[Bolton, 1976]
Bolton, 1976 (Photo courtesy of NRAO/AUI/NSF)




NATIONAL RADIO ASTRONOMY OBSERVATORY ARCHIVES

Papers of Woodruff T. Sullivan III: Tapes Series

Interview with John G. Bolton
At Parkes Obseravtory
March 15, 1978
Interview time: 3 hours, 40 minutes
Transcribed for Sullivan by Pamela M. Jernegan

Note: The interview listed below was either transcribed as part of Sullivan's research for his book, Cosmic Noise: A History of Early Radio Astronomy (Cambridge University Press, 2009) or was transcribed in the NRAO Archives by Sierra Smith in 2012-2013. The transcription may have been read and edited for clarity by Sullivan, and may have also been read and edited by the interviewee. Any notes added in the reading/editing process by Sullivan, the interviewee, or others who read the transcript have been included in brackets. If the interview was transcribed for Sullivan, the original typescript of the interview is available in the NRAO Archives. Sullivan's notes about each interview are available on the individual interviewee's Web page. During processing, full names of institutions and people were added in brackets and if especially long the interview was split into parts reflecting the sides of the original audio cassette tapes. We are grateful for the 2011 Herbert C. Pollock Award from Dudley Observatory which funded digitization of the original cassette tapes, and for a 2012 grant from American Institute of Physics, Center for the History of Physics, which funded the work of posting these interviews to the Web.

Please bear in mind that: 1) This material is a transcript of the spoken word rather than a literary product; 2) An interview must be read with the awareness that different people's memories about an event will often differ, and that memories can change with time for many reasons including subsequent experiences, interactions with others, and one's feelings about an event.

Part 1 | Part 2 | Part 4 | Part 5

Sullivan

Continuing with John Bolton on 15 March ’78. You had no reservations about maybe getting more than was actually there?

Bolton

No, in fact, we weren't getting more than was actually there. We knew it had to be, we didn't push it very far. I mean we knocked it down from what was something like 17° beam to a 12° beam.

Sullivan

Oh, is that all? I see.

Bolton

Yes, we used the, we had additional data. We had the same kind of map rising above the sea, essentially half the antenna. We knew what was in discrete sources and so on. We didn't attempt to...

Sullivan

You didn't really sharpen it up all that much?

Bolton

We didn't really sharpen it up all that much, no.

Sullivan

Okay. Once again, I have not looked at the paper itself recently, so I was only looking at the abstract.

Bolton

I think we split our beam into something like twelve pieces- a center, a surrounding circle and then maybe four quadrants surrounding that, with equal loading in the antenna pattern.

Sullivan

I see. We need to talk about the 80 foot, the building of the 80 foot. Dick McGee has told me about how you like to get out with a shovel and have your workers out there with a shovel. It seems to be the Bolton style. Can you tell me about the actual construction of the thing? Were there any particular problems?

Bolton

I think, it was really Westfold and I who started the big dig.

Sullivan

But even though he was primarily a theorist in orientation, he was out there digging?

Bolton

Yes, sure. Westfold and I started it by ourselves and Bruce Slee decided that it was going to be a good thing and later on Gordon Stanley joined in.

Sullivan

And also Dick McGee, or did he come on later?

Bolton

No, no. Dick didn't join in until the 80 foot was finished. Originally we had 160 megahertz, this was just hollowed, this was just formed from sand but around the edge we did build up some timber to extend it a bit. We initially coated it with the strip metal that you bind packing cases with. We just laid out strips.

Sullivan

I see. It wasn't a mesh then?

Bolton

No, it wasn't a mesh at that stage. We clipped the intersection and of course, that worked quite well for 160, but once we pushed it to 400 we had to put some concrete on to maintain the surface from drifting. And then we built the proper edge, I think the last four feet were just steel tubes, bent steel tubes stuck into the concrete and then wired around it and then chicken wire mesh covering the whole thing.

Sullivan

I see. Where was the location of this relative to the main blockhouse, which I’ve seen?

Bolton

Probably about 80 yards north and slightly inland of the main blockhouse.

Sullivan

But pretty much on the cliff?

Bolton

Yes. It was very close to the cliff edge.

Sullivan

And do I have it right that you actually were just using shovels to dig this thing out?

Bolton

Yes.

Sullivan

No equipment of any sort?

Bolton

No.

Sullivan

Was this...

Bolton

In fact if Pawsey had seen it, it would have been banned.

Sullivan

If you had equipment?

Bolton

No, I mean if Pawsey had seen the dish, it would...

Sullivan

You mean this was all done on the sly?

Bolton

Yes. It was done on the sly. Bowen knew it was going on, he came out and saw it one day and rubbed his hands together greatly and...

Sullivan

Why would Pawsey have objected?

Bolton

Well, it was obvious that it could be used at wavelengths which weren't in our allocated zone. You see, Radiophysics was broken up, we weren't allowed- one of the things that annoyed Westfold and I very greatly was that we weren't allowed to look for the hydrogen line very early in the piece because Westfold had translated [Iosef Samuelovich] Shklovsky's paper. We couldn't actually, we could never get across to Joe that this was atoms emitting a line frequency.

Sullivan

And what was, were you interested from the point of view of being able to get Doppler shifts, what was your real, or was it just something to do?

Bolton

Well, we wanted to see if we could detect it.

Sullivan

Just to do it.

Bolton

Yes, just to do it.

Sullivan

When was this now that you're talking about?

Bolton

Oh this must have been 1949.

Sullivan

Did you know about the Dutch?

Bolton

No, I didn't find out about the Dutch effort until I went to Europe in 1950, this was pre-1950, and I think we were told that 200 megahertz was our limit. We actually used the 80 foot dish to try to detect the deuterium line.

Sullivan

That's right. That came along a bit later. We'll come to that. This is interesting though that you had a definite strong interest in the hydrogen line at that early date. Pawsey, however, did not, then?

Bolton

I think he didn't understand, see. Pawsey was, although he did train us as physicists, got into ionospheric work and radio, he didn't understand that atoms would emit radio frequencies.

Sullivan

You think so?

Bolton

Yes. He's quite, this was quite outside of his comprehension at that stage.

Sullivan

Once again, I had almost testimonials from many people about his marvelous physical insight. What you're saying is that this had definite bounds to it. But it is true though, it wasn't just a matter of keeping you out of it.

Bolton

He must have, he knew enough physics, he knew what the Bohr atom looked like and so on, the extension to transition...

Sullivan

Hyperfine transition.

Bolton

Hyperfine transition was really subsequent to his physics.

Sullivan

But what I'm saying is that it wasn't just a matter of keeping you out of it, he didn't have any of the high frequency people try to look for it either, until they got the word from [Edward Mills] Purcell.

Bolton

Yes. And of course, I was in Holland in 1950, you see.

Sullivan

Even after you came back.

Bolton

I spent some time at Leiden and I sent descriptions about what the Dutch were doing and everything like that. And I sent descriptions from Harvard of what [Harold Irving "Doc"] Ewen was doing.

Sullivan

Well, [Frank J.] Kerr was doing that also. Kerr was also doing that from Harvard.

Bolton

That's right. Kerr was at Harvard when I went to Harvard.

Sullivan

That's right.

Bolton

And Kerr was doing it, so there was no, Pawsey just, I mean, he had a complete mental blockage.

Sullivan

Okay. Well, we've gotten this straight here. You were saying that Pawsey would not have liked the dish because it was designed for higher frequencies and it does seem to me from talking to everyone that there were very small groups with neat divisions as to their sphere of operation. But you've been in a lot of management, do you not think this is a reasonable way when you've got an awful lot of clever people you've got to keep them somewhat from running all over each other.

Bolton

It was a very good way in those early days, yes. I mean, I think, a lot of good people came together then. The outstanding people, one of the most outstanding people was Ruby Payne-Scott, and unfortunately, women in the public service had- well, she was discriminated against for basic reasons of sex and other reasons- she was a very aggressive person indeed. There was Paul Wild, Bernard Mills...

Sullivan

[Wilbur Norman "Chris"] Christiansen?

Bolton

Christiansen was sort of a later era. And with simple pieces of equipment you can make rapid progress, and we used to hold meetings in which, maybe every two weeks or a month, somebody would always come up with something very, very interesting.

Sullivan

This is a meeting of all the scientific staff?

Bolton

Yes. We had a thing called Radio Research Board, they were the actual people doing things were very [???] bodies in this meeting. But they were the important people.

Sullivan

Now this radio research board, this is the Australian organization, isn't it?

Bolton

Yes.

Sullivan

And they used to meet at Radiophysics.

Bolton

Yes, that's right. It was dominated by ionospheric physicists and so on. But it wasn't the way to go on, it was all right for the initial discoveries which could be done with not much money and so on. But Australia lost out very badly in the 1950's because of this.

Sullivan

This same style kept on going?

Bolton

This same style kept on going. And I remember in 1950 going to NRL [Naval Research Laboratory] and seeing that 50 foot dish being put together and thinking, "Hell, unless we did something like that, they're going to drown us as well." Of course the history of NRL is such that they didn't. But they could have done it- working in centimeter and millimeter ranges and so on.

Sullivan

Well, of course, that was an entirely different environment for working in. I don't see how they could have drowned you.

Bolton

Well, they only had to start a sky survey- to drown us. I mean the potential positional accuracy.

Sullivan

Well, their thing had real pointing problems, though, too, you know. It was an old gun mount, it had a good surface, but...

Bolton

Yes. It had the wrong people. It wasn’t until [Edward F.] McClain came up- there was an engineer.

Sullivan

I see what you're saying. But in any case, what you're saying is that the style was not appropriate to the way the science had changed. And you think this transition took place around 1950 or 1951?

Bolton

Yes.

Sullivan

And now once again, we've strayed from talking about building your hole in the ground. So this was the reasons that you didn’t get any simple earth-moving equipment?

Bolton

We didn't have any money. I think the aluminum mask, the 40 foot of new aluminum tubing exhausted our funds for the year, you see. Everything was built from scrap.

Sullivan

Another thing that puzzles me is how you could really do this without Pawsey knowing, because apparently he lived near there and used to stop by...

Bolton

It was behind the...

Sullivan

Was that the reason for the site selection?

Bolton

Right. There was some high scrub growing around it.

Sullivan

Okay. Having gotten this dish, what did you do with it?

Bolton

We did a survey at 160 megahertz, which didn't, in fact, do very much. I think the beam of 400 was about 1°, so at 160 it would be 3.5 or something like that. And this just said, "Well I'll work at 100 megahertz." We haven't gone wrong; we haven't pushed our deconvolution as far as we could have; we haven't overdone it. But 160 was really just, I think we did produce the contours at 160 and at this stage, we convinced Pawsey that it would be worthwhile if we could get the sensitivity of making the dish surface sufficient to work at say, 400. At that stage we got the okay to go ahead at 400. We got the money for a few cubic yards of concrete and chicken wire.

Sullivan

I'm a little confused here now. Bolton, Stanley and Slee survey is 100 megahertz that was published in 1954 was based on the old Yagi?

Bolton

This was the twelve Yagi mount.

Sullivan

Right.

Bolton

Just azimuth only.

Sullivan

So that was before the hole in the ground?

Bolton

No it wasn't before the hole...

Sullivan

Sort of simultaneously?

Bolton

It was contemporary with the hole in the ground.

Sullivan

I see.

Bolton

We dismantled the, Stanley had managed to get a 15 foot dish built and we put the 15 foot dish on the old 9-Yagi mount.

Sullivan

I've seen those pictures.

Bolton

We used the structure which held the Yagis, modified it to give us an azimuth resolution, and the 15 foot dish we used at, we used that so we could vary our frequency a little. But it was never used for scientific work really. It was just used to test out equipment and so on.

Sullivan

So you had both of these things going at once?

Bolton

Yes, oh yes.

Sullivan

And...

Bolton

Well, both were an attempt. You see, we had effective resolution in zenith angle with a sea-interferometer and the fact that we had a sharp horizon. So we spaced the Yagis fairly far apart to give us a good beam there.

Sullivan

In the vertical direction?

Bolton

Split beam- a split beam but we weren't interested in this section. We put the 6 Yagis horizontally to give us quite a lot of azimuth discrimination. And this is what scaled up the 20 source survey there to the 100 source survey there. But of course, sea-interferometer observations were very laborious. You didn't do a survey. I mean even though you might only want ten positions around the sky [Sullivan: horizon] to do the survey, ionospheric effects and so on, there were nights when you got nothing. I mean there was only one night a week that you got good observations.

Sullivan

Did you always want to have two independent observations? Of any given strip of sky?

Bolton

Oh, yes. Many.

Sullivan

And what was the result of that? Did you find that, in fact, this was a good idea or that things weren't quite reliable? I mean if you took just a single strip of sky that you could get pretty reliable thing from one...

Bolton

Oh, well, I mean as I say, we'd leave it in one azimuth for a week or two weeks.

Sullivan

Oh really? I didn't realize that.

Bolton

And then, of course, we couldn't work- thunderstorms out to sea were one problem, so that even though we might leave it in one azimuth for a week we'd only get coverage of about eight hours of right ascension. The rest would be chopped up by the ionosphere or thunderstorms. So we'd have to come back three months later and do it again to complete the sky coverage. So the 1954 paper was actually something like two years of observations.

Sullivan

I see. That explains why it was a bit later. Was this such that it had to be tended all the time or could you leave it overnight on automatic?

Bolton

We did develop, well one of the problems the galactic plane rises and so on and you have to be there to turn the strip chart down. But Stanley and I did build [Miller integrated?] circuits with time constants of an hour or more in which we smoothed out everything...

Sullivan

I see.

Bolton

And did a delayed subtraction which meant that instead of having to be there for eight hours of the night, while the Galaxy came in and went out, it was maybe only the sharpest part of the galactic plane coming in. So we used that...

Sullivan

As a filter against the...

Bolton

I think that's described in the paper.

Sullivan

But once again, we've drifted off from the 80 foot. I was just trying to find the publication of the 160 megahertz 80 foot [Sullivan: 72 foot].

Bolton

That was never published. [Sullivan: But it was- Wayne Orchiston!] [Australian Journal of Physics vol 7 page 96 from 1954. see fig 1 page 98]

Sullivan

Okay. That's why I can't find it. Because it really didn't tell you anything differently?

Bolton

No. It convinced Pawsey that we should go on and work at a higher frequency.

Sullivan

And that the dish worked.

Bolton

Yes. And, of course, McGee joined us about that period. He and I became convinced that indeed we were seeing the center of the Galaxy in the Sagittarius source.

Sullivan

Once you were at 400?

Bolton

At 400.

Sullivan

Right.

Bolton

At 100 megahertz- essentially in self-absorption. So you don't see it with, well, I think, at 80 megahertz, it’s in prominent self-absorption. I believe Bernie Mills showed that with the first cross.

Sullivan

And at 400 you would have a beam of, you said, 1° or something like that. And so that was getting down to...

Bolton

Was it a 1°? No it wasn't 1°.

Sullivan

Let's see. An 85 foot at 1400 used 40 arc minutes, so it would be...

Bolton

More like 2°. So 160 was about 6° or so.

Sullivan

But once you found that you were getting a sharp peak with a 2° beam, you were willing to call it a discrete source and I guess bolstered by the fact that the galactic coordinates went right at the...

Bolton

[???] 30° off.

Sullivan

Well, yes. But they agreed with other determinations of the center- optical ones. Or is that correct? I assumed by that time optical people also were saying that the center was 30° away from the...

Bolton

Yes. I think we had done our 100 megahertz survey which certainly pointed to the galactic center being there. And the plane is very different. One of the things the 100 megahertz survey said the galactic plane is in the wrong place.

Sullivan

How far different?

Bolton

Oh, about 1.5°. This was one thing which Oort was very enthusiastic about because when I went to Leiden in 1950, Van Taulder had just made a new determination of the galactic pole, I think, based on the motions of interplanetary nebulae.

Sullivan

What was his name?

Bolton

Van Taulder. And Van Taulder's pole agreed very nicely with our plane.

Sullivan

And not with the classical Olsen pole?

Bolton

Yes, that's right.

Sullivan

That's interesting. Even with a 17° beam you could get it down that fine, because of course, it's actually it's just one parameter for the entire survey. So that this all made sense and what is your opinion as to who should get the credit for the recognition of Sagittarius A or is your opinion that it's really a semantic thing as to when a source becomes a source- it was just a continual process?

Bolton

Well, I think Piddington was the first person, Piddington named Sagittarius A [Miller Goss: Not correct, W M Goss 18 June 2004. See Palmer and Goss, "Nomenclature of the Galactic Center Radio Sources" Galactic Center Newsletter (1996), vol. 2, p. 2]. Now at that stage, its position was not accurately known, it was terribly vague. It was an object which we couldn't find with sea-interferometer or anything else we did at 100 megahertz. It was an object which we found and defined rather precisely it's position at 400, and it really stood out there. And it stood out as a center of the contours around it. I think this was an important thing. It agreed with the location of our 100 megahertz- I think McGee and I put all these arguments together in the paper which said we are convinced we are looking at the galactic center. Now this wasn't accepted for quite a long time.

Sullivan

Oh yes, and of course, back to NRL they argued that it was only a couple of kiloparsecs away when they had some hydrogen absorption information. What other arguments were there that people did not like this to be the center of the Galaxy?

Bolton

I think the sort of optical backlash from many astronomers. "You can't just come along with a radio receiver and do what we failed to do in the last hundred years."

Sullivan

In terms of determining a good galactic system of orientation and so forth?

Bolton

Yes. But Oort was certainly one person who supported this.

Sullivan

What about someone like Baade, who was quite concerned with galactic structure also?

Bolton

I think Baade was a little bit jealous, because he'd been trying to find the galactic center by finding holes in which you could look at the increase and then the decrease in the star density.

Sullivan

Okay. The 80 foot- what other projects did it work on?

Bolton

Well, actually, of course, I got out of it at that stage.

Sullivan

Oh yes. Well, tell me about that. I don't have that.

Bolton

I went into rain physics then.

Sullivan

Right, but how did that come about?

Bolton

It came about because I lost out essentially. Bernie Mills had built the small Mills Cross, the experimental one. What I wanted to do, one of the things that we'd shown was this little 15 foot dish which Stanley had built, even though we had very poor signals, was that we had worked sea-interferometry right up to 400 megahertz on the strongest sources we could see. And shown that all the ionospheric nasties disappeared as one went to higher frequencies. So our proposal was that we should build a much more elaborate sea-interferometer. And it was going to take the form of, well, almost an Ohio, it was going to be 200 feet in...

Sullivan

You mean like [John D.] Kraus’ antenna?

Bolton

Yes. Like Kraus’. 200 feet in aperture, 20 feet high, and was going to be made of- there are lots of tennis courts around Sydney in those days, thousands of tennis courts, and it was simply going to be made of the standard tennis court construction.

Sullivan

I see, a real Australian...

Bolton

With 20 foot high poles and wires, a sort of wire mesh that was put on tennis courts. A stacked vertical feed for it, which would give it, I think it was a 4° beam over the horizon. It was going to be 400 megahertz. But an azimuth beam which was only a degree.

Sullivan

But how was it steered in azimuth

Bolton

It was steered in azimuth by moving the stacked feed. It was a [???] ratio.

Sullivan

Oh, I see.

Bolton

And it would cover, the same type of ratio as the actual dish, or a bit longer, and one could cover something like 20°. The stacked feed was going to capable of moving. And when you've done that 20°, you took the whole thing down and put it up pointing a different direction.

Sullivan

I see. And about when did you propose this?

Bolton

This must have been proposed at the end of 1952.

Sullivan

You wouldn't happen to have a copy of that proposal?

Bolton

Oh, no. That was no proposal, it was just...

Sullivan

You mean it was never written down?

Bolton

Oh, no. Just in talking to Joe and Taffy. We had lots of proposals, but one of the alternate proposals which Taffy was very keen on, was two rolling barrels with line feeds which would also work at 400, that is to say, combined the sort of 80 foot dish but as a rolling barrel. In fact, it was Taffy’s idea, the rolling barrel. And we'd make two rolling barrels which would give us 2° primary vision with the interference pattern for resolution.

Sullivan

This proposed sea-interferometer, was this going to be at 400 megahertz?

Bolton

That was 400.

Sullivan

It couldn't be much less with tennis court sort of wire. It couldn't be much higher frequency. The reason for doing that, I guess, was to keep the cost down. Would you have liked to go on to a higher frequency?

Bolton

No.

Sullivan

Why not?

Bolton

Because we knew the sources went down with frequency, so this was a kind of compromise.

Sullivan

However, Radiophysics could only support one of these largish projects, I guess, and who made the basic decision?

Bolton

Pawsey.

Sullivan

Well, that's sort of interesting, because I thought Bowen was the boss.

Bolton

Yes, but Pawsey was really in charge of the group.

Sullivan

Right, but for instance only a few years later, Pawsey lost out on...

Bolton

That's right, Pawsey lost out. Bowen took it on to his own. Bowen wanted this thing.

Sullivan

The Parkes dish.

Bolton

Yes. And he wasn't prepared to fight Pawsey over- he was prepared to fight Pawsey over this, but not over something which was not an integrated effort in the division, while we were all sort of in little sub-groups. So, actually, Stanley and I had done an awful lot of work and we proved that essentially this kind of thing to our own satisfaction would work. This was the way to go about it. At 400 we had no trouble in the ionospheric low angles, we got interference patterns on Cygnus and Crab, which were terribly consistent from day-to-day and minute-to-minute. And we felt with a 1° by 4° plus the sea-interferometer within the 4°, I mean, it's 1° in azimuth but an object seen from the horizon and then disappears out of the 1°, so you've really got much more, you've probably got the equivalent of about 1° antenna plus the sub-structure of the interference pattern. We felt we could detect several hundred objects and get accurate positions. As I say, we lost out to Mills.

Sullivan

But this must have been a difficult decision because here you had two good ideas going to do similar things. Was it really a matter that Pawsey said one is bad and the other is good? Somebody had to win it and somebody had to lose?

Bolton

Well, in a way, ours was the brute force method whereas the Cross was an esoteric. The Cross was using electrical engineering, we were using brute force.

Sullivan

So the Cavendish tradition...

Bolton

The Cavendish tradition won out. And well that’s too bad, at that stage, we lost a couple of our rain physics in an air crash and Taffy said, "Would you think of flying again?"

Sullivan

And so although you had not worked in rain physics at all, you...

Bolton

No, but I had done a lot of it. I had done a lot of flying. And I knew what one saw, I mean, I'd worked on, I'd had an interest in radar, ship radars at sea, and atmospheric effects.

Sullivan

This still seems somehow surprising to me. You were obviously a pretty well-known radio astronomer at this time and yet you were willing to just drop that subject. Or were you always thinking of this as a temporary thing?

Bolton

No, I didn't think it was a temporary thing. Well, I mean, Taffy said that, "If we ever get the dish, it's yours and so on," but I'd come to the end of what I could do with little bits and pieces.

Sullivan

You just came up against a wall, more or less.

Bolton

I'd come up against a wall, I'd have a proposal in to extend it, to break the wall down and it hadn't worked out.

Sullivan

Of course, the other option would be to go somewhere which you eventually did, to go somewhere else. The sea cliff interferometer at this stage, it would seem to me, was becoming a little bit unworkable or maybe you wouldn't agree with that.

Bolton

I think this 400 proposal would have worked.

Sullivan

But the advantages of it are, well, what do I want to say- did you feel by this time that you understood the refraction problems and so forth?

Bolton

Oh, we knew at 400 that we didn't get the irregular refractions that we got at the lower frequencies, I mean the straight refraction with optical.

Sullivan

And the ionosphere was much less of a problem.

Bolton

Yes, we were dealing with, there was no doubt with that instrument we'd have got positions to 1 minute of arc without any trouble whatsoever.

Sullivan

So would you say it's not fair to say that the cliff interferometer faded from the scene in the early 1950's because it had nothing more that it could do? It was really more because of this decision?

Bolton

It was because of this decision, yes. We could have extended it; it essentially would have done what we did later at Caltech, ten years later at Caltech.

Sullivan

In terms of minutes of arc positions on several hundred sources?

Bolton

Yes.

Sullivan

I'm trying to get at a comparison between the Michelson interferometer, which was being heavily developed at Cambridge, and the sea-cliff interferometer which was the first technique down here. Frankly, I've always thought in my mind of the sea cliff interferometer as a great idea, but all of a sudden it loses a lot of flexibility and you always have to work near the horizon and you can't change your spacing.

Bolton

Well the sea cliff interferometer enabled us to do a couple of Yagis what it took very larger aerials to do at Cambridge.

Sullivan

I don't quite follow that. The sensitivity, you're doubling your collecting area.

Bolton

4x.

Sullivan

4x. I'm sorry, I'm not aware of that. How does that come about?

Bolton

It has 4x the collecting area because the signals are added together in space, so you don't have the impedance problem.

Sullivan

That's right. Not on the line, yes. Well, still, you didn't have that big an array - they had 4x that, it's not...

Bolton

No, we didn't have that big an array, but if we had put what we were proposing...

Sullivan

Oh, yes. Now there, yes, then 4x became a huge thing.

Bolton

Became a huge thing. It was essentially a 100 x 200 foot dish, was what we were proposing to build.

Sullivan

So you could never have gotten that amount of collecting, equivalent amount of collecting equipment at that frequency?

Bolton

At that price.

Sullivan

At that price, yes. That's an interesting point. So if this thing, in fact, had been funded, it might have gone on for three or four years making such a survey.

Bolton

Well, but funding was a few hundred dollars as against $30,000 which the Cross took.

Sullivan

Really?

Bolton

Oh, yes.

Sullivan

Is that all it was going to be?

Bolton

Yes. It wanted 22 inch 20 foot poles.

Sullivan

Well, then I'm confused as to why there had to be a decision between the two. I thought it was a matter of, from a financial point of view.

Bolton

No. We had a factor of 10 on our side in doing it.

Sullivan

Then why did there have to be one or the other? Or was that not necessarily true, it's just a matter that Pawsey said, "I don't like this idea and it's not because of the Mills Cross that you can't do it, I just don't like the idea?"

Bolton

Well, part of this was the Radiophysics system of accounting, which only accounts for material you have to buy. The material for the Mills Cross was only a factor 2 or 3 higher than the material for ours, but the labor costs and workshop were not counted.

Sullivan

I see.

Bolton

That's one thing which I've always objected to; one should properly account for things. That's one reason why people like Christiansen and Mills got in terrible strife when they moved away from Radiophysics and tried the same scheme of accounting. They had to find the real costs, not the apparent costs.

Sullivan

Okay. Let's see, the 80 foot did some other things besides this survey at 400 megahertz, and once again, I'm trying to find the publication for that. When was that?

Bolton

Well, it wasn't published until after the Russians, it wasn't published I didn't think until 1956. This was Stanley and Price.

Sullivan

I see. You're not on it.

Bolton

No. In fact, I didn't take part in the experiment at all. I was in rain physics by this time.

Sullivan

Oh you're talking about the deuterium.

Bolton

Yes.

Sullivan

But I was thinking about the survey of radio sources or was there never actually a survey undertaken?

Bolton

No. The 80 foot dish was, I think McGee and I published the contours and the Sagittarius source and that's essentially the only publication that came out of it. You see, the group broke up at about that stage.

Sullivan

Because of your leaving?

Bolton

Yes. Slee went, I think, to Mills. I went into rain physics. McGee and Stanley continued. Westfold had gone to Sydney University to full-time teaching. McGee and Stanley and Paul Price, who came out a as Fulbright Fellow, did the deuterium.

Sullivan

Right. Tried to check up on the Russians who claimed detection.

Bolton

No. It was the first experiment.

Sullivan

Is that right?

Bolton

This was 1953.

Sullivan

The Russians were 1955, I guess, the Jodrell Bank Symposium.

Bolton

And we got our old records together and we didn't publish the negatives you see, which I think was ten times below the Russian positive plane.

Sullivan

I didn't realize that. And was that ever published? After the Russian claim?

Bolton

Yes.

Sullivan

Just taking the old data?

Bolton

Yes. In Nature in 1956, I think.

Sullivan

I see.

Bolton

But it was published from Caltech, not from Radiophysics, you see. Published from Caltech and MIT.

Sullivan

So you worked in rain physics for two years or three, was it?

Bolton

Around three, I think.

Sullivan

And just to complete the story, I should ask you just very briefly to describe what were the problems that you were working on?

Bolton

I looked into, Taffy was keen that actual experiments to modify weather should be carried out. I really had a free hand. I did a lot of work on the design of burners to work safely in aeroplanes. In fact, the first thing that greeted me when I came back from Caltech in the beginning of 1961 was somebody who was trying out a new burner and said to me, "Well, this is the model that supersedes yours," which was eight years earlier and its ten times more efficient and solid, "You should have been something eight years." I worked on determining the critical temperatures of- I essentially worked myself through inorganic chemistry and vaporizing, producing aerosols from chemical substances I could find, and finding out what temperature then produced [?] nuclei. I built equipment for monitoring the upper atmosphere, for trying to pick up meteor dust in high flying aeroplanes. This was a long [?], an accelerator which particles impinged on moving film of a substance which shall remained sticky at -40° centigrade.

Sullivan

So this was not really Radiophysics then.

Bolton

No, I worked on- I tried out ground based generators for rainfall stimulation in the Victorian Alps and [?] hydroelectric scheme. I also did some work on how difficult or how easy it was to prove that you'd done something if you did make rain and so on.

Sullivan

From a statistical point of view?

Bolton

From a statistical point of view. Try and find two areas in which you can actually measure what you've done, either in snowfall or river runoff or that kind of thing. And all the problems of going through it like different evaporation rates, different seepage rates and that kind of thing.

Sullivan

Yes. That must be a terribly difficult process.

Bolton

People have done these things, you see, without ever looking at...

Sullivan

If it rains two days later, you caused rain, yes. But then you came back into radio astronomy, and how did that come about?

Bolton

This was mainly through Taffy again. It was sort of an old boy network from the radar people during the war and the Office of Naval Research had tried to get Caltech interested in radio astronomy and Lee DuBridge was then president of Caltech wrote to Taffy, who was one of his war-time colleagues, to suggest a person who should come to Caltech to start it. Taffy produced my name and this of course was supported by Minkowski and Barlow from our old association. So I went to Caltech.

Sullivan

What was the attraction of it to you?

Bolton

Essentially, that I could take off, continue where I'd left off in the problem of radio identification. The intervening years essentially hadn't produced anything, and of course, I did start again where I'd left off- at the high frequencies...

Sullivan

Had the decision been made for the two large dishes?

Bolton

No. As a matter of fact, Caltech was sort of thinking in terms of a Mills Cross and Stanley and I went into the Mills Cross and we realized its very great difficulties. The fact that it was voltage product thing and side lobes would be one hell of a trouble, particularly with standing waves along the long line and that kind of thing, which later turned out to be correct.

Sullivan

In terms of producing bogus extended sources? Well, not necessarily extended.

Bolton

It gives you a confusion background. And so we proposed the two 90 foot dishes working, well we had decided to work at 400. Stanley had finally got hold of a Western Electric 437, 436 combination, which enabled you to get really good noise figures at 400, down below the 3 dB level. He continued to work in that field and built switches. So we believed we could make very sensitive radiologist at 400 megahertz.

Sullivan

Let me just go back to, you say that ONR [Office of Naval Research] actually approached Caltech instead of vice versa?

Bolton

Well, this is the story I'm told. In fact, I was always told at Caltech when I got pretty shirty about why I couldn't have some staff which the University would pay for, and they said, "Well, you know, we were talked into this - it wasn't our idea."

Part 1 | Part 2 | Part 4 | Part 5


Modified on Tuesday, 16-Dec-2014 15:52:54 EST by Ellen Bouton, Archivist (Questions or feedback)