it were.
So speaking for the layman, what was the significance of this?
Well, this was a new reaction that took place at extremely low bombarding energies, and produced a new kind of hydrogen that had never been seen before, you see. But in addition to that, we found that there were neutrons being produced and that opposite the neutrons there were appearing the helium atoms, doubly charged particles. These doubly charged particles puzzled us. They had very short range and, because of their low energy coming opposite a particle of mass 1, they only had one-ninth of the energy that was produced in the reaction, so they only went a short distance through the air and were difficult to detect, but we knew that they were doubly charged because of the ionisation they produced. And we puzzled and puzzled as to what these could be, and couldn't think of an answer. Six o'clock came and the lab closed at six, Rutherford was insistent on stopping work at six, and you weren't allowed to work at night because he said the evenings were times when one should be thinking about what had been - one had been doing experimentally, and we dispersed and I went home and thought a bit about this after dinner about this interaction and couldn't make head or tail of it, went to sleep still puzzled, and at three o'clock in the morning the telephone rang, and my wife who woke up because of the baby of course, was awake before I was - even heard the thing, and I was deaf anyway, and in any case I didn't like answering the phone. She got up but she came back to me and she said, 'The Professor wants to speak to you'. We always called Rutherford 'The Professor', and so I went to the telephone and sleepily said, 'Good evening', and he said, 'Do you know Mark, I think I know the answer to that problem of ours'. And I said, 'Well what is it Professor?' and he said 'Those little particles are particles of helium of mass 3; not only have we got hydrogen of mass 3 we've found helium of mass 3'. And I said, 'But Professor how - what on earth reasons have you for that?' I said, 'Nothing on earth can make two plus two', because deuterium was mass two, the target was mass 2 so 'two plus two equals three' and he said, 'Reasons, reasons Oliphant!' he said 'I feel it in my water'. And the next morning I set to work to do the experiment of passing these particles through crossed electric and magnetic fields, to determine their velocity and hence for we knowing there energy one could calculate their mass, and their mass was three. He was absolutely right, and we had in one experiment, we'd discovered two new ...
[end of tape]