The Manhattan Project

John Manley's Interview (1965) - Part 1

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John Manley was a nuclear physicist who originally worked in John Dunning’s group at Columbia. In his interview, he describes how he later moved to Los Alamos, where he was in charge of a group making measurements for the reflector on the bomb. He also served as secretary of the general advisory committee until he left Los Alamos. He recalls recruiting experimental physicists to come to Los Alamos, and working with Seth Neddermeyer, Hans Bethe, and other scientists.
Date of Interview: 
March 9, 1965
Location of the Interview: 
Los Alamos
Collections: 
Transcript: 

Stephane Groueff: Yes, Dr. Manley, from the beginning. Then I’ll start asking questions.

John Manley: Alright, fine. I guess the first relevant business is the fact that I went to Columbia in ‘34. I was sort of on the fringe. I worked mostly with [Isidor] Rabi for the first couple of years.

Groueff: You are a chemist?

Manley: No, I’m a physicist.

Groueff: Physicist?

Manley: Nuclear physicist, primarily. I worked mostly with Rabi for the first couple of years. Then I started getting into neutron physics. That way I got acquainted sort of, again on the fringe. Well actually, I was working essentially in [John] Dunning’s group. I got acquainted with [Enrico] Fermi and [Leo] Szilard and [Herbert] Anderson and [Walter] Zinn and—

Groueff: [Eugene] Booth?

Manley: Booth, yes. I knew all those.

Groueff: [Alfred] Nier?

Manley: Yes. Well Nier was, of course, in Minnesota. I knew him from physical society meetings and so on. So there was that pyramid. And then I left Columbia and went to Illinois. That section is sort of irrelevant. Then just shortly after Pearl Harbor, I was tapped for the metallurgical project. I went there in January of ‘42 and worked with [Arthur] Compton and [Samuel] Allison, and so on. [Gregory] Breit was in charge of the so called “fast neutron.”

Groueff: Breit?

Manley: Breit, Gregory Breit, who’s now at Yale and about seven different laboratories in the country trying to make measurements for weapon information—just nuclear physics measurements really. Those were kind of coordinated out of Chicago. Well, Breit had some difficulties; he’s a hard person sometimes. I got that job. About the same time—

Groueff: He resigned? Breit?

Manley: Yes. Well, he did something else. I’ve forgotten now exactly what he went into. But anyway, this threw me into more definite contact with Oppenheimer, because I wasn’t supposed to look after the experimental work. Oppenheimer was still in Berkeley at that time with a group doing the theory.

Groueff: For fast neutron?

Manley: For fast neutron. That was the fast neutron end of it. Right. And at the same time, my headquarters were in Chicago with the Met Lab, so I was sort of a part of that activity, although I had to make quite a number of visits to these other places and so on. Then of course, it was decided along that next spring or early summer to establish Los Alamos. So I got together with Oppenheimer about that.

Groueff: Did you know him before?

Manley: No. I first met him during this period in early ‘42 of his looking after the theory and wanting experimental results, which I had some responsibility for after having taken over from Breit. So then I decided, gee, this is too much administrative business. I wanted to get closer to the laboratory, you see. So when Los Alamos was established, I was in charge of a particular group here at Los Alamos making measurements primarily on the reflector for the weapon.

Groueff: You were one of the first to arrive here with Oppenheimer? You and [Edwin] McMillan, I think?

Manley: Bob Wilson’s group was the first one. Of course, I had the job of trying to talk to these people in these various groups at Minnesota and Wisconsin and Purdue and DTM, outside of Washington.

Groueff: You were like the recruiter?

Manley: Yes. Right. To see how many of the experimentalists would move out here and so on. A few of them came out before I actually did. Wilson’s group was the first from Princeton. Then I came in April, I think. He came in March or something. I don’t whether it’s just one of these sort of things that always interested me as an anecdote in the sense because in—it was roughly December of ‘42, I went to Boston to consult with Stone and Webster about the design of the buildings of Los Alamos. They were the consulting architect and engineer firm.

This was for some of the machines. One of the machines required a nuclear accelerator—Van de Graaffs and so on. One of the machines required a fairly firm foundation, and the other one required a basement. I designed the buildings to have these two machines at opposite ends of the buildings with laboratory space in between. Then I carefully specified, and I’d never seen Los Alamos, I didn’t know anything about it. I carefully specified they should take advantage of the terrain on where this building was located so that they wouldn’t have to put a fill under the machine that required a good foundation and excavate for the other machine that required a basement. So I thought this was all taken care of.

When I came out here, I found, of course, that the Army engineers had done it just the other way around. They’d actually put a fill under one end and dug deeper than they would’ve had to if they’d had to if they’d turned it around.

Well then I was here all the time during the War and my particular group shifted at the time of the Trinity test because we got the responsibility without ever having any background knowledge previously of measuring the blast effects from the Trinity test. Then after the war, Oppenheimer talked me into becoming the secretary of the General Advisory Committee of which he was Chairman. You remember that McMahon set up these advisory committees.

That was, for me, a very in many ways sort of a thrilling experience, because it was working with all of these people like [James] Conant and [Lee Alvin] DuBridge and Rabi and Fermi and Cyril Smith and Hood Worthington and Hartley Rowe on this Committee, you see, under Oppenheimer’s chairmanship. And in that period – I was four years in that, from essentially from ‘46 I guess it really got started. Late’ 46—the first meeting was in early ’47, and I left in ‘51 when I left Los Alamos to go to the University of Washington in the Physics Department.

Groueff: So during the war, you had a particular division or group here or you acted generally?

Manley: No, I had a group. It was an experimental group in the physics division.

Groueff: With [Robert] Bacher?

Manley: Yes.

Groueff: Bacher was the head of the division?

Manley: Well, he changed. He was head from the time he came here from MIT until a so-called gadget division was established. I don’t know, you can check in the history about when that was. And then Bob Wilson took over. And Johnny Williams was head of that for a time too—of the physics division.

Groueff: And the division had several groups?

Manley: Several groups, right.

Groueff: And your group was a particularly interested in what?

Manley: In the problems of how to reflect the neutrons from the fissionable material back in to the bomb in order to conserve them, because any that escaped—

Groueff: I see. They’d circle the tamper.

Manley: Tamper. Right.

Groueff: I see.

Manley: I don’t know how much background [you have] and so if I use these technical terms, I was trying to avoid tamper, you see.

Groueff: About the tamper, I wanted to ask you one particular question, which could be amusing for the public. I understand that when you tried several metals and discovered one by one until you found the right one, you tried also platinum and gold.

Manley: That’s right.

Groueff: I think that can be amusing if you can tell me about platinum or this precious—how you got it.

Manley: Yes. I remember the specifications on it because we wanted two discs of these materials—roughly an inch thick and twelve inches in diameter. So this gives you some idea.

Groueff: So that’s a rather—

Manley: For our experiments you see.

Groueff: Very few people have seen so much platinum.

Manley: That’s right.

Groueff: Now where did you get it from?

Manley: That, of course, was one of the mysteries of the Manhattan District. That it was handled, I’m quite sure, through this, what started the name Manhattan District—namely the procurement office in the beginnings in New York City. You see in the very early days, they handled the procurement of that stuff. The platinum and gold was not to me the most interesting one. Namely, it was our request for osmium.

Groueff: What? Why osmium?

Manley: Again, it’s the heaviest known metal.

Groueff: Yeah.

Manley: You see, it has a density of twenty-one or something like this—much more dense than gold or platinum.

Groueff: And very rare, no?

Manley: Very rare. In fact, the request that we made turned out to be greater than the whole known world’s supply, you see. We didn’t know this of course.

Groueff: Did you get it finally?

Manley: No.  

Groueff: Because—

Manley: It was obviously too rare to be of any practical—

Groueff: It didn’t exist. But you received the platinum and the gold?

Manley: Yes, and I’m quite sure – yes, I’m sure we had the platinum. I remember the gold one very well and I’m sure we had the platinum.

Groueff: How did you handle the gold? Did you keep it in some safe?

Manley: Yes. Yes. Sure. It was locked up and only out during the actual experiments.

Groueff: So it must have been quite a thrilling thing for the outsiders.

Manley: Yeah, but the physical labor of getting it out and in place—

Groueff: Very heavy, no?

Manley: Oh, yes.

Groueff: And platinum, even heavier?

Manley: Right. Yes.

Groueff: So you were in charge of the group dealing with the tamper?

Manley: Right. With the neutron properties or nuclear properties.

Groueff: Not the manufacturer or the theoretical—

Manley: The theoretical – of course, like all of the parts of Los Alamos, most of the theoretical work was done by the people in the theoretical division. We worked very closely with people like [Hans] Bethe and Bob Christy.

Groueff: Where was your lab, here around the pond somewhere?

Manley: Yes, it was a building. I don’t know whether you’ve seen an old map of the tech area or not? 

Groueff: No, I’ll take—

Manley: It was called Z Building.

Groueff: Z Building?

Manley: Yes.

Groueff: And you had what, several rooms?

Manley: No, just one real large room. I think it was forty by forty feet. It was built around the Cockcroft-Walton accelerator. That was the machine that we used for the most part in making these magnets.

Groueff: How many people were around—you and a couple of assistants?

Manley: Oh no. There were more than that. I think my group might have been a dozen at one time.

Groueff: And you were working—

Manley: [Ted] Jorgensen, whom you have a picture of there, was in my group.

Groueff: I see.

[Laughter]

Manley: And Mrs. Graves.

Groueff: She was a scientist too?

Manley: Yes. Oh, very active. She still is.

Groueff: They were very young people. How old were you then?

Manley: I was forty in ‘47, so thirty-five.

Groueff: Thirty-five. And the other people, they were younger?

Manley: Except Jorgensen, I think, is about my age. Most of the rest of them were younger.

Groueff: So you worked on the tamper problem from when you arrived here in the spring of ’43 until Trinity?

Manley: Yes, right. Until very early spring of ’45.

Groueff: Now what was, in a few words, the main difficulties with the tamper problem? Why was it so difficult? First you didn't know the metal?

Manley: No. You see, we had nothing to do with the metallurgy of the fabrication or anything like that. The main thing that we wanted to try to find out was to get—there were two requirements from a mechanical point of view, just as with dynamite. It’s nice to have something that’s heavy because then when an explosion takes place, it doesn't move very fast. So, it was obvious to try to use the heavy metal. We even tried lead of course, but then you have to look at the neutron properties, and the property that you want is that the neutrons which are born in the middle actually go out and strike this. Then, many of them are reflected back.

And furthermore, there’s another part of the problem, is that if there’s any uranium-238 around, as there was—In fact, that was part of the design actually—you want to have the neutrons not lose energy in this process because if they are below 1 MeV—you may remember—then they do not cause fission in U-238, only in 235.

Groueff: Yeah.

Manley: Of course, that was a secondary concern. The main thing was to get them back into the U-235.

Groueff: Why wouldn’t they go through the tampering?

Manley: They do, a certain fraction.

Groueff: But some of them—

Manley: It depends on the nuclear properties, yes. In general, of course, if you have a nucleus here and a particle strikes, there will be a few that will go right back just like billiard balls. But most of them go this way. It turns out that in heavy elements, the distribution is pretty uniform around, so that you have about as many going forward as back. But different nuclei have different properties in respect to these characteristics.

Groueff: Anyhow, more neutrons will come back than if you didn't have a tamper?

Manley: Oh yes, because then they completely go out you see, and they’re lost.

Groueff: I see.

Manley: This is exactly the same reason why you put a moderator around the pile.

Groueff: You worked entirely with plutonium? You didn't try this system with the uranium bomb?

Manley: Oh yes, yeah sure.

Groueff: Uranium and—

Manley: Actually, at that time, when we started this work we had neither you see. All of this had to be done by putting an artificial source in the middle of the material, or do experiments in which –this was the-the Cockcroft-Walton accelerator. It simply produced neutrons of roughly the right energy to duplicate what would come out of the fission of U-235. So, we had to make measurements with those neutrons then. There was no uranium or plutonium.

Groueff: Before?

Manley: Oh yes. That was way before. I think all the tamper business was well settled.

Groueff: But wasn’t the tamper business—it came to be important only after it was realized that the gun metal couldn’t be used.

Manley: Oh yes. You see that’s a sort of universal principle that you want to prevent these neutrons, as many as possible, from escaping, because every one contributes to the energy release.

Groueff: So you have that in gun metal also?

Manley: Sure, sure, sure.

Groueff: Could you tell me something about the discovery of implosion and [Seth] Neddermeyer? At the beginning, I understand it wasn’t taken—

Manley: Very seriously. No, that’s right. Neddermeyer pushed it very much on his own. I’ve always thought that he deserves much more credit.

Groueff: What kind of a man was he? Could you describe?

Manley: Oh yes. I know him quite well. You see, I just saw him last week. Another reason is after I became head of the physics department in Seattle, he was a member of the staff even before I came. So, I had known him all during the period I was in Seattle. I just recently—

Groueff: Who brought him here? You did?

Manley: No. He came from Cal Tech here, I think. No, I think he was in one of the other agencies just before the war.

Groueff: Young man?

Manley: Oh yes, quite young. He’s not very much younger than I am, I guess.

Groueff: I see, but he was in the early thirties? 

Manley: The thirties, yes.

Groueff: And what kind of a man was he? A physicist?

Manley: Yes, a physicist. I would say a very imaginative, and he’s also the kind of individual who thinks very highly of the educational philosophy of Alfred North-Whitehead—if that sort of describes him a little bit—very much a liberal. The latest thing he has done is to write a big proposal—a billion dollar proposal—for the city buying up all of the shoreline around the lake in Seattle.

Groueff: So, he’s a man interested in other fields than physics?

Manley: Yes, yes. He’s very broad.

Groueff: Bright? Intelligent?

Manley: Very, very, very much so—very intelligent. I never noticed any interest in art and music and so on.

Groueff: I see. Where does he come from? Was he a man from Seattle?

Manley: No, I don't know. I don't know really his background before he went to Cal Tech. That’s where he got his Ph.D.

Groueff: Was he a friendly man or was he kind of the man that draws into fights?

Manley: He was tense. He has always been a rather tense individual. He could get into fights. But, I think that’s being a little unfair in a way because he’s generally very good-natured. This is sort of balanced by his intensities. If he really feels that something is right and so on.

Groueff: Do you know how he discovered the implosion or when, during the work here?

Manley: Oh yeah. Sure, sure. It was—

Groueff: It was an unknown principle before that?

Manley: As such, yes. There of course was a similarity in these shape charges, which the so-called Munroe Effect, and things like that. But this whole idea, I think, was really as far as I know, completely original with him.

Groueff: Original. Yeah.

Manley: Part of the real problem, you see, was how do you measure anything?

Groueff: Yeah.

Manley: The only way he could do it in the early stages was to try to adjust the explosive well enough so that it wouldn’t blow the thing to pieces. He could actually recover samples.

Groueff: And it had to be done symmetrically, no?

Manley: Right, very symmetrically, or it would just fragment into pieces. He had to see from final inspection afterwards how much shape change there had been, how much compression. Then later, he and others developed very ingenious techniques for measuring this sort of thing.

Groueff: But when he proposed this idea, people here generally, the meeting people, were not convinced?

Manley: That’s right. Yes.

Groueff: I understand [John] von Neumann was the one who saw the real value.

Manley: Yes. Of course, it saved the day, as is well known, after the other isotope of plutonium was discovered.

Groueff: Because it wouldn’t be possible to do it with gun method.

Manley: Right, right, right.

Groueff: But your work was both with the gun and implosion, and both with uranium—

Manley: You see our investigations of the nuclear properties of various materials that would be good for tampers—the results were equally applicable to either gun or the implosion.

Groueff: But your group determined what metal it should be?

Manley: Yes.

Groueff: Make it out of this and this metal?

Manley: Well, you see what really happens, and it’s just an example of the general way Los Alamos worked, is that we were working very closely with the theorists. The theorists, of course, would use the numbers that the experimentalists would provide, say on the tamper materials, and do calculations on weapon behavior. Then, try to predict how much better one tamper material was than another and so on—on the basis of our experimental measures.

Groueff: That was also Bethe?

Manley: Yes, his division, right. So, in no sense did we as a small experimental group tell the whole laboratory to use this material. It was a decision that was based on our measurements and then interpreted through the theory in terms of the behavior of the weapon you see.

Groueff: But when the whole thing was decided on the tamper, your group didn't participate in the actual manufacturing?

Manley: No, absolutely nothing to do with it.

Groueff: And until Trinity, you were not quite 100% sure that it would work the way you were—

Manley: Oh no. I think there were no real serious doubts about the tamper problem. No. That was moderately straightforward, just filling in missing nuclear information that nobody had measured before. We did that because it had to be applied immediately in the choices of the material.

Groueff: But your main difficulty was the measurement—the lack of instruments? Is that so?

Manley: No, the main difficulty was the lack of having plutonium and uranium.

Groueff: I see.

Manley: Let me just make a quick sketch. We were taught as a function of the energy of the neutron, the number of neutrons as a function of their energy from fission process is essentially something like this. And, this is one million electron volts. What we had from the Cockcroft-Walton was a source which gave us essentially a line, one energy of neutrons at about two and a half maybe. Therefore, we had to be ingenious in devising experiments to take this source and try to make it look like what you would have in the weapon, then make our measurements on that basis.

Groueff: That was for the first part of your work, but later you began to receive more and more quantities, no?

Manley: Yes. I’m trying to remember now. I’m just not sure. I don't recall really that we ever made any measurements with active material.

Groueff: With active—

Manley: Yeah.

Groueff: So, all this was done with kind of ersatz material?

Manley: Now there were some measurements made. There were measurements made of the critical size, stacking, taking the material, and then putting blocks of tamper around. Those experiments were done before the final design. We didn't actually do them in my group.

Groueff: But you had to also work without knowing the actual size, because the size of your tamper of course depended on the size of the metal.

Manley: Right. But that, again, is subject to calculation. So, one relied on the theoretical calculations for that. As soon as you know what the nucleus is doing, then you can start predicting.

Groueff: And this work—who among the great scientists [did] you work most closely with? Did you work with Oppenheimer on this?

Manley: Well, he was very much interested in our results. As I mentioned, I think we mostly, among the theorists, we worked most closely with Bethe.

Groueff: Bethe.

Manley: And with Bob Christy, who was almost assigned to keep in close touch with our experimental results and to help us on—

Groueff: Christy was the one who perfected Neddermeyer’s implosion? What was his contribution?

Manley: Well, he made many contributions just as a member of the theoretical division, doing various theoretical problems. He was the type of individual who the experimentalists found they could talk very easily to him. Many theorists aren’t that way.

Groueff: So he was your contact man with Bethe and him from the theoretical?

Manley: Yes, that’s right. Yes.

Groueff: And then Bacher was, at the beginning, your immediate superior?

Manley: Right, yes.

Groueff: And, did you work with Fermi?

Manley: Not directly, no.

Groueff: And [Neils] Bohr?

Manley: No, not directly again.

Groueff: And von Neumann?

Manley: Not very much.

Groueff: Not directly. [George] Kistiakowsky was on the explosion?

Manley: That’s right.

Groueff: Not with your group?

Manley: Not at all.

Groueff: And ­­Teller was mostly on the super bomb?

Manley: Yes, yes. That’s right.

Groueff: I see.

Manley: I did have a little to do with him then, because we had made measurements on the reaction actually even before Los Alamos, and more were made later on the DD reaction and the DT reaction.

Groueff: What’s that?

Manley: Deuterium and deuterium, that’s one fusion reaction. And then deuterium and tritium is another. Both of which are relevant to the super. Again, it was nuclear measurements. So I was associating a little bit with him on that.

There was one other thought that crossed my mind. I remember one instance of which we had spent many arduous hours, weeks, doing a particular kind of measurement, which Bethe had really sort of generally suggested. We developed a very special technique which nobody had ever done before for measuring these back reflected neutrons.

I gave a talk at one of the weekly meetings. I was so mad because I thought it was a real nice piece of work, and I thought I presented it reasonably well. Afterward, Oppenheimer got up and said it was a very nice piece of work but it wasn’t anything that we wanted to know. It turned out that they used that information, it was very good information.

Groueff: So that killed you?

Manley: No, it didn't kill me but—

Groueff: It was very unpleasant.

[Laughter]

Groueff: Was Oppenheimer in his manner or in his relationship with all of you sort of bossy?

Manley: Oh no. In fact, that is an abnormal instance, actually. Very friendly, and his whole technique was one of persuasion.

Groueff: Friendly—

Manley: Yes, right. No direction. You know, and that’s one of the reasons I think it was such a successful enterprise, is because scientists just can’t really be told what to do, you know.

Groueff: No, [nothing] at all like the army. He didn't pull rank on you?

Manley: No, no.

Groueff: Was he also personally participating in experiments when he had—

Manley: Not experiments. He’s a theorist.

Groueff: I see.

Manley: He was very close to the theoretical work, and I’m sure very active in discussing how to go about theoretical problems and so on with Bethe and von Neumann, and very much interested in the experimental results as they would be used in these calculations.

But it was one of the things that I think is really quite interesting—was to me at the time—is after it was decided to establish Los Alamos, and he was placed in charge of the laboratory, about every time he’d come to Chicago from Berkeley, I would get after him about all of the problems that needed attention in the way of organization of the laboratory—stock rooms, personnel matters, and all of these things. Well, remember, he had not had any contact with anything but high-brow, theoretical physics.

Groueff: Never had experience how to organize a laboratory?

Manley: No, no. Well, I wouldn’t say that exactly, but the bigger instance is after a considerable needling, I remember going to Berkeley about some common business and having had a miserable airplane trip. Oh, I am feeling horrible. And getting up to Oppie’s office at the top of LaConte Hall, as I walked in, the door just sort of dragging, you know? Well, I had oxygen sickness and so on—lack of oxygen sickness. The first thing Oppie did was to throw a piece of paper—he was behind the table and he threw it out.

He said, “Here’s your damn organization chart.”

[Laughter]

Well, I think this expresses the way he felt about that. It might have been August or before Los Alamos.

Groueff: ’42?

Manley: Yes, right. But the amazing thing to me was the rapidity of which that guy developed into a very competent administrator, and the way he got people to work and things pulled together and so on.

Groueff: Those early days, as you say, your job was to be kind of recruiter for—

Manley: Well, that was just one short period, you see. Because—

Groueff: How did you find it? [Was it] relatively easy or difficult or very difficult?

Manley: Well, the biggest difficulty of course was that I couldn’t say anything about it.

Groueff: To anyone?

Manley: Really, yes. I mean it was essentially an unknown location. Excuse me [coughing]. The surroundings were described only in the most general terms—the living, all of this. I mean, I think my reaction was that it was just simply amazing, the sort of loyalty and—

Groueff: They all accepted—most of them?

Manley: Yes. Most of them accepted. There were very few—

Groueff: Did you tell them about the nuclear bomb?

Manley: Oh I think they knew, they all knew.

Groueff: Most of the people already engaged in different work sites of the Manhattan Project?

Manley: Well, it was wholly the business of trying to find out the nuclear properties of various things that might go into a weapon from the point of view of fast neutrons as contrasted to the reactor pile.

Groueff: So all of those men you visited, they were already working in the field?

Manley: Yes, right.

Groueff: So they were, to different degrees, briefed about the big secret?

Manley: Yes. I don't think there was really any organized attempt to tell them even the barest outline of the thing. But remember, they were all physicists. They knew what the possibilities were for nuclear energy release and—

Groueff: So, they could guess?

Manley: Sure. You didn't have to tell them.

Groueff: But when you would go in to first take somebody to come here, he wouldn’t ask you “Alright, but I want to know what exactly we’re doing and why, and why should I come there?” No?

Manley: Well, for one thing, it was pretty obvious because almost all of these groups—we took the machines from Wisconsin, the Van de Graaff machines, the same ones that those people had been working on. They came with the machine and they did similar work to what they had been doing back there.

Groueff: So, they continued? Most of them continued their work?

Manley: Right. And the Minnesota people, they didn't use their machine. It was similar to the machine at Minnesota which had been used and so on. Then cyclotrons, although it came from Harvard, Nobel Harvard people I think came, unless it was Keith Boyer maybe. But, by and large, it was Wilson’s group, which took charge of the cyclotrons. Wilson had experience with cyclotrons at Berkley and at Princeton.

Groueff: Quite a few people came with their work?

Manley: That’s right.

Groueff: And the water boiler. So, that wasn’t a problem.

Manley: There was no big change. It was just a geographic change really.

Groueff: Would you say practically everybody accepted?

Manley: Yes. I think actually, of the groups, I don't believe anybody that I remember from the Department of Terrestrial Magnetism outside of Washington came. They decided not to. That was the only sort of single group that didn't come. But then we inherited this Princeton group, which had not been in it before. They were working on a different method of isotope separation.

Groueff: [Richard] Feynman was working with it. It was a junior—

Manley: Was he at Princeton then? I may have forgotten that.

Groueff: I think so, yeah. So, you were very much in contact with Bacher and with Bethe?

Manley: Here, yes.

Groueff: Could you describe, in a few words the two men?

Manley: They are similar. It doesn't sound very flattering to say what I was going to say, but I always had a little bit the association of the typical Prussian, a little like.

Groueff: Yeah, Bethe is like that.

Manley: Both Bethe and Bob have just a little touch of that—just an element of it. I think it shows up more in the preciseness of work, the preciseness of speech and communicating ideas—

Groueff: Not at all a kind of emotional—

Manley: No, no, not at all. Not overbearing or any difficulty on personal relationships from that. I don't mean that at all.

Groueff: So, steady?

Manley: Very steady and stable.

Groueff: Meticulous.

Manley: Extremely so. Bethe is—I just have great admiration for his ability to sit down and concentrate long hours working on a problem.

Groueff: So, what we imagine is a German methodical scientist?

Manley: Yes. Right.

Groueff: Very unemotional, precise, methodical?

Manley: Right, very logical.

Groueff: Logical.

Manley: Yes.

Groueff: And his private sort of life, was he the same kind of man in his—

Manley: Actually, I don't remember any sort of general social things. I remember very much his love of the outdoors, liking to go on hikes, and being a very agreeable companion that way.

Groueff: But also, his human contact with you scientists?

Manley: Oh, that was very good.

Groueff: Also very subtle.

Manley: Very human.

Groueff: But very precise and organized man?

Manley: Yes, yes. That’s right. Very convincing and very—

Groueff: No fantasy or volatility or emotional?

Manley: No. And, very almost cold. But, he had a rather warm human individual. Except, one never—

Groueff: Kind of a serious man.

Manley: Yes, exactly.

Groueff: And Bacher?

Manley: Bacher has many of the same characteristics, I would say. You've not met Bethe yet?

Groueff: No, no.

Manley: I think you'll notice this even now. I think Bacher is perhaps a little less serious-minded and maybe a little less abstract. Bacher is essentially an experimentalist and Bethe is a theorist. That’s just the sort of difference in a way.

Groueff: Yeah, I think from your description I see what you mean. Now, how was [George] Kistiakowsky?

Manley: I didn't see much of him really. I saw him really only at the Trinity shot because he was completely concerned with a different area. He had nothing to do with nuclear physics, only explosives. And, I don't know chemistry.

Groueff: And do you remember any colorful sort of anecdote, or something that would describe Oppenheimer and the way he was in those years?

Manley: No, those are the things that are always so difficult to remember, I think. There are just a couple of these, like this business about the organization chart and the comment after my talk, which—

Groueff: But at the weekly conferences, how would he behave? He would open the conference?

Manley: I don't think so, unless he were talking. I think it was very informal. I do remember, of course, that he had considerable difficulty in maintaining the principle that there wasn’t the need to know—

Groueff: Of compartmentalization.

Manley: Yes, that’s right. And he fought Groves on that quite successfully. We did have these meetings every week, which people spoke quite freely about. It was good discussion. He had a knack. I saw this not only during the Los Alamos period, but during the general advisory period afterwards he would really bring out the best thoughts and so on of other people by his questions or even maybe by his way of summarizing things.

Groueff: Is he a good speaker himself?

Manley: Oh, extremely.

Groueff: Very articulate?

Manley: Very articulate individual. But, he does have a characteristic that you just almost sit enthralled by the speech—the wide variety of words and phrases.

Groueff: Beautiful command of English.

Manley: Extremely so. And then afterwards, you wonder what the content was.

[Laughter]

Groueff: The delivery is easy?

Manley: Oh very, yes. Just like that. You know, after these general advisory committee meetings, which would last usually as a minimum of about three days and perhaps longer, he would sit down and dictate to a secretary a summary of everything that was—

Groueff: The weekly conference?

Manley: No, no. I’m talking about the general advisory committee now on the post-war period.

Groueff: I see. But during the war, where were the meetings held?

Manley: They were initially held in the Theatre Number One, which was a big movie theatre that was built for entertainment, frankly.

Groueff: I see. In the same area there?

Manley: It wasn’t in the technical area. It was just down to the east of the pond a ways. I remember the security guards had fits about it because you could kind of crawl under the building.

Groueff: So it was in a big room, in a movie room?

Manley: Yes. There were 400 or 500 people probably in attendance at night.

Groueff: At night?

Manley: Yes.

Groueff: They were at night?

Manley: Yes.

Groueff: And later? You said this was in the beginning.

Manley: Yeah, then there was a building, an auditorium in B Building. I think most of them were in that at that time. Maybe those were smaller meetings.