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Oral History Transcript — Theodore Dunham, Jr.

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Interview with Theodore Dunham, Jr.
By David DeVorkin
At Cambridge, Mass.
April 30, 1977

 

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Theodore Dunham, Jr.; April 30, 1977

Extensive interview covering early life and family in New York and Maine; schooling and early interests in astronomy in New York City; observing Halley's comet in 1910; World War I and college years at Harvard University majoring in chemistry; medical degree from Cornell University; contacts with Henry Norris Russell and Harlow Shapley, and decision to move into astronomy; graduate work at Princeton; postdoctoral work and staff position at Mt. Wilson in the 1930s; interests in instrumentation and planetary atmospheres; the role of the Schmidt Camera in spectroscopy; planetary spectroscopy and the nature of the interstellar medium; founding of the FAR (Fund for Astronomical Research); World War II and work in optics for NDRC and OSRD; travels to Britian during the war; decision to leave astronomy after the war; move to Rochester for biophysical research; return to astronomy in 1952. The second interview concentrates on his contacts with Henry Norris Russell and activities during World War II.

Transcript

Session I | Session II

DeVorkin:

Dr. Dunham, I know you were born in 1897. And that was in New York City. But I don't know anything else about your family, and your early life. Who were your parents? What did they do?

Dunham:

Well, my father came of a medical family, with a strong medical background for two generations at least before him. His father was a doctor in Irvington, N.Y. My father was a physician in New York City. He was a graduate of Harvard College in '85, and the Medical School in '88, He spent a year in Vienna. Then he started to practice medicine and surgery in New York. He was very keen on using what at that time were the most modern methods he could.

He carried a microscope with him in his bag in New York; and up in Maine in the summer, where he practiced in Northeast Harbor, on Mt. Desert Island. He was up there about four months every year. Some of his patients were up there, and my brother and I went out in the motor boat with him to the islands, in the dark and the fog and everything , we learned a bit of navigation very well that way. Also how to pick up lobster pot buoys with a boat hook, when they caught in the propeller in rough seas. He had a small laboratory in our house on 63rd St. in New York. He did all sorts of things, on working up the opsonic index of pneumococci, to see what they'd react to in the way of serum. As I look back now, I realize that I learned a great deal from him about how to really find out answers about things, and not just to do things by rote.

He did quite a bit of research: Stretching the esophagus by using a series of bougies of increasing diameter, when many of the youngsters in New York drank lye, which wasn't good for them, and so on. He was always developing methods, as well as being Professor of Surgery at the Babies' Wards, at the Postgraduate Hospital, in New York, on 23rd St. in those days. Then up in the country, when we were there, he had the first X-Ray machine in that part of Maine, I'm sure. My brother and I were fascinated by the 15 inch spark, especially in the dark, that those coils gave in those days.

DeVorkin:

-- 15 Inch?

Dunham:

Yes, 15-inch sparks, blue sparks in the dark. 0h, it was terrific for us boys to see. We'd turn it on sometimes when he was out seeing patients!

DeVorkin:

When was this approximately?

Dunham:

Well, we were old enough to know what we were doing, so it must have been 1910 to '13, or so. I guess we left off after that, realizing it wasn't exactly cricket to throw out of adjustment somebody else's scientific equipment. He had a 2 1/2-horsepower gasoline one-cycle engine out in what we called the Engine House, for the generator that ran the X-Ray machine. We'd turn that on. You'd crank it, you know. It made a terrific noise.

DeVorkin:

What was your father's name?

Dunham:

Theodore Dunham. I'm a "Junior," yes.

DeVorkin:

What was your mother's background?

Dunham:

Josephine Balestier. Her grandfather came from Martinique. Her great-grandfather, I was told, escaped from the French Revolution and all that. One of my mother's sisters married Rudyard Kipling in 1891. I think. they lived in Sussex until 1935 when he died. They spent several years in Brattleboro, Vermont and built a house there. This doesn't make me a literary character in any sense. It was just an accident as to who married whom, in England when the two Balestier sisters were over there.

But anyway, we have a little background up in Vermont, and still have 32 acres of woodland there, and we don't know what to do with it. It's an island. You can't get to it. There's no right of way, A helicopter's the only legal means of access. Well, my mother's family had been in Denver, Colorado, and came to Rochester, New York, where my grandfather ran a small business for some time. But he died quite young, here in Boston, in the twenties. And my grandmother brought up the family, my mother and her sister and a brother who stayed as a farmer and businessman in Brattleboro, Vermont, and a younger brother Wolcott Balestier who was a publisher, and a friend of Kipling.

My mother's grandfather was a lawyer, Erasmus Peshine Smith, who was counselor in the State Department, who spent four years in Tokyo. That's something we're looking into now, He advised them on making early treaties with western countries in the 1870's.

DeVorkin:

That's just about when Japan was opened,

Dunham:

Yes. Just after Comodore Perry had opened it, He went over to help the government make their treaties with Westerners. They didn't know how to handle this strange bunch of people that came flocking in on them, and he did a pretty useful job for them, I think. We have a sword that the Mikado gave him when he left, which nobody understands the exact meaning of. We're trying to learn about Japanese swords, but we haven't got very far yet.

Anway, when we went to Japan in 1970, we made a point of seeing if we could learn anything about this back history. We talked to the people in Tokyo. And we talked to some of the people who know a good deal in the Foreign Office there, and they had looked it up ahead of our coming, and had some documents describing my great-grandfather's activities there to some degree. But I'm afraid the bombing burned some of the records, in fact, many of them. But they had some, written in Japanese script, of the earlier era. I think when the Meiji emperors came in they changed the script.

I'm not sure how that was done, but it was different. They found some old timers who could translate it into modern Japanese, and from that into English. These are not very extensive, but there's several pages. I haven't asked the Japanese scholars here, people who must know. But I think it is worth looking up, because this was one of the first cases of an American trying to work with Japanese, to see how they could get on together.

DeVorkin:

That's very interesting.

Dunham:

Yes, that's all Mother's side, of course.

DeVorkin:

Very interesting. Your father's occupation, all the while you were at home, as a family, was as a surgeon --

Dunham:

As a physician and surgeon, and he insisted on doing what was natural, in the earlier days. Doing both: practicing medicine, and knowing about surgery and being able to carry out major surgical procedures. The super-specialists were only just coming in. He died in '52, and of course he covered that transition. So, he did both, especially up in the country, where he took care of all the people there on the big island of Mt. Desert, and all the little islands dotted around it. That's where the Acadia National Park is you know. We have 25 acres on the slope we're trying to make into an observatory site, if the Park doesn't take it over first, We're having a minor battle.

DeVorkin:

How's the weather for that?

Dunham:

About 48 percent clear, at the Bangor airport. Weather isn't the only thing. In winter it runs from about 25 percent clear at Erie, Pennsylvania, the low spot, to about 50 or 55 percent along the Atlantic Coast. The coast is much better than inland. So that isn't unduly bad. We just happen to have the land, and we love the island, so we're trying to persuade the universities and colleges to join in building a 31 inch telescope, up there. But that's another story that hasn't happened yet. It's on its way. My father worked up there, on both medicine and surgery, and with other doctors up in Bangor, when they needed hospitals for the patients. Of course there wasn't anything in Ellsworth then. There is now.

DeVorkin:

Could you describe your home life, and how you developed your early interests? What your early influences were on you? I'm sure your father was a very significance influence.

Dunham:

He was very much tnterested in what any of us boy's thought was interesting. I have one brother, Wolcott Dunham -- I'm the oldest of the four -- my brother Wolcott is 2 1/2 years younger. He's been working on virus research and cancer research on mice and tumors and what affects their growth at the Jackson Laboratory in Bar Harbor Maine. And my two sisters, one of them here in Boston and one in New York, have been doing social work, and teaching in schools on special problems, and are still very active.

My sister Josephine is active in music, following her social work. She wanted to do the hardest kind of thing, of course, because that was supposed to be the Dunham tradition; use all your energies as well as you can. So she went for psychiatric social work, which I think is devastating, and she agrees that she wasn't made for it.

She sat up all night, every night and weekends, writing reports, you know, that nobody else would do of course. There were four of us. We boys went to school in New York, all the way to college. And of course, we didn't have much time to do other things. I was playing with astronomy, and writing letters to telescope manufacturers, reading in the public library in New York everything I could get about stars. I first looked at them out of the windows on West 76th St., before we moved to East 63rd. I think, and wondered, what do you suppose those are? And I got quite fascinated in star charts and the names of them.

DeVorkin:

About how old were you then?

Dunham:

I was seven or eight or nine, when I was first going to school and first became interested in astronomy.

DeVorkin:

Were the stars the first thing that you saw that got you interested in astronomy?

Dunham:

I think so. And then I realized that some of them were planets, and they were interesting too, I got interested in constellations. Frightfully scientific. Down in the Southern hemisphere where we've worked a lot, no astronomer knows the constellations. They just set the telescopes with circles; and the night assistant checks. But constellations aren't much good down there, except the Southern Cross, of course, I was interested in telescopes, and was getting catalogues to see if anyone could buy a small telescope, since hardly anyone had the nerve to try to make one in those days, and I didn't have that kind of nerve at that age (about 13).

So I saved up small allowances of 50 cents a week, when it got that high. It built up slowly, and finally the family chipped in and made it possible for me to buy one that we saw in a store window in Philadelphia one day, and I used it in Hampton, Virginia, where we were going for a month. We had a great time showing stars and planets to the students.

DeVorkin:

Was this a French telescope?

Dunham:

It was French. It was sold by Williams, Brown and Earl who were dealers. That always sticks in my mind, as I was trying to get together enough money to buy the thing. It's down in Australia now, and it's with a lot of equipment that's got to come back here from the Australian project, that has no further use down there. It's got to find its way back.

That's one of my other main jobs, to get all that equipment sorted, by means of photographs, tapes, and by listing down there, so we can get the right things to the University of Rochester, where much of it was borrowed, and to the FAR project, and some of it is our own. We're sorting it by mail now, to get it shipped to the right places. But that telescope's among those things. We used it in Hampton for a while, and had a great time with all those students, looking at the moons of Jupiter and the rings of Saturn and star clusters. It was my first experience with a telescope, as well as for most of the students.

The next thing I did was to put it up on the roof, not in New York but in Maine, on the roof of a porch up there, and looked at stars, and I thought I was a great astronomer when I saw my first variable star change brightness. I made out one of those forms that the Variable Star Association used. It was the first form I ever filled out, I guess, for the government or anyone else.

DeVorkin:

For the AAVSO?

Dunham:

Yes, for the AAVSO. I was one of the early members with Tyler 0lcott and some of the others, but I was too young to know just what I was doing, of course.

DeVorkin:

How did you find out about the AAVSO?

Dunham:

Goodness, I don't know. I suppose, reading in the public library in New York. That's a guess, I had no previous contact with Harvard at all. But I remember, on a rainy afternoon, I thought it was so urgent, I brought this first form, with six entries, I think, of great observations of variables against their comparison stars, and rang the bell at the Observatory, which was not enclosed by the Perkin Building or by anything else at that time.

DeVorkin:

On Garden Street?

Dunham:

Yes. And Professor Pickering himself, with his great beard, came to the door and looked very severe, rainstorm and all. I said, "Oh Sir, I have a little sheet of paper about variable stars. I didn't want it delayed. I thought it might be useful. I wonder if I might bring it in?"

DeVorkin:

You came up from New York?

Dunham:

No. We went back and forth twice a year, you see, up to Maine and back to New York. Anyway, I felt this was, oh so important. I have the original red notebook, that I put all those observations in. There weren't very many of them.

DeVorkin:

What was Pickering's reaction? Dunham; Well, he was very pleasant. He smiled and said, Won't you come in?" as any good gentleman would in those days. Rather than, "See my secretary for an appointment."

DeVorkin:

You were about 16?

Dunham:

I was about 16, 1 guess, something like that,

DeVorkin:

Do you have any recollections of Pickering?

Dunham:

I saw him, occasionally, later, going back and forth from Maine, and I went to some meetings and talks at Harvard and saw him a little. But he was not exactly the kind of person to take a youngster in and say, "Sit on my knee and I'll tell you about astronomy," as some others have been since,

DeVorkin:

Did you meet any of his staff? Henrietta Swan Leavitt?

Dunham:

I saw her in a back room. I didn't realize it was an historic sighting at that time; but she was in the back room, where I think Cecelia Payne has been since then, and several other distinguished people -- Cecelia Payne Gaposchkin of course. I didn't respond correctly, ask her about classification of spectra, which I didn't, I suppose, know existed. I knew there were prisms, and that Sir Isaac Newton had broken up sunlight into colors, and that this had also been done on stars.

But I had no idea of what some of the good British astrophysicists had done on that in the earlier days, first, and then there at Harvard. Annie Jump Cannon, of course, we knew very well here, in the early days, and we talked about all sorts of things. But that came later on. No, I just played with variable stars, and thought they were rather worth doing, They justified having fun with the telescope. That's what it came to, really. And that was as far as it went, in school, because of course, we were pretty well occupied in school,

DeVorkin:

What about your early schooling? Was it in public school in Manhattan?

Dunham:

No, it was at some of the private schools in New York, First at the St. Bernard's School and then at the Browning. We used to have little red caps at St. Bernard's that said "STB" on them, and we used to roller skate down Fifth Avenue and count the ratio (my first study of statistics, I suppose) between horses and automobiles, whipping down the stretch from 63rd St, to 48th St. I at least knew enough to put brackets with a question mark on the result, because I knew it would be more commercial downtown, and different up along the park, perhaps. So we got the ratio. I remember it crossing the 50-50 line, I can't say what date that was. It might have been about 1910. I don't know exactly.

DeVorkin:

What strengths were there in your early schooling? Did you find mathematics and science in your schooling? Was that available to you?

Dunham:

Yes. The science was distinctly low there. St. Bernard's School was run by two English headmasters who came across from England, and they of course were very strong on the classics. So, we went further than usual, not excessively far, in Latin and somewhat in Greek. But our closest contact with Latin was Richard's FIRST STEPS IN LATIN, hurled at our various foreheads, as a suggestion that you buck up and work a little faster at your desk!

DeVorkin:

Yes. What about your mathematics?

Dunham:

Well, there was just the standard mathematics, arithmatic: and then at the Browning School for a couple of years after that, we used to have 15 minute sessions for the whole school where they had competitive addition and multiplication examples. You had trick cards you could cover up here and there and get different sums and products. There were some nice things about it. It always came out 15, as you checked it, if you did certain things, and you knew it was right.

DeVorkin:

What do you think stimulated you to do this interesting little statistical study while you were on your skates on Fifth Avenue?

Dunham:

I suppose, seeing diagrams on astronomy and physics in the public library, where I used to spend the weekends and evenings reading a good bit. The 42nd St. Library, you knov.

DeVorkin:

The 42nd St. Library. This was primarily then a self- taught interest?

Dunham:

Oh yes, almost entirely, yes. I don't think I knew anyone in astronomy. There weren't any amateurs around, that I knew about anyway. I just got interested in it.

DeVorkin:

Did you talk to your father about it at all?

Dunham:

Oh yes. We talked somewhat. He didn't delve into it with me. But he did supply a continuity of steady background in practical application of the subject, with a scientific attempt, an experimental attempt, to follow through on understanding factors, and get your feet on the ground, on how medicine worked, as far as you could. Medicine was just coming over the threshhold of what could be called proper science -- biology, and physiology of course, We hadn't distinguished biochemistry and biophysics at that time, all these hybrid names hadn't quite come over the horizon.

You just looked at it either as a perfectly definite subject that was practical and applied, or you looked at it to see why. And he tried to do both, and he did it very successfully. He was very calm in his approach, didn't get excited, had a delightful manner with patients and with the family, and gave us the stimulating feeling that we belonged to something, that he'd help us to get started to go further, in whatever field we thought was fun. He didn't drive us into medicine. I had two uncles besides my father in that generation who were physicians. They were doing research, both of them. Edward K, Dunham did important work on emphyema during the war. He was for many years at New York University, working in pathology and biochemistry.

DeVorkin:

What was this?

Dunham:

Laboratory research in biochemistry. He had a good laboratory, up at Seal Harbor, Maine, near where we were at Northeast Harbor. He worked up there in the summer. My other uncle, Dr. Carroll Dunham, didn't have very good health, so he didn't practice medicine, but he watched it from the sidelines and we all talked together. It was a kind of a background. My grandfather, Dr. Carroll Dunham, whom I never knew, was in Irvington, N.Y. He became very much interested, for several years, in homeopathy, At that time (about 1860) it looked more logical than it does now. But when you read some of the papers that he read and collected, it's very interesting to notice the similarity with the present field of immunology.

Because although their equivalent of antigens, if you were to call them that, which they supposed would stir up an immunity, were quite different -- they gave people small doses of the actual drugs and chemicals that would produce a condition similar to the disease in question -- now they give patients live or killed bacteria or toxins, or some other kind of antigen, that produces immunity. But for all we can see, they were looking at it in a somewhat similar way.

It was a justified scientific approach, to look into it, and it was, a small team of people, quite intelligent people in this country and in Europe, who went into homeopathy, and tested it quite hard, for a number of years; and then dropped it in favor of microscopes, vaccines, and other methods. But my grandfather worked on it quite hard, and he was one of the officers of the Homeopathic Society for a number of years, and I'm quite intrigued when I look over his records.

He wrote some very interesting accounts of it. He was the Dean of the Homeopathic Medical School in Philadelphia, I think. He wrote a very excellent, highly impressive valedictory address that had nothing to do with homeopathy, on advice to young physicians -- how they ought to think about the subject, about their patients and about themselves. It would stand very well as an address by any Dean of the Harvard Medical School at the moment -- possibly better than some.

DeVorkin:

Did you appreciate these ideas, which seemed to be highly empirical approaches to medicine and research -- did you appreciate them while you were in your teens?

Dunham:

No, I don't think so at all. I thought they were probably nonsense. These people had all gone crazy on a queer tack. It wasn't approved. One grew up, in those days, at least I did, supposing that the way that the most successful or effective people in their subject were looking at their subject was, in fact, what you called the "right way" to do it. I didn't realize the great importance and propriety of looking at any problem from several aspects.

The crazier, the better, in a sense, because whoever brings up an idea deserves to have it looked at, evaluated, and thrown down or brought into the mainstream at some point. But in recent years, looking back over those papers of my grand father -- I have several volumes of them up In New Hampshire -- I find them extremely interesting, to see how he came to think the way he did, and to see the perfectly rational, scientific common sense of it, at that time, in the .5860's. I have a cousin, Edward K. Dunham III here in Brookline on the staff of the Harvard Medical School. He is also at Beth-Israel and in private practice. He is working in immunology, and I want to get him to look at the early approach to homeopathy, because I think there's a very interesting comparison or point of view to be derived from attacking the same subject in quite different ways, depending on which century you're in. A hundred years later, it will be a different approach, but it's the same problem. We haven't got it yet. Well, that's medicine.

DeVorkin:

In your early schooling -- it was private primarily?

Dunham:

It was primarily private, but rather mixed and somewhat self-taught. I did all my mathematics up in the country between scraping the paint on the house and re-painting it, and working on calculus and analytic geometry and things like that, just enough to get into college here at Harvard.

DeVorkin:

How old were you then?

Dunham:

Well, I suppose I was around 16.

DeVorkin:

That was around 1910?

Dunham:

1914. I'm always two years older than the year.

DeVorkin:

How come?

Dunham:

I don't know-- just having been accidentally born the wrong side of the century mark, in 1897, practically '98. I always just add two. That's the only way I can keep track of anything.

DeVorkin:

Do you remember Halley's Comet?

Dunham:

Yes -- just. I was 12, and I think I had the measles. I was picked up by my mother and taken to the window, and the first time it was a failure, because the comet wasn't doing very well. It hadn't come far enough along. And then there were three or four nights when I was led to the eastern window -- I think it was the eastern -- and saw it coming up before. sunrise. Of course I've seen pictures of it since, and this is a disturbing influence, but I really think I remember the great big fuzzy tail, going way up, and would like to be around to see it do it again.

DeVorkin:

Do you remember the excitement?

Dunham:

Yes, I certainly do, and I was quite intelligent enough to realize the question of cyanogen that some people raised, and whether we'd all survive to the end of May or only till about the 20th. It went by in the teens of May, didn't it'? It was a dramatic expexience. Every- one was talking about it. I was perfectly aware of what was being said. I think it was the measles that had me down a bit. But I remember all the papers with their flaring headlines and pictures, and people talking about the dire risk to the human race. It had been a bad race and done badly. Some said it was going to get it now. This was as far as it (the race) would go.

DeVorkin:

What did your father say about the comet? Do you recall how he felt about it, whether he was worried about the cyanogen?

Dunham:

No. Nobody had measured the absorption spectrum of cyanogen in that comet! We had never heard of it then, but I'm sure he thought that, just looking at that tail, whatever came from the nucleus must be so dilute that we could stand a few particles of cyanogen for a few hours. After all, it takes more than one molecule of cyanogen to knock a person out. It has a powerful reputation. One of the most violent nerve poisons, I suppose, in existence, But it isn't that way quite. It takes a few dozen, if not a few thousand, if not a few million molecules, to do you much, harm.

DeVorkin:

Did you have any formal religious instruction?

Dunham:

Perhaps not instruction, so much, as just growing up in a family where it was more or less assumed that everyone went to church and thought about the meaning of life. I don't think I even went to Sunday School. We just went to one of the New York churches, as a matter of course, generally to St. George's. Sometimes way down to Trinity. We knew William T. Manning there, who was the rector and then the bishop of New York, and quite a colorful character, highly conservative and had strong opinions on everything. We knew his family pretty well, and his daughters, and saw them up in Maine. They went to Seal Harbor, Maine.

They were patients, among other things, but that was entirely, incidental. They always kept well! But there was a connection there, and at other churches, St. James and some others, up town in New York. We just picked religious experiences, but didn't have any formal instruction, no Bible school, no official anything. We went through the usual procedures. I was confirmed in the chapel of the Episcopal Theological School here on Brattle Street in Cambridge when I was in college, but I don't think it changed my life completely.

DeVorkin:

Did you ever go to the Columbia University Observatory, the Rutherford Observatory, at that time? Did you ever see the telescope?

Dunham:

I saw the telescope there, probably the year before I went to college. I had a family that had definite ideas about some things, and one was that you shouldn't go to college too early. They were probably right entirely about it, I realize now. So I held up a year and tried to think what I'd do about it. I came up to Cambridge and took the famous, ten or twelve entrance exams in roaring hot weather all through a week, the way you did it in those days.

There was no scoring of people ahead of time and admitting them on paper, you know. They do it now on computers. I went to Columbia. I got myself worked in somehow to do a course in physics there, for a year, before coming up here to college. And this was very stimulating indeed, to do actual experiments in the lab with real equipment, I didn't have to put together myself in the basement, so as to try things out.

DeVorkin:

Who were your teachers?

Dunham:

There were two of them, Professor Davis, I think and Mr. Parwell, who was younger and with whom I talked primarily. My connection with Professor Davis wasn't personal contact, more than just enough for him to say: "Go ahead and take this course," and later; "Now you're doing pretty well." I got through it officially, with grades. It did get counted a little at Harvard, after the war. I had 16 2/3 credits or hours or whatever they call them nowadays, for my degree, my AB degree here, and they forgave me the missing 1/3 of a credit. We went on over third year terms during the war, and I was off doing chemistry in the Army, and the course at Columbia counted a little bit, that physics, to get me through without spending another year at Harvard.

DeVorkin:

What did you do in World War I?

Dunham:

World War I. Well, that goes back a year to 1917, when I entered Harvard college, when I was terribly interested in chemistry. And of course, everyone was saying, "Do I enlist in the Army and rush off to France?" My family had an idea, maybe it was wrong, maybe it was right, that it was better for me and my brother to be doing something in a scientific way.

Whether they wanted to save me from the risky maneuvers in France, or whether they really thought so completely, I never will know, and I don't think it's very important. But they thought that science was the way for us to do something useful here at college. So, I concentrated, I wanted to anyway, pretty heavily in chemistry. We'd known Professor Theodore V. Richards, who worked on the atomic weights, had the Nobel Prize and all that.

He was a tremendously calm but very wise advisor and thinker, and guided much of my, first contact with science. How to do everything carefully and well, and thinking about it from every point of view. He used to have me around his house here on Fallan St., two streets down, quite frequently. We got to know his family very well. Patty Conant, his daughter, finally married Jim Conant while he was a professor of organic chemistry with Kohler. We got to know him that way.

Richards' point of view led me to make an intensive effort in chemistry, apart from English A and one course in economics that I never could understand. I don't understand economics as a science yet. No one ever looks back to see whether the predictions came out right, They never say how they predict; they never look back to see how the score was. They always say, "It's going to happen." I think it"s very interesting. But I took two courses, as a Freshman and then about four courses more in chemistry. I was too young to enlist in the Army.

Jim Conant, who was a young professor of organic chemistry at that time, and Professor Lamb, the head of the chemistry department on the organic side here, both went down to Washington and set up two laboratories for the Chemical Warfare Service, one on offensive materials and one on defense, at the American University. I got in on the defense, as a private, when I was allowed to be inducted in August, .59.58, when the Congress finally passed the great historic Draft Act. I went and watched Congress vote on it. The temperature was over .5.50 for nine days. It was the highest record that the Weather Bureau has ever had, then or since.

DeVorkin:

110?

Dunham:

Over 110. It went to 117 one day, on the recording thermometer on Pennsylvania Avenue, halfway down between the White House and the Capitol. It was so hot that everybody was exhausted, but they all col-lected in the evening to see whether it had made a record that day.

When it gets really hot, they get excited, There were no refrigerators, of course, just a little ice, and of course it melted and all the food went to rot and ruin. But we watched Congress pass the Draft Act, and then I took quick steps to get inducted under the draft, because you couldn't enlist. I was able to be assigned to the American University Experiment Station, up on Wisconsin Avenue, where Jim Conant and Professor Lamb had set up a very fine laboratory, with chemists from all over.

We went out and sprayed mustard gas in the field outside there. Our immediate leader, Captain Carleton from Wisconsin, was very enthusiastic about the five-liter vacuum bottles in which we collected samples of the air. We went out and exposed them on racks at different heights above ground, different numbers of hours, after spraying it with mustard gas, to see how long it would last if the Germans should use it. And the thing I'll never forget was his insistence we be very scientific, and try the experiment not only in the middle of the day and at midnight or a little after, when it was cold, but also when the moon was shining, the full moon. And so we tried "full moon" vacuum bottle -- tests of mustard gas concentrations.

We said nothing, but we have it in the notebook there, the warfare records. No general could possibly say, "Well, did you try it in moonlight?" We'd be able to say, "Why, yes sir, I certainly, did" and then he'd be promoted to be a major-general, I suppose. Well, I think Carleton was a very good chemist. He tried to do everything throughly, and he knew his Army technique -- that you mustn't miss a point. So we worked under the moon. And it was more pleasant in the moonlight than it was at 100 degrees in the daytime, with rubber suits on to keep the mustard off you, and off your clothes of course. Well, this, hasn't much to do with astronomy, but it was a scientific experience about how you do things. It was so different from Theodore Richards and his very careful work on atomic weights, and my first work on real research in his laboratory, on the potential of the zinc electrode.*

DeVorkin:

You did that with Richards?

Dunham:

Yes, with Richards, during my senior year here. He let me work full time on a research project, in his new Gibbs Laboratory, right here up the street beyond the Law School.

DeVorkin:

Would you talk about how you came to work for T.W. Richards?

Dunham:

Well, only because the family had somehow known him a little, I don't remember just how. I went to see him to ask if he could be my advisor in college. In those days you had an advisor right through four years, unless you didn't get on together or something. He watched and talked with me about all my planning. It had a great effect on decisions that were made. He thought I ought to go to Germany and study chemistry further, for a year, after I got through here. I concentrated on chemistry heavily in college, and took almost all the undergraduate and graduate courses.

They let me take an examination for honors with an examining committee that included Richards, Forbes, Kohler and Conant. This was rather fun in a way, and resulted in my getting my AB with Highest Honors in Chemistry which had not been done at Harvard for quite some time.

DeVorkin:

Who would you have studied with in Germany?

Dunham:

I don't know exactly. We didn't quite get to making the plan, because I had to decide between that and going to the medical school. And with all the family background in medicine, that was where, if you call it that, a long-continuing conflict began between astronomy and medicine. It wasn't so strong a conflict while I was in college, but it was when I graduated in `21, and it has been there ever since. Actually, I have managed to resolve any conflict that may exist by using experience and equipment from one field where it applies for selected problems in the other field.

DeVorkin:

That was more a conflict between physical chemistry and medicine, at that time?

Dunham:

Yes. Probably research in biochemistry rather than in physics. I hadn't gone as far in physics and optics as I did later. But that was the real choice. One possibility was to go to Germany and continue in chemistry. Or here, but in those days you went to Germany quite normally.

DeVorkin:

Even right after the war?

Dunham:

'21. In the First World War, they didn't smash everything up as much as they did during the second war.

DeVorkin:

Right, And to your recollection, there weren't feelings of *Dunham and T.W. Richards, J. AM. CHEM. SOC., 43, 1921 hostility that continued? In other words, it was still considered very very important to go and study in Germany?

Dunham:

Yes, I think it was. Certainly, if you really wanted to go ahead and get ideas on research, and talk to the people who had profound ideas. There were certainly several, I suppose many individuals in this country, in different universities, who were top notch on thinking and planning. But of course, in those days people in one university like this one* didn't know nearly as much about what was going on in the Middlewest and the West. As you know, the general theme was that if you were in Massachusetts., you were somewhere.

If you were at Harvard, you were really somewhere. And other universities existed, but they weren't quite as important, and you didn't have any catalogues that would quickly tell you the quality of other universities such as the Universities of California, Chicago, and many others. They had very good men, but they weren't understood as well from an eastern center. If you'd been out there, you'd have had a much better look at the whole country, and realized that Harvard was just one of the good places.

DeVorkin:

What about astronomy at that time? Was this the feeling in astronomy, too -- that Harvard was the place?

Dunham:

No, not nearly to the same extent. Because in those days, it was observational astronomy that was done at Harvard, rather than theoretical. Theoretical astronomy was very limited in this country. There was more in England, and still more in Germany. So, here in the U.S., the bigger the telescope, the better the astronomy. I am very strongly opposed to any such overall point of view now. I think the middle-sized telescopes with first class photoelectric detectors, and computers following them automatically right down the line, and dropping photography as fast as you can, but not too fast, is the way to do it now. And it doesn't matter if the telescope is even 20 inches if you have the right kind of detectors on it. You can do a terrible lot that's never been done. If it's 30 or 40 or 50 inches, you're well set. I'm now trying to compute the optimum size of a telescope, to get the most data for a dollar. I don't think that's been done very carefully.

DeVorkin:

That's a very important thing to do.

Dunham:

I think it is. And I'm trying to get figures on the Space Telescope. We're very much interested in the program of space telescopes now. Individuals are putting in proposals. That's what they want now at NASA, rather than big teams and universities. And we're trying to work out just what it costs, per dollar, and then see how to plan. Whatever I propose probably won't be accepted; it will just go into the mill.

But I want to see now, using my proposal, what could be done in space for a given expenditure, to see how nearly you could come to the same result if you used the absolutely best on the ground. It is very expensive in space. If you used the space apectrograph and recorder for just limited *Harvard regions of the spectrum, one spectrum line of interstellar this or that, going way out into space, with its perfect images above the atmosphere, as compared with the best you could possibly do with image slicers and glass fibers and the best detectors down here. How nearly could you beat it? And how would the cost compare, per dollar?

If you built ten telescopes down here, and only spent a tenth as much for these ten as you would for one telescope in space, it would cost .500 times as much up there, and ten of them down here might go just as far, except for the ultraviolet, which you can't ever get when the light comes through the atmosphere. All that kind of thinking comes into it now. Theoretical people now get observations out of Kitt Peak and other places, where they can have the telescope for a few-nights and get data; and then they bring the data back to home base and run computer print outs on them.

DeVorkin:

Right. Let's go back now to the point where you were to choose between chemistry and medicine. What were the arguments on both sides?

Dunham:

Arguments on both sides, yes. Well, of course, on the medical side --

DeVorkin:

-- there was your family.

Dunham:

I think tradition had an important bearing. In those days youngsters thought sometimes they ought to do what was most useful for the world. I don't know how often they think of that now. I think they say, "If I can get any job first, I'll take it, and then I'll think what I want to do, and what I probably am adapted best to do." But in those days you thought about usefulness, and medicine has a human side to it that looks useful, and my family had done quite a bit in this area that seemed useful, and I think it was useful. And so there was a draw, a pull slightly that way. But medicine also used the best that was known at that time in chemistry.

It was just developing very fast and was very exciting. Penicillin hadn't been latched onto, of course, until the second war, and even insulin came in during my first year in medical school. But nevertheless, chemistry looked as though it had powerful applications. Organic chemistry in particular. And so it looked as if research in medicine could be both very exciting and stimulating, although I didn't know much about it at that time. On the other hand, all this work in chemistry, from the physical approach with Richards and other people here was most exciting. I never took a full course in physics here and only one course in astronomy, which had two students, myself and one other, Carpenter.

DeVorkin:

Who was that?

Dunham:

It was Astronomy 7, in about 1920 by Harlan True Stetson. He was strong on photometry, measuring the brightness of stars -- measuring photographic plates, with a little photoelectric machine that he fixed up in the basement of the Jarvis Street Observatory. That's since been submerged by the Law School. Carpenter went out and ran the Steward Observatory, before it became the big thing that it is now.

DeVorkin:

Carpenter?

Dunham:

Yes, Carpenter. He and I sat side by side and talked mostly photometry, of course, with Stetson, and went and ran the telescope. It might have been an eight or ten-inch, out there on Jarvis field?

DeVorkin:

Yes. When was the last contact you had with Carpenter?

Dunham:

Out there in Tucson, when I was at Mt. Wilson, we used to go through Tucson. It had dirt streets and all that, a little bit of a town, and we used to see him there at intervals. He operated the 30 inch at the University of Arizona.

DeVorkin:

He built it?

Dunham:

Yes, I think he built most of it.

DeVorkin:

How did he end up at Arizona at that time? That was very early. Did he set up the Steward Observatory?

Dunham:

I don't know. But one ought to know the history of the Steward Observatory. The Steward people gave a small grant and helped to start it, I think. And I don't know if anyone was before him. He may have set up the 36-inch.

DeVorkin:

We should try to find out. I'm going to Tucson some time.

Dunham:

I'll ask Fred Chaffe out there. We work pretty closely.

DeVorkin:

Who's that?

Dunham:

Fred Chaffe, here on the staff of the Smithsonian and Harvard. Chiefly Smithsonian, but you can't tell the difference any more here. He's out there running the 60-inch program on Mt. Hopkins, you know, the Harvard-Smithsonian station south of Tucson.

DeVorkin:

Then he would know possibly.

Dunham:

Well, he'd know who to find out from, and he has his office there in the Steward Observatory. It's a Smithsonian office. And he's out there continuously.

DeVorkin:

The course then with Harlan True Stetson was the only one that you had.

Dunham:

That's the only course in astronomy. I used to talk to people up here, and to Harlow Shapley. He was director then, of course, he'd taken over from Pickering, and I used to go and see him.

DeVorkin:

I'd be interested to hear about Shapley.

Dunham:

Well, I can tell you a little about him. He had his office up on the uppermost floor of what we now call "Building C," one of the first office buildings of any sort here, and he and all the middle-aged women with "fly swatters," you know, on small glass plates, held by a wire handle -- photographic sequences of stars, brighter and fainter, that they'd compare, with variable stars, many of them in the Magellanic Clouds from the telescope in South Africa.

There were four or five of them. And they'd sit there assiduously writing down magnitudes from plates out of the plate vault. But Shapley was there in his office, and you got in to see him without too much effort. He had a secretary who kept track of him, to save him from too many students and queer people. He always was very friendly about anything you were doing. I came up here and spent three or four months, when I was a graduate student at Princeton, to get observational material in spectroscopy.

DeVorkin:

That's right.

Dunham:

At that time spectroscopic material here was entirely from objective prisms -- one, two, three and I guess even four prisms, in front of the objectives of the ten-inch telescope here; and the one in Chile, at Arequipa, in the early days. And that was where I first saw the spectrum of Canopus, which I've become profoundly interested in since. And in the 1960's I photographed an extensive series of very high resolution spectra of Canopus from Mt. Stromlo. I now have them up here at Harvard to work on.

DeVorkin:

What were your experiences with Shapley?

Dunham:

With Shapley, they were primarily making plans about using equipment, using spectrum plates, and who to talk to about specific problems.

DeVorkin:

Oh, this is after you were at Princeton.

Dunham:

Yes. When I went into the Harvard Observatory, it seemed to be a dramatic place where you had a feeling of awe; that you were entering something that really was it, don't you know, on a subject that you'd first touched as an amateur. The word "amateur" had hardly been invented then, I guess -- you were just interested in astronomy. But interest wasn't classified either way.

We just talked and had fun. But the thing about Shapley that I remember most, of course, was his big revolving desk, that went round and round. And as you probably know, his son Allan -- in Boulder-- has that desk now. There's a photograph of it. I want to see if I can get enough details, or a sketch, to make something a little like it, if he'll let me, and put Harlow Shapley's name plate on it, giving credit to its inventor, because it is wonderful. I think it probably had 12 sections around the periphery, with shelves at the back and desk space in front, for each of 12 subjects.

He had subject matter, data and whatever he was working on, correspondence, anything at all, in a slightly confused way. But at least they were separated. He'd have them partly out on a triangular shelf, in front of those shelves, and partly in the shelves, and then he'd just spin it and say, "Oh yes, about that subject," and then he'd spin and come to a halt at the right place. "Yes, I think I have that here" -- and if he didn't, he'd call his secretary, and get it out of the file. But people didn't live with great big files the way they do now. And I thought this was simply terrific. I've managed it in a somewhat different way, this problem of papers on various subjects.

When I was at Rochester, at the university, in the Institute of Optics, I knew the people up at Eastman Kodak pretty well. Somehow,I found out that they were selling off some of their wooden frames, each with 36 shelves, that they used on the assembly line in the Camera Works to hold parts, and they'd roll them around on rollers to people who put them together. They, were selling those off at $2 apiece, so I bought two of them. I find them invaluable, by putting labels, under each compartment, I had 72 possible subjects and sub-subjects. Strangely enough, it isn't enough! I had those in my lab in Rochester, under the library building, where we finally built a laboratory for microspectroscopy, using a Burch reflecting microscope.

I took them to Australia, and now I have them back in New Hampshire. They're very good for shipping paper, because you just stuff them in, and put the two shelf frames together with. a steel band coupling them around, and so you can ship papers from one continent to another, and they're still all sorted. They have been very useful. I painted them green, and they're screwed to the wall above the desk. Well, that's my version of Shapley's invention. Entirely different. His was much better. I want one like that, if we can get enough space. It would take up this whole room.

DeVorkin:

What were your experiences at Cornell? How, did you choose to go to Cornell?

Dunham:

I have the feeling that you want to get primarily at what all of us knew, about Henry Norris Russell, and other greater characters in physics and astronomy.

DeVorkin:

Certainly, but we're getting to that. I would like you to talk a little bit about how you finally chose to go to Cornell, and just a bit about your experiences there. And then from there, your decision to go to work with Henry Norris Russell.

Dunham:

Oh, yes. Now, that was really historic. I wish I had a tape on that. That evening in Princeton, when we talked about the relative merits of a future in astronomy against biophysics.

DeVorkin:

When was that?

Dunham:

That was in the early spring, certainly of 1925, because I had to make that decision, what was going to happen. I graduated here at Harvard in `21.

DeVorkin:

How did you decide to go to talk to Russell specifically?

Dunham:

I knew he was a great character. I don't know how I knew, but at that time it was recognized that he was the leader. He was in the East. He was profoundly interested in -- I'm skipping a few years here, but that's all right.

DeVorkin:

We're talking about `21. You initially met Russell in 1921. Do you have a lot of correspondence with Russell?

Dunham:

Well, I have some, yes. A fair amount.

DeVorkin:

Let's try to think about that first meeting in 1921.

Dunham:

I'm only supposing, but I should think it must have been thanks probably to Shapley, who of course had been through Russel's mill and knew him very well, and it must have been through talking with him. We had very friendly times with Shapley, and we went to his parties, which were the great thing up there, and I suppose Sunday evenings mostly.

He had the whole staff in and students. There weren't 350 of them as there are now. We all sat on the floor and drank cold drinks, chatting, and had a wonderful time. I don't know, it just went, with Mrs. Shapley to make it go, too. It was tremendous. But I think it must have been just by elimination. I didn't know any other great astronomers. I was just struggling along here in college in chemistry, trying to do what I could. I was thinking about biochemistry quite a bit, and of course Shapley was an astronomer.

He thought I was a somewhat promising young chap who might do something in astronomy if I did go into it. I suppose it was like that. But anyway, I don't think I would have said to him (that I wanted to see Russell). I don't think I realized the importance of people at a distance all around the field, talking with them as I would now and have since, in making decisions. We always go and talk to other people, of course, about this Australian project and everything else. But he must have said, "Before you make a decision to go into biophysics, why don't you go and talk to Henry Norris Russell"? He's a very wise person about the whole field, and the values in science, and he isn't over-biased. He thinks in wide terms. I think that was it.

So I must have written him one of my notes. In those days you didn't just call people up so simply on the telephone, telephones didn't always get connected. I still like to write notes, rather than call people on the telephone, if I don't know them a bit. I just work that way. I think better on the typewriter than on the telephone, perhaps. At least I never can sell anything very well. I never went in for selling the. HARVARD CRIMSON or selling newspapers or magazines. I think I'd have done better if I had, in my freshman days. It's a good experience. Gives you self confidence, But anyway, I arranged to go down and see him, and I did go down to Princeton and spend an evening there, as I remember.

DeVorkin:

At his home?

Dunham:

At his home, yes, He had his office in those days in a little building on Prospect St. The observatory and a few offices and Charlotte Moore's place where she did all the Multiplet tables.* It's a small place. But he did most of his talking to people (at home). He went up to his office and got out his pads of yellow paper, and did things with them, up there at the office. He went back and forth every morning and afternoon, and went back for lunch. But I think it was more likely an afternoon, leading into an evening, -- he had me stay for supper, and Mrs. Russell was always tremendously cordial to any young people who turned up. And so I spent quite a few hours there, talking back and forth and also having a nice time. I'd never met any of them before.

I got to know them all exceedingly well since, of course, the whole family. I just told him the facts, as plainly as I could -- that there was a great case, I thought, for putting chemistry to work on medical research, of an unknown sort. Partly you could foresee it, and what would follow, probably. And at the same time, having worked on detailed chemistry and physics, or realizing physics without ever having taken courses in it much here. The whole thing went together, physical chemistry here, the idea of getting at the ultimate, or smaller simpler atoms, and molecules, but chiefly atoms in those days. It was getting to the ultimate of simplicity where you could really hope to understand the workings of things. M. Saha had just got out his ionization equations, and Russell hadn't yet applied them to astrophysics in and interpreting stellar spectra.

DeVorkin:

Did you talk to him about Saha?

Dunham:

I think a little. Yes, this was the case, of course, the Saha application there of physical chemical equilibrium -- the same simple equilibrium equations we're still using right now today, in interstellar space. The ratio of Calcium I to Calcium II to get electron densities. About as simple an equation as you can think of, if you put the right numbers in, and it was just coming over the horizon, in 1919, if I remember now. And I'd read some of the very good summarizing books on astronomy and astrophysics at that time.

DeVorkin:

What were they?

Dunham:

Dingle, wasn't it? Wasn't it Dingle who wrote his book on astrophysics?

DeVorkin:

That was in 1925, approximately, MODERN ASTROPHYSICS** *MULTIPLET TABLES OF ASTROPHYSICAL INTEREST, Nat, Bureau of Stats, **H. Dingle, MODERN ASTROPHYSICS, (Macmillan, 1924)

Dunham:

Well, it could have been 1925. That led me to think I'd better go and take a pretty strong shot at astronomy again after all.

DeVorkin:

Well, that was when you got your MD. I'm interested still in 1921.

Dunham:

Well, it is interesting. I talked with Russell and, from my point of view, as I put it to him, I think, medicine was really applying chemistry to biophysics, and patients in the end, but I thought of patients only as something you ought to do to understand the problems of biophysics.

I insisted on keeping my hands on a stethoscope occasionally, and knowing something about how to read an EKG and a few things like that, and going over patients. I haven't done it now for several years, it's time to go back to it. But I have managed to do that sort of thing, and not get entirely out of it. But it was primarily chemistry, going toward solving problems of biochemistry, on the one hand -- that's organic chemistry.

Much simpler and clearer cut and understandable in those days, physical chemistry, going to individual atoms. And I'm sure the ioniza¬tion equation had a great deal to do with my thinking about it at that time, what Saha did. So I put these two approaches to Russell and said, "Which do you think is the thing for a young person to go into?" And I am pretty nearly sure that his reaction was, as usual, that of any intelligent person, "You'll have to see which you're drawn to most, of the two. They're both useful, there's no question about it. They're both logical. You can't say medicine's no good, and let it go its own way.

You could probably have a very interesting time and perhaps contribute something useful on the chemical side." It's rather alarming to read what they're doing now. I haven't any idea whether I could even keep up with it mentally. I suppose, if you went step by step, you probably could. Other people have. They're not super-geniuses. I suppose you could. But it looks terrific, now.

DeVorkin:

Did you talk about astronomy at all, the possibility of going into astronomy at that time? Or was it just physical chemistry as opposed to organic!

Dunham:

No, you see, physical chemistry and organic chemistry, leading to biochemistry; or physical chemistry, leading to astrophysics. And what is there in astrophysics? I asked him, "What do you think astrophysics is good for, as you might say? Where do you think it will get to? Or will it just collect a few more numbers?" I hate people who do tables and numbers. And yet, at the moment, I'm trying to collect, out of .585,000 stars in the SMITHSONIAN STAR CATALOGUE, a sequence of stars, successively centered in each of six six degree squares, to aim the Space Telescope on. Fantastic. You have to learn about these things, but I hate catalogues and I hate just raw data of that kind about real astronomy, (what comes of it is) interesting, the structure of the Milky Way that Bart Bok is so thrilled about. Well, it is of course fascinating to see how it came about. But I get more interested in the ultimate things.

DeVorkin:

Did you talk this way with Russell at that time, about your relative likes and dislikes?

Dunham:

Yes, I think astronomy is fascinating as a subject to look at, just as anyone else might find it. And I think felt that way about it. But he had a very wide range of vision and understanding, and he enjoyed the constellations. He'd lie on his back at Mt. Wilson and look at them, and watch meteors in 1932 come across the sky, and all that kind of thing.

DeVorkin:

Really? Were you there with him?

Dunham:

Oh yes. We both lay flat on our backs. We had a f ast spectrograph camera that I had put together quickly in wood and mounted on the 10-inch Ross telescope for the night of the meteor shower in 1932. I used a prism, the biggest prism I could get. It was bought by G.E. Hale, years before, for the big tower telescope spectrograph, before gratings came in. So I took the prism from the optical shop, and put it in a wooden mounting and mounted it on the 10-inch Ross photographic telescope. We sat or lay on the ground till we saw a meteor. And then we rushed up to the telescope and snapped the plate.

DeVorkin:

Did you get anything?

Dunham:

We got a few spectra, yes. It was rather difficult. But there weren't as many meteors in `32 as they'd predicted from '99. So, we had a great time talking astronomy that night about all sorts of things -- but that was several years later, of course.

DeVorkin:

We can talk about that later.

Dunham:

He went out to Mt. Wilson every year, gave everyone there a shot in the arm about what's worth while in astrophysics, and then went back to Princeton.

DeVorkin:

I certainly hope we'll talk about that later. Have we finished with the talk in 1921?

Dunham:

Yes, except that he was, I thought, remarkably broadminded about it, and felt that both fields would lead to a great deal. They wouldn't be dead ends at all, just an exciting stab. He thought astronomy would go much further when you really understood new things about it from Saha's work on the ionization equation. It had been applied to the sun first, and then to the stars, right afterward -- in getting abundances of elements, by knowing that all atoms are not in the same state of ioniza¬tion, but that some of them are hidden in a state that's far in the ultraviolet and you don't see them. And if you know what the ionization is, you can get the total abundance of each atom moderately well, because you've got quite a lot of data, between 3000 and 8000 or 9000 angstroms, that you had in those days. I still don't like the nanometers.

DeVorkin:

Yes. This is a very interesting period in Russell's life.

Dunham:

Yes.

DeVorkin:

When there was still a lot of changing in his own career. Did he talk about that at all? About the new types of work that one could do, with. Saha's work, and with theoretical foundations?

Dunham:

Yes, you're thinking of changing his emphasis more from eclipsing binaries? I've never known as much about his earlier work, frankly, as I ought to have, or as I would have. I barged in on it at Princeton there, as a graduate student. We didn't go into the past, because the exciting thing was the present and the immediate future.

DeVorkin:

The difference was more in the philosophy, of the way he worked, because he certainly was involved in his great synthesis in 1914, where he put together the H-R Diagram -- he used just about every observational clue that he could, to support his work. He did not rely to any great extent upon theory. By 1921, especially with Saha and with A.S. Eddington's radiative transfer work, he had changed tremen¬dously, and become far more concerned directly with the analysis of spectra, on the theoretical side, as well as the laboratory observations.

Dunham:

I don't think he ever went much into it -- except to know about it, he knew everything, of course. He just scanned something and he knew it and remembered it. But he didn't go into the development of theory, like Eddington on the constitution of stars and so on, to any real degree, did he?

DeVorkin:

Somewhat he did, he constructed a number of polytropic models in the thirties.

Dunham:

Yes. I never followed that in detail. I knew he did some of it. I mean, he never made a frontal attack on it the way other people have, as a basic tool. He was great on using what other people had developed, and using it very quickly, and immediately plugging it in on a new problem, to interpret observations, such as the spectra of stars, using all the Mt. Wilson data that he could handle while he was out there for a month, and bringing it back to Princeton.

DeVorkin:

Of course, the LS coupling work pretty much developed from a completely theoretical side. And his work on alkaline earths.

Dunham:

Yes, that was. He was very strong on that. That's where he worked with so many other spectroscopists, doing the details on that, and had a terrific time.

DeVorkin:

Well, with Shenstone and with Saunders.

Dunham:

Yes.

DeVorkin:

Well, we should deal with you in the center of interest. During your Cornell years, when did you start thinking seriously that after your MD you were going to go to Princeton and study with Russell?

Dunham:

Well, of course, I had another choice then, when I got towards the end of the work at Cornell.

DeVorkin:

This was 1925.

Dunham:

Yes, `25. At Cornell, they never told you what your marks were. All of us thought, in the class, that we were probably going to fail. And it was very fantastic. Just by accident, I happened to come out with the highest record in the class, I don't know why. But we never knew anything about our standing until a couple of days before graduation. Then we got various prizes distributed, and all sorts of things, and I got a prize in otology, among other things, on the way up.

That was apart from the general records in class. Well, I felt a terrific responsibility, naturally, to go ahead with doing something medical, because I had used up all this effort by Cornell. I was just aware enough to realize that the university puts a good deal into somebody's education, and the class and the professors and all, and it wasn't a proper thing to just throw it away. So I had to see what I thought about that. But the normal thing that everyone else, the other 49 in the class, was doing was getting good internships in New York and all around the country, and going through hospitals to practice medicine, and a few of them to do research.

But I had a feeling that I also had a background in this other area of basic science, from what I'd done here for four years, and that I had to really look at the two, and see what about it, and in particular about astrophysics. I think that's where Dingle's book came in. Whether or not it was published earlier and I saw it before. Well, at some time when I was in medical school -- I don't know how I came to see it. Because medical school is quite a grind, and you get involved. You don't go reading other things.

DeVorkin:

Well, certainly Dingle's book was out by then.

Dunham:

Yes. It produced a very tremendous impression on me, probably more than anything else I'd read. Seeing what the possibilities were, and realizing how it would probably develop from there on. So I was led to go and talk with Russell, for whatever reason I did it. I wasn't at Harvard, and I wasn't in contact with Shapley much then probably in '25. Anyway, I did have that very good thinking through conversation, and I suppose perhaps I've always been adventurous enough, or whatever it is, to think, not that I'll drop what I have been doing, but that I'll try to do something in addition. I had a feeling I'd get back to doing some medical thing, and I did, for very different reasons, somewhat later. But it wasn't entirely a waste. I just had to choose between the two, and I can't make out why, exactly. I have a wife to whom I wasn't married at that time. She was in Radcliffe, here, one year behind. We used to talk about this quite a lot. She'd say, "Of course, you ought to do what you think you'd do best," which didn't help at all. But she always hoped it would be medicine, I think.

DeVorkin:

You'd met your wife by that time?

Dunham:

Oh Yes.

DeVorkin:

You were married one year later, in 1926.

Dunham:

'26, yes.

DeVorkin:

That was after you were already at Princeton.

Dunham:

Well, the spring of '26. I'd been a year at Princeton then.

DeVorkin:

What was the final thing that decided you upon Princeton and further study with Russell.

Dunham:

I think, just the feeling that I was more drawn to, and perhaps would do better at simple models, elementary particles, than complicated molecules, working up to viruses, which weren't really understood at all. They were only just recognized. And all the complications, leading on toward clinical medicine. The way a scientist ought to start is with the simple building blocks, if you're really sincere about it, and understand them fully. We didn't realize they were there in interstellar space, of course, quite, at that time, in '25. I don't think, very well at all. Calcium I lines, Calcium II lines, had been detected.

DeVorkin:

V.M. Slipher had detected something by that time, and people had known about stationary lines in spectroscopic binary stars. But they just couldn't believe that these were interstellar?

Dunham:

They pretty well thought they were just on the edge of the stellar atmosphere. I don't think they were bold enough to think the whole space was filled with atoms. And when they first did realize it, we all had the feeling it was more or less evenly distributed. And then it got to the point where almost all of it is in bunchy clouds, and much less between. That's just what we're trying to unravel now. No, I don't think that came into it.

That is to my mind the most fascinating ultimate atomic physics that there is. You've got these atoms one at a time. And I once tried to figure out how often they get disturbed, and I think the calcium atom perhaps is absorbed and jumps up once in -- I wouldn't like to be quoted -- but it may be three weeks, something like that. The rest of the time it rests there waiting for a photon to get near enough. So it was rather fascinating. I once made a cubic meter of interstellar space, a box, for the Carnegie Institute to exhibit from Mt. Wilson, as we had to get up once a year, you know.

I made a glass box, with three sides glass, one meter, and had little balls in there of pith and various things, that would balance with an air blower under them, throwing them around, more or less the right numbers for what we, at that time, in the middle thirties or late thirties, thought was a good population for a cubic meter of interstellar space. But we didn't know much about it in the beginning, of course. We only know a little now. But anyway, it went on. I think it was that look to the ultimate that finally made it turn out that I'd go and try Princeton, at least for a year, and perhaps go through as a graduate student, at least give it a chance for a year.

DeVorkin:

Russell was happy to have you? He was not wondering why you weren't going into medicine?

Dunham:

No, he didn't think I was entirely queer, because I'd had a little experience with fairly significant chemistry. I probably over¬concentrated on it. My father gave the last Greek oration here at Harvard; it hasn't been done since, and he did that exactly because he wanted to do the opposite of what he was going to spend his time on later. He said, "I'll never get a chance to do something really classical and literary again. I'll be entirely enmeshed in science as a profession." So he went for Greek in his last two years in college, I guess, and did quite well at that.

So I pushed the chemistry pretty hard, and I finally got Highest Honors in chemistry here, which wasn't generally done. I thought maybe this would help me get started on something. It was really quite fun, because you had Jim Conant and several other people, Lamb and Richards, on the committee, asking you fantastic questions, on the blackboard. It was all very friendly and it was stimulating. But you know, I've noticed a very interesting thing, that perhaps ought to be brought to the attention of undergraduates.

Anything that I did in getting the records in my class here in college has never, so far as I can make out, done a particle of good, or otherwise. It's entirely submerged, except for the fact that two or three men on the staff, professors, knew that I was doing things pretty accurately and moderately well, and that probably did quite a lot, more than you'd realize, to help me get a start at Mt. Wilson, and on other things that I've done since. But it's absolutely submerged otherwise. You could burn that record, and it wouldn't make a particle of difference now.

You go to NASA and try to put in a proposal for the Space Telescope -- they don't ask anything about your academic record at Harvard. They want to know what you did last month and might have published. And that kind of thing. It doesn't count. It's only for locating your very first job, I think, that any of that record counts.

DeVorkin:

Did Conant, Richards and others write the recommendations for you that helped you get to Mt. Wilson?

Dunham:

Well, my National Research Council Fellowship for work at Mt. Wilson was due, I think, almost entirely to Russell.

DeVorkin:

We'll talk about your years with Russell, then. This would be of tremendous interest.

Dunham:

Yes. Well, I got down there, and he got me a fellowship there the first year. Arthur Fairley, who's since been at Colby College in Maine, was the only other graduate student at the time that I was there. Don Menzel had just finished, a couple of years earlier I think. And Cecelia Payne had just arrived on the scene here at Harvard while I was at Princeton. I came up and talked to her, and she was such a dramatic character, and so impressive in every sense.

It hasn't anything to do with this, but I really seriously wondered whether it was worthwhile to keep on in astrophysics, if anyone who had that kind of background and ability, coming from working with Eddington, was working up all the Saha theory on the interpretation of stellar spectra. It seemed to me she would finish the field quickly. There was just that much to do, and there wouldn't be any more astrophysics to do. She would do it all. I said, "What's the use for a young graduate student at Princeton to go much further in this field?" But then I said, "I'll probably find a way around, there'll be some fragments left." But I was hugely impressed by what she was doing.

DeVorkin:

What did Russell say about it? Did you talk to him about that?

Dunham:

I don't think I admitted it very much. It was just one of my silent worries -- that perhaps I'd made a mistake. It looked, you know, as if one person who took the right approach, on analyzing stellar spectra -- and there were only that many lines in a spectrum -- and they were all similar -- would finish it off. I didn't realize how special some stars are. Nobody knew it. And I thought, one person could clean it up in about three or four years. And that would be it. Well, that's just incidental, but it is the way people got affected sometimes, by a dazzling meteor coming in on the scene.

Dunham:

Russell did some extraordinary things. One incidental thing he did was, he made it possible for us to get married down there. You know, there isn't any fellowship at Princeton that covers anyone who is married, and we needed one very much indeed. There isn't any that is, except one, the Jacobus Fellowship down there, which is a very high grade fellowship.

It's a distinguished fellowship, and we had no right to it or anything else, but it's the only one of the fellowships at Princeton that can be given to anyone that's married. So he said, "You must have the Jacobus Fellowship, of course." So he went to work, and I got appointed in my second year, and we lived in the little upstairs apartment on Nassau St. in Princeton, having a very nice time. Then the next year, we moved out to the new observatory in the polo field. It had a little apartment, and he fixed it that we could live in that apartment, and have breakfast and look out and see the polo players. We could look down the field in the morning, and then I could go in and play with the telescope when I wanted to, on variable stars.

DeVorkin:

The telescope was built then in 1925?

Dunham:

No. That was an old telescope. It was up on Prospect St. in the old observatory building, a wooden building, where Russell had his office. I don't know if those buildings are there still, as a matter of fact. I'm not sure.

DeVorkin:

The Halsted?*

Dunham:

Yes.

DeVorkin:

The Old Halsted Observatory.

Dunham:

Yes. But the observatory was right on the end of that, on an angle, as it came in and met with one of the college dormitory buildings. But these old wooden buildings were there. And that telescope was simply moved a little over half a mile down to the field near the lake, where they rowed. This was near the polo field, and it was halfway into the polo field, more or less. So it was a very pleasant place to live, and also, to have an astronomical setting right there in front of the apartment.

DeVorkin:

The dome is still there. There's a 36-inch reflector in it now.

Dunham:

I wonder what happened to the refractor?

DeVorkin:

Well, the refractor was purchased by the Naval Observatory. But anyway, the important thing is to identify your educational experiences, as a graduate student at Princeton. I'd be very interested to know what kinds of courses you took, what you think you found the most fascinating studies in astronomy at that time, and what Russell was working on, and how you got along with Russell. OK?

Dunham:

Oh yes. Well, as far as what I did in courses, of course it wasn't organized as heavily as it is at some of the great big institutions now. It was pretty informal. It was a question of who would you like to go and take courses with and learn something from, and talk about problems in astrophysics with? In physics, it was almost entirely K.T. Compton and a little bit Shenstone. K.T. Compton was giving a course in general physics, atomic physics I think probably mostly.

I can't recall exactly what the coverage was, but he was a very stimulating person, and very good to talk to, as well as to go to lectures with. These were small courses, of course, relatively. And Shenstone was very good to talk spectroscopy with. Russell got me to work on trying to analyze the Manganese I spectrum. When I first got there, I think, he said this hadn't been done. Catalan in Spain came out with a partial significant analysis of it. I wasn't aiming to publish it at all particularly, but just to get practice in analyzing spectra, as far as the spectral energy levels went.

DeVorkin:

How was Russell's relationship with Shenstone and Compton?

Dunham:

I think very good. I don't think they were terribly close friends exactly, but scientifically I wouldn't know absolutely. Russell lived very close to his family, walking back and forth with his old briefcase swinging, across the campus, every morning and noon and evening. And he'd stop in Physics, and talk to them on the way sometimes. The *23-inch refractor at the time, now a 36-inch reflector conversations that I heard were almost entirely about energy levels. And which way do you think this works? And are we getting anywhere? And how about these high ones we don't quite understand? And so on.

I think it was that way. I don't know that they had much personal interest in common, exactly. They didn't go out and look for wildflowers, which was one of Russell's great passions, of course, or other things, humanly. Children and wildflowers came very high on the list of priorities of what he really cared about, emotionally. But he cared about these energy levels and spectra almost emotionally, I think. If he'd given them names, he would have, but he didn't have time to.

DeVorkin:

Did Russell ever talk about his work with Shenstone and with Saunders?

Dunham:

Oh, I think so. Because he shouted back and forth with them all the time.

DeVorkin:

No -- to you.

Dunham:

Oh, yes. I'd go in and chat with him, and he had his little office in there and his yellow pad, desk all covered with yellow sheets he'd torn off, and thought rather the worse of. And then he tried another start. And he was mostly analyzing spectra at that time. Various parts of the periodic table, all the way up, and he was always fascinated by rare earths, that didn't get untangled entirely by a long shot.

DeVorkin:

How was his feeling about working with physicists? Did he ever complain about them, or did he feel that the physicists were doing all they could, or did he hope that they should have a different direction, especially in atomic research?

Dunham:

Well, I think he was always a little impatient with the fact that they didn't work faster. I think he thought, if he had time and if it wasn't their job already, he'd take it over, and very many times, unless I'm mistaken, they'd get stalled and say, "You take a shot at this for a while," and give him all their data. Now, I'm not sure about this, but I think that's the way it seemed to be, down there at Princeton. Because whenever he went to Washington, the Bureau of Standards, and talked to all those people there -- and back and forth to other universities -- he would often come back with all sorts of partially worked out spectra. And I think they were very generous in the point of view of letting him take their data, as far as they'd got.

There wasn't any feeling that "I own Chromium IV or something, or "Iron" or something. I think that they had a terribly good working relation, so far as I know. There wasn't any feeling of -- very much at any rate that was obvious to a graduate student -- any competitive feeling about it, that: "You mustn't know what I'm doing, because I may make a ten-strike tomorrow, and I'd better make it myself if I can." I think they worked as a rather widely distributed team, whenever they had any common reason for meeting.

There was a very fair amount of correspondence, I thought. I only saw this on the side, going back and forth with physicists all over Europe. He had quite a correspondence with Catalan on the Manganese I business. Not only that but about other spectra, I think, and others in England and Germany. He was pretty well in touch with them. Of course, the numbers of them were limited. Meggars was a great one, of course. Charlotte Moore put it all together very perfectly, and spent practically her whole life on it, of course. It's been very valuable.

I spent the other night with her multiple tables again, making a list of all ultraviolet interstellar lines and a list of all the pairs of neutral and ionized lines that will be revealed immediately by the Space Telescope that we can work on, for ionization ratios. Now, we have nothing but the very faint Calcium I line, in the blue, 4226, and the H and K lines of Calcium II. That's the only ratio that's any good, in the visible, except for inter-combination lines and one or two others. This will open the whole thing up. Magnesium I and II and Carbon I, II. 16 of them in all visible from space. So, I realized all over again what a perfectly devastating job Charlotte Moore did. She did realize it would be very useful. But I don't know if she realized people would read it in bed, in the planning for the space age, where you have to make a program six years ahead of what might be done with the first pointing of the telescope.

DeVorkin:

Were you at Princeton while Charlotte Moore was there?

Dunham:

Oh, very much so. She was living upstairs in a little apartment there at the observatory. It was a wooden apartment building, and the offices were all downstairs, where I was and Russell was. Arthur Fairley was the only other graduate student. He had an office there and that was about it, except for our friend who was the secretary. It was a very calm affair. And John Q. Stewart, who came in at intervals. He worked at home, and did much of his work there, but he came in.

DeVorkin:

Was Dugan there?

Dunham:

Yes, and Dugan lived in the other end of the building, in what was the original house before it was built on. He had his wife there and two children. Yes, he lived there. Very friendly to people like myself who were trying to find out how to do things. Of course he persuaded me to run the 23-inch telescope with the polarizing photometer, that went around and required 16 measures reversing everything. Finally you got one number out of it eventually, if you could do the computation later without a little H.P. calculator. It took a while. But this was great fun, and very good experience in running telescopes. I used to ride down there on a bicycle, from the graduate school, about a mile away, whenever it cleared, down on the ice and snow in February -¬- pretty near blow off the road. I would open the dome and then the clouds would come back and you'd shut it again, but we caught as many intervals as we could.

DeVorkin:

As many what?

Dunham:

Intervals of clear sky.

DeVorkin:

You were doing sky polarization?

Dunham:

No, polarizing photometer measurements on the eclipsing variables. We had to do that or we weren't properly on the team at Princeton, you know. It was a very good experience. It gave me a feeling for site testing that I carried to Australia and other places.

DeVorkin:

Tell me a little bit about some of Russell's interests at that time. During the years that you were a student there, he was finishing up his book with Dugan and Stewart.

Dunham:

Yes, they certainly were.

DeVorkin:

And as I recall it, from his correspondence later, with Eddington, his chapters on stellar constitution and stellar structure, when they appeared in the book, were actually new contributions. He had never published his ideas before. And he was coming to a realization at that time that many of his early ideas had to be modified, quite extremely, because of the new ideas on internal constitution of the sun and stars.

Dunham:

Yes.

DeVorkin:

Did you talk to him about these new ideas about evolution?

Dunham:

I never really talked to him much on that as a semi-equal even, because I never followed into that. I was too much involved in the spectroscopic work as a graduate student to really read all that. I ought to have, of course, as a graduate student.

DeVorkin:

What about your impressions of what he was up to at that time? How was his thinking?

Dunham:

Well, everyone got drawn in on working on that book, of course. I remember drawing the orbit of Eros, for instance, and various other diagrams, for ink drawing later. But we all worked up tables and tabulations and facts and numbers, to some extent, on the side, not as an official job or anything, but just for the experience, and it was great fun to do it. And he was very stimulating. So in that sense, I got to see and hear quite a bit about the discussions of what was going into the different chapters. He'd call in Dugan and sometimes Stewart, and they'd talk together, "How shall we modify this draft?" He certainly was in correspondence with quite a number of people. Was it H. Vogt, in those days, who was developing it* and had to do with the internal constitution input, there?

DeVorkin:

That's right.

Dunham:

I thought it was at that time. I never understood that or went into the theory of it, because I was so much involved in other things, but I had the feeling that he was tremendously anxious to have that book *The Vogt-Russell Theorem stand as really an adequate representation of the best idea of how things worked, in astrophysics and stellar interiors, at that time, as he possibly could, right up to the immediate moment. It wasn't ever possible to really do this, but he came, I thought, remarkably close in many ways. I had a feeling that he was in close contact, and very friendly and cooperative contact, with the theoretical people in Europe particularly, who were working in these fields. And they were very glad to have him use their data, in its form, as far as it had come, up to that date, to have him use it in those final chapters in the book. And it got in there.

DeVorkin:

Do you remember any specifics about the discussions that he had? What was he most concerned about or excited about?

Dunham:

No, I can't quite think, except the overall fitting together of the picture. I got that impression when I wasn't working on the details or going in on the detailed discussions. He wanted to see a complete picture of how a star works, and how the relation ran, between absolute magnitude and mass, and why -- as far as you could explain it at that time. Eddington had a lot of it, and the other theoretical people added quite noticeably to it certainly, as we all know.

But he wanted to see that overall picture, complete, from the point of view of the student, of course, partly; but for his own satisfaction, of course, first, really, and put it down that way. I'm afraid I can't get into the specifics, of the theoretical controversies that came and went. He added interpretations, certainly, that he sent back to people, like Vogt and so on, in Europe, and they sent over numerical calculations on what this might mean. Whether it would be trying to interpret what must or probably went on, from what the atmosphere was, from the side, as I saw it. I wasn't concerned with it, and I thought I'd never go into that kind of thing.

It didn't somehow appeal to me as much as observation of the surface of a star, and how far can you bore down into it, as Eddington would like to think, with observation from the surface. What he and E.A. Milne did on the atmosphere of the stars was as far as I got inside a star. I left the period-luminosity curve and the Russell Diagram to the people who knew about that, and let them work it out. I saw a little bit of the other side of it here at Harvard when E. Hertzsprung was here. We used to go out and have lunch up at the corner, where there isn't any place to get lunch any more.

DeVorkin:

What kinds of talks did you have with Hertzsprung?

Dunham:

Well, of course, I didn't understand the internal structure of the star, and he was working mostly on the empirical relationship, from observations, putting it together. He was a very stimulating person, who would sit and eat a sandwich and suddenly come out with something about a star and how it must work -- "I think I see it! I'll go back to my paper now, quickly, and see if this works." He was always drawing diagrams, always thinking in stimulating terms. He rather startled us young students, undergraduates and graduates, who were around about.

DeVorkin:

You met him in the early twenties?

Dunham:

Yes, that must have been along '23 or '24, about there.

DeVorkin:

Did Hertzsprung ever talk about Russell, or Russell about Hertzsprung? In front of you?

Dunham:

I think, very little somehow. How much were they really aware of what the other was thinking and doing?

DeVorkin:

By 1910 they were aware of each other.

Dunham:

I think they must have been. Yes. I don't know if they had any direct correspondence much, did they?

DeVorkin:

Yes, they had some.

Dunham:

I never heard about that much at Princeton at all.

DeVorkin:

Did Russell ever talk about Hertzsprung in a lecture?

Dunham:

Oh yes. He'd draw the old diagram and he'd give him credit for at least a considerable part of bringing the observational data together there.

DeVorkin:

Did Russell ever talk about how he developed the diagram himself?

Dunham:

Yes. He talked about that. I'm afraid I'm not awfully clear at this second on saying much, which you know much better, about the actual degree to which each contributed to the whole picture there. I know it was quite different.

DeVorkin:

Well, I know something about it, but I'd be quite interested in Russell's own ideas, as you recollect them.

Dunham:

Yes. That, I think, is an area I couldn't say very much of anything about, because though he brought it in in his discussion of astrophysics and stellar structure and luminosity and all -- at the time I was there, what he was more keen about, certainly, was the interpretation of stellar spectra. And that meant forgetting the spectrum for a while and going at the summary of the stellar atmospheres.

DeVorkin:

Was he becoming interested in the hydrogen abundance and relative abundances of elements?

Dunham:

Well, he was beginning to. But that really came more after I moved from Princeton to Mt. Wilson in 1927. That's when he began to dig it out, with W.S. Adams particularly, and A.H. Joy and R. Sanford a little less, about the intepretation of stellar spectra in terms of abundances and ionization. So in his lectures at Princeton and his talk with graduate students, he foresaw that this could be done, and he was the one who did much of it, certainly, but he didn't have the data to support it at all.

DeVorkin:

Did he have suspicions that hydrogen was very abundant?

Dunham:

Oh yes, I think he had. There's no question he had the strong impression that it would be the most abundant. He thought it was too bad you couldn't get at the 1215 line. But he knew what it looked like and he'd draw pictures of it on the blackboard, "This is about how wide I think it ought to be..."

DeVorkin:

Oh, that must have been very impressive.

Dunham:

Very impressive. We didn't know whether to believe it or not, since hydrogen was a little element down there at the beginning of the table, and it is known to be pretty abundant, where you can get at it, but only because it's part of hydrocarbons, here -- and not much of our atmosphere, except a skin at the top. A lot of water, of course, locked up hydrogen. Hydrocarbons in living material must be a very small percentage of the total hydrogen that you know is here.

So, to infer that it was vastly abundant in the sun and the stars, interstellar space, was not something you could be sure about -- except that it probably ought to be that way. It would be interesting to look, now, from the early twenties, how strong was there reason to suspect it, before you either measured it or got at it indirectly? It wasn't needed, I suppose, to produce the ions that were part of the ionization equilibrium of the elements heavier than hydrogen. They produced a good many electrons by themselves. If you took hydrogen out, you would still have a stellar atmosphere that would work, on paper. I don't know what would happen to the average stellar atmosphere if you instantaneously abstracted every hydrogen molecule? It would collapse and change, certainly, the relative strength of lines. I suppose hydrogen's more important down under, isn't it, in the star?

DeVorkin:

Well, I was going to just ask that, because people were looking, at that time, at hydrogen as a possible source for thermonuclear fusion. Proton synthesis was something that was coming into consideration by Eddington and others, for the source of solar energy, stellar energy, and you had to get the protons from somewhere. It seemed like hydrogen --

Dunham:

No, you wouldn't get protons from the heavier elements, because you couldn't strip them all down and produce the proton.

DeVorkin:

Right, but you could from hydrogen.

Dunham:

You could from hydrogen. And then helium became recognized pretty soon, perhaps after hydrogen, I don't know, about the same time, it isn't important really. Now, that may have been why interest began -- why interest focussed on hydrogen first.

DeVorkin:

In terms of hydrogen, though, that later created the problems that I'm wondering if Russell foresaw. With Eddington primarily, it was the problem of opacities -- if you have so much hydrogen there, how do you get the opacities? Did Russell ever talk about that?

Dunham:

I don't think he was too much concerned about the opacities. That seemed like a theoretical box that other people could work on. I mean, he didn't try to do everything. He was interested, and he talked with them an awful lot, but I don't think he brought it back into the shop at Princeton very much, at the observatory there. He knew what they were doing awfully well, because he put these opacity expressions into his calculations when they were needed, and he followed Eddington and Milne on the stellar atmosphere development, back and forth, as it went in every issue of the MONTHLY NOTICES for a good long time.

He knew that absolutely, and that was what he liked to talk about, on the blackboard, to us graduate students, probably more in quantity than anything else, over and over again, this process of opacity, and different lines being formed, primarily different levels. I never could see why they had to do that, because the lines formed at all levels, and it's just different. And now, of course, the computer does it all, if you just feed the things in right. Well, about how the interactions go. But he was keenly interested in this, and when I got back, lecturing to these graduate students in '35 and '36, after I'd been at Mt. Wilson several years.

I did this for graduate students as well as I could. I found it quite a stress, compared to running telescopes and developing spectrographs at Mt. Wilson. I didn't have time to work any of this out. I'd sit up all night reading all the papers and trying to make simple outlines. I didn't go into profound theory about it, but just enough to make it look as if it was a story of how stellar atmospheres worked in those days. One didn't have models, of course, in the sense that we do now. Up the street here, you can just plug in A and B and C, find out how a spectrum ought to look, and vice versa. It is different. But he liked that part of astrophysics; to talk to graduate students, and about stars in general and what kind of animals they are. He knew them all by their first names, I think, probably not as much as you do, but he'd know what was special about more stars than anyone I've ever struck. "Oh yes, this one (that I'd hardly heard of) -- it has a very peculiar spectrum, this way," and so on -- "This one really needs watching with a powerful spectrograph." Terribly strong, of course, on getting the maximum detail possible out of the spectrum of a star.

That meant the highest possible dispersion, or more properly resolving power, as it's called nowadays, and that was why, when he was out at Mt. Wilson, after the first year I'd been at Princeton, he brought back a roll of film which had the spectrum of Alpha Persei on it, in somewhat enlarged form by Ellerman from ten-inch plates. He had two of these rolls, for the blue-violet and near green, and he said, "Here's your thesis!"

DeVorkin:

You mean that's how he gave you the thesis?* *"Spectrum of Alpha Persei" CONTRIB. PRINCETON U. OBS. No. 9 (1929).

Dunham:

Yes. Just pulled it out of his left pocket, I'm sure it was the left pocket of his jacket. He had it rolled up, without any elastic on it or anything to protect it -- he didn't need it. I don't know where that film is now. It may be down at Princeton. I don't think that I have it, though I may. I may have taken it back to Mt. Wilson.

DeVorkin:

Did he ever explain to you why he was interested in Alpha Persei?

Dunham:

No, except he'd seen the plate that Adams had taken, of course, with the one-prism, 15-foot camera that was in use at that time, soon after Hale had the vision to get that long 50-foot path, down in the pier of the 100-inch where you could bolt every known thing onto the concrete, or onto a steel plate you'd put on the concrete, and then hook on lenses, prisms, concave gratings, one after the other, as we did in the next few years, and try them all out. This was the standard spectrograph of that time, when I got there, before I messed things up by trying other experiments with concave mirrors and things. I don't know why he picked that one of Alpha Persei. It was just a fairly bright star that was easily available, with high dispersion there, about two angstroms and a half to the millimeter.

DeVorkin:

What he basically wanted you to do, then, was simply to analyze it exhaustively?

Dunham:

To analyze. First, identify all these lines, which had not been done adequately on that resolution. It approached the resolution on the solar spectrum, not all the way, but most of the lines were there, not with as much resolution. It had resolving powers I suppose 80,000 or nearly 100,000. About like that.

DeVorkin:

The question is, how did he give you the project? Did he really just pull it out of his pocket, give it to you and say, "Here is your thesis"?

Dunham:

Exactly. That I remember very clearly. He explained why. He said, "These spectra out here at Mt. Wilson are an extraordinary achievement in observation, due first to Hale and then to Adams following through on making good use of Hale's big prism for the solar 75-foot spectrograph which has been replaced by a Michelson grating. Second, Adams' determination to go over bright stars one at a time, first. This was before he did the big interstellar survey of Calcium lines. He did 300 stars, which he concentrated on in the late thirties and forties.

DeVorkin:

That was with you?

Dunham:

He did that survey himself measuring radial velocities and structures of lines, the Ca lines, and some of the other lines too. Then I did this separate thing mostly about the ionization ratio, which fascinated me.* But at any rate, he just set up this .55-foot spectrograph.

DeVorkin:

Adams did?

Dunham:

Yes. At about 2.9 angstroms per millimeter, at H I think, and the resolution varied, of course, violently since it was a prism spectrograph, more in the near ultraviolet and less in the red. It was a dense lead-glass prism, which of course Hale got to be the densest he could, from Zeiss, so as to get the maximum resolution on the sun in the visible and into the red where the resolution collapses. This was used by Adams all the way through, to the red, as far as plates went in those days -- not beyond 6600, about -- and down to about 3500, where the lead glass would cut it right out, bang. He went over Arcturus and Capella and Alpha Persei and Vega -- in fact, anything that was up to the second and sometimes down to the third magnitude, if there was a reason. But the exposures were fairly long.

DeVorkin:

I'm just wondering why he chose Alpha Persei, as opposed let's say to Capella, which would be a solar type star, more than Alpha Persei, wouldn't it be?

Dunham:

Yes. Yes, it would. I don't quite remember what happens with Capella, with its two components. I think the second component shows and smears the first, doesn't it? So you either have to accept two stars, and that would be complicated, if you couldn't tell them apart. We worked extensively on the two components of Alpha Centauri, down South, where they are now I think 12 seconds apart, and we could get two spectra separate, if the seeing was anything reasonable at all. But if you kept it so that the other component was way off the slit you could get pretty good spectra, I think. But you never could with Capella. It's about 2/100ths of a second, isn't it?

DeVorkin:

Oh, is it 2/100ths of a second?

Dunham:

About like that.

DeVorkin:

OK, I didn't know.

Dunham:

It hasn't been seen, separate, has it, except with the interferometer.

DeVorkin:

Anderson was the only one who measured its position angle and separation, with the interferometer. *Dunham, PASP 49, 26 (1937); NATURE 139, 246 (1937), Proc. Amer. Philosoph. Soc. 1939.

Dunham:

He got that straight, then. Of course, now, at Narrabri* they've been doing all sorts of remarkable things.

DeVorkin:

Oh yes.

Dunham:

But that's a different chapter in history now. Done very differently.

DeVorkin:

At any rate, getting back to Russell and your thesis, did you have any guidelines for how you were to identify all the lines?

Dunham:

Yes. The first job was to identify lines, in his opinion, because you can't do a lot of theory on it, and we didn't have any spectrophotometry anyway. These were uncalibrated spectra. I realized that pretty soon, after I got to Mt. Wilson. It was silly to take any spectra without being able to use them photometrically, just to look at and measure. So his suggestion was, "Go ahead and measure every known thing you can see or think you see, even if you're not sure of faint lines, and we'll see whether they have enough evidence from multiples." He was great on the multiple structure, which was just available then, for a very large number of the lines.

Probably more than about three-quarters to 80 percent, anyway, were tied into multiples. There were only a moderate number that couldn't be identified somehow. So with his advice -- he gave me a steer on how to begin -- I pulled out everything, from the big German tables of all the individual lines of all the elements, done with every kind of an arc and a spark and flame and everything, and they were all different and disagreed on wavelengths and everything else. And I put them together as well as I could, made up a perfectly devastating card catalogue of all the lines from all these sources and where they came from, and how reliable some of us guessed they were.

And Charlotte Moore was a great help on this, of course, because she had a mass of unpublished data on the multiplets, as she always has, in the top drawer somewhere, and knows how to get them immediately on any element. And so, I just wrote everything down that I could. Then on each line of the spectrum I used what seemed to come somewhere near possible agreement in wavelength, close enough to be considered. I looked for possible blends, and so on. And then I talked it over at intervals with Russell, and he was very helpful about it. But it ended up by being a situation (where) for every one of those lines in the star, you had a fairly significant number, half a dozen or more often, of possible contributors. And often a principal component that did most of it.

So I worked up a code, as I remember with .5 plus or 2 pluses or something, how much they contributed, and put them all in, with perhaps a decimal wavelength, if there was room on the typing sheet, and put them in opposite. So we had the story, as far as you had it, we thought, out of the literature of what they were. And then we looked at the multiplets *Intensity interferometry. See: SKY AND TELESCOPE. 28 (1964), p. 64. of every one of them, every component that had any classified mul¬tiplet elsewhere in the spectrum, looked to see how that was doing. And finally, in a mental balancing game, I judged how much the principal contributor was responsible, and how much the others contributed something worth mentioning, at least, and put them all down, as far as I could.

Well, that wasn't a very theoretical and highly intelligent undertaking. But it led you to know about where the status of atomic analysis of spectral structure was at that time, and how to apply it. And I think it was a good experience. There wasn't time left to do much theoretical study. If there had been, I don't think I'd have done much with it, because the theory wasn't really developed, and you couldn't stop and wonder whether you could develop it all yourself at that stage. We knew the ionization was there. I talked at intervals with Cecelia Payne, not too much, about all this.

She was very much interested in it. But she was a little more interested in a broad look at the sequence of spectra and how they changed. And that of course is the thing you want to do next. But I wanted to know all I could about one spectrum, so I just dug into that one spectrum, to see what I could find out, in .5927, on what was known about it, and realized that a lot more observing with photometry was needed, and that was why I was rather keen to get out to Mt. Wilson and begin to see if I could get some photometry on these, with calibrating the spectra and building a microphotometer that would record the spectra.

DeVorkin:

Well, considering that you worked for Russell, I assume that's how you got to Mt. Wilson.

Dunham:

I think, almost entirely. He said, "Mt. Wilson is the place for you next. We'll have to see how you can get there."

DeVorkin:

And how did he do that? How did you get there?

Dunham:

Well, the informal way, not just to write and ask Adams if he'd take a youngster on his staff, which I don't think was done in those days -- people invited people. You didn't write letters of application, as is done quite a lot more, like the British, nowadays.

DeVorkin:

That was a National Research Council Fellowship?

Dunham:

Yes. Well, I think by knowing that these fellowships existed. I'm sure Russell put me onto it, and I wrote a letter outlining what I would like to do there in developing equipment and using it. I can't remember whether I have that letter or not. But I think I must have said that I had been working on one spectra.

I thought it would be wonderful if I could look at the spectra of some other stars, and have a basis for getting photometry on the profiles, and density dips in the total intensity of the lines, as we then understood them to be. This required developing a system of photometric calibration which wasn't available, certainly, at Mt. Wilson and not at most other places at that time. Also a microphotometer, which wasn't available anywhere at that time, to run them through and put them against the calibration curve.

So I think that was about it. And I'm sure Russell must have given it some approval and recommendation to the National Research Council. But I just don't think the National Research Council was as much overwhelmed with applications as they must be now. So it was more obvious, from Princeton and Russell, to go and spend a year or two years -- it was extended for a year, two years. And then they invited me to be a member of the staff and work along with them, and so on, for a number of years. I think it worked that way very simply; it was the National Research Council. This was the impersonal means for entry into a Western obser¬vatory. The chance of anyone getting an invitation, in those days, to join the staff at Mt. Wilson wasn't very high. It was looked up to as quite an exalted institution, of course.

DeVorkin:

You must have felt pretty happy to go.

Dunham:

I certainly was. Family was here in the East. It was an interesting reaction, because they all thought I was taking a wife to the ends of the earth in California.

DeVorkin:

Was there any serious resistance from your family or your wife's family?

Dunham:

Not really, no. My wife's family thought this was terrible. The interesting thing was, when we started to go to Australia in '57, they didn't pay much attention. Said, "Oh well, we'll see you now and then..." It's interesting.

DeVorkin:

Things have changed.

Dunham:

It really did look isolated. But it wasn't, really. Of course, you went on the train in those days, and it was the California Limited, and it was hot as all get out, going through the West.

DeVorkin:

When you got out to Mt. Wilson, did you go directly to Los Angeles?

Dunham:

No, Pasadena.

DeVorkin:

Well, yes, to the area. You didn't come down from the north or see any other observatories?

Dunham:

No, actually. I'd never seen Lick. I'm sure I'd never seen Lick in those days, or Victoria, it wasn't till some time afterward. We went out on California Limited, no, on the Santa Fe, I think. We didn't have any car at that time. It was afterwards that we made a number of trips and drove back East. We brought Rupert Wildt back one time when he was out there, and wanted to get back to Virginia, if I remember correctly. We drove East in February and had wonderful weather till we hit the lower tip of eastern Tennessee and lower Virginia, and then there was .56 inches of snow overnight. We could hardly go anywhere. But we got to Charlottesville somehow.

We drove back and forth quite frequently in those days, to save money, primarily. And of course we could take things with us. We were great on developing all sorts of photoelectric equipment out there, and trying to take it and use it later at Oxford, on the solar spectragraph, to try to get contours of spectral lines, and so on. But we got out there, and rather quickly got involved in photographic spectra on the Coude spectrograph of stars, with the instrument as it was.

DeVorkin:

When you went to Mt. Wilson, I'm very interested to find how you felt, as you got there. What were your impressions of the entire structure for doing research? And how was it socially? What was the general environment at Mt. Wilson when you arrived?

Dunham:

Well, I'd say it was largely what Merriam once told me, when he was the president of the Carnegie Institution, "We have this observatory set up, with the biggest telescope in the world." I don't think he knew whether to say "the best," and I don't think he did, but he would have because being Carnegie it must have been, and it was, of course, terrific. But just because it had a 100-inch as its aperture didn't impress me all that much. It seemed probably better than the 60-inch.

Of course the mounting had some advantages, but some disadvantages. It didn't go all the way up north. Certainly neither of them would go to the north, with the Coude, of course. But my impression was that he said "We've got the finest telescopes anywhere," or the best or the biggest, "and we've got a team of very fine astronomers. We've got an operating budget to keep them going, and we can buy them photographic plates. Now it's rather up to them to produce astronomy. They've got what they need in equipment, running supplies, salaries -- " Mine, I think, started at $3000 a year out there in the beginning, and worked up slowly into the $4500 level, or something like that, before I came East to Rochester. "We've got the running show, and this ought to produce astronomy." But the thing that struck me, more forcibly as I went on, was that I came at it more with the approach, although without any extensive experience at all, of a physicist.

There weren't any other people out there who looked at it quite that way, except John Anderson and Sinclair Smith, of course. They were all very friendly, and we got on very well together, but we represented a different sort of look at the thing, I think. The others were top notch observers, really top notch. They picked intelligent programs that, looking back even a few years afterwards, looked as if they were, I think, well selected. And they measured plates like mad, worked very hard at it, between runs, and were up there on the mountain three and four nights, usually, sometimes five at a time each month. The observing program was posted on the ground floor, and it was very exciting to look at, and to see how much time you'd get each month. Then they wrote papers describing these results and interpre¬ting them as far as they could, but not too far in the physical direction, you know. It was Russell who got that to happen, insofar as it did, very much more.

DeVorkin:

You mean when Russell would come out?

Dunham:

He'd come out, once a year. I don't know who arranged that. I suppose it must have been Hale. He got him to come out and stir up the plates and data. And he'd go rushing around with his yellow pads, and people would come in to ask questions, and he'd suggest what would be a wonderful thing if only they could get the data, and then they'd work it out together. He'd talk with them a great deal, and they'd publish many of the papers, but he published some of them based on their measuring and his interpretation. But he really revitalized the place, every September or October, when he was out there.

DeVorkin:

Well, Hubble and van Maanen were there.

Dunham:

Oh yes, they were very much there, all the time I was there, practically.

DeVorkin:

There were other people there at the time too.

Dunham:

Oh yes.

DeVorkin:

I'm interested, just a few more comments about Anderson. He did some remarkable instrumental work, and I think that he was largely responsible for the successes that they had with the inter¬ferometer.

Dunham:

I think he was. He put the scientific physics into the thing, and the better engineering. F. Pease had the thing designed in detail and drawn and put through the shop, and set up and adjusted. I rather feel sure that Anderson was up there with them at nights, quite a lot, adjusting it. I don't think Pease had that physical imagination -- pictures of rays of light doing this and that in your head, the way some people do easily. Anderson did, and he knew what would probably work, if you did it this way. What you'd have to adjust and change in order to make the result come out on these fringes and so on. So between the two, I should suppose that they supplemented each other. I wasn't in on working on this at all. I only heard them talking, and watched the thing happen.

DeVorkin:

But Anderson moved off into administration. I was wondering why? He never really produced a lot.

Dunham:

No, he was there, on the early development of the 200-inch project at Cal Tech largely. I didn't see an awful lot of that early stage of the administrative planning of the 200-inch, the design. I saw it as it went along, but I wasn't really working on that part of it at all. I think he just got roped in, probably. He was not a very strong character in resisting a request, if not an invitation, that he was the one person who could do it. I suppose he was the only person on the Mt. Wilson staff who could tackle the thing. He'd never done much administrative work, had he, before that?

DeVorkin:

Not to my knowledge.

Dunham:

I don't think so. You see, the people at Mt. Wilson certainly had no experience in administrative projects, as they call them nowadays. There weren't any projects. People were just on staffs of institutions and pretty much did what occurred to them. They didn't get ideas or plans more than slightly suggested to them by any director. I've never been able to make out what the real power or position of a director in an observatory is. It never seems to get written in any constitution at all. The good director watches what's happening, apparently, and suggests to people what would work well if they did it with or without the effort of other people, and trying to get funds from budgets that would make work that seems important go further. But I've never seen the director of any observatory I've had to do with really lay down the law.

DeVorkin:

No.

Dunham:

Some of them have. I imagine W.W. Campbell did.

DeVorkin:

What about Adams?

Dunham:

He never laid down any laws. He talked in a very friendly way with me and with other people, and he was very sympathetic. If we seemed to have the confidence to try something out, he'd be strong for an experiment. But not a great experimental project. That wasn't part of Mt. Wilson, as I was trying to say before. From Washington, the word came down that you have your observatory, and with occasional exceptions, you'd better be content to use it.

There's an awful lot to be had from just what it is. It never was said just that way, but that's what I think Merriam was saying. Most of the time I was there it was Merriam and Vannevar Bush later. But I was all messed up with war work at the time that he took over the Carnegie. So he wasn't the direct policy maker when I was there. It showed up most in the early days in trying to see whether you could get any new physical experimental equipment at all.

The striking example I remember was trying to persuade first Adams, and through him Merriam, that it would be an awfully nice thing if we could somehow have a Leeds and Northrup galvanometer. I gave him the specifications, the sensitivity, and resistance coil that would match, and all that. I wanted to use it with a photomultiplier. In those days. It was a photo cell, in fact, in the beginning. And measure line intensities, first in the sun, where you had enough flux, and later a photomultiplier on stars, where you could do it. I did it perfectly well on the sun, when I got a galvonometer. But it was a longwinded battle to get one galvonometer -- nothing else.

Everything else I picked up from the junk heap there, a wonderful organized junk pile out in one of the sheds they have there. I think they sold it all off a few years ago. I think that's a real mistake. That means that you can't walk down that pile between shelves for inactive equipment, parts of spectrographs that were on the Cassegrain of the 60 inch, parts of all sorts of mountings, with screws to adjust and cranks and worms and that stimulated me when I had an idea of what we might do, say, with the concave grating mounting, in the Coude of the .500 inch, which turned out to be very successful on the infrared spectrum of Venus.* That was done with the concave grating, which had enough resolution to get those C02 lines in the infrared spectra of Venus.

DeVorkin:

You mean they got rid of all that stuff?

Dunham:

I think they sold it for junk. I'm pretty sure, but I'm not certain. It would be interesting to know. Because I wouldn't have done that. The reason is that the way to start a new project is not by looking for inactive equipment, whether or not you call it junk, other people do but I don't. I see all sorts of nice slides and things that I could build things out of, and I used to do that time and again out there.

I built the mountings for the first Schmidt camera, the 32-inch camera that really did work. But I had no authority to build it at all. I had to do it myself in the carpenter shop, and take it up there, bolt it together with a 13-inch mirror, and get a spectrum. The minute you got a spectrum, you could go into the drawing office and get it drawn in metal. But I didn't want to try to build a galvonometer. I don't think I'd have got very far. Whether I might have, I don't know. I tried all sorts of things, but we finally got $250 out of the budget to get a pretty good galvonometer and photo cells.

That was an example of how difficult it was to do any experimental work. And that was one reason why it seemed helpful, when there was a chance, to start this little FAR organization that would first feed some optical equipment to Mt. Wilson. But that's another story that I'm interested in. But it was because of that. I emphasized to a number of people that it was extraordinary that a big observatory had so little opportunity to get any experimental physics equipment to go on the tail ends of telescopes, except photographic plates. And that was so, wasn't it, at most of the other observatories of the country, good observatories? They had their equipment. They had one or two spectrographs, and they just used them. But they didn't develop very much in the way of physical equipment, until at least the middle thirties, did they? I don't think so. Or new optics.

You accepted optics the way they were, and then the Schmidt camera came along, and reflecting optics in general, and that was the only really striking change in the whole optical area, and that's been improved, and still changing every week. But we all thought we'd be finished, in .5934, when we had the Schmidt camera working -- we thought this was the end of optical developments, but it has gone on steady, of course. The point is, they didn't think they needed to use anything from physics. And you know, there weren't very many astronomers who had all *PASP 44, 243 (1932) with W.S. Adams. that much contact with physics, except to talk to physicists, in our case at Cal Tech, and I'm sure at Lick, but Lick was pretty isolated from physicists really, in the early thirties, wasn't it?

DeVorkin:

Yes. Donald Menzel was about the first.

Dunham:

He was the first one that brought that in, of course. Yes. He really saw the point there. We had great times talking about spectrographs, when he came to Mt. Wilson in the early days, especially about eclipses.

DeVorkin:

Did he ever talk to you about Russell and about Russell's influence on him?

Dunham:

Somehow I don't think he did very much. Have you had a chance to talk with him while you could at all?

DeVorkin:

No, I missed him, I'm afraid. He already had written a very extensive autobiography.

Dunham:

I didn't know he had.

DeVorkin:

I just wondered if you had any recollections.

Dunham:

I couldn't really, I'm afraid, add much, except that he must have -- and this is only inference -- he must have acquired a great deal of his feeling about the importance of the physical processes and trying to understand them in astronomy, not just to look and see what's happening up there, from your spectra and your photographs; record and describe it, you know.

DeVorkin:

You felt the same way, I imagine.

Dunham:

I think so. Well, I got it from Russell, and from K.T. Compton, I'm sure. Not much from Shenstone, because he was primarily interested in the analysis of just two or three spectra, of course, which was part of the whole picture. Well, I think it was the reason I wanted to work in astronomy anyway, that I was determined to see if we could get at the atomic level of the thing. Obviously if you had a big telescope, you had a good deal of light coming, and you could get some of it through the slit. We always used to think we did pretty well if we got 5 percent through the slit! We never told anyone about this, about there being 95 percent lost in the .500-inch telescope! Because we always thought, at least I did, that the administrators would say, "If you throw away 95 percent of the light, with the .500-inch telescope, why can't you get along with a five-inch telescope and get all the light through? You'd have the same amount."

DeVorkin:

You had something to do with the development of the image slicer?

Dunham:

Oh yes. I did a lot on that with Bowen. He had the idea, but we made several image slicers in the Mt. Wilson shop, with Don Hendrix again, who could do anything that looked impossible. As long as it definitely looked impossible he was interested. He was an absolute whiz at getting things to happen experimentally.

DeVorkin:

He must have been very important to have there.

Dunham:

He was. Do you know about his background at all?

DeVorkin:

No, would you tell me?

Dunham:

He was doing electric wiring in houses, and for some reason unknown to man, Dalton in the optical shop (who was running it alone practically, as he had ever since early days) hired him. I think he got paid 80 cents an hour. And he was allowed to be used on the FAR project part time or after hours, to make the string of seven spectroscopic camera mirrors, going up to 120 inches in focal length.

DeVorkin:

This was much later.

Dunham:

This was in the late thirties.

DeVorkin:

Yes. How did he come to Mt. Wilson?

Dunham:

I can't say, but I should have thought, it was after I arrived in 1927, a good deal after practically. I should think it was 1931 or 1932.

Dunham:

Hendrix picked up all the techniques, as far as Dalton had them, in optical figuring. He was never afraid to do the impossible, or what then looked like very difficult things; making aspherical surfaces for Schmidt plates, and figuring out ways to use existing grinding and polishing machines for making big optics, up to the Palomar 72-inch mirror which he and I designed on brown wrapping paper on the floor of the optical shop. We got pieces of the frame welded, and we bought this 80-inch (grinding) machine for about $400, original cost, from Cal Tech. The other machine, 36-inch, for doing the correcting plate, was built at Mt. Wilson. But we bought the 80-inch machine from Cal Tech and have it down in Tasmania at the moment, all ready to do a 72-inch mirror that's right there, for a large spectroscopic telescope, if we ever get the funds for the telescope.

DeVorkin:

It must have cost more to ship it down there.

Dunham:

Just about. Well, it was done in 1957, and that big box alone cost about, I think, $800. The disc is inflating rapidly now. We got that disc from Corning for $1700.

DeVorkin:

Really? The 72 inch disc? That's pretty cheap.

Dunham:

Yes. It was worth about, 11 or 12 thousand, last time we got a price on it from Corning. The one they contributed to the FAR was priced at $33,000 about five years ago, and it's gone up more since. So they do change. They're probably as good an investment as gold is. Gold goes both ways.

DeVorkin:

That's right -- and mirrors only go up.

Dunham:

I think so. You have to have a purchaser somewhere, in Australia preferably.

DeVorkin:

It's very interesting, about your feelings about Hendrix, and the developing policy by Merriam and the Carnegie regarding Mt. Wilson.

Dunham:

Well, this changed, gradually. I would suppose Hendrix deserves a noticeable amount of credit for that, because whenever anyone on the staff had a funny idea, as they all thought it was -- the standard astronomer is a queer being -- he would make it, right there. Like some of those other solid-block cameras, devised and computed by people like Ross and others. Sinclair Smith also had quite a bit to do, not with the details of the optical design, but with thinking up schemes. And we all did.

Hendrix would make them work in very simple fashion, without any mounting, and there you'd be. We'd really have a moral obligation to mount them in the shop. And it worked. And from that, I think, the impression grew through the staff that some of the newer systems and ideas were perhaps worthwhile. And the photoelectric end of it came in gradually, partly because I thought it was almost irresistible to use a photo-cell to scan the solar spectrum on the big tower spectrograph up there. I got out some contours which they didn't feel sure were realistic because they hadn't been done by photography. And also, with the grating spectrograph in King's lab, down in Pasadena. Then Joel Stebbins and A.E. Whitford were out there every summer, working on photoelectric things. We saw them almost every summer, I think.

DeVorkin:

They came to Mt. Wilson, from Washburn.

Dunham:

They started with electrometers -- gold leaf things, and a measuring microscope. I helped them do that. I mean, I looked through it too. But it was Whitford's job to read it, and Stebbins' job to pick the stars and set it on and do the guiding. It took both of them, one way downstairs on the floor, and one up on the platform, of course. It was a great thing. Those two rapidly latched onto improvements as they came along.

DeVorkin:

Was it Stebbins who mainly directed that enthusiasm, or was Whitford acting too?

Dunham:

Well, he helped, and latched on, too. But I think it really was Stebbins primarily who first got the very best possible potassium cells from, who was it who made them in Germany? He kept very sharp track of who was making what, in the thirties, and there weren't very many sources.

DeVorkin:

Still the Germans?

Dunham:

Oh yes. I think so. I've forgotten where he got those, but he had three good potassium cells. He let me have what he called his third best, for a while, to work on the solar spectrum, because he said, "I'm going to use the best on the 100-inch, observing. I'm going to have the second best in reserve, in case anything happens to it and it doesn't work. But you can temporarily have the third, if you'll be careful of it."

DeVorkin:

Do any of these old cells still exist?

Dunham:

Well, the trouble is, I wouldn't know. I think Stebbins had some control over the one I had, that earliest one. And it must probably be back at Washburn. A.D. Code might know, I suppose. You think it would be worth looking up?

DeVorkin:

Yes.

Dunham:

The other thing I want to know about, and your advice would be valuable, is whether the first Schmidt corrector plate that I primarily figured (with a little advice talking to Hendrix) exists at Mt. Wilson? I did it myself essentially, a 12-inch plate, and then he had the nerve to cut it in two with a glass cutter. He said, "All right, here we go -- bmmpt..." and it snapped in two! But I was not sure it was going to do this, you see.

DeVorkin:

Why did he cut it in two?

Dunham:

Because I wanted to use it in the off-axis system and I didn't want the other part to block the incoming light. So we cut it two, and put it off axis, on the incoming beam from the 4" x 6" grating, as it was then. But it was figured for a 30-inch concave mirror, to take the aberrations out of it, and it made really, I must say, gorgeous spectra of fainter stars than you'd get with the long 114-inch camera there.

DeVorkin:

And where is this?

Dunham:

That is in Tasmania, in a drawer, I know which drawer, in our dark room down in the new buildings there on the hill. But I'm wondering if that has any historic significance? So far as I know, that was the first Schmidt correcting plate made in this country, and probably by anyone anywhere except by Schmidt. I went over and talked with Schmidt a little and he was a little cagy about how we did it. Well, this is a story by itself. It was of course W. Baade, coming from Hamburg, who brought news of the (only slightly, if at all) published invention of the Schmidt plate, by Schmidt, in about 1933, or perhaps 1932, when Baade came over.

Later he was followed by Minkowski. But Baade came, and we knew him very well. They found a house right next door to us, and we knew them all the time through, and he came down to Australia later when we were there. But he told us about this extraordinary development of the Schmidt plate and the Schmidt camera for photographing stars, and he had with him the famous Schmidt picture of the windmill in the "dark," in Holland, which was a selling point.

DeVorkin:

What is it?

Dunham:

Absolute dark sky, with a four-blade windmill standing there perfectly quiet. You ought to have that. I've got one somewhere.

DeVorkin:

I'd love to see that.

Dunham:

But that is the outstanding beginning of the Schmidt camera, because to anyone in my position, this struck instantly as a possibility for revolutionizing spectroscopy. You didn't have to use lenses now. The ordinary lenses of those days, for short focus cameras were perfectly horrible compromises. So we rubbed up this aspherical plate, and got Hendrix to cut it and put it up there in a wooden mounting, as usual, 4 x 4 wooden beams, with bolts to hold the 13-inch mirror that happened to be around the optical shop, and happened to have a hole in it for a Cassegrain. And we got some gorgeous spectra out of it instantly.

DeVorkin:

Do you know where that picture is of the windmill?

Dunham:

I think it's up in New Hampshire, probably, or else it may still be in our darkroom collection of papers, we didn't bring up in the container three years ago from Australia, but I can get it, if you'd be interested. I know I can.

DeVorkin:

Has this been published?

Dunham:

I think it is published somewhere. You know, Schmidt's original paper on the camera is only a page long. Just a note, in the publications, I think, of the Hamburg Observatory. No ordinary person would ever notice it. I never would. I can't read all these publications of European observatories every time they come out in the library. But it was Baade who came over with perfectly terrific enthusiasm. He thought it ought to be put to work on stars, and we ought to have a somewhat bigger one than the .58-inch Schmidt that Schmidt made. It led to the 48-inch at Palomar eventually, but after a good time lag, you know.

DeVorkin:

This sort of material, your corrector plate, and the picture would be very, very interesting to be able to locate and preserve. The plate itself most definitely should be considered by the Smithsonian.

Dunham:

What about the Optical Society? There's some collection of optics, and I don't know whether this is at all the most useful place to leave something like that, but to leave it around the dark room to be lost someday is not a good thing. Someone might be interested. You could even set it up and have it focus through, you know, on a very small demonstration, with a concave mirror back there.

DeVorkin:

Yes, this is the sort of thing we're trying to do.

Dunham:

Look at it with a microscope or something, and see that these lines are just as sharp at the edge of the field as they are at the center. You can think of a lot of things you might do. Now, the other half of that plate that was cut, of course, is somewhere, if it hasn't been thrown in the ash can. At Mt. Wilson, the best recollection I have of it was that Hendrix and I set it on a top shelf, above all the other shelves, of a frame there in the storeroom of the optical shop. Perhaps it's still there, as far as I know.

But I never got up to see if there's dust on a piece of what looks like a chunk of half round plate glass. You couldn't tell it was a Schmidt corrector, to look at it, at all, of course. It's only got a dip of I think less than a thousandth of an inch anywhere in it, but it has to be right to a couple of millionths, anyway, and it's probably out there still. But I have the other half, we started all our spectroscopy at Mt. Stromlo with that, on a 32-inch focal length mirror. It worked well enough on a 32-inch mirror that Hendrix had made in his sequence of seven mirrors, and the .520-inch, on brighter stars.

We got some of these very high dispersion spectra that I've got up the street now, and am working on here. And also some of the 32-inch spectra. But we started with those two cameras, and then we got, from the French, a bigger correcting plate that would go with bigger gratings down there, when we got a budget at Stromlo. So that one became in¬active, but I would expect to start this new project with the 50-inch telescope, perhaps using that, and perhaps not. If we can get some cash together we ought to get a bigger correcting plate because the gratings are bigger now. This was an old Wood grating that I latched onto, from R.W. Wood at Johns Hopkins. It was only 4" x 6", so this was big enough to be all right.

DeVorkin:

Did you work with R.W. Wood at all?

Dunham:

I did not work with him, but I saw quite a bit of him, and he came out there, and was another stimulating influence, in a very different way from Russell, on the mountain.

DeVorkin:

What was your impression of him?

Dunham:

You couldn't have any one impression of R.W. Wood.

DeVorkin:

Well, give me a few.

Dunham:

He was absolutely everything at once on different days. He'd have his moods. He was this way on experimental physics one day, and about people and wildflowers the next, of course. He'd come to have dinner with us one time, out there in Sierra Madre near Pasadena.

DeVorkin:

Oh, I know where that is.

Dunham:

My wife Marian could tell you about the dinner. She tried to cook for him. She cooked two small chickens, and somehow it didn't work just right, and it was all I could do to cut them at all. I mean, it was partly the fault of the chickens, and not the way they were baked. But with a fairly decent knife, I couldn't make much progress, so I had a physics job to dissect them at all. We've always referred to them since as "the iron chickens" of R.W. Wood. But he was so interested in other subjects that he didn't seem to express anything. No, he was very fine.

Of course, one of my earliest recollections of him at all was at Johns Hopkins, when I went there to talk to him about what he thought about gratings, because we'd done as well as we could with these massive dense prisms of Hale's on the coude out there. I wanted to get into the red, you know, and the infra-red, and you can't do that, of course. And so we went through a tremendous, at least I did, procedure of trying to work out what you could do with prisms, if you had the best you could get or could choose. I went over all the data of the Schott catalogues on glass.

I came to the conclusion that it was F-2 glass that had the best compromise between having significant dispersion, not nearly as much as these lead prisms, and transmission in the violet. So then to get the red, you have to have more than one prism. So I worked up a scheme, with the equivalent of five 60-degree prisms, about six inch through aperture, about ten inches on the side, putting two of them here and two on top, and running upstairs with two half prisms that were cut off at 45 degrees on the way up.

DeVorkin:

The whole train --

Dunham:

The train went down and back again, you see. It went back. It had its own reflector in that half prism, with the 45 degree reflectors, to go up to the top, with the upper train. So I went over to Schott in connection with an I.A.U. meeting or something.

DeVorkin:

The Schott Optical Company at Jena, in Germany?

Dunham:

Yes. That was before the war, of course. It was in 1934, I think. There was a great question, how we'd ever get these imported without paying too much duty on them. I was advised to go and see Anderson Clayton of the big cotton merchants in New York. They've become a massive firm, and wouldn't talk to any scientist now, I guess. But Clayton was very nice and let me come in and talk to him in his great New York office. -- it wasn't quite so great -- He said, "The best way to get those prisms in --" (there were all kinds of international transfer-of-funds questions at that time) -- "-- was to see if you can't fix it so you buy cotton from us, and we'll trade the cotton for the glass prisms in Germany, and get them in that way." I don't think it was a customs problem. It was a question of paying for them. They had a half a dozen exchange rates or so. I've got that all down in correspondence.

DeVorkin:

Contact with Germany was difficult.

Dunham:

Yes. I guess Hitler was just starting. He hadn't got very far. But the economic situation was disastrous after the First War, of course. So we were wondering what we could trade -- prisms for cotton. Well, I went over to try to explain this in my halting German, to the Zeiss people in Jena. They were awfully nice about it, and they were very much interested in the requirement of trying to see how far you could possibly go with the best glass they could do, and not absorb too much of the light, and get the maximum dispersion. Well, we worked out a system, on paper, of a prism train that looked fairly promising.

I worked this out before I went over there, and the F-2 glass looked to them about the right answer. So we had an idea about what it would cost. It cost a moderate number of thousands, but not like some projects I know about in this country now, that are not regarded as very difficult to put through, if you're the right people and have the right institution back of you. I think it was on that same trip back that I brought back first some of the super-infrared Agfa plates that they made, and packed them in dry ice in New York, and refilled them in Chicago and St. Louis or somewhere, and got them out West. Probably the equivalent to, or forerunners of, "z" plates now.

I think we always tried to combine things on trips. That was probably when I stopped at Johns Hopkins. No, it was a different trip, because I came back, on a Pullman sleeper, and I had the grating under my pillow. Didn't want it to be picked up by a porter and put off in St. Louis somewhere! I came in and that was probably the first time I met R.W. Wood. I'd written him a letter saying, "We've gone as far as we can in planning prisms. We want to know what we can do with gratings." Gratings, you know, of course at that time were regarded as a nice thing to have in the lab, where you had plenty of exposure time, but they weren't regarded as very bright, and not efficient enough to use. They hadn't aluminized them, I think, at that point. They wouldn't have done that until John Strong got his aluminizing tanks going properly about .5933.

What most astronomers knew about gratings at that time was that they weren't bright enough to even consider. They were used in the solar spectrograph where you could at least have moderate exposures, even with very high dispersion. You could do it in a few minutes with no trouble. But observing time at night is regarded as very valuable, as it ought to be, even now. And so, gratings weren't regarded as the promising way to go. But we just thought we'd better be sure, before we started to build this rather fantastic train of prisms, and put Dalton and maybe Hendrix to work figuring out all these internal abnormalities, to some extent, in that glass; and you had to locally figure the surfaces to allow for it, you know.

So I stopped to see R.W. Wood. I said, "You know, I want to learn all about gratings and what you think they'll be like five years from now -- whether there's a chance that if they were ruled for this kind of purpose, to give just the resolution you thought you could get, with an exposure of say five hours on a medium bright star, third magnitude, it would be worth planning for, in the next design of the spectrograph." We were changing every two or three months, bolting different units onto the wall there, and steel plates. First he didn't seem to be interested at all in gratings. He said, "Let me show you an explosion first. I want to show you I've got something."

DeVorkin:

An explosion?

Dunham:

Oh yes. You know, he was great on explosives.

DeVorkin:

When was this? It was about 1933?

Dunham:

Call it 1933 or 1934. 1 think it would have to be just about then. We wouldn't have had the Schmidt camera running. That was in 1934. I had a short note on the meeting of the Physical Society, up in Berkeley, in 1934, I think, mentioning it, that it seemed to work.* I talked to him somewhat about this. But he was great on explosives, you know. He was an expert witness in all trials involving explosives in the Baltimore area. At least, he was the one they always wanted to get, because he would always be so humorous about it, and yet so convincing and able to be established as an expert in his field, as a physicist, that they all went after him.

But he thoroughly enjoyed the explosions, as well as testifying in court. I think he thought this was great fun, to take a jury and try to surprise them. I'm not sure he took the explosives into court, but I'm sure he tried to and wasn't allowed to, to show them how it worked. But he had a new kind of fulminate, a kind of silver fulminate or something, that was just a little more sensitive than anything he'd ever had. It had been that morning that it got just dry enough to go off, he thought. So he put it on the other end of his lab table.

He had a wonderful table in his lab. It was probably on concrete piers. It was some kind of a slab of unmachined steel on top of it, I think, and he had it completely loaded with every known kind of an optical device, particle and component you could think of. Insides and outsides of spectrographs, optical focussing systems for looking at and measuring the quality of images, and a few gratings I think, of moderate size lying around. Well, he had this silver fulminate, which I think it may have been, over on a piece of photo paper, drying, on the far end of this. And he said, "Now, just hold on a minute. Don't be frightened. Something may happen, and it may not. But now let's see -- here's a hammer, I'll tap this end of the steel plate here -- it's over there." All this mixed up equipment between. Sure enough, there was a great bang, and it went off.

Not much flash or anything, I guess, but it just *"The Use of Schmidt Cameras in Plane Grating Spectrographs" (abst) PHYs. REV. 46, 326, 1934. went off, bang. You could feel it shaking the floor under you. I don't know about the optical components -- it takes more to break optics than you think it does, usually. So we went through that, and I was duly impressed that he knew about explosives, but I was more interested in stationary optics at the moment. And I said, "What do you think about gratings? Do you think they'll ever be any use. Do you think we could, if we tried, beat the prisms, because of the infra-red, and we can in principle get more angular dispersion off a grating, even in the blue, if you tilt it up and use the second, third or fourth order of it?" But the third and fourth orders were never thought of as having any brightness.

They were just sort of there, to show students that they exist, and that that's the way diffraction works. So he said, "You know, I think that's quite a good challenge. We'll think together, perhaps a little, what the requirements would be for the best grating, and we'll make one. But I've got one lying right here in a box. Maybe you'd like to take it out and try it at Mt. Wilson?" So there it was, a ruling with about .55,000 lines to the inch.

DeVorkin:

He'd done this himself?

Dunham:

Oh yes. He took it over from H.A. Rowland, you see, and this was the Rowland engine. He'd improved it noticeably and got the ghosts down, I think; but I'm not sure that he had a corrector cam on it to control the ghosts. I'm not sure. This was before the interferometers got to be used by George Harrison down the street. This was the thing you did, of course, naturally, as a mechanical engineer, you put cams on it.

But anyway, he said it was fairly good, but he warned me that it had scattered light on half of it. The diamond did something different, ruining the first or the second half, so the lines were just over four inches, about 4 .5/2" long and 6 .5/2" high, the width of the ruling. And it did something fuzzy to the lines, and if you looked at in the light, you could see the difference between them. He warned me that it had more scattered light especially in the ultraviolet. And it did.

So at Mt. Wilson, we put it into the spectrograph, blocked off with a metal plate in front of the mount and attached to it, half of the ruling exactly, when we were trying to use it in the ultraviolet, because it filled in absorption lines, with too much scattered light from the rest of the spectrum. But it worked very well indeed, and I think that's still out at Mt. Wilson now. I just said, "Isn't that wonderful? Can I really borrow this and try it? We'll bat it against all the prisms in California, and see where it stands, and see if you can do a better grating," which he did and which Babcock later did, with the ruling engine at Mt. Wilson. Now nobody uses prisms at all.

But I went West with that under my pillow in the Pullman car, to try to keep it away from the porters. And it got there all right. That was really where we decided to drop Zeiss, and to go to gratings. Then it was a question, how to focus these nice grating spectra, and that was where we began to use these concave spherical mirrors of different focal lengths, and the little short mirrors with a Schmidt corrector plate ahead of the grating, centered on the center of curvature of the mirror. Of course, the cameras had to be twice as long as the focal length, and that was awkward, but not really, because you had a long enough frame there.

You could put anything you liked on it. So that was all right. But that was R.W. Wood. He came out and watched this develop over the next few years as we got better and better gratings, and used them entirely, and took out the original prisms and lens that Adams had, which was all right for strips in blue and green, but not much use in the ultraviolet and not any good at all in infrared, of course.

DeVorkin:

Where are these prisms now?

Dunham:

I think in the optical shop at Mt. Wilson. There are some great big prisms, about ten-inch base, 9 or 10 inch base.

DeVorkin:

Do they have any large objective prisms out there at all?

Dunham:

I'm almost sure they had an 18-inch objective prism of something like two or four-degree angle on the 18-inch Schmidt camera at Palomar. F. Zwicky had that put on, of course, to get his spectra, and now, as you probably know of course, there's an objective prism on the 48-inch Schmidt, isn't there?

DeVorkin:

That I don't know.

DeVorkin:

You were talking about the conversion, your conversion and Mt. Wilson's conversion from prisms to gratings, and that's quite an interesting story.

Dunham:

Yes, well, that was definite within about three years. I mean, we had to get absolute evidence. But it came perfectly naturally, entirely through R.W. Wood. The ruling engine at Mt. Wilson, as Anderson was operating it, was a very long range development, you know, and tremendously complicated.

Until modern ways of doing engineering and thinking came further, he was way up on that, of course. But the whole subject hadn't developed, and it was long and expensive, and he had one absolutely top notch machinist working with him, but only one, and you couldn't run big projects very fast. So we never got to the point where the gratings were (vastly better). I don't know the detail now, but they weren't overall better than what R.W. Wood had from the Rowland engine, in moderate size.

They were trying to make much bigger ones, but they were willing to compromise and get smaller ones first, six inches or so. But anyway, from our point of view, and we kept watching both teams, it wasn't possible to get a grating, and really get it. It was always going to be marvelous on Anderson's engine, because they were always improving it, of course, and they weren't doing so much actual ruling. R.W. Wood was more nearly but not entirely satisfied to take it as it was, making minor changes that didn't hold the whole thing up for a year or more. So we got one more good grating from him. And then Babcock took over ruling at Mt. Wilson. Horace Babcock, of course, at Mt. Wilson, appreciably later. He produced some absolutely top-notch gratings, as you know, and they were used in the coude at Mt. Wilson, replacing the Wood grating largely, probably entirely now. He very kindly let us have one of his 600-line per millimeter gratings in Australia at Stromlo.

This put Stromlo on the map, on these high resolution gratings. They were bright enough, ruled in aluminum of course, and blazed so that you could use them in all the blue and in all of the yellow. And then, we finally got an addition, an ideal one I think it is, from Bausch and Lomb. It's no bigger, but it's blazed in the first order at .56000A, which means the fourth order at 4000A. And I used that on everything from the infrared first order, you see, to second-order 8000A; third-order green, and fourth-order violet, all at about the same angle. And it was very decently efficient. I measured it photoelectrically and all sorts of things. It was very, very effective indeed; and I think, in some areas, has marked advantages over the new echelle spectrograph gratings. They're the popular thing, you know. If you want to be in fashion, you must have an echelle, and you must say "echelle" at least every two sentences. Then you're a good .5970+ spectroscopist.

DeVorkin:

I never liked those spectra, it looks so confusing.

Dunham:

It has its problems. But it is remarkable. You can get yourself one of these spectrographs for around $20,000, if you build the instrument yourself. That's been established here. They built one, a duplicate of the one at Mt. Hopkins, for the station here at Agassiz last year, and it's working all the time now. It's in one box, and you've got it and there it is, and it takes high resolution spectra. But they're very narrow spectra, and they're on a slant. That isn't in itself too much of a problem, but they've got a lot of astigmatism in it still, that could be killed, but they don't seem to mind it. I don't know why they don't.

DeVorkin:

Well, they can always work that out. Once astigmatism is understood, they can work it out numerically.

Dunham:

Yes. You can in a way. But it's one more complication in reducing these plates, even with a Kron camera, where there's supposed to be no astigmatism.

DeVorkin:

I have some directed questions about your experiences at Mt. Wilson. I certainly want to talk to you about your planetary spectroscopy, and later about the interstellar medium. I have a question, in another vein. I know that there was some ill will in the thirties between H. Shapley and E. Hubble. And later on, when W. Baade came in, there were some feelings, difficult feelings between Baade and Hubble. But I haven't been able to pin them down. And since you were both at Mt. Wilson, and then came out here in the summers and possibly had some contact every so often with Shapley --

Dunham:

I didn't talk with him about any of that sort of thing.

DeVorkin:

Do you know what the issues were?

Dunham:

I don't really. I know there was a lack of -- well, there was all this question, wasn't there, about the luminosity curve and where it ought to go. I'm afraid I'm not an expert enough on that to be very helpful about it, except to note that there were, as you say, feelings. I would not have seen it well from the complete sidelines, because I wasn't in on it, and they didn't talk much about it. You could just see that there was a feeling; that every time you said anything about Harvard in Pasadena, it wasn't the best thing to say, even to mention the name. Exactly. I mean there was some kind of electric tension that appeared on the scene, between Hubble, perhaps, who was a very pleasant kindly character, but had his feelings definitely about things, and A. van Maanen, who was a little bit more ready to express jump reactions, you know.

DeVorkin:

I knew there were difficulties between those two.

Dunham:

But they were just different in personality. I think they never sat down, as far as I knew. If I ever thought about it, whenever I did, I would certainly have thought, why don't they ever get together and talk about it? I think they didn't want to meet very much because they didn't find it convenient.

DeVorkin:

This is Hubble and van Maanen?

Dunham:

No, I mean Hubble and Shapley. Is that right? You would know more of the background. I only got impressions, not facts. But I got the feeling that they hadn't really got together on the data. It was in an era, you know, when people rather had a jealous feeling that their data was IT, and they didn't want to have other people examine it very much. I don't know that it existed in this particular area, between those two, but it was a much more prevalent feeling in those days.

Nowadays, if you have data that gives a result, by being interpreted a certain way, and your friend down in Princeton or somewhere has another interpretation of it, the first thing you do is to grab the telephone and talk about it, the way it's done now, on government telephone lines, where nobody meters your telephone calls. You just talk about it, as if you could go down and meet. Otherwise you say, "Let's look at some of this data next time you're up this way..." And they do, and they all talk about it. There's so much more to do than anyone can do nowadays.

There's no feeling that you've got to hold onto your data because it's your private property. You want to really get on to the best result, and I suppose incidentally not be shown to have been wrong by somebody else. You want to have it very much out in the open and talk about it. But I should suspect, I strongly suspect that this was not the case so much in the thirties. I wasn't there much in the forties, except back and forth. So I think they just had a feeling they were at a distance, and didn't want to come closer on it and settle it. And they'd come out with appreciably different results, about these Cepheids and about the distance of galaxies. Wasn't that mostly what it was all about?

DeVorkin:

I believe so.

Dunham:

And they didn't resolve it. Of course it would, I suppose, have been found that they'd gone at it in slightly different ways, and that the two sets of observations weren't entirely easy to compare. They'd done it probably rather differently here at Harvard, the way they measured things. They hadn't any spectroscopic velocity measures, as M. Humason got, and they were getting out there, that had to be fitted in, or they thought they had to be fitted in to a curve. And it turned out to be a pretty good looking curve, about distance and velocity, of course. Harvard didn't have that.

I think they just stood on their own data and just didn't talk about it much, and it didn't appear greatly in the literature, did it? Very few people reviewed the whole subject in the thirties, just to bring out these discrepancies. Or someone would have gone to both places, some third person probably, and talked to each of them. If either of them didn't want to talk about it, it would make it look pretty queer, at least in these days it would, and so, it didn't get cleared up.

Now, that's just talking about impressions, from walking up and down the hallways, in the labs at Mt. Wilson and up in the Monastery at night on the mountain. I'm not really looking at data at all, just the impression of the way they seemed to be reacting to each other. It was a kind of unfinished business, between Harvard and Mt. Wilson there. And I don't think Harvard was very popular out at Mt. Wilson in those days, for some additional reason. I think they had a feeling their philosophy was different. It certainly was very excellent in its area of investigation. They had masses of data that Mt. Wilson never thought of having, and they went on individual objects much more. The whole thing just grew up with a different approach. (I hope this doesn't get published or anything? Not for another 50 years!)

DeVorkin:

It's very important material.

Dunham:

I was the youngest person, of course, on the staff, for a long time. I was supposed to know how to do things with my hands, as well as take spectra a little bit, so I got to running up and down the halls and asking a lot of questions about astronomy and how observing was done, and trying to make spectrographs that looked queer to everybody work on the mountain. And they always had a story that I'd run down to Pasadena, 26 miles, to get a screw driver, and go back. That kind of thing.

I was regarded as just moderately queer, not excessively queer but moderately so. Still, probably useful to have around. Sometimes I could get these instruments to work, besides observing, you know, a little bit. Then I got a little further along, and other people came in, and I was a little more on the team. But I was always looking at it, I'm afraid, in a different way from the earlier members of the staff, who naturally, as pure astronomers, knew probably .500 times as much astronomy as I'll ever know now. I only get into looking up astronomy when I have to to find out what to get the spectrum of.

DeVorkin:

How did you get interested in planetary spectroscopy? Was St. John still around?

Dunham:

Oh yes, he was very much there. He kept pretty much by himself, measuring away on his measuring machine on the solar spectrum. More and better plates, of course, doing a very noble and magnificent job on accuracy, on revising the solar table. I was just looking it up for the space program the other day. How strong are some of those lines of phosphorus or whatever, out in the red, that might be used as ioniza¬tion pairs? He revised that solar table, of course, didn't he, and made it look very different from Rowland's version, in the early numbers of the ASTROPHYSICAL, weren't they, just as tables.

DeVorkin:

P. Merrill was there also, wasn't he?

Dunham:

Oh yes, he was very much there.

DeVorkin:

Let's talk about your planetary spectroscopy first. How did you get involved in that?

Dunham:

I'm just trying to think what came first. It may be in that REVIEW paper. That 60-page or so summary of methods in stellar spectroscopy?* That's really the story of the coude spectrograph and what might come next at Mt. Wilson. If you're interested -- look at that spectrograph, on which there are some rather surprising differences of opinion at the moment, especially when it comes up about the space spectrograph, where you use photoelectric detectors instead of photographic plates. There are some rather competent people up at this observatory (Harvard) that very much question whether you need to have big gratings any more, or whether you don't. In principle, you expect to get all the light through the slit, because the image is perfect, up there, where there's no atmosphere.

DeVorkin:

This is in space, of course.

Dunham:

Yes. You don't need image slicers any more, but you may not need large gratings any more, and the space telescope may have no advantage over ground-based instruments in the visible. Of course, it reaches the ultraviolet on account of being over the ozone. But there's a question about some of those very fundamental relations, about speed of the spectrograph and how much light goes through. And I think those formulae in that little paper there are more or less reliable. At least nobody's caught it in the last 20 years. That was written back in 1956.

DeVorkin:

This is the VISTAS article we're talking about. *"Methods in Stellar Spectroscopy" VISTAS IN ASTRONOMY II (Pergamon, 1956), pp. 1223 - 1283.

Dunham:

Yes. But I think some of that basic stuff is still valid for students, and it's been found slightly useful, in some other departments in showing students in one little area there what the design compromises have to be, and how they can be worked at, that's all. But it's all very elementary, of course, compared with present day elaborate optics. But the basic optics still seem to work, and it's a good take-off point for some of the others. And the comparison between photography and photoelectric detection. We tried to work out what it would be like.

DeVorkin:

Does this help you recall how you got into planetary spectroscopy?

Dunham:

Well, I think that was entirely accidental. I think we just took some spectra of planets, and found there were some interesting bands in the spectra. I'm trying to think what came first. I think probably the Venus and carbon dioxide. I fixed up I think it was a concave grating (I'd have to go back and look), of .55-foot radius; a concave grating, that Anderson had ruled, I think probably at Mt. Wilson, on his ruling engine there.

DeVorkin:

This was after your initial work with W.S. Adams.

Dunham:

After the initial work. But we were working together, back and forth, and we used to run on the mountain pretty much together, and I'd help him and he'd help what I was doing, one way and another, and we used to develop plates together in the dark room. The dark room, you know, had a temperature in the winter of about 34 degrees!

DeVorkin:

Oh, no!

Dunham:

And I thought that wasn't a very good temperature to develop plates at. And it was in the pier, you see -- right buried in the pier under the telescope, the dark room in the concrete, -- the upper part of the big concrete pier. They didn't think I ought to but I said, "Let's put a heater in here, do you suppose we ever could? -- to heat the dark room, and put a little insulation around it so it wouldn't take too much electricity?" The powers thought this was awful. You mustn't have a warm dark room -- first, you mustn't be comfortable. They said, "Why, you'll go to sleep." Well, I thought that would be a good idea, since two people ran a telescope, and there always were two to have them rest occasionally.

But that wasn't the reason. It was for the sake of the photography. Well, W.S. Adams never would say "no" to anything, he sometimes wouldn't be enthusiastic, but he would never turn it down. He thought it would be rather backhanded, you see, to heat the whole of the dark room -- it must have been all of .52 feet square. To heat it to 65 or 68 degrees, perhaps even, if you stretched it to the right temperature that you usually use, this would be backhanded. So we worked up a rocker there, with a copper plate on top and a few little heating coils. They thought it would burn up too much electricity, you see -- be awful on the budget. Think of heating your dark room in a concrete pier! I worked it out. Of course, it's obvious that a little ceramic or any other kind of a dark heater would do it -- I don't know, I suppose .5500 watts would do most of it, wouldn't it? Of course it would.

DeVorkin:

That's fascinating. How was it powered? Were there lines running up the mountain?

Dunham:

There was a standby generator, but it had power lines up from Los Angeles I'm sure all the time that I was there. And it had a standby generator that went on if that went out, and it did go out in ice storms for a week or more, sometimes, and they'd turn it on.

DeVorkin:

Why were they so concerned?

Dunham:

Well, I think the cost of it, probably, if you asked me to guess. But it just seemed ridiculous, to heat a whole dark room in order to heat a little dish.

DeVorkin:

Well, there's more to it than that.

Dunham:

I mean, there are stoves, you know, and they heat dishes. Well, I mean, just the general thinking would be that way, rather conservative. If you went back to that, isn't there any way you can develop a plate? Do you really have to have it up to 68 degrees? It would develop but develop more slowly. I don't think it would develop quite the same at the low temperature. But it goes up by a factor of two, yes, for every 8 or 10 degrees. So you have a pretty long development time.

So we worked up a heater that rocks. I'd heat it up, turn the switch on, have the developer with a thermometer in it, the old fashioned way -- till it was about 60 degrees. Then I'd turn the heat off, and by a little experience of watching what happened with the lights on, I'd know it would go to 68 degrees, and then come back, so in about five minutes it would be back to about 62 degrees. We didn't run it much over 70 degrees. We sometimes got it into the seventies, I guess, so it averaged around 65 to 68 degrees. And it worked pretty well. But you have to know your switch and your equipment, and have the right amount of developer in it. Anyway, we got this .55-inch concave grating, which I fixed up and which of course had lots of astigmatism in it off the axis, but was very very good optically, because there was no optics to it except the grating, of course.

We had a collimnator that threw parallel light on it. It had no astigmatism then on the axis. It couldn't have too much, or it would widen the stellar spectrum and you wouldn't get an exposed photograph. So we ran that on a number of stars in the ultraviolet, because you could go way down in the ultraviolet, in the first order, and we used it in the second order, for the infrared. We ran through a number of stars in the ultraviolet, Adams and I, and wrote it up as an exploration in the ultraviolet on some representatives of the B stars and so on. Then one night -- I'm sure it was Adams who said, "Why don't we take a shot at the infrared of Venus? It's bright up there in the West, and easy to get at." You don't have to turn the grating of course any particular amount, if any, to go from the first-order violet and ultraviolet, to the second-order infrared.

They're about the same resolution, of course, but half the resolution in the infrared. So we turned it on Venus, which was bright, and it just happened that at that time, Kenneth Mees of Kodak was very closely associated with what we were doing, and terribly interested in it, all through the stretch of the thirties, anyway. If we hadn't had Mees on our side, we never would have done a great many things, and that ought to be heavily impressed on everybody and recorded.

DeVorkin:

I wanted to ask you about Mees.

Dunham:

Well, he came out there primarily to tell the movie people how to use film for the movies, you know, and that was a very important relationship. I don't believe Hollywood would have been Hollywood without Mees. I don't know how much du Pont came into it a little later. But he was out there, anyway, and he used to spend four or five or six days out in Hollywood.

But he'd always manage, I think almost without exception, to come and spend a day or an evening or most of the night on Mt. Wilson and talk to us people, because he was terribly interested to see how his dyed emulsions would work in the long-wave region, beyond where the ordinary undyed blue leaves off. And at that time, he had chemists going like mad, of course, as you know. They tested 5000 or more different dyes on different emulsions. Tested them all at Rochester, and he'd got enough interested in it so that whenever he had what he thought was a really top-notch emulsion, that had high speed over a considerable stretch of the red and infrared spectrum, he would tell us about it, and send us a box to try out on the coude spectrograph. This was perfectly invaluable. He had some of the early emulsions that you would now call 4-N, but I don't think he had a name for them at that time.

DeVorkin:

He didn't have the 103-series?

Dunham:

No, not yet. But that was different.

DeVorkin:

The II's.

Dunham:

II, and II-A, he used that a lot. But this was for the infra¬red I'm talking about now. I'm pretty sure it was Emulsion 496, we always referred to it that way, and it was an absolute prize. It had high sensitivity, very little fog, tremendously high contrast, because it was in the nature of the 4 emulsion -- a very high contrast, basic emulsion. And with Venus, the planet was bright enough to get an exposure.

It would have been a pretty sad job on most stars, and other planets. With stars you only get a little of the light through the slit to begin with. Venus, of course, isn't intrinsically all that bright, but it has a lot of area so you can get a wide spectrum of it. But it did yield a well-exposed spectrum. And I remember, we both went in and developed that plate, and we put it in the fixer on the other side of the developing rocker. The fixer was cold. But it did fix.

We turned the light on after five minutes or so, just to see if there was anything on this spectrum, whether it had an exposure on it, you know. And even before we got it out of that white 8 x 10 plate, you could see that it had some extraordinary features, that looked like a funny band structure, and you didn't know whether it was defects scattered across it. So when we got it a little more fixed, we lifted it out and looked at it with an old corroded eye piece that had plenty of fixer on it by that time. And then "by Jimmine" here was this perfectly beautiful pattern of pairs of lines. This was, I'm sure, the 7820-band, of CO2 as it finally turned out to be. But we weren't prepared for anything like this at all and didn't know, what to make it. We said, "How can a planet have a lot of parallel lines?"

It didn't first of all occur to us that it was band structure of the atmospheric gas, exactly. We didn't know. We didn't think very hard in the dark, with the fixer there. We did pretty soon, but it seemed rather peculiar at first. So of course, the next day, I guess, we got another spectrum of it. You can't run Venus all night, very well. It has a tendency to set. But we got a second plate of it (those plates are still out at Mt. Wilson, of course) and we did another one, and it came out exactly the same. It certainly wasn't defects, with all that beautiful pattern on it, running up to a head and coming back. And so the question was, what do we do about this? So of course, I got to work and looked up all the literature I knew anything about band spectra. I was not an expert on band spectra in those days-at all. I was thinking of atoms and atomic spectra.

DeVorkin:

-- molecules --

Dunham:

-- Yes, sort of complicated things, yes. I mean, they're a specialty in spectroscopy, and only after a while did they come to be important in cool stars and in planets especially. But I couldn't find any evidence whatever of anything having been observed there in the laboratory, and as a matter of fact it hadn't been. So the question is, what do you do to identify this funny animal? You could look through the rest of the spectrum to see if there were other bands there that had been worked out in the laboratory. But the visible spectrum of Venus is perfectly well known to others, and I'm sure not very unusual.

So I looked at it, and I wondered whether you could get something out of the spacing of those lines that would show anything about the thing. And I talked to R.M. Badger down at Cal Tech whose very much up on band spectra and had worked on them. He gave me a few clues on how to look it up, and how to look up the relations that will give you the moment of inertia of the molecule from the spacing, which I hadn't known about, So R.M. Badger really deserves, credit that he hasn't, I think, had properly,. I think he'll have to have it all right, because he really put me onto the train of events -- to calculate the moment of inertia, and then look up the known moment of inertias of molecules. And this did agree quite well with 40 times .50 to the something or other, for carbon dioxide. And of course carbon dioxide is pretty reasonable.

But who'd think there'd be enough of it up there on the planet to give this, if it hadn't ever been observed, in a perfectly accessible region in the laboratory? Badger didn't suppose that was very reasonable, and yet it seemed to look that way. So, since it hadn't been observed, I thought it was up to us to establish it, somehow; so that's when I set up the pipeline in the Snow Telescope, on the west wall, the only place you could do it on Mt. Wilson. I clamped a 70-foot long pipeline, about .5 .5/2-inch pipe, with glass windows sealed onto both ends. I used half of one of these flange couplings, you know, and cemented a glass window, nothing good optically, onto it and filled it with CO2 and nothing happened.

I lugged the optics over from the .500-inch coude into the Snow telescope spectrograph, which Hale had used -- a little coop up there, if you've seen it, up in the southwest corner beyond the big spectrograph. I fed the light from a lamp through this tube and into the same optics exactly that we'd used on Venus -- the concave grating and all, and collimated it, I put them in wooden mounts there and shot spectra, And nothing happened, at all, until I pumped the gas up to more and more pressure. At about .50 at¬mospheres, which was enough to pretty nearly blow the glass off, the way I had it mounted with sealing wax, it did show something that turned out to be at exactly the right 7820 wavelength, the head of the band. But it was all broad and fuzzy. That is of course, exactly what you'd expect f rom .50 atmospheres on a gas like that -- the CO2 molecule,

DeVorkin:

Well, what made you pump it up -- just to get more gas in there?

Dunham:

Just to get more gas. I couldn't afford to make a fancy multiple reflector system, as lots of people, White and others, have done since. I realized we'd probably damage the sharpness of the lines, but I didn't know how much. I mean, I didn't know what that band in the infrared would do at so much pressure. I didn't bother to go and try to find out, theoretically. I just pumped it up. Now, it did bring a very pretty little dip, like this, a curved dip, that went down like that. I measured it up -- I got a comparison spectrum, through it somehow from an arc.

It measured just right on posi¬tion for the head of the band, but none of the other lines showed. Well then, of course, we left it to Herzberg and other people in Canada to get the fine structure. We thought this was good enough for an identification. We talked about it to Herzberg and he thought it looked interesting, But when we looked at the amount of CO2 that it represented, from our pipe, it was perfectly, fantastic. It turns out it is fantastic, DeVorkin, This seems to be another instance where something was observed first astronomically before it was, observed in the lab.

Dunham:

In that case, those bands, yes. The astronomical source gave the structure of the band first, before it had been observed in the laboratory. The overall band and the position of it, the whole band, was detected in Venus, and could be compared to others that were known in the far infrared. They are much further out. The ones in the infrared of course are the ones that block the sun from coming in too hard, and all that kind of thing.

DeVorkin:

That's the far infrared.

Dunham:

Yes. You see, this is important, because, for the 7820 band, if you take the higher members of the band system, the formula that gives wavelengths of bands worked out perfectly with the two infrared bands that had given the constants of those bands for the infrared spacing of the bands, band by band, not fine structure. And it turned out that by putting the intermediate integer in, you got the position of an expected band at 7980A, and that was then a prediction.

So then you went and looked for that, by using the same infrared plates and turning the grating a little. It took a little more exposure in that region, but not much. It was about 150 angstroms further out. But the dispersion was pretty high, and it didn't show on the first plate. But sure enough, on the second plate it came exactly where it should, and the fine structure came, exactly agreeing with the fine structure of the 7820 band. I think that nailed it. But that was after we got the pipe to suggest that it really was CO2 . We didn't know absolutely, from the moment of inertia -- that isn't enough. There are too many molecules that might be near it, you see. We had pretty good accuracy in measuring, because these were really sharp lines.

DeVorkin:

Did you get in contact with Mees at all about your successes?

Dunham:

Yes, we told him about it. That was in the days when people didn't call up on telephones, in the thirties, quite the way they do now. We surely did tell him about it. And was most enthusiastic. We got to know Mees quite well, out in Pasadena, and when we were in Rochester later, of course. He was very much interested in every astron¬omical application of photography.

DeVorkin:

Do you have personal correspondence with Mees?

Dunham:

I think so. I've tried not to throw those things away, because I thought they might be worthwhile later.

DeVorkin:

Yes, very valuable,

Dunham:

I can look that up somewhat gradually, perhaps, when I'm up in New, Hampshire, because I'm not going to be up there very often, and I've got a job in Maine to do for a fev days or a week and then back here on thing.

DeVorkin:

All your letters are up in New Hampshire?

Dunham:

Yes, most of them. I think none of those are in Australia. We tried to get all the basic correspondence out. We had it all in the files while I was working there for some years. We didn't have any base in the United States at all.

DeVorkin:

Would it be possible for me to come up and visit you some time in New Hampshire and look through your files?

Dunham:

Oh, yes. I can get them together or I can xerox them, but you might like.

DeVorkin:

Yes.

Dunham:

Then we can make copies of those you wanted.

DeVorkin:

Thank you. If we could get back to your planetary work, at this time, your work on the water vapor and oxygen bands.

Dunham:

Yes, that was I suppose a little earlier than this. 1934, I guess. Yes. That was simply trying to use the resolving power that we had, at fairly accessible wavelengths, in the 7000A region for the water vapor bands. The oxygen of course was at 6800A. That was interesting but perfectly obvious, of course. Everybody knew that there was oxygen there. There was a great problem of seeing any possible Martian oxygen bands through our own telluric lines.

So I just took the spectrum when Mars was approaching maximum velocity of something over 20 kilometers, isn't it. And later when it was receding, and compared the two profiles. I just took differences in profiles on the coming and going spectra. Rather than trying to interpret them individually as such, I plotted the difference between several spectra approaching and several spectra leaving for individual lines that were apparently as little blended by any solar lines as you could get, and used several of them. I don't think they were much upset. Of course, you can't tell much about the solar system spectrum with the oxygen on top of it.

DeVorkin:

That's right. What I'm interested in, who you talked to about these problems. This was a longstanding problem. As I mentioned to you at lunch, W.W. Campbell was still quite concerned with the whole problem.

Dunham:

How did Campbell react to this whole situation?

DeVorkin:

Well, he was very happy with the work of Adams and St. John in 1927, 1928, when they seemed to set some definite ratios for oxygen, water vapor, that fell below his minimums.

Dunham:

Oh yes.

DeVorkin:

But he was still concerned, and he wrote extensively to a lot of people in the thirties, about his misunderstandings of his own work, and V.M. Slipher was still involved and still writing about it. I wonder if you had talked to anyone -- Hale, Russell, Adam, St, John, or even Slipher?

Dunham:

No, I didn't go around the loop at all. I just put the planet on the slit and said, "Let's see what we"ve got," I think. I talked somewhat to Adams about it, and he was the kind of person who'd say, "Fine, go ahead." But I think I did that regardless of Adams. I mean, he wasn't involved. I don't know, he may have taken some of the plates, he may not have. But it was mostly my attempt to compare asymmetries of the oxygen lines when the planet was approaching and receding. How did Adams and St. John go at it exactly? Were they measuring the radial velocity of the whole line?

DeVorkin:

Yes.

Dunham:

And they were, of course, experts. I have a great regard for people who can put a wire of a measuring machine on the center of gravity, as it were, of a line. And that's what these Grant measuring machines now do for you automatically. I think they did it by radial velocity, and assuming that if the line had any significant strength, from Mars, it would pull the center of the line to one side.

Now, it might or it might not. If the radial velocity were enough to put the component anywhere noticeably in the wing and if it were very faint, it might have jolly little effect on the center of the deepest part of the line. And visually, I think you'd be affected by that. This is debatable, and it's entirely a matter of psychology. You'd have to run some eye tests on artificial lines with people to find out whether this works. Because if the line were far enough out, and they tried to get it as far as they could, in radial velocity, at the point in the planet's orbit that is tangentially, to the Earth's orbit, didn't they? It wouldn't have moved the deep center.

But that's debatable, how much the wing affects, individual eye setting of the wire. But it was radial velocity. What I was trying to do was to get entirely away from that, by just measuring the profile, and the two profiles, and taking the difference between the two, and plotting the difference and depending on that. We've all got that in the ASTROPHYSICAL somewhere.*

DeVorkin:

Yes.

Dunham:

You know, it was that kind of thing, And then you superimposed on it a line that might have had a shape like that. Then if I'm right, and I think it is, the displacement for radial velocity here was sufficient to push that fully halfway up the intensity curve of the profile, up toward the background. I mean, it was not right down in here. It was pretty well up. So by taking the difference between the profiles, you got a sort of scattering curve like this that predicted what this curve of difference would be, don't you see, delta, or whatever you call it for these two, as you go along in wavelengths here.

We had the predicted value for, oh, 3/100ths of a percent, a tenth of a percent or something. We had these two curves I think in the ASTROPHYSICAL. That was what you'd expect, and how high they would be, if there were a specified percentage of oxygen, percentage of our oxygen, there. All very elementary. But to my, eye, I APJ 79, 308, 1934; PASP 47, 171, 1933; PASP 49, 209, 1937 didn't put a supercomupter or any formula on it, to see what the probability was that there might be this much. You could do that very well. But it was obvious that even if you did it, nobody'd be convinced, and it wouldn't be worth a cent, as information. To say, "this has a 4 percent probability of being a tenth of a hundredth of a percent oxygen, or something." I don't know, that doesn't appeal to me very much. It"s straining the data. It was just obvious there was no visible correlation in the scale and accuracy.

This is pretty good accuracy, because those are awfully good lines, and we had pretty good resolution, sufficient for this, the resolving power of the instrument must have been something like that, anyway, and it was a lot better than the width of the line. So I looked at it that way.

DeVorkin:

What fascinates me is that you came out with the feeling that, if there was oxygen and water vapor, it was below the instrumental limitations.

Dunham:

How was that said in the paper? Didn't it say that there was an upper limit to it. But I don't think there was any evidence that it wouldn't exist. I wouldn't have been so silly as to say I thought it ought to be there but I can't see it.

DeVorkin:

That is what Campbell said.

Dunham:

There wasn't any evidence for it, and so you can't say anything. It turned out to be not much below that limit, and I think that's how it compares now.

DeVorkin:

That's quite a bit different than what Adams and St. John said in 1928.

Dunham:

How did they put their conclusions?

DeVorkin:

They concluded that there was 5 percent oxygen and 15 percent water vapor, or the other way around, that of earth.

Dunham:

Was that the way their radial velocity measures came out?

DeVorkin:

That's right.

Dunham:

Within probable errors perhaps and so on? I suppose they must have in those days. People were pretty strong on errors. They knew how to handle them.

DeVorkin:

They thought they'd found the shifts.

Dunham:

I haven't had any occasion to look at that since. Did Campbell think so too?

DeVorkin:

Oh, Campbell was, very happy, that they'd come up with this, because they had come up with values that were well under his.

Dunham:

Oh yes. If you take the psychology into account, he didn't mind their thinking they had evidence for oxygen, as long as it kept below the Campbell limit.

DeVorkin:

That's right. So I'm wondering if you talked to anyone when you came up with a totally inconclusive observation, just a few years later. Did anybody talk to you about these things?

Dunham:

Not seriously, they didn't take the initiative. I talked to them about it and said, "Do you see anything wrong with this, before we write it up?" I mean, I didn't go around the circle, I never met Campbell, except to see him at a distance, I think, up at Lick. And certainly I didn't ask anyone's advice. I was on with other things so much, this was incidental, in a way.

I, of course, showed it to Adams, who'd worked on it, and I'm sure to St, John, and they said, "Well, yes, that's very interesting, isn't it?" But they didn't seem worried. They didn't think they had to defend their measures. Because this, I think, was done with rather higher resolving power than had been available, probably a great deal higher. Until the Coudé spectrograph and gratings came out, you couldn't do anything more than just nibble at the red, you know, as far as structure of lines, went.

You could only see whether they were there or not. So I don't think there was any excitement about it. It was just an observation that looked as if it were documented after a fashion, and probably not worth following through with. We should have followed it. But after all, if you only could look ahead, and no one ever does, and realize that entirely different methods will soon be used, I don't think you'd do any astronomy. I've often thought of going back and working purely on medical research, because it's perfectly obvious, the momentum is set.

The methods that some of us helped to develop have been used as much as they can, and entirely new methods are just calmly taking over from them, The whole photoelectric pulse-counter technique, and Digicon and Vidicon and all the rest, going into action, and it's wonderful. So you might as well really just take a back seat and let the boys finish it up!

DeVorkin:

You'd be perfectly happy to let them do that?

Dunham:

No! (laughs) I need to keep at it. Even if you know that in less than ten years, perhaps, five or eight, whatever you're doing now, next month up here at the lab, will be done better. I have thought occasionally, when I see how long it takes to run these spectra, from Stromlo through a microphotometer, and the computer, I've thought of waiting for the Digicon and other linear pickups working on an inch of spectrum at a time. It's too bad they can't photograph or record the whole thing, But there you get the whole data out without any of this process, and get it out at the observing station, and you bring it home and work on the data. I may do that yet, I'm going to measure how long it takes me to do this, and maybe it will turn out that I'm better employed some other way, I won't smash the Stromlo plates, perhaps, immediately. Let somebody else do that.

DeVorkin:

No, please don't.

Dunham:

There are plenty of ash cans around. But I do suppose, that in the long run, it's probably silly to do it. It won't help anyone to have that data instantly, or next year, and I think it might be quite sensible to have the intelligence to see the new process do it. We're going to have the Digicon or one of the others working on the Mt. Hopkins telescope, presumably, about Christmas. It will probably happen next year anyway, the way these things work. And we'll get these interstellar lines more or less free of charge, all recorded, without any photography or Kron camera or anything. No echelle business or anything else.

DeVorkin:

This certainly seems to be quite a significant advance -- Digicon work.

Dunham:

Well, it really is. I ran tracings on spectra at Stromlo with the photomultiplier and a very good self-balancing electronic system that monitored. That was the case where I took the whole system from my biophysics lab in Rochester, to Stromlo, because nobody else could think of anything to do with the lab in Rochester. I put it on the coudé after we got it built at Stromlo, and it worked pretty well, but we never had time out there to go further. That was of course step by step scanning. It worked. Would you like to see just one of those high resolution spectra? I've got it right here.

DeVorkin:

Yes.

Dunham:

And the other thing there besides the oxygen, of course, was the ammonia and methane in the outer planets.*

DeVorkin:

Right.

Dunham:

And that was entirely stimulated by the fact that R. Wildt was out there, as a research fellow, for a year, at Mt. Wilson.

DeVorkin:

Was this 1936 or 1937?

Dunham:

About that, yes. I think 1935 is right because we drove him back to Princeton. I suppose in the spring of 1936.

DeVorkin:

Did you meet him out there, or did he come out?

Dunham:

He came out as a research fellow. I think I met him there first, when he came out. But he had observations as you know with low dispersion in Germany that showed fuzzy bands in the red. They weren't resolved at all, to speak of, except little fluctuations up and a little fluctuations down. There were two parts in the 6400 region of Jupiter, and some in the 7000 region. And the general location agreed quite decently.

There wasn't anything to check them by exactly -- with ammonia for the 6400 and 7000 regions, before you get into too much water vapor. That was a stimulus for putting the same equipment on Jupiter, which required a pretty long exposure, because it hasn't got the same surface brightness at all as Venus. But I managed to pull off some spectra of it that did show sharp lines. Again we got out the pipe and pumped it up, with ammonia. This time we didn't have to put the pressure up so much. Ammonia really does take away the light. And methane (was also tested) after we'd cleaned out *PASP 46, 231, 1934 the smell of ammonia from the whole place -- and the mountain people didn't like it much, even in the Snow Telescope, which is pretty wide open.

We could get these gases from Los Angeles without much trouble. So we just let it go from the tank, and had a pressure gauge on it, and let it go to an atmosphere or a little more. And sure enough, the methane band showed structure, and it agreed perfectly with the spectrograph. So that was all there was to it. We got an estimate obviously, because it was low pressure, for the total path length of the atmosphere, which I've forgotten, but it's only a few kilometers, instead of all the stuff there is on Venus. But that was following the lead, as far as Wildt had it, from low dispersion at Bergedorff, I think it was. I'm not quite sure. And of course, Slipher at Lowell. Now, I'm not sure right now, because I haven't looked at this for ages, whether Wildt had been looking at Slipher spectra, and compared them with laboratory spectra, and saw that they were in the same general region as ammonia and methane; or whether he had spectra that he saw, that some of the people at Bergedorff had taken. I don't believe he went out photographing the planets themselves, although he may have, over there, I really am not sure. That ought to be checked by somebody, The main thing is, we just looked at those bands -- so obvious , and this was a short and quite incidental study.

Then when Pluto was discovered, just about that time, the challenge was to see, can we get a spectrum of Pluto with the coudé spectrograph? I couldn't see any reason why not, if you could see it on the slit, just as well almost as you did with the Cassegrain spectrograph.

DeVorkin:

About 15th magnitude though?

Dunham:

Yes, and I worked up a guiding system and a pickup system. In those days, it wasn't as obvious what to do as it is now. But we did it rather quickly. A few wooden frames and lenses, to get it on the slit. We thought we could just see it there, with enough magnification to make it look bright enough, and I fixed up, a very short camera. I took the 7-inch focus camera out of the spectrograph at the 60 inch, and mounted it on a wooden frame back of the grating, and held it there for a few nights. And we caught it. Yes, I did get a streak - but that was all. Just kind of an amusing experimental start. But I couldn't see any bands in it, and I don't know how much the spectrum of Pluto has been fully investigated since. It's a bit light, and I don't believe it would hold those light gases very long. But that was incidental. Well, we've got to the end of the solar system, and I never tried Mercury.

DeVorkin:

OK. After you jumped out of the solar system at that point, you started doing interstellar work.

Dunham:

Yes, of course I was doing all these things more or less over¬lapping. I was doing the interstellar business, one way or another, from about 1934 or 1936 on, I guess.

DeVorkin:

Shapley remained pretty well convinced that interstellar absorption didn't exist.

Dunham:

In space, and big space.

DeVorkin:

Yes. But even so, reddening and that sort of thing, he was a bit skeptical about such things, But were you aware of what Trumpler was doing? With his galactic clusters at Lick, at that time?

Dunham:

I wasn't too much aware. I really depended more on Adams and what he was working on, and I worked somewhat in a separate direction. Working more on what I thought we could get out of a new instrument, really. Where would it apply. I knew about what Trumpler was doing in general.

DeVorkin:

But you knew the important problems.

Dunham:

Yes. I knew the important problems. Adams was always interested in H and K lines and what he could see in the way of structure and radial velocity, both. He did this magnificent paper, which I guess was finally put together in the early forties, wasn't it? Late 1939 or 1940 probably, something like that. That was on the velocities and multiple structure of these lines.

I got rather intrigued by reading Charlotte Moore's tables of ultimate lines and wondered what other interstellar lines there might be besides the sodium and potassium. That led to making up a little list of what you might look for. The list included sodium of course and you couldn't help asking what would potassium look like, out around 7800. I had to do that with the 32-inch camera, because it was further out, and that camera gets stars that aren't all that bright, along the 4th or 5th magnitude. Fifth magnitude seems to me a pretty good place to go, to get distance combined with the use of high resolution.

So, I used the 32-inch, and some of Mees's best infrared plates. He had the same contribution to make as before. I told him, "Never let that emulsion go." Of course, they had to cook it up again, and it didn't, I think, come out quite as well. But it was still very much the best thing you could do. Better than any commercial infrared emulsion by a factor of ten. We've tried to sensitize them with every known method at that time we could think of, chiefly ammonia and ammonia and water. Sometimes they came out with blotches on them.

Sometimes, they didn't. We never knew how much was the emulsion, and how much was bubbles that we couldn't get rid of by brushing them as we dried them. But anyway, we got some pretty good hypersensitized plates, which increased the speed by factors up to 20 sometimes. And this is essential if you're going to work on a star. But we got plates. I think I got one or two exposures. I never followed it very far, but I got one or two exposures out there, at the end of the A band of oxygen. It overlaps in there, these two, the. pair of potassium lines that correspond to the sodium D lines.

They're very much fainter. I suppose the abundance is down. So that was potassium. I never followed it up further to try to measure its exact intensity or anything. I was just after the identification, to see what was there. And then I suppose the titanium was next, in the ultraviolet, the Titanium II lines.

DeVorkin:

You worked on titanium II for awhile. You were finding it in the interstellar medium?

Dunham:

Yes. And that struck me as one of the most interesting situations I've had to do with, because of the extraordinary simplicity of the physics of it, and how it works..

DeVorkin:

The Grotzian diagram?

Dunham:

Yes, the Grotzian diagram. As a matter of fact, the ground state of the atom is what counts in interstellar space.

DeVorkin:

Let's identify the article for the tape. This is in NATURE, 139, (1937), page 246,

Dunham:

Yes. (reading paper) You see, these three transitions from that very lowest ground state of this term level, this A quartette F term -- atomic levels in the titanium II spectrum -- there are these four sublevels. Now, there is the absolute ground resting state, that you'd say every atom likes to get into, in interstellar space, and rests there until a photon comes along and knocks it up to one of these others. And that, we tried to workout, is a matter of several weeks, perhaps.

I'm not sure the theory's right now, but that's the way it looked then, talking to Houston and other people, at Cal Tech. But the next state is up by .52/.5000ths of a volt. And the interesting question, if you look at this backwards is, would the lines from the upper sub-states show at all? The quantum numbers are greater there. And these are tremendous multiplets. Perfectly whacking strong multiplets. But the next sub-state shows exactly nothing that we could see in any interstellar spectrum. And this is a pretty respectable absorption line in the lab. So that shows that all these atoms collapse completely into the absolute ground state, and even at .52/.5000ths of a volt, they're not excited enough to have enough atoms to show.

There may be a few, but you'd have to go to higher resolution, and it would need very powerful tool, say, to look for the radiation into space from a downward transition within a single term. Of course, it's forbidden -- a transition up and down there between the sublevels of a single term; but "forbidden" is only a generalized term. You can break the rules if you try hard enough. With enough push. It's just a question of calculating. It's a low probability. And at that low density, they don't go back and forth and distribute themselves with a Boltzmann distribution. But when they jump up to another state, they can get down again right away.

They can go to any of the states that are allowed. But when they do, they fall almost immediately apparently, in a very short time, even though the transition is forbidden to the ground state, and then they just sit there. But the theoretical discussion of it, which I could only do partly at that time needs a full study. I'm not an expert in that kind of thing. I said what I thought was safe at that time, but it ought to be looked over again now. One ought to go at that line with really high resolution to see if that next line up is visible falling from the next sub-state. Because it is a very fascinating problem I think and ought to be followed. I think that's one of the most beautiful situations in physics -- that turns up only, in astrophysics.

I don't see how you could do anything experimental about it. They could do it on a computer saying they think this is the way it ought to be, if they put the right factors in. But titanium is not the simplest of atoms to work with.

DeVorkin:

It seems to be quite interesting astronomically as a probe to the nature of the interstellar medium.

Dunham:

It would be, if you followed it up fully now. It's a tool. There's very little you can do about this interstellar medium, really, except to observe lines as they come. You can't move the stars around.

DeVorkin:

Did you talk to anybody about it at that time? Because I know Russell was very interested in the density of the interstellar medium. Others were interested in it at that time. People were looking for even the possibility of the energy source of the sun being due to accretion, or supergiants, being due to accretion.

Dunham:

Yes. Falling in stuff.

DeVorkin:

Right. Were you interested in any of the cosmological questions that were coming up at that time?

Dunham:

I don't think I got that far. There was too much else. You see, I was primarily trying to hit a few interesting observing problems, and see what came out of an entirely new instrument. At the time we did this, there wasn't any other coudé spectrograph around anywhere. McDonald got the next, in a somewhat different way. But they had some problems.

They had space limitations and couldn't fix it up so that you could walk around inside it to adjust it. You worked through hatchways and all sorts of things. But anyway, the coudé was the only tool at that time for detailed spectroscopic exploring. So the excitement, in the second half of the thirties, was to explore a number of situations, without getting involved in any one great tremendous problem. I've never been strong on cosmological theory at all. I know there are plenty of people who are doing that awfully well, and I wouldn't half learn the subject before it had advanced.

DeVorkin:

Did you talk to 0. Struve then on the development of the McDonald coudé?

Dunham:

Oh, yes. Yes. We talked a lot about the McDonald coudé. I went down and ran it with him on a number of nights in the earlier part of the time when he had it going there.

DeVorkin:

How was he to work with? Was he very receptive to your ideas and suggestions?

Dunham:

I think so, yes. I think he was quite impressed with what was going on at Mt. Wilson. In fact he invited me to join the staff at Chicago and McDonald and I thought about it carefully. There were some features of it that sounded attractive. But I thought I'd get off my track of doing things the way I knew you could. You couldn't develop things easily down at McDonald; because of the way they were designing the instrument, you couldn't change it very easily.

At Mt. Wilson we could unscrew anything with a wrench in a few minutes, and put some new elements in, and make an entirely new spectrograph. And the setting: I rather think it worked out at Mt. Wilson that I was allowed to play games with that instrument. It was regarded as slightly "queer," but it sometimes brought out interesting photographs and spectra, and nobody interfered with anyone. And it didn't interfere with anyone. They were mostly running the Cassegrains in those days except for Adams and myself, and R. Sanford came downstairs later and Merrill and Joy, and of course Russell.

Russell was always there, but he didn't take spectra himself at all, I think. He always sat on that little platform there, by the slit of the coudé, where you could sit about 3 1/2 feet off the floor, with two little iron ladders to climb up. You probably remember this.

DeVorkin:

I think so.

Dunham:

It's about eight feet long and about 2 1/2 feet wide, and the observer sits on one end, with a telescope for looking at the slit. Russell's standard position was on the opposite side, sitting on a chair that had four round wooden legs. And he'd get so excited talking about spectra, his inevitable progress was backward. He'd go step by step backward, and one night the back legs went off and he went off, and the first thing that happened was, the back of his head hit the iron steps that go up to the telescope.

So I rushed over to help pick him up. He said, "Oh, that's all right, don't bother -- what about that nebular, now!" He really got a blow, on the head. The steps, where you go up a little ladder onto the observing platform, are at the south part of the clock room. There is the great centrifugal governor, as it used to be, all polished brass. And then there's a flight of iron steps, strips of corrugated iron, you know the sort of stuff, that goes up to the telescope. So you don't fall all the four feet. You probably fall about l 1/2 or 2 feet; and he hit one of these steps.

DeVorkin:

He hit the back of his head.

Dunham:

Yes. It seemed to me it was a pretty serious matter, and I said, "Don't you think you'd better lie down and see how it feels for a while?" Because though I know something about medical possibilities you really ought to sit down. You. could get at least a concussion if you don't get a fracture, and it takes a few minutes or an hour or two to find out.

DeVorkin:

Sure.

Dunham:

"Oh no," he said, "no, that's fine," So he went right on through the night. He had a big bulge on the back of his head when we went off to midnight lunch, but he didn't care anything about it at all. He was too excited. The situation up there is devastatingly exciting, if anybody really thinks about astronomy on the spot where the information is coming in. And if he doesn't have the responsibility for making the spectra come out, by being sure that he'd remembered everything, including focusing inside, and that there isn't any diaphragm in the way, that you may have put in when you're focusing, with the Hartman test or something awful like that.

And if you're just standing by, as Russell always was, he just got more ideas every ten or fifteen seconds, and it was the most stimulating thing. Of course, nervewracking to the observer, who's supposed to make the machine work right, and think, what next? And all the clouds coming up, and thinking what can we hope to get? It's a sort of strategy, all night long.

DeVorkin:

How did he talk to you? Just constantly talk and talk?

Dunham:

Yes. I said very little and he said very much. I really had to turn my mind somewhat on the instrument, or it wouldn't work, you know. It was not one of these awfully automatic devices. You had to think of everything right through that you had to do -- did I put the calibration on? How long am I going to expose it for this dispersion? We tended to over-expose spectra because we didn't want to under-expose them, and we didn't spend enough time getting it set up and established, what the exposure should be for every kind of spectrum that we could get. So he did most of the talking, and I did a lot of semi-intelligent, but rather interested, listening.

DeVorkin:

Do you recall any of those talks?

Dunham:

Oh., it was mostly, what could we do? Thinking of more problems. Not about basic theoretical astrophysics so much, no, very little of that. Because when he was at Mt. Wilson, he threw himself entirely, I think, into the atmosphere of the observing astronomer with the best new equipment, both for star spectra and in other fields. He talked to Hubble about galaxies. I can't tell you now more than the fact that he did talk with him, because he always did it in his office, and I wasn't struggling with galaxies because I had a lot else to do.

But I knew what was going on. Whatever it was, whenever a new field had a new method of exploration, as the spectroscopy had at that time, he got tremendously excited and on the go, and his imagination went red hot. "We ought to get this -- And as, I say, he knew most of the stars by their first names, spectroscopically, if not by Greek letters and other names. But he knew what every star was special for, and if I'd had a tape recorder there, that would have been something, But I didn't know all t these stars by their first spectroscopic names.

And so I only absorbed a little of it, because he'd give it back to us later. I don't know if I've ever shown you the letter he wrote, that's in one of our reports, back three years ago, when we wrote it up then, about the advantages of spectroscopy in the Southern Hemisphere, for FAR project down there.

DeVorkin:

You mentioned that he encouraged you.

Dunham:

He had a two-page letter in which he put out in quite striking terms the importance of work in the Southern Hemisphere. I'll get it for you later.

DeVorkin:

I'd like to see that. He certainly did encourage you to consider the Southern Hemisphere. Would you say he was most important?

Dunham:

Well, he urged us to f ight for it very hard. No, it was not only encouraging.

DeVorkin:

Did he have the original idea or did you have the original idea?

Dunham:

I don't know. We all did, I guess. Everybody knew that the Southern Hemisphere, at that time, had been untouched. That was before Cerro Tololo or anything.

DeVorkin:

Sure, yes.

Dunham:

Stromlo had no big spectrograph that would do anything at all. We saw Canopus come up over the horizon for 20 minutes, I think exactly, over the southern hills down towards San Pedro, from Mt. Wilson, flashing all sorts of colors and -- well, you know. It was very tantalizing. I had no knowledge of it except from the spectra here (at Harvard). And the spectra here, with four prisms, that I found are really very im¬pressive. I looked up some of those, just a year or two ago. I wanted to photograph them and enlarge them on the same scale as these and compare them. I think it would be very interesting, for those were taken I think in the 1890's. Anyway, we have some of the best of them we picked out there.

DeVorkin:

Right. OK, when did you decide to establish the F.A.R.?*

Dunham:

I hadn't decided to establish anything at all. I was just working along. A fair number of people knew that Mt. Wilson had a good telescope, but that it was terribly poor off about other equipment. It wasn't the cash for operating the place. But it didn't have any significant cash for developing new equipment, except occasionally new mirrors in the optical shop, and they didn't cost anything, only the glass. Except very cheap opticians' time and a few discs, of small *Fund for Astronomical Research, Inc glass usually. It was just a general situation that was known.

DeVorkin:

Well, the money originally was personal money, wasn't it? Still personal money?

Dunham:

Yes, at the start. It has come from some other sources, but there hasn't been much of it. It's probably the least funded and the least expensive project to operate. Everyone has volunteered his time -- trustees and officers. I suspect if one computed it, it might come out that the scientific results were quite a number of factors of ten higher than for most projects, per dollar invested in it.

DeVorkin:

What was the major funding?

Dunham:

Well, it started entirely in 1936, with a very sudden idea by Charles G. Thompson and his wife. They knew what we were doing out there in California. He happened to be a brother-in-law of mine, a lawyer in New York, now living in New Hampshire.

DeVorkin:

What was his background? He was a lawyer?

Dunham:

He was a lawyer in New York. He and his wife, Alice Bemis Thompson, had some funds, especially his wife from the Bemis Bag Company. Not anything very large, but something. They thought it would be very interesting to have a small fund that could help some of these poor, but scientifically rich observatories to do the right thing with their telescopes -- to have accessory equipment that could be done right. So he and his wife, with a moderate sum, established a small non-profit research organization in New York State, that is properly organized to be tax-free and so on.

That was quite easy to do in those days, Another lawyer, a classmate of his in Philadelphia, Robert M. Blair-Smtth -- the two of them did it together. Charles Thompson for a while was the President, and then he turned it over to Bob Blair Smith, and he became the Secretary-Treasurer. I was put down as a trustee. You have to have at least three in New York State, and I've forgotten whether we had any others.

DeVorkin:

But it was your initial idea?

Dunham:

Well, I realized that something like this was needed, but it never occurred to me to ask anyone to give any financial help on it.

DeVorkin:

Well, how did the Thompsons make the decision?

Dunham:

Well, they knew that this was a situation out there.

DeVorkin:

By your talking about it.

Dunham:

I just talked about it. I never even suggested to anybody that we needed outside assistance on funding, because Carnegie couldn't think well enough to distribute their budget so that we could buy a galvanometer or mirrors occasionally. But they just came up with this. This was a bright idea, in a telegram one day, when I was down at Princeton. In 1936. And we got together and talked about it, with great enthusiasm and excitement. No idea of an organization that could work the Southern Hemisphere at that time, but chiefly to get special equipment for important projects, and of course on a very small scale, because the funds were very low by ordinary standards. I don't think it has ever had assets over $60,000 total, and it's running around 45 to 50 thousand now, with an income of about $3,000.

That makes it possible to do a few things. But mostly, by working very carefully on cooperative projects with other groups, and especially by acquiring relatively inexpensive key optical equipment, if you knew how to do it, and lending it to institutions, and then taking it away later and let them replace it. This is a technique that I think is worth considering carefully. Nowadays if you have a good project, you talk to NSF and you get a whole project and that's all there is to it. Provided you are on the right side of the fence.

DeVorkin:

What's the fence?

Dunham:

Well, I mean, you have to be approved by NSF. They have to think you're sensible. They may not think a small independent organization can tackle a project. They may think that everything should go to Cerro Tololo. Well, that may be a good point of view. I don't think it's necessarily correct. It's distributed pretty widely up here in the Northern Hemisphere, but it's not distributed in the South.

I don't know why the equator should make the difference about policy. But I'm not going to worry about it. There are plenty of other ways. If you've got a good idea, it can always be put through, with corporations and other foundations. So all we need now -- this is something really - is a mounting for this 50 inch mirror. I think that can come with the right enthusiasm, and I'm going to turn this over to other people. I can't keep up my part indefinitely. It isn't good for the organization, and I really want to get some physics, astronomy, and possibly some medical things done, and a few other projects that I think are worth playing with a little.

So this started with a terrific enthusiasm to see if they could get something for Mt. Wilson. The first thing we did was to get the 36-inch disk from Corning, which I think must have cost all of $500 in those days. And we got Hendrix, by persuading Adams in .5938 to allow him to put in a little overtime, at an 80-cents- an-hour rate. So the FAR paid Hendrix 80 cents an hour to grind and polish the 36-inch sphere. And this he did very promptly. I don't know the total cost on the optical work, but I don't think it was much over $200 or $300, certainly. It was of course a perfect optical sphere, for practical purposes. Anything Hendrix did had to be perfect. He had a wonderful knack of knowing what kind of tools and what kind of pitch to use to get the zones out. He had all sorts of old machines lying around from the early days, for making secondary mirrors for telescopes. So, he pulled this one off, and we weren't thinking about the Southern Hemisphere at all at that time. We had a great time getting it into (the coudé) at the .500-inch.

We had to cut a hatch in the roof, to get it in through the concrete, into the coudé spectrograph. Because you don't go in around corners and down the stairs and through the doorways with a 36-inch mirror very easily. We put it in a rough welded steel frame at that point, because we thought we would leave it there. We bolted it onto the main frame of the spectrograph. When it worked, we screwed it on, with adjustments, and used it with a plate holder off the axis. The mirror was tilted a little to one side so that the beam from the grating focused on the off axis plate holder. Being spherical, it had terrific field, of course, and covered nearly 20 inches of spectrum, if you didn't use too much aperture, so as to begin to get spherical aberrations and coma. There was a scrap of astigmatism, but that didn't matter. It was really only a scrap.

We had a 20-inch plate holder, we made it in wood, of course, at the start. I made it in the optical shop, with wedges. I just ran them against another piece of plywood, with sandpaper, so that they came spherical, two of them alike, and then ran them back and forth and mounted them in a wooden box with metal sides, heavy sheet metal, screwed on. We bent the plates to the spherical curve, with a back that had sponge rubber on it, and it worked perfectly well. It couldn't help working, it was so simple. There was practically no optics in the system. Just a collimator, a grating, and the big 36-inch spherical mirror. And it gave a field of nearly half the 36 inches. Of course, there was some vignetting at the top of the beam, which was a 6-inch beam. We had a 20 inch plate holder, and it began to fall off over the last two inches, but it was worth it to see the spectrum even if it wasn't fully illuminated.

So we had about .56 inches of fully illuminated spectrum, and practically perfect optical definition. As good as the photographic emulsion, anyway. And it's the same thing we used in Australia, and that's been used almost identically at other observatories since, of course. But it was very simple going. That was the first thing that the F.A.R. did. It was never noised abroad very much, and I don't think many people knew what was going on. There was no reason why they should. We weren't out looking for additional funds. We thought we were going to do just small things. We also covered some equipment for cosmic ray research, nothing to do with Mt. Wilson. Wilson Powell, in Colorado, up at high altitudes there.

He knew about this, the existence of a small foundation that was interested in astrophysics and not in sociology and other things, and he asked if he could get a small grant of a few hundred dollars. I don't remember what it was. I think it was a camera to photograph a cloud chamber up there. That was back in the early forties, I think. That's one of the few outside bits of support that have been covered by the F.A.R.. In the early or middle forties, after the war, it was a small group working together, on this idea, and they realized that this coudé spectrograph was a useful tool, and that something in the United States, somewhere else than Mt. Wilson, for teaching and research, could be useful. And later, perhaps, some day in the Southern Hemisphere, it could be very valuable because there was nothing of the kind down there then. Just small Cassegrain spectrographs.

So we looked for several years at possibilities for this, we talked with people at the Lowell Observatory, and also at the University of Rochester which had very good physics and optics at the Institute of Optics. I was there at that time. Then several things happened.

DeVorkin:

After the war?

Dunham:

Yes. And we talked with people in Texas. There were some other institutions that wanted to do something new. And Lowell, with its one trustee who could make decisions, and Slipher, where there was a simple possibility instead of great big institutions, with trustees all over the place and a big staff. And they were quite interested in doing this at Lowell, but they never quite thought they would have time to.

If they could build some buildings, and FAR being constituted so that it could definitely put in for grants, you see, elsewhere, without competing with their budget at all -- that had some appeal as a mechanism, which isn't the usual way of doing it. Any institution that thinks up an idea has to balance their present budget with what they might get, and they usually can't expect to get much more next year, and usually just enough to cover inflation on the present plan.

So, a second institution that has no overhead or obligations, really, just two or three people running the simple paperwork, and so doesn't cost anything. Nobody's ever been paid anything on the FAR, no staff or trustees or officers receive anything. We've all just worked as volunteers. That's all. It just looked like a possible combination of effort. The same thing was discussed at Rochester. They thought about it for some time, but they never really got frozen on what they would do. We almost bought a radio station, the WHAM station, out there. They'd abandoned a station on a small hill.

It looked like a very very small but suggestive edition of Mt. Wilson, with a road that went up in a switchback, on a little hill about 40 feet high! It had a concrete building where you could put a dome on the roof of one of the rooms with a telescope and feed light out into another room with a spectrograph, It might have worked. But I'm glad we didn't get caught in doing that, finally. But then we began to look at the Southern Hemisphere, and I talked to Woolley (the Director at Mt. Stromlo) about it, when we were both at the IAU meeting in .5952 in Rome, and that led to his finally saying, "We really ought to do something spectroscopically ... " They'd designed a little depression to the north (as it is in that hemisphere) of the lower polar axis bearing for the new 74-inch telescope at Mt. Stromlo. It has a hollow-polar axis on this Grubb Parsons telescope, and nobody knew just what to do with it.

DeVorkin:

They must have had something in mind.

Dunham:

Well, but only in very general terms. Woolley had realized that they ought to have a coudé spectrograph. But he hadn't thought about it in detail. It was a little affair that could have been about six or seven or perhaps eight feet long, which isn't up to the sort of thing we think of nowadays, if we think that way at all. We want 30 or 35 feet, probably.

DeVorkin:

Did Woolley have the original idea, again, to bring it south, or was B. Bok more involved?

Dunham:

No, Bok wasn't involved in that at all. Bok wasn't on the books to go down to Australia at all in those days. This is 1952. Bok went down in 1957. 1 don't think they really decided to invite him to come down and be director of the observatory until about 1956. No, he talked with the powers that be -- especially Mark Oliphant who started the School of Physical Sciences at the Australian National University. He came up to Harvard and talked Bok into coming to Australia. And he came out to Rochester and talked with me, after I'd been back from a trip down to Australia, but hadn't gone permanently. We both (Bok and I) went down in 1957. He went down in February and we went down in August when we could clean up Rochester and pack up the whole laboratory and took it down.

DeVorkin:

I don't think we'll get that far in this session, talking about Rochester, but I am interested in your war work. In 1942 you started working for the NDRC?

Dunham:

In 1941. You know, it was NDRC first, for a year, and then it became OSRD, the National Defense Research Committee. That was a less formal and less elaborate government group, under V. Bush. And the divisions weren't so numerous, and it wasn't so highly organized. The next year in 1942 it became obvious, there was an awful lot for us to do on the basis of that experience. G. Harrison and I had worked on the application of gratings, and talking about all sorts of applica¬tions to astronomy. He'd always been terribly interested in applica¬tions of all the ruling effort he was putting in at MIT. And so when he was asked by V. Bush to head up the optics division of NDRC, as it was in 1941, he asked me if I'd take on responsibility for the optical instruments under that. Others took on infrared and other kinds of optics.

DeVorkin:

What were some of the major projects that you completed during that time?

Dunham:

Well, the first thing I did was to go over to England and spend about four months over there, trying to see what the British were doing. Everybody thought we ought to know what they were doing there, and what they thought we could do here, and be quite diplomatic about it, and not tell them we thought we knew very much, but that we'd be glad to help the war effort.

We weren't in the war then, you see (this was in September, 1941.) But while I was over there, they captured a German submarine and we had a great time going down and looking at the periscope and guessing what the optics inside were. The Admiralty wouldn't let us take it apart, of course! But we got its characteristics, and it was devastating, with its wide field and sharp images. We put test targets out there in the harbor at Liverpool, where we had it lashed, and secret guards on the docks so nobody'd look at it and all.

I went over with shock-mounted binoculars with flexible gimbel mounts, designed primarily to put in the cockpits of fighter planes, to let the R.A.F. pilots see what they were running into before they hit it. They got targets on the new radar they had running at the time, but they couldn't tell what it was on the screen and they wanted to see it before they intercepted it too closely. So these binoculars, standard, pretty much, wide field binoculars in gimbel mounts, were made up at the Institute of Optics at the University of Rochester. We had other contracts at about 26 different commercial and university labs, a group of us. Paul Kloptsteg and quite a number, four or five others, made up this small committee on optical instruments. I went over there to test those binoculars in aircraft and to see what the British R.A.F. pilots thought of them. This was a very interesting experience in itself, of course.

DeVorkin:

OK, you were talking about your projects with binoculars.

Dunham:

Yes. Well, it was that and quite a number of other projects, but I also was expected by the team over here to help on quite a number of other things. They were very uncertain and moderately on the defensive, this group of acientists, being asked by Bush and others, and by the military people, to work with them and help them.

But you have to be terribly careful not to tell them that you knew better than they did, about a problem. The method of solving it might be in our area, but you had to be sure you didn't tell them what you thought might be an answer when they said, "'We have a problem." First you had to make the right contacts to get them even to admit there were any problems -- that they didn't have everything all working perfectly -- aircraft, submarines, on the ground equipment, but chiefly, aircraft and submarines. But by being moderately diplomatic, and just being interested and saying, "We've got some projects we're working on, and there are a number of facilities that we know exist around the country.

We would be glad to help and see if there's a place where some experiments could be tried, if you think --" We didn't suggest we even knew how to develop a new instrument, of course. That would be taking over too much. So we had to be rather diplomatic. I think I was the only American scientist in this whole kind of area, in England at the time, the fall of .594.5, before Pearl Harbor, and so I just did it, and felt my way around. But our people wanted to know very much how the optical production facilities were working in England, and how much they could take on, and, without saying so, how competent they were, and how, their testing went, and so on, and what their methods were. So I wrote up quite a bit about that, and got myself into the main range-finder f actories and all that, and the other production factories.

They hadn't changed them much by then. The war hadn't gone far enough. And I got at the methods they were using and the kind of thinking, of the people at NPL (National Physical Lab), who were very competent. But they hadn't worked with crash programs, like this sort of thing. So they hadn't urged industry to take up the kind of vigorous methods that our optical teams, and firms, worked up very rapidly in this country. But they were more flexible, a little.

DeVorkin:

Why do you think there was this difference?

Dunham:

Well, I think they'd just gone along gradually, and perhaps because their firms were older than ours. They were established. Our firms that had gone into optics, hadn't been at it so many years. Isn't it often true that people who are new in a field are more flexible, to modify ideas? Bausch and Lomb weren't at that time all that flexible, but they became so rather quickly.

We had to be exceedingly diplomatic with our own firms, of course. We talked to them to try to ask what an unorganized, or only feebly organized, separate scientific team in wartime could do to help, by setting up arrangements under contracts, at various good labs, around the country -- industrial labs, and university labs like Penn State and so on. They've done some quite good optics. And all sorts of places, for example, Polaroid, on the hardening of plastic lenses, and Technicolor on cameras, where they tended perhaps to think they knew everything, but had some rather odd ways of going at it.

I don't want to say they didn't have the best ideas, but we got our own impressions of who worked along quickly and would get the right idea, and know how to line up guns on a B-29 one day, and do something quite different about lenses the next day, you know. It was a tremendous experience, of course. But I spent a vigorous three or four months in England, running around these to different firms and the R.A.F. stations, and flying in their fighters at night over the North Sea and so on.

They had a great way of taking visitors in some of their fighters. Especially their Mosquito fighter, which appealed to me very much because it had two seats up there for an observer and the pilot. But the visitor who goes along to see how it runs doesn't get to sit in the co-pilot's seat, because he can''t very well run the plane, so he gets to stand behind the two, with an open hatch way, it seemed to me about a foot and a half wide. I suppose it's a foot wide and about three feet long. You put your feet on both sides of it, and there's the North Sea down there. Nice moonlight. I remember the ripples on the waves. It was really good. But it was a great experience. And we were at these fighter bases.

It wasn't at a time of heavy bombing. It was between two stretches of heavy bombing. But these R.A.F. boys were absolutely on the go, to jump into their plane, from their quarters or from their mess hall, and jump in and go off, and chase. I never got involved in chasing, because it didn't happen to come up. But the pilots were very much interested in these binoculars. We'd mount them on various trolleys. Pulling a handle would bring them along on a track and set them instantly in front of their eyes, and they could immediately remove them.

They were more interested in removing them than in getting them there. Because of the safety factor, and not wanting to get too close to a plane they were going for by radar, you see. This time in England was quite interesting. Seeing a number of stations all over England that did this kind of thing, including submarines and many other things.

DeVorkin:

It was a mechanical design, then, for the retrieval of the binoculars.

Dunham:

Yes, that was it. We all knew by tests in the lab, we didn't have to go up in a plane, they worked just the same in a plane. You could tell just how much closer you could see a plane with six-power binoculars. You couldn't give them much power because obviously the field would go down.

The design work was all done at the Institute of Optics, in Rochester. Brian O'Brian was there in charge at that time, and terribly enthusiastic about eight or ten different war projects in optics at the same time. I don't just know what's happened to him. He left Rochester and went to join the American Optical Co.

He had close connections with them for a long time, as a consultant, and now I think he's one of the officers. I don't know if he's still at it or not, but he lives somewhere in that area, Southboro. But all the optical designing and the making up of lenses to be wide-angle and high resolution, on the field, were all computed there by people like R. Hopkins, who's there still, at the Institute of Optics, and they made them up there, but put them into standard binocular bodies. Then they built these anti-oscillation gimbel mounts. It may have been a ridiculous project. I don't know.

But it had potential merit, if you could make it so that they could use them in fighter planes. That was the main thing I did in England. But I looked at the whole industry, and talked to a lot of scientists, and got to know all sorts of interesting people over there, of course.

DeVorkin:

You were there for quite some time.

Dunham:

About four months. And there weren't other Americans really doing this kind of science over there, because it hadn't been organized, except this little team of NDRC people who thought it would be good to get in touch with them. I got a lot more chance to see people and do things with them than I would have had if there was a swarm of Americans there, as there was later. I was out at a small R.A.F. station in Wales, the night of the 7th of December, when the Pearl Harbor news came in. It was really dramatic, to see the reaction of the RAF boys, sitting around the mess table. They all got up and clapped and cheered.

DeVorkin:

Why?

Dunham:

When they heard this news, of what had happened at Pearl Harbor.

DeVorkin:

Why did they, clap and cheer?

Dunham:

Well, they saw that it would bring the Americans into the war immediately, and there wouldn't be any of this double talk about it, with Roosevelt saying, "We want to help over there, but not too much," because he wasn't sure he had support here, wasn't it? And he kept escalating slowly. But this snapped it off in a minute. Of course it did snap it off, in Washington, and the whole country was behind him all right. But it was very interesting to be at that exact place at that time, because most other people were listening to their radios and they didn't see a mass reaction. But it was good. I got along even better with them than before, during the next two months. It had, however, been very good up to then.

DeVorkin:

How were conditions when you got back to the United States?

Dunham:

Well, they'd of course developed a great deal more than before. I was entirely concerned with the relation between a limited but rather active scientific group, and the Army and Navy and Air Force. That had developed much further. They had seen a few trial tests of scientists developing equipment, and they were glad to have more of it. So the budget, and particularly the confidence, which is what we were after more than anything, was growing fast.

We knew jolly well, we were just intelligent enough, all of us on the team, to know that we didn't know the military problems. We only knew either the theoretical or the practical optical solutions to some answers if they wanted them, and you had to mesh those in. There were the tank telescope people, for instance. The officers in the tank telescope business, responsible for it, had a very great tendency, which I think one can understand, to write fairly tight specifications for a tank telescope.

They wanted to be sure that the tank telescope specifications were good enough and tight enough so that they were better than other officers who had come along before them. They want to be sure that no higher review officer would say, "Why isn't this able to do this?" So they always wrote, for magnification as high as you can have it, for aperture as small as you can get it, so that you don't get shot when you're looking through the telescope through an opening in the tank armor -- and the maximum possible field of view. They'd heard this thing about field of view, so if you have field of view, you should have lots of it.

The specifications. got up to 50, 60, 70 degrees field of view. Looking through the eye piece, of course, you have to have your eye just there in the exit pupil of the telescope. But large field of view doesn't go with large aperture and exit pupil and with high magnifications. So there were these three fighting specifications. We had to explain to them what you could get away with, and what you would rather have. To get out at night and look at other tanks in the woods with them. And see how far away you could see them. And balance this against the chance of being shot in the right eye while you're doing it? It isn't a particularly good place to be shot with a high powered bullet, and we knew that perfectly well, but we had a great time working that out. Some of E. Land's plastic lenses actually did get into one model of the tank telescope in the invasions -- I think -- of North Africa but almost certainly of Italy, as they came up north. And they were used there fairly effectively.

They had higher aperture, being plastic. I don't think plastic stops bullets particularly better than glass. But it was carefully designed partly by our team and partly by Polaroid. They had Dave Gray there in optics, who's done very well, and I think he must have designed the optics, and they made them. We went around and talked to them, one or two of us, every month or so. They were down on Main St. here in Cambridge, at that time. And it was quite a thing. But that was, I think, the only plastic optics that really got heavily used. I might be wrong about that. We tried them for aerial cameras and all sorts of things, but Jim Baker always had a better one in glass,

DeVorkin:

Did you work with Jim Baker here?

Dunham:

Oh, a great deal. He set up an optics lab, under OSRD here, on Soldiers Field, where the football team was. There's a building there that was taken over for the Harvard Optics Project, under contract with the section of OSRD, you see. I was entirely on the government side of things,

DeVorkin:

You were here then?

Dunham:

I was at MIT mostly, in an office there, and I went out to California once a month. We had a project going out there, on trying to make roof prisms., with accurate angles within two seconds of arc, you know, so that they would give sharp images for all sorts of military instruments.

DeVorkin:

Apart from James Baker, who later developed the Super-Schmidt, did you have contact then with the Harvard staff again?

Dunham:

The astronomical staff?

DeVorkin:

Yes.

Dunham:

Not until I came East, and was here working in Boston for entirely different reasons, You probably don't want to hear about that now, but that was an entirely separate chapter of my re-immersion in medicine for an interval. I go through periods like this, you see, back and forth.

DeVorkin:

Well, possibly what we can do, in this session, is end it with the end of your war work, and I know that you did initially go back to Mt.Wilson for a little while.

Dunham:

Yes, that's right, for about a year. I didn't go back very much, only at intervals, because I was writing the terrific reports on this OSRD project. I was editing it but I had to get all these characters who wanted to get back to their other work to write the separate sections on these 26 or so different contracts, Eastman Kodak and all the universities, and I did that here in Boston.

DeVorkin:

Was it during this period, then that you decided to go back into medicine again?

Dunham:

Yes, I think it really was, by correspondence. But you probably don't want to hear about that now. That was quite an extra-ordinary story.

DeVorkin:

Well, could we hear that story, and then that would be the last thing for this session.

Dunham:

It needs to be thought out a little. I have what I regard as some very significant letters, up in New Hampshire. Correspondence with I.S. Bowen and with Bush about the possibilities of what I might do when I got through with this OSRD work. And this had better not be published until it's been thought about. It was their opinions.

DeVorkin:

This will not be published.

Dunham:

No, I realize that, but I'd rather think carefully about it. I'm not sure that it shouldn't be. It may not be very important, but as the point of view of a major institution and its officers, it's interesting. It was a perfectly reasonable point of view, in one sense. But it wasn't, to me, in another sense.

I had a strong feeling all through these years, up to 1947, 1946, that I would like to put some of the experience I had in optics and spectroscopy and in general scientiftc thinking, into looking at problems that weren't much worked out in those days, in medicine -- looking at what the problem is, on the firing line with patients, translating it into the laboratory, and then solving the problems with physical methods if possible, I may have been crazy, but I thought I sort of owed it to medicine for one thing, perhaps, I had a feeling that I had been given a valuable medical education and owed it to those who had given it to me (at Cornell).

It was fascinating, too, because it seemed to be a nearly insoluble problem. From looking at a patient in bed in the Peter Bent Brigham Hospital to getting laboratory data and studying that by physical and mathematical methods, to getting an understanding of what the problem was with the patient. And then look for means whereby that problem could be solved, at least in part, but optical and other physical means, Briefly, I raised this question. I wanted to keep on with what I was doing at Mt. Wilson very much, but I wanted to nibble at trying some ideas on the spectroscopy of cells down at Cal Tech.

These were organic molecules, and what the composition is and what's abnormal about them. You can bring cancer research into it, which you always do, and it's perfectly proper you should, because it's a very important application. It's one where you have one spectrum with a certain amount of nucleic acid for normal cells, and a different spectrum for cells that are abnormal.

Well, Linus Pauling has always been a very good friend of ours, and lived near us halfway to Sierra Madre, out there east of Pasadena, for years. We were all quite young in those days and had lots of enthusiasm. He was doing all sorts of things in chemistry, of course, at Cal Tech. He was very much interested in biological problems, and brought Bonner and other people to work.

He and I talked a great deal about the application of physics to biological methods, and especially optical methods, which I had more contact with, and some pure chemistry. I asked him if he thought, if I didn't spend too much time from Mt. Wilson, I could do a little work down in one of the labs there on the campus at Cal Tech, trying out a few things, to see if anything would come of it; and whether I could do it as a sideline, mostly evenings or weekends, with no major program, and no real responsibility. And he thought, oh yes, that would be wonderful. Well, I may have made a mistake, but I did raise this question with Bowen, and later we brought it up and both talked with Bush about it.

Briefly, I wondered if I could do a little biology because it was interesting to me, and I thought that it was an opportunity and perhaps an obligation to apply some of the experience I'd had in this wild field of physics, as the medical people think, They think it's perfectly wild, of course. Anything about astronomy means a long beard and looking through telescopes, But it's a little more than that now. They thought about it, or at least Bowen did first. I was here writing these reports still, and we corresponded. It would have been better to talk about it -- or better not to talk about it, I think, just to do things. Nowadays that's what you do; everybody understands it.

But he got fairly serious about the matter, and won-dered how it might be that anyone on the Carnegie Mt. Wilson staff who had a definite and significant other interest, even with no real obligation at all to it, like a consulting job or anything, but just wanted to look at things in another lab and do things in the evenings or over weekends, could give "full time" attention to astronomy at Mt, Wilson. I compared it to playing golf, I said, "Some day I may talk up golf, and that will take time off. Or I might go to the movies some time." But I'm not keenly interested in the movies. I don't know too much about them, and I haven't got to golf yet. That seems to me to happen later in life,

DeVorkin:

You were making this compartson to try to explain it to Bowen?

Dunham:

I was trying to explain that this was just a personal quirk, a special interest in biology,

DeVorkin:

Well, how, did he see it?

Dunham:

Well, he saw the point of it. But he wondered whether it was a really correct plan, to do something in addition to work at Mt. Wilson. No one else, of course, on the staff did any other definite work somewhere else -- they were playing golf, many of them, but that may have been different. Hubble had a great many outside interests, and knew a great many people, and saw them about all sorts of things -- business connections, friends, he knew almost all the active people in the Los Angeles area.

He helped raise money, I'm sure, for Cal Tech. In those days, Carnegie didn't want money raised for it. It wasn't dig¬nified! But others on the staff had some outside activities although mostly not scientific activities. But most of them were just working continuously on astronomy. So I'd be doing something a little out of line if I were to do any biology at Cal Tech. I think he felt it wasn't a good idea, entirely, for anyone on the staff to be having any even semi-serious interests, even after hours. "After hours" don't exist, from that point of view, you see. It takes away from work that you might mentally cogitate on. He didn t put it that way.

But you might think up an idea in the evening, if you didn't have your mind on developing a microscope, or a photoelectric circuit. I did mention that some of those problems in biophysics at present can lead back to what can be used in astronomy. But that wasn't the main reason. I did find that was true, at Rochester later on. I actually took the whole lab for microspectros- copy and all its photoelectric gear down to Australia, and I've still got it down there, and got to get it back, or dispose of it some time soon. But anyway, it ended by his questioning this very much, and saying, "We ought to talk to Bush about this." So we both talked to Bush.

DeVorkin:

So Bowen didn't say no?

Dunham:

He didn't exactly. But he wasn't the kind of person who would exactly want to say no, hard, make a firm decision. But Bowen wasn't that kind of an administrator. He was primarily a physicist, and realized his responsibility very seriously, when he was asked to be director, which he hadn't been very long at that time. And so, he said, "We ought to talk with Bush about it,'' and I can't recall exactly what more. I went down and talked to Bush, down on the Cape, at his place down there.

A good deal of this is on paper. I did talk to Bush a little about it. I think we met at some other place, where he happened to be, and I happened to be near. But it ended up that Bush didn't feel that he could really say that he approved of anyone on the Carnegie staff, or at Mt. Wilson, really doing anything except what he was appointed to be primarily responsible for.

And if it were a question of really expending any significant time, not just talking occasionally, he didn't think I ought to really have even a minor lab down there. It didn't have to be a lab of my own specially, but anyway, it looked rather doubtful all around that they'd be happy about it. I don't think they absolutely got to the point of saying, "You can't come back. here, and stay on the payroll." I was, I think, off the payroll and on the OSRD payroll at the time up to that moment, so it wasn't that question, It was a question whether I went back, as a full time staff member.

There were several really interesting letters to and from Bowen and Bush. Some day these letters may be rather interesting as examples of the way institutions in the middle forties were looking at problems like this. Nowadays, as we all know, almost any respectable staff member of any university is able quite generally to carry on some outside activity, with or without income from it, and certainly if no income comes from it. I think this is done almost without any discussion about it. But the point of view at Carnegie was rather special, because Carnegie felt that it was quite definitely (special). Under the direction of Carnegie it was doing all the things that ought to be for the benefit of mankind, wasn't it? And so if you're on the Carnegie staff, even if the stars aren't very directly for the benefit (of mankind) -- that is what they are working on.

Finally, after considerable trepidation, and having no idea what I'd do next, I mailed a letter to Bowen in the postbox here in Boston saying I was ever so sorry, but I thought that really under these circumstances I'd have to resign my position at Mt. Wilson, and not go back there as a staff member. But I hoped I could come back and work with them occasionally and talk with them and all that. That was quite a dramatic, traumatic event, as from the point of view of my career, because I had no idea what I'd do next. I'd finished this OSRD thing, and I didn't know where I could work in astronomy, and I had no footholds in biophysics whatever.

DeVorkin:

How long was it before you got to be at the University of Rochester?

Dunham:

That was about a total of two years. I was here at Harvard, one way or another, at the Harvard Medical School, working on research, and the Peter Bent Brigham. I had a license to practice in New York, you see. I fortunately got it after graduating from Cornell. I had been for part of the first year at Harvard Medical School (in 1921), and then transferred to Cornell in New York City.

DeVorkin:

You did do some practice.

Dunham:

No, I didn't do any practice, but I had the license. So I had a right to write a prescription as long as I crossed the line into New York State. I wouldn't want to, and you wouldn't want to take the prescription, but it's legally possible. And I might go back to that, but I don't think so. It costs too much for malpractice insurance now for any individual, let alone an inexperienced one. No, I've only practiced on patients in the hospital here at Peter Bent Brigham and while I was an intern at the Strong Memorial Hospital in Rochester, after that I got my internship about 18 years after I graduated in medicine, after this gap. I did that, thinking it would make it possible to keep up with medicine, but that's another story, quite separate from astronomy.

DeVorkin:

OK. Well, thank you very much for this first session, and taking things up to that very poignant period of time for you. I hope that we'll be able to see you again some time.

Dunham:

I'd be delighted if you'd come up to New Hampshire. You don't mind living in a tepee, I hope. Our son has built himself a tepee out in the field.

Session I | Session II