Edward Andrade

Heilbron:

Well, Sir, I wonder if you would tell us a bit about the subjects taught you when you first entered school at the University of London.

Andrade:

Well, they used to have Planck’s theory brought in in connection with the distribution of energy in the radiation from black bodies; you remember otherwise it went up. And to bring it down Planck’s theory was brought in there, but the idea that it had any further application was not taught; it was merely in connection with the lectures on the radiation from black bodies.

Heilbron:

Was it introduced as a semi-empirical law, or was it discussed in terms of any fundamental significance?

Andrade:

I don’t think it was recognized that it was anything but a way of getting after the great difficulty of getting the right distribution. ... You see it is difficult. ... Even Rutherford, quite clearly, didn’t realize what he had done. You know that famous saying of his in his letter to Geiger: “Those were happy times in Manchester, and we wrought better than we knew.” It was something to that effect. Do you want the exact words?

Heilbron:

I think we have them.

Andrade:

I’m sure you’ve got them, but they’re in Eve’s Life of Rutherford which is a very bad book well, it’s just a lot of letters and stuff put together. I’m writing a life of Rutherford right now, for an American concern — the Educational Corporation.

Heilbron:

Have you any idea when it’s likely to appear?

Andrade:

Well, I’m about three quarters of the way through it; I should think it would appear somewhere around next summer or autumn. It’s not very long.

Heilbron:

Well, we’ll look forward to its appearance. But as you were saying, the quantum, when you first entered school at any rate, was not considered a matter of fundamental importance.

Andrade:

No, it was merely mentioned in connection with this distribution of energy in the radiation from a black body, which is a thing we all had to deal with. There was Rayleigh’s thing, of course, which went all wrong at short wave lengths. And it was pointed out that Planck’s thing gave a formula which was carefully checked by Paschen, I think.

Heilbron:

What about the later applications [of the quantum] such as Einstein’s theory of the photo-effect? Did they get into the curriculum at all?

Andrade:

Well, I was under Lenard, and… I don’t think Lenard took much notice of it, but I should look at his collected papers . [You’ll find there] what he’s written on the photo-electric effect at different times. I’ve got them at home, but I haven’t had time to hunt these things up. I’m in an awful jam at the moment; I’ve got this rather good book, on, I’ve got several researches on that I’m writing up, and I’ve also got various things for the Royal Society. I haven’t really had time to look into it. I think you’ll find Lenard was not very receptive, but I think he must have accepted it — you know, the hv business for the photo-electron. I don’t really remember if this application was mentioned at London before I went to Heidelberg. I know that at Cambridge in 1912, of course, that’s what Bohr was discussing with Jeans. I know then that everyone accepted that an electron that went around had to radiate. And then Nicholson, of course, no doubt saw, as I said in my Rutherford Memorial Lecture [locates the paper] ... You see, Jeans had been interested in it from the early times. Bohr talked it over with Jeans in 1912, kind of feeling his way, and I didn’t understand it. I mean, I thought that an electron that went around radiated, and I think Jeans did too, but Bohr was thinking on those lines.

Heilbron:

Do you recall that Jeans was greatly opposed to —

Andrade:

I wouldn’t say he was greatly opposed. He was obviously impressed with Bohr’s intelligence, but I don’t think he took it seriously. I think he thought it was rather an eccentricity you see. Then there’s this Nicholson business which I think you must refer to [refers to the Memorial Lecture] where do I mention Nicholson? [Finds something else of interest and reads from Lecture] Yes, of course it is true that at Heidelberg in 1911 “whereas Wilson’s cloud chamber aroused the greatest interest, nobody took any notice of Rutherford.” Neither did Nature if you look at Nature in l9ll, the only reference you’ll find to Rutherford’s atom is a brief abstract of the paper he gave to the Manchester Literary and Philosophical Society which was the first appearance. That is just the same kind, of notice all the other papers had four or five lines.

Heilbron:

Why had he not written a note to Nature himself?

Andrade:

I don’t know. Nature then published short accounts of what went on at the learned societies. And they published this notice from the Literary and Philosophical Society, and if you turn up Nature of 1911 and look up Rutherford, you’ll find that’s the only reference to it. ... [But] I think you’re bound to mention Nicholson because … I think Nicholson must have been one of the people to whom Moseley referred [in a letter quoted in the Memorial Lecture], and the other was probably Lindemann. I think be was writing on that thing.

Heilbron:

I see. But [in] the papers of Lindemann's with which I am acquainted, I think he doesn’t build an atom out of e, m, and h.

Andrade:

I haven’t had time to look it up, but I remember that Moseley had discussions with Lindemann. Moseley refers to his [goes to look up a letter from Moseley and reads]. “You may have noticed that F.A. Lindemann has been going for me in Nature. I propose to reply and I enclose a copy of my letter. I sent it to Nature this evening. As it is long, I hardly expect to see it this week.” That, I think, is a letter you ought to quote. That’s Moseley to Rutherford, 5 January, 1914.

Heilbron:

Yes, that’s quite interesting. Perhaps we can in some other way run down what the third of those theories was • There was another attempt to make an atom with e, h, and m by Haas. …

Andrade:

I don’t think Haas attracted any attention at all. I never remember anyone talking about him. But Lindemann, of course, was a forceful character.

Heilbron:

But he didn’t appreciate the Bohr theory when it appeared, as I remember.

Andrade:

No, no, no. He was a rich man and had his own opinions. It makes a difference. Just let me see if there’s anything in my Rutherford [Biography]. Yes, [reads] “It was at the Manchester Literary and Philosophical Society where Rutherford first gave an account of this theory. Then I say that the famous journal, Nature which published scientific news of the day, “only mentions a very brief summary of the Manchester paper the same length and style as the regular treatment of all the other papers, many of no great significance. Rutherford himself does not seem to consider his work as the epoch-making innovation that it turned out to be. Even in his book Radioactive Substances and Their Radiation which was completed some 18 months after the publication, there are only two references to the paper — both where the scattering of alpha particles is the topic.” He was interested in the nucleus, and Rutherford’s lecturing depended entirely on whether he was interested in the subject. I remember him lecturing on the atom, and he gave an account of the Bohr thing which anyone else could have done equally well. And when he came to the nucleus, he began to get excited. The nucleus was his pet child.

Heilbron:

What did he think about the Bohr theory and his model when you worked with him in ‘14?

Andrade:

He didn’t think much of it — I refer you to what he said at Melbourne in l9l4. He was there just after the war broke out for a meeting of the British Association, and he said something to the effect that it was very interesting and obviously had something in it, or something like that. I think I actually quote that. As I said about Nicholson, he speaks of elements with single rings of electrons and as far as I know his is the first use of the word nucleus — nucleus and protiles and so on. Now, this rather took peoples’ fancy, this (symptom). As if he had heard an atomic conversation a few years later. without really understanding it that, I think, sums up the paper very well. You also want to refer to this thing of Jeans’, this report on radiation and the quantum theory, because that was just after. He’s the man who first appreciated it, I think. [Continues to read from his manuscript of the Rutherford biography] “So had the British Association met at Melbourne in August, 1914, just after the outbreak of war. On the 18th of August there was a discussion on the structure of atoms and molecules opened by Rutherford.” The only record that apparently exists is that abstract, but what I’ve got for this thing is an account of the meeting from the local paper.

Heilbron:

In Melbourne?

Andrade:

No, no. Yes, this is what he says, “Referring briefly to spectral emission, he said that Bohr faced the difficulties by bringing in the quantum in a novel way, and that at all events there was something going on in the atom which could not be explained by the ordinary mechanics. The impression given is that Rutherford thought that Bohr was probably on the right road, He had not attributed its full importance to Bohr’s work.” Rutherford always liked to see things, you know, and you couldn’t see this. I’ve quoted elsewhere the violent discussion at the Atheneum once when somebody — I think it was Eddington said that the electrons might not have any real existence, that they wore figments that were very useful. And Rutherford got very indignant, it was as much as to say, “You have insulted the woman I love,” you see. [And he got up and said,] “Not exist! Not exist! Why I see them as plainly as I see that spoon in front of me!” And he could; that was his secret — and, of course, in Bohr’s thing you can’t see anything plainly in front of you. I mean, alpha particles and electrons, well, he saw them like a baseball player talking about an old match will see the balls flying. But Bohr’ a thing was not quite in that line. And I think he always, at that time anyhow, thought it was very clever, but like that he said about relativity I’ve quoted it somewhere — when Willy Wien said to him, “No Anglo-Saxon could understand relativity,” Rutherford said, “No, they have too much sense,” or words to that effect. And I think he was very much impressed with the fact that Bohr got these exact numerical relations. Otherwise he doesn’t seem to have taken any notice of it at all. That was, of course, the thing that won people over to the Bohr atom — that he got out the fundamental constants. He got their values. And, of course, that work of Evans was quite important; that showed that the helium lines were not quite the same as the hydrogen lines, and it brought in the finite mass of the nucleus, you know, owing to the fact that the nucleus of the helium atom is bigger than that of the hydrogen. The lines don’t quite agree, which they would otherwise, because of the difference of mass.

Heilbron:

And this was more impressive than the derivation of the Rydberg itself?

Andrade:

No, I think Rydberg’s constant was more, but I think this was a quite strong support. It was found by Evans a spectroscopes working in Manchester — that the lines did not coincide. He just showed that that difference existed; I think that was quite important.

Heilbron:

In connection with the reality of electrons, I wanted to ask you about the attitude taken towards atoms during the period before 1913. When you began school, was there still much skepticism about the reality of atoms?

Andrade:

I don’t think so. Everybody thought there were atoms. ... (You might) refer to Oliver Lodge. I knew him very well. He had a lively mind, but he wasn’t a Rutherford. Of course these floating magnets, you know, were a popular thing. But I forget who it was who doubted; it was somebody like Nernst. ... No, everyone generally accepted the atom, and, of course, Perrin’s work attracted great attention. That was I think about 1906 or ‘07. I know that Perrin and the Brownian movement were discussed in lectures when I was young.

Heilbron:

Was Lenard still interested in his model as late as 1911?

Andrade:

Oh, yes, yes, certainly. And really Lenard’s work was very important; he was the first man who showed that the atom was mostly empty. But unfortunately he put the positive charge in little bits with the negative charge in his dynamids.

Heilbron:

Did anybody pay much attention to that theory?

Andrade:

I don’t think so. There was a man, Stark, who wrote a great deal on the atom theory. He had certain particles archions were they called? Stark, of course, was a good physicist, with the Stark effect and so on; he was a Nobel Prize winner, No, I don’t think I mention Stark here, [in the Memorial Lecture] but oh, yes — [Reads] “Stark spent much not very successful effort on an atom model containing certain positively charged massive particles called archions.” It is perhaps not unfair to say that for the average physicist at that time and I’m talking around about 1911 — speculating about atomic structure was something like speculating about life on Mars. It was very interesting for those who like this kind of thing, but you don’t much hope for support from the convincing side of evidence. People thought it was quite interesting to talk about the structure of the atom, but I don’t think anybody took it terribly seriously. And as I say, Rutherford himself never mentions in his book in 1913 anything about chemical properties or spectral properties. He doesn’t mention them, doesn’t consider them. It’s just the scattering. You can verify that by looking at his 1913 book. And in that book mind, you the preface is dated 18 months after his paper, he had had time to think about it he doesn’t even say that it may be possible on these lines. He doesn’t mention spectral or chemical properties. And I don’t think he thought of the atom model as though it had any bearing on these things.

Heilbron:

That’s quite curious. I wanted to ask you a little about the history of the Rutherford atom. In Rutherford’s first announcement the atom can have either a positive or a negative nucleus.

Andrade:

Well, from the mathematical point of view, you see, it’s effect is the same. And that’s why I point out that at the beginning he didn’t really care which it was, so to speak. In fact, in his first paper, he says it can be either. I think somewhere he says that for convenience he’ll take it as positive ... and that shows that he had no conception of electrons as being an essential part of it. But if you consider that the alpha particle was his pet and that what he was really concerned with was the alpha particle you… see, they had got no suggestion of the alpha particle coming from the nucleus at that stage. That I think was when you got the displacement law combined with Mosley.

Heilbron:

So that would be the course of its change from the positive or negative nucleus to the positive nucleus and discrete negative charges?

Andrade:

Yes. When you wanted negative charges outside, then you had to make the nucleus positive. And I think Rutherford had a leaning that way, but from his mathematics it didn’t matter, from the scattering point of view.

Heilbron:

I had suggested under this 4th head that we might discuss the process of the acceptance of the quantum theory in England, say from 1914 on.

Andrade:

Yes, well in 1914, of course, we had a war, and everything went into abeyance during that time. I was in France; I didn’t like it very much. And, you see, Rutherford himself was messing about with that antisubmarine business and so on, so not very much happened during the war. And after the war I think the position was generally accepted, and of course the photo-e1ectric effect was accepted. … Of course, the theory of relativity was not accepted at once by any means. I remember a man called Cunningham, a mathematician of some ability. He never made a name in science, but he was a senior wrangler. He gave a paper on it shortly after it came out. It was at University College, and I was the student president of the Mathematical and Physical Society, and I got Cunningham to come along [There is some confusion about whether Cunningham or Eddington is involved.] and talk about relativity. It must have been about 1907, I think. And my professor of physics, who was a very nice [man], got up and said, “Now let me see; does this mean that if I look at my watch like this, and I turn around and look in the other direction that the time is changed?” And everybody laughed, and they did take it as something of a joke that time should change in this way. ... Eddington came and gave a lecture later, and it was rather better accepted, I think. Yes, I think that was Cunningham's lecture, that first one where Trouton was so amused as to whether if he turned around and. looked at his watch the time would change. You see, we were all very much bound up in the aether then. As Kelvin said in his Baltimore Lectures, if there was one substance which was absolutely certain one substance whose properties we knew, it was aether. The aether of space was still going very strong in those days. Trouton, my professor, did some experiments on the resistance of wires, whether they changed when they turned from this position to that position. Of course, then they didn’t, which was against the aether. The aether was getting a little bit attacked, but every student had to learn about the aether very much when I was a young man. It was taken very seriously. There were enormous experiments: rotating huge discs to see if they dragged the aether with them.

Heilbron:

When would you say special relativity managed to creep into the curriculum?

Andrade:

That I don’t know. Of course, it might be interesting for you, and you could do it quite easily to go to the London University and. look at the physics honors examination papers. That would give you a very good idea [of the curriculum].

Heilbron:

That’s an excellent idea. Thank you. What about some of these events in the early twenties, for instance, the Compton effect? Did that create great problems here, or was it immediately accepted?

Andrade:

Oh, by that time I think everything was well settled, and I think there again, if you look you’ll probably find questions on the Compton effect within a year or so. But as regards this point you seem interested in, the academic business, the examination papers are really the best because they are a summary of what’s being taught. They’re set by the professors who are giving the lectures, and actually they set questions on what they have been dealing with, and what the others have been dealing with. You had better bear in mind that there are two things, the internal examination and the external examination. The external examination is set for people outside London who are going to take a London degree. As a matter of fact, mine is an external degree because I took it after two years, and you had to be three years at the University before you could take an internal degree. Now there is one essay paper — that’s a pretty good guide as to what’s going on. I remember for instance that I wrote myself on the pressure of light — that helped to get a first. I happened to know about the pressure of light, and it was one of the subjects set for an essay. … My examiners were H.A. Wilson and Townsend, both Cambridge people. I would say that nobody is asked about the pressure of light as the subject for an essay nowadays, but it was paid, I think, particular attention then.

Heilbron:

May I ask you also about the acceptance of the new quantum physics, particularly of de Broglie and Schrodinger?

Andrade:

I think they were accepted; I think people by that time were getting ready to accept anything so to speak.

Heilbron:

Well, that’s interesting in connection with that article of yours in the Mathematical Gazette in ‘26. It doesn’t mention de Broglie, Heisenberg, Schrodinger —

Andrade:

Well, I was talking to school masters, and I wanted to (go easy on them). No, another trouble you see, is that when my laboratory was destroyed, most of my reprints were destroyed too, and I haven’t got a lot of those things. The whole thing was blown flat, including about 5,000 pounds worth of old books. They weren’t worth as much then.

Heilbron:

When did you first become actively interested in the history of science?

Andrade:

Oh, in ‘21 I think I began collecting old books, anyhow. I remember going to Edinburgh — in ‘21 the British Association was meeting there — and I went into Thin’s bookshop and asked if they had any old scientific books. They said they didn’t think so, and then a youngster said, “Oh, yes, in the cellar we’ve got the remnants of Professor Crystal’s collection.” I went down and I spent a hell of a lot of money, I think about 14 pounds, and I was buying Robert Boyle at about ten bob each. I bought Huyghens’ Horologium Oscillatorium for 18 schillings. As far as I remember Crystal had given two bob for it. That’s a sport that’s gone now.