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Oral History Transcript — Dr. Yoshihide Kozai

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Interview with Dr. Yoshihide Kozai
By David DeVorkin
At Tokyo Institute of Technology
September 2, 1997

Transcript

DeVorkin:

This is an oral history interview with Professor Kozai taking place under the auspices of the American Institute of Physics. We're in the Residence Hall of the Tokyo Institute of Technology in Tokyo.

Kozai:

Yes. [laughs]

DeVorkin:

Well, Professor Kozai, could you state your full name.

Kozai:

Yes. My first name is Yoshihide [pronounced yo'-shee hee-dih] and my last name is Kozai.

DeVorkin:

Professor Kozai, could you tell me a little bit about your family background? Who your father was, what his profession was?

Kozai:

My father was an electrical engineer in a national railway under the government.

DeVorkin:

This is the national railway?

Kozai:

Yes, railway.

DeVorkin:

And his full name?

Kozai:

Yoshimasa Kozai.

DeVorkin:

Okay, good. He was an electrical engineer for the railway.

Kozai:

Yes. He suffered from a stroke in 1935 when I was seven years old, and he stayed in bed for almost ten years.

DeVorkin:

Ten years.

Kozai:

Yes. He died in 1945, June 1945.

DeVorkin:

So you were born in 19?

Kozai:

28.

DeVorkin:

This must have been very hard on your family.

Kozai:

Yes, that's right.

DeVorkin:

Were you an only child?

Kozai:

No, I had five brothers and sisters — sister, me, sister, brother and sister. [laughs]

DeVorkin:

You're the oldest son.

Kozai:

Yes.

DeVorkin:

What did the rest of your siblings do in life?

Kozai:

My eldest and youngest sister died during the war. My brother is still working for some company, he's a so-called business man.

DeVorkin:

Okay. Did your father have a college education?

Kozai:

Yes, he did. He studied at Tokyo University in the faculty of engineering.

DeVorkin:

Did he go beyond the Bachelor's degree?

Kozai:

No, at that time, before the war, before the new education system came in, very few people did graduate study. Even scientists didn't go to graduate school.

DeVorkin:

I see. In your case, what kind of schools did you go to when you were a child?

Kozai:

I attended the usual schools in Tokyo. After six years of primary school I went to a Japanese middle school, and then after five years at middle school, I entered high school.

DeVorkin:

This was the first high school, the highest —

Kozai:

That's right. First high school means the best.

DeVorkin:

You must have done very well in middle school to get into this.

Kozai:

Yes, but I was born on the 1st of April, and you know that in Japan the academic year starts on April 1st.

Kozai:

That's why as soon as I became six years old I entered school, so maybe I was handicapped a little bit.

Kozai:

I was the youngest in class.

DeVorkin:

Yes.

Kozai:

That's why I didn't do very well in primary school. My teacher at primary school advised me not to apply for a very good school. [laughs] So I entered a newly built middle school. I was the first to graduate from that school.

DeVorkin:

You must have done quite well there to go to the first high school.

Kozai:

Yes, but at that time you see the competition to enter the university was not so severe as now.

DeVorkin:

The competition.

Kozai:

Yes, the competition. Also, now if I wanted to go to the university, it would be too hard. [laughs]

DeVorkin:

Because the competition is greater now?

Kozai:

Yes.

DeVorkin:

Tell me a little bit about your home interests. When you were seven your father had a stroke. How did your family survive economically?

Kozai:

I think that employees of the national railway system were well paid. My mother used to say that when my father went abroad to attend the railway system meeting in Spain, he visited Europe and USA for a year in 1930 with 10,000 US dollars and one-third of his salary was paid to my family and it was financially the best period of my family. I do not know how much he was paid after he left the railway system as a pension. However, I guess that it was not so low. Therefore, before he died, our finance system was not so bad. However, after the war, severe inflation attacked Japan and, particularly, my family.

DeVorkin:

You worked while you were in school.

Kozai:

Yes. High school, after the war, was open only half day. So you had plenty of time. Usually I did some tutoring.

DeVorkin:

Well, let's talk now about how your interests developed. Did your father have hobbies, or your mother have special interests?

Kozai:

No, I don't think so. I must also tell you that I never talked with my father on important matters: he was always angry when he was in bed, [laughs] and he forgot about Katakana.

DeVorkin:

Katakana is a form of writing.

Kozai:

Yes a form of writing. A Japanese paper consists of Chinese characters and Katakana. And maybe he forgot about Katakana. That's why he asked me to read the newspaper to him.

DeVorkin:

After the stroke. Yes, sure.

Kozai:

But still we didn't talk to each other on important matters.

DeVorkin:

Well what about your own interests then? What interests did you have?

Kozai:

I wanted to do something in science, but from 1944 to 1945, more than one year, we had to work at the military industry, eleven hours per day.

DeVorkin:

Eleven hours a day?

Kozai:

Yes, eleven hours per day with two shifts. So you understand why I did not want to be enroled in the engineering faculty. And I was afraid that any industrial company would not like to employ me. And I told you that I didn=t have any elder brother. My father was the eldest son and my mother was an eldest child with two younger brothers. That is why in my relatives elder boys did not exist.

DeVorkin:

I see.

Kozai:

And also, after my father suffered a stroke, not many people came to my house.

DeVorkin:

Oh, to visit.

Kozai:

Yes, we were isolated in some sense. And in the middle school there was no class senior to us.

DeVorkin:

And you were in that class.

Kozai:

Also there was no very good information about science in those days. So I didn't know what to study. But I could decide up to the third year of high school. At that time when we applied for university we had to point out which department — physics department, mathematics, science. I remember that it was in November, November in the last year of high school, that our teacher of mathematics told us that now a good book was available. It was the book by Hagihara.

DeVorkin:

Hagihara.

Kozai:

Hagihara's book on the foundations of celestial mechanics. Later on this book was translated into English around 1970 in five volumes. But at that time only the first part of the first volume was published — by the way my teacher of mathematics was a classmate of Hagihara, and Hagihara gave a copy to him. Books were hard to come by in 1947.

DeVorkin:

This was 1947.

Kozai:

Yes. Still the owner of this book store told me, "Why don't you take without paying." But finally I paid.

DeVorkin:

Oh, so you paid him a little bit at a time?

Kozai:

Yes. In fact it was a difficult book to read.

DeVorkin:

Oh yes.

Kozai:

And so after I finished, I recognized that if I could have understood that book it would have enabled me to enter university.

DeVorkin:

You mean high school.

Kozai:

No, university. It was a very difficult book.

DeVorkin:

Yes, it was your high school math teacher who told you about the book.

Kozai:

Yes, that's right. It's very good. This teacher of mathematics was a little bit strange, and he used to say that he would never teach a subject recommended by the government of education.

DeVorkin:

By the minister of education?

Kozai:

Yes, and he used to say that if you want to succeed in the entrance examination why you don't read another textbook, something like that.

DeVorkin:

But evidently you were successful?

Kozai:

Yes. And then I tried to enter the university in the department of astronomy, but people said that graduates from the department of astronomy usually had difficulty in finding jobs and would go hungry.

DeVorkin:

Yes. There wasn't much food around.

Kozai:

No, not much. We were always hungry.

DeVorkin:

Did you work through this time also?

Kozai:

Yes, two full days a week.

DeVorkin:

What did you — what kind of jobs?

Kozai:

Oh, as a tutor.

DeVorkin:

As a tutor. So that was your primary job.

Kozai:

That's right, yes.

DeVorkin:

Back during the war when you worked for a year, the eleven hours a day in war industry, what did you actually do?

Kozai:

I worked on a milling machine.

DeVorkin:

A milling machine.

Kozai:

Yes.

DeVorkin:

So it was metal work.

Kozai:

Yes, that's right.

DeVorkin:

And you operated a large mill to shape metal.

Kozai:

Yes.

DeVorkin:

Did you know what these parts were for?

Kozai:

Do you know anything about a balloon bomb?

DeVorkin:

Balloon bomb. Yes.

Kozai:

Yes. They said it was a part of a balloon bomb. At the end, they said that they were trying to produce a missile to home using the infra-red.

DeVorkin:

So they were working on infrared homing devices.

Kozai:

Yes, but they never succeeded, I suspect.

DeVorkin:

Okay. Well let's go back then to your graduating from high school. Was there any question that you would go to university?

Kozai:

No question. I wanted to go.

DeVorkin:

What about your mother?

Kozai:

Yes. You see my mother was brought up in an educated family.

DeVorkin:

They were educated.

Kozai:

Yes, my grandfather was educated majoring history and served as professors and masters in several schools. He was in Osaka and advised me to enter University of Kyoto which is near Osaka. However, I entered Tokyo University. In my family, one of my uncles was a communist, often was arrested and had to stay in jail. Therefore, I had much excuse not to apply for military schools.

DeVorkin:

Oh, I see.

Kozai:

Yes. Even though I applied to the Navy, my application probably wouldn't have been accepted.

DeVorkin:

Because your uncle was a Communist.

Kozai:

Yes.

DeVorkin:

Oh, that's interesting. I didn't realize that there was that feeling.

Kozai:

Yes.

DeVorkin:

Now, is it fair to say then that receiving or getting a copy of Hagihara's book helped you decide in choosing astronomy?

Kozai:

Yes, that's right, yes.

DeVorkin:

Did you like mathematics?

Kozai:

Not so much. [laughs] If I say I do, then Koshiba will be upset. [laughs]

DeVorkin:

Oh, why is that?

Kozai:

Kodaira's examination was very difficult, but he said that even if we couldn't solve it, he would not give us very bad marks. Just after that he went to Princeton University.

DeVorkin:

Kodaira did.

Kozai:

Yes. Without marking the examination. Then somebody else gave us our marks. That's why we had to retake the same test again. Koshiba did also, therefore, he know that I was there.

DeVorkin:

Oh, I see. Retake the test. Now, as an undergraduate at the University of Tokyo, did you have to take a set series of courses, or did you have choices in courses?

Kozai:

I entered the department of astronomy as a three year course. The first year only two courses of astronomy were required. In the second and third year, we took primarily physics. By the way, Nakayama was my classmate.

DeVorkin:

Oh, Shigeru Nakayama?

Kozai:

Yes, that's right.

DeVorkin:

And what were the first astronomy courses you took?

Kozai:

Oh, spherical astronomy.

DeVorkin:

Do you remember the textbook you used?

Kozai:

There was no textbook, particularly in Japanese. After that textbooks gradually appeared, but still at that time there was no textbook in Japanese.

DeVorkin:

Did you know English well enough to read English textbooks?

Kozai:

Yes.

DeVorkin:

Or German.

Kozai:

German and French. And in the library of the University, I found textbooks on celestial mechanics by Tisserand.

DeVorkin:

Tisserand. Yes.

Kozai:

I did not attend any class for French. However, Tisserand=s book consists of four volumes, the first of which is devoted to classical mechanics. Since I learned already the classical mechanics, by reading the first volume, I learned French.

DeVorkin:

I see.

Kozai:

I translated the four volumes into Japanese. At that time I didn't believe that I could buy such expensive textbooks.

DeVorkin:

So you translated it into Japanese.

Kozai:

Yes. But I never read it again. [laughs]

DeVorkin:

You never read it again?

Kozai:

Yes.

DeVorkin:

Probably translating it —

Kozai:

Yes, and also around 1961, I visited Paris and visited the Gauthier-Villars Book Store.

DeVorkin:

The book store?

Kozai:

Yes, Gauthier-Villars, which published this science book.

DeVorkin:

Ah, okay.

Kozai:

And I found Tisserand's book, and it cost only US $2. I w as very much disappointed.

DeVorkin:

It was much less expensive.

Kozai:

Yes!

DeVorkin:

Were you definitely interested in celestial mechanics during this time?

Kozai:

Yes, and I myself believed that I was not good enough for modern science at all, modern physics, modern mathematics, and so on. I believed that I should take up a classical subject.

DeVorkin:

Well, did you have any course in general descriptive astronomy or astrophysics?

Kozai:

We didn't have any general descriptive astronomy, but astrophysics I learned from Professor Fujita.

DeVorkin:

Right. Do you remember the text he used?

Kozai:

No. Again, no text existed.

DeVorkin:

In Japanese. Right.

Kozai:

And later on Professor Fujita wrote a textbook on astrophysics.

DeVorkin:

Ah, he did.

Kozai:

And also we had Unsöld. Five students got together to read Unsöld.

DeVorkin:

Unsöld.

Kozai:

Sternatmosphäre..

DeVorkin:

Now that's an advanced textbook.

Kozai:

Yes. Professor Hagihara was very busy at the time as he was director of the Observatory.

DeVorkin:

Right.

Kozai:

So one of his assistants, Taro Ura, arranged some seminars for me, and we did Poincaré's book, Mecanique Celeste, together.

DeVorkin:

Right.

Kozai:

By the way, he went to France after that as he got a scholarship from the French government. He studied with J. Chazy. After Ura came back to Japan he became the professor of mathematics at Kobe University. So in fact he was my teacher.

DeVorkin:

He was your teacher.

Kozai:

Yes.

DeVorkin:

Not Hagihara.

Kozai:

Not Hagihara. But, Hagihara advised me to read a paper by Woltjer's father. His father was at Leiden and a professor of mechanics. Hagihara advised me to read one of his papers on the Saturnian satellite, Hyperion.

DeVorkin:

On the orbit of Hyperion.

Kozai:

Yes, the mean motion of this satellite, Hyperion, is in 4 to 3 to that of Titan, the most massive satellite.

DeVorkin:

Four to 3 resonance.

Kozai:

Yes. Then he suggested to me that I do similar work on the asteroid Thule, which is another case of a 4:3 resonance with Jupiter.

DeVorkin:

The asteroid's name again was what?

Kozai:

Thule.

DeVorkin:

Oh, like the place in Greenland, Thule.

Kozai:

Yes, that's right.

DeVorkin:

Okay. Thule. Now, by this time had you had any practical work with astronomical instruments at the observatory, or with telescopes?

Kozai:

Yes. When I was employed by the Tokyo Astronomical Observatory I observed some occultations.

DeVorkin:

Occultations.

Kozai:

Yes. And Professor Hagihara said — he was a very frank man and very outspoken — "You are not very bright. That's why theory is not so good for you," and things like that, so he requested me to make observations of occultations. Occultations at that time had some meaning in Japan. Japan was isolated geodetically from any other country as triangulation survey across the Pacific and Siberia was not possible. And in 1945-50 Japanese started to know that the Japanese system is by several hundred meters off by occultation observations.

DeVorkin:

What deviation?

Kozai:

Vertical deviation. The data for occultations made in Japan were not adopted by some central bureaus, like Greenwich Observatory or the Yale University Observatory. Hirose, at the Tokyo Astronomical Observatory, found that occultation data made in Japan were not good because of poor coordinates. Occultation observations made in Japan were rejected because Japanese coordinates are not consistent with world-wide ones. Therefore, when annualar eclipse in Hokkaido in 1948 was predicted, it was difficult to determine the eclipse zone which was very narrow for this one. Do you know the name of O'Keefe, John O'Keefe?

DeVorkin:

John O'Keefe? The geophysicist?

Kozai:

Yes. He came for the purpose of connecting Japanese geographical data with the U.S. by using a solar eclipse.

DeVorkin:

Yes.

Kozai:

But still Dr. Hirose had the idea it was better to use occultations, because occultations took place more frequently than solar eclipses.

DeVorkin:

These are occultations of stars by the moon.

Kozai:

By the moon.

DeVorkin:

You were still an undergraduate during this time.

Kozai:

In the university system in Japan at that time I was told that courses taught included both under-graduate and apart of master=s curricula. In fact, Dr. Hagihara=s lecture, for example, was of very high level even for graduate course. Therefore, although I did not study at any graduate school, I believe that I obtained a degree equivalent to master=s one.

DeVorkin:

So it was equivalent of the master's degree.

Kozai:

Yes, I think so, because I did write a thesis on the asteroid Thule.

DeVorkin:

On Thule.

Kozai:

Yes.

DeVorkin:

And this was your equivalent of a master's.

Kozai:

I think so.

DeVorkin:

Okay. When did you complete the master's degree?

Kozai:

Oh, 1951. I finished university in 1951.

DeVorkin:

Do I have it right that Professor Hagihara, even though he wasn't your teacher, paid attention to all the students and watched their progress.

Kozai:

That's right. Yes.

DeVorkin:

And he suggested to you that you were not strong in theory, so that you should do observational work? Is that fair?

Kozai:

Yes.

DeVorkin:

How did you feel about that?

Kozai:

He was a teacher with very high standards. So, I accepted it.

DeVorkin:

Did you feel disappointed?

Kozai:

No.

DeVorkin:

Did he say there was a place for you?

Kozai:

Yes.

DeVorkin:

That made a difference.

Kozai:

Yes.

DeVorkin:

Now, in 1951 with your master's thesis on the resonance orbit of the asteroid Thule, what were your plans for the future once you finished the thesis?

Kozai:

Oh, I tried to continue this type of work.

DeVorkin:

This type of work.

Kozai:

Yes. And so I did after I came home from the observatory.

DeVorkin:

Came home —?

Kozai:

From the observatory. I was employed by the observatory.

DeVorkin:

Oh, so you became a research assistant?

Kozai:

Yes.

DeVorkin:

At the observatory?

Kozai:

Yes.

DeVorkin:

Was that during your student undergraduate years or —?

Kozai:

No, after that in 1951.

DeVorkin:

Oh, in 1951 you became a research assistant.

Kozai:

Yes.

DeVorkin:

What were your duties as a research assistant?

Kozai:

Observing occultations and analyzing them.

DeVorkin:

Okay. And when you came home, what did you do?

Kozai:

I continued my work on perturbation for Thule.

DeVorkin:

Did you say secular?

Kozai:

Secular.

DeVorkin:

Now that is not the simplest theory in the world. It's rather complex. Yet Hagihara said that you were not that good in theory. So what were you doing, trying to prove him wrong?

Kozai:

No, but still I wanted to apply the perturbation theory.

DeVorkin:

Good. Did you carry it through to publication?

Kozai:

Yes. But I may have made some mistakes in the paper.

DeVorkin:

In the process of publishing a paper in Japan as a research assistant, did you have to submit your paper first to someone at the observatory?

Kozai:

No, even at that time, I submitted my paper directly to the editor of the Astronomical Society of Japan.

DeVorkin:

Okay. And so you didn't have to send it to your director, like Hagihara or somebody like that?

Kozai:

No.

DeVorkin:

I see. In other observatories they did.

Kozai:

Yes, but still before submitting I sent my manuscript to Hagihara.

DeVorkin:

Oh, for checking.

Kozai:

Asking for his advice.

DeVorkin:

And what was his advice?

Kozai:

He had no advice. Maybe at that time he was busy. I suspected that he didn't see or wasn't able to read my paper.

DeVorkin:

I see. Okay. So how long did you remain a research assistant at the observatory?

Kozai:

Oh, until 1958.

DeVorkin:

So from '51 to '58 you maintained your research assistant's position at the observatory.

Kozai:

Yes.

DeVorkin:

And your primary job was observing occultations?

Kozai:

That's right, yes.

DeVorkin:

Did you do observing and reduction?

Kozai:

Yes, I reduced the observations also.

DeVorkin:

Which telescopes did you use?

Kozai:

At that time, as I told you, observations of occultations were for geodetic purpose. We had a 40cm movable telescope. To measure the distance between two points precisely we chose the places, where the occultation took place at the same place on the lunar limb. In fact in limb regions there are high mountains here and there. The fixed site was at Tokyo Astronomical Observatory, Mitaka, and we brought the 40cm telescope to the place to fit this condition. We used a photomultiplier to detect the occultation epoch.

DeVorkin:

What you did was you followed the brightness of the star and watched the brightness dim as the star was occluded.

Kozai:

By using a photomultiplier.

DeVorkin:

Right.

Kozai:

And so I was able to compute distances, and to compare them with the distances obtained by using triangulation.

DeVorkin:

Distances between different parts of Japan.

Kozai:

Yes. The observations we made to test how much accuracy we could attain by such methods. And if we found them good enough, they tried to extend this technique to connect the trianagulation nets across the Pacific. However, when satellites were launched, it was made clear that satellites are much better target than the moon for this purpose, and, therefore, this project was terminated.

DeVorkin:

This project was terminated you said.

Kozai:

Yes.

DeVorkin:

Okay. Let me just quickly ask about the photomultiplier. Who at the observatory built the photomultiplier system, do you know?

Kozai:

We bought it.

DeVorkin:

Do you remember where you bought it from?

Kozai:

I don't remember, but it was a 1P21.

DeVorkin:

You bought the tube, but who built the system?

Kozai:

A very small company.

DeVorkin:

Here in Japan.

Kozai:

Yes.

DeVorkin:

Do you know the name?

Kozai:

It doesn't exist now — Fuchu Kogaku. The Fuchu Optical Company — Fuchu is the name of a city near Tokyo. Now one of its employees is operating the Mitaka Optical Company, nearby the observatory.

DeVorkin:

So optical companies like Goto did not exist, or Minolta?

Kozai:

Yes. You see the Fuchu Optical Company made telescopes cheaper.

DeVorkin:

Aha. So the other ones may have existed.

Kozai:

Yes, of course, Nikon already existed.

DeVorkin:

Let's find out how you got to the Smithsonian.

Kozai:

I continued to work on the motions of Saturnian satellites. At that time the observations made by the U.S. Naval Observatory were published and I analyzed them later.

DeVorkin:

Okay.

Kozai:

And in 1957 the first Sputnik was launched.

DeVorkin:

Right.

Kozai:

Also in 1958 the IAU Assembly was held in Moscow, and perhaps an IGY meeting. Anyhow, Whipple came to Japan on his way to Moscow.

DeVorkin:

Whipple did.

Kozai:

Yes, and he knew the name of Hagihara. He then tried to find somebody in Japan who studied celestial mechanics.

DeVorkin:

So he was looking for someone in Japan. Why do you think so?

Kozai:

Because in the United States there were only a very few people who knew celestial mechanics, and at the Smithsonian Astrophysical there were none. He was also in charge of tracking artificial satellites in the United States.

DeVorkin:

That's right.

Kozai:

At that time the high speed computer was not very high speed. But when high speed computers became available, they thought everything could be done by using a computer. But they found it was not true.

DeVorkin:

Had you had any experience with computers here in Tokyo?

Kozai:

No. What I used was an electric machine. At the beginning we used mechanical computers.

DeVorkin:

The hand crank.

Kozai:

I was very fast — nobody defeated me. [laughs]

DeVorkin:

Did you used to have competitive races to see who could calculate faster?

Kozai:

Yes. [laughs] There was one high speed computer in Tokyo, but the expense of using such a computer was very high. I remember that the Tokyo Astronomical Observatory was responsible for computing ephemerides of several minor planets. They said at the time that if we asked such computations to be made by that computer company, the cost would be very high — double or three times my yearly income. So I told them that if I could have the money I would do the job. [laughs]

DeVorkin:

You could do it yourself. Yes.

Kozai:

In any case, after I visited the Smithsonian Astrophysical I used the computer.

DeVorkin:

Let's talk about this. Now Fred Whipple, did he meet you directly?

Kozai:

Yes, directly. But I couldn't communicate with him. I tried to tell him that I made some analysis for the U.S. Naval Observatory on their Saturnian satellite observations. He couldn't understand.

DeVorkin:

Oh, I see.

Kozai:

Even so he invited me to come.

DeVorkin:

Even though your English wasn't very good.

Kozai:

I heard that there was a warning in Smithsonian's physical observatory that I didn't speak very good English.

DeVorkin:

A warning?

Kozai:

Yes. [laughs]

DeVorkin:

I see. Well, where did the money come from? Did the Smithsonian pay for your travel?

Kozai:

Yes, otherwise we couldn't have gone.

DeVorkin:

Yes. Did you go alone?

Kozai:

At first I went alone. Then I saved enough money to buy a ticket for my wife to come.

DeVorkin:

When did you get married?

Kozai:

Before I went to the Smithsonian.

DeVorkin:

Oh, I see. So you were a newlywed.

Kozai:

Yes, that's right.

DeVorkin:

Okay. So did you know what you were going to be asked to do while you were at the Smithsonian?

Kozai:

Yes.

DeVorkin:

And what was that? What were your duties?

Kozai:

My duties were very small. I was in charge of making predictions for one satellite. When observations came in, I improved the orbital elements and made predictions. But still most of the work was done by an IBM 704, which existed at MIT.

DeVorkin:

Right. When you went to the Smithsonian, did you take a leave of absence from Tokyo?

Kozai:

Yes.

DeVorkin:

So you knew you were coming back.

Kozai:

Yes.

DeVorkin:

How many years were you to go to the Smithsonian?

Kozai:

At first they said that only half a year grant was available. Also Nakayama was there in Cambridge, Massachusetts.

DeVorkin:

Oh, Nakayama was there too.

Kozai:

Yes.

DeVorkin:

Who did you work with when you went to the Smithsonian?

Kozai:

My colleague was Chuck Whitney.

DeVorkin:

Oh, Charles Whitney. Right. You knew him as Chuck.

Kozai:

Yes. Also George Veis, who was a geodesist. He studied at Ohio State University, and originally came from Greece.

DeVorkin:

Who was this?

Kozai:

George Veis. He is now in Greece.

Kozai:

One year later, Imre Izsak came. He had escaped from Hungary in 1956. He was very good in celestial mechanics, and died around 1964 or 1965.

DeVorkin:

Now, all of you were providing expertise in celestial mechanics and geodesy that did not exist before at the Smithsonian. Was your particular duty the celestial mechanics part of computing the ephemerid of Sputnik?

Kozai:

Yes.

DeVorkin:

And then of other satellites?

Kozai:

Yes, that's right. I started to develop a theory of the motion of artificial satellites. I wrote a paper on the subject which was finished in March '59, and submitted it to the Astronomical Journal. The editor of the Astronomical Journal was Dirk Brouwer, who was doing similar things. One day he came to the Smithsonian with my manuscript and checked with me. He said that he was doing the same type of research and his method was much better than mine [laughs]. Also, at that time, even Smithsonian people didn't think that my paper was very good.

DeVorkin:

Oh. So what happened?

Kozai:

I think in June or July, Brouwer organized a summer school for celestial mechanics, and somebody from the Smithsonian attended. He brought back Brouwer's paper, and I found some mistakes in it.

DeVorkin:

You went to the summer school?

Kozai:

No, I didn't.

DeVorkin:

Oh, but somebody went to the summer school and brought back Brouwer's paper.

Kozai:

Yes.

DeVorkin:

And you found a mistake in it.

Kozai:

Mistakes. I wrote to him about these mistakes. Then finally he accepted my paper, and his paper and Garfinkel B

DeVorkin:

Oh yes. Boris Garfinkel.

Kozai:

And my paper, the three papers appeared in the same issue of the Astronomical Journal, 1959.

Kozai:

So if he hadn't made any mistakes my paper would never have been published.

DeVorkin:

And this was a paper on the theory of the motion of artificial satellites.

Kozai:

That's right, yes.

DeVorkin:

Now, you applied that theory of motion, didn't you, to the figure of the earth?

Kozai:

Yes, before the paper was published I applied the theory to the gravitational field of the earth. I think I had some advantages, because the case of an artificial satellite is similar to the Saturnian case. I also discussed there the matter of north-south asymmetry.

DeVorkin:

The north-south asymmetry.

Kozai:

Yes, John O'Keefe found it.

DeVorkin:

Oh, he did.

Kozai:

Yes.

DeVorkin:

How did he detect the north-south asymmetry?

Kozai:

O'Keefe found that the perigee height of one of the U.S. satellites changed with a period of almost a hundred days. This was due to north-south asymmetry.

DeVorkin:

But he couldn't tell what the actual figure was just from the perigee height.

Kozai:

Yes, one of his colleague derived 3rd order term of the geopotential from the data. However, I thought that their formulation was not complete. Therefore, I derived the 2nd, 3rd, and 4th harmonics terms from observations of another satellite. I published the paper in a special report series of the Smithsonian strophysical Observatory, but not in any scientific journal. Then on day, a fellow visited me to ask questions. He was B. Murray who became later the direct of JPL.

DeVorkin:

Oh, Bruce Murray.

Kozai:

Bruce Murray, yes. He was in military uniform at that time, and maybe worked at the Cambridge Air Force or someplace like that.

DeVorkin:

Oh, the Air Force Cambridge Research Center.

Kozai:

Yes, I think so. He was in military uniform and came to me and asked several questions.

DeVorkin:

He was interested in what you were doing?

Kozai:

Not in my work, but this asymmetry. He thought that if you shifted the station coordinates north or south, then north-south asymmetry would be introduced into the motions. But I told him that was not the case.

DeVorkin:

It wasn't due to the observing station.

Kozai:

No. Of course, the coordinates of observing stations were off from each other. However, what we found were dynamical effects in the motion of artificial satellites and they were dynamically amplified so that we could detect them easily. On the contrary, geometrical effects due to non-uniformity of the coordinates of the stations cannot be amplified.

DeVorkin:

Which observations then, or observation stations, did you use?

Kozai:

I could use observations by Baker-Nunn cameras and there were 12 cameras over the world in the Smithsonian net. Before Baker-Nunn observations were available we had to depend on Minitrack data.

DeVorkin:

Mini-Trak stations. The radio. Yes.

Kozai:

After 1958C9 we depended on the Baker-Nunn camera observations.

DeVorkin:

Did you ever depend at all on the Moonwatch visual observations?

Kozai:

No. They were very useful for producing ephemerides, but were not accurate enough.

DeVorkin:

So good as a first, quick -C

Kozai:

Before the first Sputnik was launched, we had very few knowledge how precisely we could predict the positions of satellites for, say, 10 days. Therefore, the Baker-Nunn camera was designed so that it could cover 20 degrees in its field. And the Moonwatch teams were trained to find satellites even more than 30 degrees off.

DeVorkin:

Even though it was a very wide field, it wasn't wide enough.

Kozai:

Yes.

DeVorkin:

Yes. That's why the Moonwatch people looked at the meridian, all parts of the meridian.

Kozai:

Yes, that's right.

DeVorkin:

Oh, I see. Now I understand.

Kozai:

I also participated once in Japan.

DeVorkin:

In Japan?

Kozai:

Yes, but not in so serious a way.

DeVorkin:

Okay. While you were at the Smithsonian, you must have met some of the other astronomers.

Kozai:

Yes.

DeVorkin:

Did you meet J. Allen Hynek, who worked with Whipple?

Kozai:

Yes, he was the boss.

DeVorkin:

Oh, Hynek was the boss.

Kozai:

Yes, he was in charge of tracking satellite projects.

DeVorkin:

Whipple was over everything.

Kozai:

Yes.

DeVorkin:

So your group worked for Hynek.

Kozai:

Yes. And Karl Henize was also there.

DeVorkin:

Yes. Was Brian Marsden there too?

Kozai:

He came to Yale University Observatory as a graduate student after I came to Smithsonian. And he visited us once and I first met him.

DeVorkin:

Okay, right.

Kozai:

He came after I left.

DeVorkin:

You met him at Yale.

Kozai:

Yes. He came to the Smithsonian.

DeVorkin:

Did you ever go to the Yale summer schools in dynamical astronomy?

Kozai:

No.

DeVorkin:

Why not?

Kozai:

Frankly, I did not think it was necessary for me to attend.

DeVorkin:

Okay. These were real schools to train people in celestial mechanics.

Kozai:

Yes.

DeVorkin:

You were already well enough trained.

Kozai:

Yes.

DeVorkin:

Did they ever ask you to be a teacher there?

Kozai:

Yes, Brouwer asked me to teach there at one of the summer schools. However, it was not realized because he died before this school was open.

DeVorkin:

That was about sixty — so you must have had your appointment extended. I mean you were there more than half a year.

Kozai:

Yes. In fact I stayed almost four years.

DeVorkin:

That's right, until about nineteen sixty —

Kozai:

'62.

DeVorkin:

Did you find contrasts? Do American astronomers work differently than astronomers in Japan?

Kozai:

Yes. At that time in Japan an assistant was an assistant, and so I was surprised to see in the United States younger people, as young as me, applying for a grant. In Japan, this was not possible. As I said, I had to do what my boss was doing.

DeVorkin:

In this case it would be Hagihara.

Kozai:

No, not Hagihara. I belonged to Dr. Hirose.

DeVorkin:

Okay, Hirose, yes, okay.

Kozai:

Also I said that I made some occultation observations — the paper was published under the name of Dr. Hirose.

DeVorkin:

Really?

Kozai:

Yes.

DeVorkin:

This was on the corrections of occultation calculations?

Kozai:

Yes. To measure distances by using occultations.

DeVorkin:

And even though it was your work, he published it under his name?

Kozai:

Yes. In fact, this work was made by his idea and actual computations were made by me under his supervision.

DeVorkin:

How did you feel about that?

Kozai:

I felt it was not my work and I did not like that kind of work.

DeVorkin:

So you just let it go.

Kozai:

Yes.

DeVorkin:

You spent a number of years in Cambridge.

Kozai:

Yes.

DeVorkin:

Did you want to stay, or did you want to come back?

Kozai:

It was a very difficult decision, and I discussed it with my wife. My two daughters were born in USA, and my wife used to say that we should go back to educate our children. Finally, an offer came in from the Tokyo Astronomical Observatory. So we decided to go, and come back here in 1962. At that time I thought that after we worked in the United States for several years we would have a pension which would allow us to live in Japan. [laughs]

DeVorkin:

Oh, that's what you thought then.

Kozai:

In fact my monthly income before I went to USA was $60 US dollars.

DeVorkin:

Here in Japan.

Kozai:

Twenty thousand yen.

DeVorkin:

And did a position open up at the university or observatory?

Kozai:

At the Tokyo Astronomical Observatory. Yes.

DeVorkin:

What position was that?

Kozai:

Just below the rank of associate professor.

DeVorkin:

Did they offer it to you, or did you apply for it?

Kozai:

No. At that time, there was no system for open application.

DeVorkin:

So how did you hear about the position?

Kozai:

Oh, in 1961 August, there was an IAU General Assembly in Berkeley.

DeVorkin:

Yes, that's right.

Kozai:

The director of the Tokyo Astronomical Observatory at that time was Dr. Miyadi who came to USA to attend the IAU General Assembly. I met him there and he offered me a job at the Tokyo Observatory. Dr. Hagihara also attended the General Assembly and then went to Yale University to teach at the Summer Institute for dynamical astronomy. I guess that he gave difficult lectures. In fact, Brouwer complained to me that his lecture was too difficult for students.

Kozai:

Yes. But Brouwer complained that his lectures were too difficult to understand.

DeVorkin:

Really?

Kozai:

He openly insisted that if there were two or three students who understood his lecture, he was very happy, [laughs]

DeVorkin:

Now who was it that you talked to? The director of which observatory?

Kozai:

Oh, the Tokyo Astronomical Observatory, Miyadi.

DeVorkin:

By the way, when you were at Berkeley, did you attend the entire General Assembly?

Kozai:

I think so, yes.

DeVorkin:

What did you find most exciting there, do you remember?

Kozai:

The most exciting paper was a paper on the numerical integration of Pluto's motion.

DeVorkin:

Of Pluto's motion.

Kozai:

Yes. The orbits of Pluto and Neptune seemed to intersect each other, but numerical integration found that they never approached very closely.

DeVorkin:

Yes. I have to go back and ask you a question about Hagihara's textbook. You said that you couldn't really understand it for a good while.

Kozai:

Yes.

DeVorkin:

When did you finally understand it?

Kozai:

[laughs]

DeVorkin:

When did you finally really read it and understand it?

Kozai:

I could not understand completely his lectures. In any case I brought his books on celestial mechanics in Japanese to USA and showed them to Imre Izsak and Peter Musen who as at NASA Goddard Space Flight Center.

DeVorkin:

Peter —

Kozai:

Musen.

DeVorkin:

Okay.

Kozai:

They asked me to translate some other Japanese books, but I hesitated. I told Professor Hagihara about this story, and he said that he himself would like to translate.

DeVorkin:

Oh, I see.

Kozai:

When he was a professor he carried his huge batch of manuscripts with him. [laughs]

DeVorkin:

Really.

Kozai:

At the beginning he intended to publish this book in five volumes, but he tired towards the end. Then Peter Musen and some other people approached some publishers and finally MIT Press decided to publish it. MIT published the first two volumes and the second volume in two separate books. After that MIT gave up. At that time, I was between Hagihara and MIT Press.

DeVorkin:

Oh, you sort of were the go-between?

Kozai:

Yes. And then MIT asked me to find another publisher in Japan. At the time, I thought that a publisher in the Soviet Union might take it on. I spoke to the Japan Society for the Promotion of Sciences, which is engaged in the exchange of scientists and so on, and the people there were interested, and eventually this society published the last three volumes.

DeVorkin:

In English or in Japanese?

Kozai:

In English.

DeVorkin:

Okay. That's interesting. What would you say was the relationship between Brouwer and Hagihara and people like Samuel Herrick and Baker? Was there competition between them, did they all respect one another, or was there friction?

Kozai:

I don't know exactly, but Herrick and Baker were quite different types — practical people. However, I am sure that Brouwer admired Hagihara=s work and recommended him for the Watson medal. For Herrick and Baker I think that their interests were quite different from that of Hagihara.

DeVorkin:

Yes, applied.

Kozai:

Yes, devoted to computing orbital elements. Hagihara's book is more theoretical and mathematical. Brouwer is somewhere in between. Brouwer respected Hagihara very much.

DeVorkin:

Would you say that Hagihara's textbooks were the successor to Tisserand or Poíncaré maybe?

Kozai:

Maybe, yes, Poíncaré.

DeVorkin:

Yes, okay. Was that generally accepted by celestial mechanicians?

Kozai:

Yes, I think so.

DeVorkin:

In the United States, who did you find to be the most competent celestial mechanicians?

Kozai:

I think of course of Brouwer.

DeVorkin:

Brouwer.

Kozai:

Yes.

DeVorkin:

What about Boris Garfinkel?

Kozai:

Oh, he was a specialist. I mean he didn't have so wide an interest, but he could do quite well in developing theory.

DeVorkin:

Yes. He was more of a mathematician, if I recall.

Kozai:

Yes.

DeVorkin:

Did you meet people like Danby?

Kozai:

Yes.

DeVorkin:

He was a student of Brouwer's, wasn't he?

Kozai:

I don't remember where, but he studied in England.

DeVorkin:

Oh, I see.

Kozai:

And he came to Yale as a instructor or something.

DeVorkin:

Oh, right, yes he was junior. Well, let's go back to your study, the use of artificial satellites for the determination of the figure of the earth. If I recall correctly, this created something of a reaction. I mean this became a famous study, did it not?

Kozai:

Yes. But when Professor Harold Jeffries came to the Smithsonian he used to say, if he had enough money, he could do much better than we did.

DeVorkin:

Well that's nice of him.

Kozai:

But still, we didn't use a satellite especially designed for us. We used a satellite designed for other problems. [laughs]

DeVorkin:

That's right. Did you first call it a pear-shaped earth, or who called it pear-shaped?

Kozai:

I don't know. But anyhow, we did the third order harmonics.

DeVorkin:

Third order harmonics.

Kozai:

Yes.

DeVorkin:

That's how you phrased it.

Kozai:

Yes.

DeVorkin:

But you don't know who started calling the earth pear-shaped.

Kozai:

No.

DeVorkin:

Okay. I wonder if it could have been Whipple, or Hynek, or somebody like that.

Kozai:

I don't know.

DeVorkin:

Okay. Did this bring you a certain amount of notoriety? Did your position improve after you made this determination?

Kozai:

Even before somebody from the Smithsonian sent me a letter asking how much money I earned in Japan. So I consulted a Japanese colleague, who was already in the United States, and he advised me not to answer the question. [laughs]

DeVorkin:

Really?

Kozai:

Yes. [laughs]

DeVorkin:

Oh, I see. Because you —

Kozai:

Because my salary was $60. [laughs]

DeVorkin:

Because it was so low.

Kozai:

Then another letter came in asking me how much money I needed, and I was told that $500 was a reasonable figure.

DeVorkin:

Five hundred dollars a month?

Kozai:

Before I had a chance to ask for a raise my salary was increased, so I was very happy.

DeVorkin:

Yes. But you did finally decide for personal family reasons to go back to Japan.

Kozai:

Yes. Professor Hagihara also pointed out different reasons.

DeVorkin:

He what?

Kozai:

Hagihara pointed out different reasons. He told me that to stay in the United States was a non-Japanese policy, an anti-Japanese interests. We should be patriotic.

DeVorkin:

Patriotic.

Kozai:

Patriot, yes. We should go back to Japan.

DeVorkin:

Well, that was pretty direct.

Kozai:

Yes.

DeVorkin:

So he evidently wanted you to return.

Kozai:

Yes.

DeVorkin:

And so you returned in nineteen sixty —

Kozai:

In October of 1962.

DeVorkin:

And what was your position and who did you work for?

Kozai:

In April of 1963 I was promoted to associate professor, and then I was independent. I had no boss, no direct boss at all.

DeVorkin:

Okay. That makes a big difference.

Kozai:

Yes.

DeVorkin:

Did you know this would happen if you returned?

Kozai:

Yes. I was recognized abroad, so they started to recognize me at home.

DeVorkin:

By gaining recognition abroad, then you're noticed at home.

Kozai:

Yes, that's right.

DeVorkin:

Oh, I see. That's interesting. Was that true do you think in a case like Takamine's?

Kozai:

I don't know.

DeVorkin:

That was too early for you.

Kozai:

Yes.

DeVorkin:

Okay. Well, you came back, you quickly became an associate professor, and so what did you choose to do? What were your research interests?

Kozai:

Before I returned to Japan I thought that high speed computers were not available, and so I planned to return to celestial mechanics, asteroids, and so on. But when I returned high speed computers were available in Japan and I worked to introduce them into science. For maybe ten years after I came back I worked on artificial satellites and also introduced the laser tracking system.

DeVorkin:

Data tracking?

Kozai:

Laser beams.

DeVorkin:

Oh, laser tracking. So you introduced laser tracking?

Kozai:

Yes.

DeVorkin:

So you started developing some pretty large systems. Did you learn how to use the 704 while you were in Cambridge?

Kozai:

I attended a class on Fortran.

DeVorkin:

On Fortran, right.

Kozai:

Fortran II.

DeVorkin:

Okay.

Kozai:

I never developed beyond Fortran II.

DeVorkin:

Okay. But you promoted using computers here in Japan for celestial mechanics when you came back.

Kozai:

Yes, but younger people came in and they knew much more about computers.

DeVorkin:

Were there high speed computers at the observatory when you came back?

Kozai:

No. At that time, we depended on a computer at the University of Hongo.

DeVorkin:

Okay.

Kozai:

Later we used a computer equivalent to an IBM 650.

DeVorkin:

Right. Yes, an earlier version.

Kozai:

Yes, but not very fast.

DeVorkin:

It performed basic functions though.

Kozai:

If you tried to compute numerically the orbit of an artificial satellite, it took about 90 minutes.

DeVorkin:

Wow.

Kozai:

This means, you see, that the revolution period of an artificial satellite is 90 minutes. [laughs]

DeVorkin:

So it was equal to the revolution period. Well, that's pretty slow. But for the time it was pretty fast.

Kozai:

Yes, that's right.

DeVorkin:

So you continued working on artificial satellites, but then eventually went back to natural satellites.

Kozai:

Yes, asteroids.

DeVorkin:

How did your position at the observatory change? Because you eventually became director, is that right?

Kozai:

Yes, I was promoted and my salary was increased. In fact before I left Japan in 1958, I received a letter from Smithsonian asking my salary in Japan. However, according to the advise by my colleague who came back from US, I did not answer to this question because it was very low by US standards.

DeVorkin:

So a lot was going on in astronomy in Japan in addition to celestial mechanics.

Kozai:

Yes.

DeVorkin:

But you stayed very much in your own field.

Kozai:

Yes, but of course I was very interested in developing astronomy in Japan, and so the first project which I was involved to promote, was to build the 45m radio telescope.

DeVorkin:

A radio telescope.

Kozai:

Yes. And I don't remember when it was started, but the funding took many years. As I told you, what surprised me in the United States was that younger people applied for grants.

DeVorkin:

Right.

Kozai:

I couldn't do it. Still after I came back to Japan, several younger people wanted to start a new project.

DeVorkin:

So you got more familiar with the American system and wanted to promote what younger people wanted to do?

Kozai:

Yes. And then you know about the Nobayama Radio Telescope.

DeVorkin:

Not too much about it.

Kozai:

I think the funding started around 1975. This is a millimeter telescope, with a 45-meter dish. At its planning stage I did not believe that construction of 45 meter dish with a sub-millimeter accuracy was possible.

DeVorkin:

Right, very accurate. At least one-tenth of a wave, yes.

Kozai:

In fact, now after they built the telescope, they measured the surface accuracy, and found it to be much better than one-tenth of a millimeter.

DeVorkin:

Very good.

Kozai:

They also introduced the optical acoustic spectrometer.

DeVorkin:

Optical acoustic?

Kozai:

Yes, an acoustic wave spectrometer. At the beginning they built a 6-meter telescope at Mitaka. Before that, for example at the United States NRAO, they built spectrometers by using a computer. But we didn't have much money at that time, so that's why we couldn't buy a computer. Other devices were introduced which were, in fact, very successful — very good resolution in the millimeter region.

DeVorkin:

What type of objects were they looking at?

Kozai:

At the beginning interstellar matter — the Orion nebula, new stars.

DeVorkin:

Stellar evolution sort of things.

Kozai:

Yes. A few years ago, Nakai with his colleague found a group of hydrogen maser sources are moving around the center of a galaxy with a very high speed. In fact according to their observations of doppler shift they found that in one part they move out and in the other part they move in.

DeVorkin:

Doppler shift, yes.

Kozai:

With a speed of 1000 kilometer per second. But at Nobeyama they couldn't measure this distance. So they proposed to use the VLA (Very Large Array) in New Mexico. They could then measure the distance, and with a large radial velocity, determine the mass inside and also the distance to this region.

DeVorkin:

Right.

Kozai:

I heard that this is one of the strongest pieces of evidence of such a massive black hole.

DeVorkin:

Yes, the very rapid motions.

Kozai:

Yes.

DeVorkin:

Exactly. Let me move back, because we don't have too much more time, and I'd like to just pick up on a little more of what was going in astronomy in Japan while you were training as a student and as an assistant. I know that Professor Hagihara, let's see his first name was?

Kozai:

Yusuke.

DeVorkin:

Okay. He was a member of Commission 35 of the IAU, which was stellar interiors.

Kozai:

Is that right? Maybe this was Hiyeshi?

DeVorkin:

No, this was Hagihara.

Kozai:

I see.

DeVorkin:

This was before. And I was going to ask B

Kozai:

He studied not only celestial mechanics, but also astrophysics.

DeVorkin:

Right. Yes, he was interested in astrophysics.

Kozai:

He went to Cambridge University around 1922, and attended lectures by Eddington on relativity with, he said, Dirac.

DeVorkin:

With Dirac as well.

Kozai:

For me, his most important paper was about the motion of a particle in a Schwarzschild gravitational field. And his paper was quoted quite often.

DeVorkin:

Okay. Was Hayashi one of his students?

Kozai:

No. Well, Hayashi graduated from the physics department in Tokyo, and he said that he attended Hagihara's lectures a few times, but he gave up.

DeVorkin:

I see. Was he a colleague of yours at any time?

Kozai:

He majored in physics at Tokyo University during the war and after some military service, he became a staff member of the Physics Department of Kyoto University. Therefore, we had no chance to work or study together.

DeVorkin:

Hayashi.

Kozai:

Hayashi.

DeVorkin:

There are some other names who were people at the Tokyo Astronomical Observatory I wanted to ask about. Shin Hirayama.

Kozai:

Shin Hirayama. Yes, he was the second director of the Tokyo Astronomical Observatory.

DeVorkin:

Was he still around when you were a student?

Kozai:

No, no. He died I think in 1944.

DeVorkin:

Oh, okay. Fukumi.

Kozai:

Yes. I know his name, but I didn't meet him.

DeVorkin:

Okay. Because he worked in ephemerides and was also director for awhile.

Kozai:

Fukumi worked at the Tokyo Astronomical Observatory as the director of its ephemerides section, however, he left the observatory before I entered the university.

DeVorkin:

Y. Hagiwara?

Kozai:

Maybe this is Hagihara.

DeVorkin:

No. Oh, well maybe there's two of — there was a Hagiwara and a Hagihara.

Kozai:

Yes, maybe they're the same.

DeVorkin:

Oh, the same person, and this was a typo.

Kozai:

Yes. There are many Hagihara's, and some spell their name Hagiwara, but others Hagihara. Yusuke Hagihara spells his name Hagihara.

DeVorkin:

Hasimoto, who worked in the variation of longitude.

Kozai:

Yes, I know.

DeVorkin:

Did you work with him at all?

Kozai:

No. You see, when I was employed by the observatory he was already 70 years old, something like that.

DeVorkin:

Oh, okay. But do you know anything about their training generally?

Kozai:

Shin Hirayama was the first graduate from the department of astronomy.

DeVorkin:

Shin Hirayama.

Kozai:

Yes. And then he went to Germany.

DeVorkin:

Yes. I'm interested mainly in which ones had contact with the West and worked in the West.

Kozai:

All of them went to Europe.

DeVorkin:

At one time or another.

Kozai:

Yes. You mentioned earlier too, Fukumi. He didn't have a doctor's degree, but he spent more than three years in Paris.

DeVorkin:

What about R. Sekiguti?

Kozai:

Sekaguti, yes. Yes, I know his name.

DeVorkin:

Do you know anything about him?

Kozai:

Yes, he also studied astronomy in Tokyo University, but he has never been abroad, at least not to stay for several months. I thought he worked at the Weather Bureau, and was interested in the meteorology of the sun. He then he became the director of the Tokyo Astronomical Observatory around 1935.

DeVorkin:

He was in Commission 12 on solar radiation.

Kozai:

Yes, that's right.

DeVorkin:

And I think he did sunspot work.

Kozai:

Yes, that's right.

DeVorkin:

Okay. Shinzo Shinjo.

Kozai:

Shinjo. Shinjo founded the department of astronomy of Kyoto university. He made several studies on the history of astronomy.

DeVorkin:

I see. But he also was interested in variable stars. Do you know how he trained?

Kozai:

I think he studied physics in the University of Tokyo and then went to Kyoto and founded the department of astronomy.

DeVorkin:

He had an interesting title. He was professor of cosmical physics.

Kozai:

In University of Tokyo the name was at the beginning department of star work, and then was changed to department of astronomy. In Kyoto University they named Department of Cosmic Physics (or Astrophysics) which sounded more modern and different from classical astronomy.

DeVorkin:

Was Shinjo more of a radical person?

Kozai:

Yes, I think so. And also I think he then became president of the University of Kyoto. So maybe Nakayama knows Shinjo quite well.

DeVorkin:

Okay, I'll ask about that.

Kozai:

And he published some papers, let's see, the history — history means the Oriental history of astronomy.

DeVorkin:

Yes. Understood. Sotome.

Kozai:

Sotome. Sotome was a professor of astronomy in Tokyo,

DeVorkin:

He was on Commission 12 also, solar atmospheres, then he was director of Tokyo —

Kozai:

Yes, that's right. Before Sekiguchi.

DeVorkin:

Oh, before Sekiguchi.

Kozai:

Yes, and after Shin Hirayama. So Shin Hirayama was the vice- president of the IAU just after it was established.

DeVorkin:

Yes, 1931 I think it was. That's right. But do you know anything more about Sotome, what his training was or anything?

Kozai:

Saotome was the third director of Tokyo Astronomical Observatory, and I understand that he worked in various fields of astronomy.

DeVorkin:

Okay. Now there are two Yamamotos. There is Issei Yamamoto and J. Yamamoto. Do you know either one of them?

Kozai:

Issei Yamamoto was a very famous astronomer in Japan and served as a professor of astronomy at Kyoto University and founded Oriental Astronomical Society for amateur people which is active even now. In Japan, very able students like S. Hirayama and Y. Hagihara were sent abroad soon after graduating from the university by Government for astronomical research. However, I heard that Yamamoto went to USA with his wife by his own money. He was active also in IAU and proposed to establish a sub-commission for zodiacal light and success and was nominated as its chairman.

DeVorkin:

Zodiacal light.

Kozai:

He was appointed chairman, and was very proud of that.

DeVorkin:

Okay. Well, those are the names that have come up.

Kozai:

I must let you know about Hirayama.

DeVorkin:

Okay.

Kozai:

There's another Hirayama, K. Hirayama. Do you know anything about the family of asteroids?

DeVorkin:

Kiyotsugu Hirayama. Right. He did asteroid groups. Families. I don't know much about him.

Kozai:

He was a teacher of celestial mechanics.

DeVorkin:

Where was that?

Kozai:

At the University of Tokyo. Hirayama is not so common a name in Japan, but at some period, maybe about ten years, there were only two professors in Tokyo, and both were named Hirayama.

DeVorkin:

Hirayama. Yes, S. and K. That's right. Where is Azabu?

Kozai:

At first the Tokyo Astronomical Observatory was within Azabu. It is in the center of the city.

DeVorkin:

So that was the old site, in Azabu.

Kozai:

Then the observatory moved to Mitaka in 1920.

DeVorkin:

Now I know you remain very much in celestial mechanics and orbit analysis but, in developing modern astronomical techniques, you supported the development of radio astronomy. What about the development of spectroscopic astronomy, such as what Yoshio Fujita worked in? How did that fare?

Kozai:

At Mitaka around 1930 two major instruments came in from Zeiss in Germany, one was a 65-centimeter telescope and the other was what we called the Einstein Tower for observing the sun. It has a very good spectrograph. It was used by a physics professor called Tanaka. Then Professor Fujita was made an assistant to him.

Kozai:

Even before that the Japanese sent special teams to observe solar eclipses; I don't when, but around 1930 there was one in Malaysia. At that time there were three or four very good spectroscopists/astrophysicists. Unfortunately, after they came back to Japan, they all died.

DeVorkin:

They all died?

Kozai:

Yes. We had a problem with tuberculosis at the time.

DeVorkin:

Tuberculosis?

Kozai:

Yes. It was said that they worked so hard in such a hot area they got the disease.

DeVorkin:

I see. So there were some people doing solar physics or solar spectroscopy, but they died collectively.

Kozai:

Yes. They were quite young.

DeVorkin:

Well let's go back to your later career then and finish up the interview let's say in another 5-10 minutes if we can.

Kozai:

Yes.

DeVorkin:

How did you get involved in IAU activities?

Kozai:

At first I worked for the IAU as president of the Celestial Mechanics Commission. Later, I was nominated the director of the Tokyo Astronomical Observatory.

DeVorkin:

And when was that?

Kozai:

1981. At that time the radio telescope project had already started. The optical people wanted a bigger telescope. Also there was much discussion about whether the telescope should be built in Japan or abroad, and where it should be sited. And some people, particularly older people, said that it would not be possible to have a telescope outside Japan.

DeVorkin:

Oh, for the Japanese to have an observatory outside of Japan.

Kozai:

In fact the Mauna Kea site was only approved by the government of Shiri in April of this year.

DeVorkin:

The Subaru station.

Kozai:

Oh, Subaru was funded, but still we didn't know the restrictions. But this observatory was the first one where a Japanese civil servant could stay, except for a diplomat.

DeVorkin:

I don't understand.

Kozai:

If some civil servant, even in education, wanted to stay for several years abroad, he would have to have a joint appointment with the department of foreign affairs. We were the first who were able to stay abroad except for diplomats.

DeVorkin:

I see. So your resident observers were the first ones to be able to work for long periods of time away from the homeland getting around this rule.

Kozai:

Yes.

DeVorkin:

I see. That's fascinating.

Kozai:

The project to construct a 8 meter optical-infrared telescope at Mauna Kea, Hawaii, started in 1991 and the Subaru Observatory was formally founded this year. Ten years ago we discussed about the construction of large telescope as well as reorganization of Tokyo Astronomical Observatory, which was a research institute of University of Tokyo. As an output of the reorganization Tokyo Astronomical Observatory no more exists and National Astronomical Observatory, Japan, was founded as an Inter-University Institute.

DeVorkin:

Were you the person who changed the Tokyo Astronomical Observatory into the National Observatory?

Kozai:

Yes.

DeVorkin:

When did you do that, and who did you have to convince to do that?

Kozai:

Discussion of the project of the large telescope as well as the reorganization of the observatory was made inside the observatory and then outside astronomers joined. And we concluded that we needed the research center for astronomy which will be accessible by everybody. The idea of inter-university did contradict with the basic principle of Tokyo University because before and in the World War Two not only high officers in the Government but also politicians and others disturbed the university policy and even some of their professors were purged out by their pressure. Therefore, after the War the University decided to eliminate any disturbance from outside.

Kozai:

Some professors at the University of Tokyo, and other national universities, had to go because of political pressures.

DeVorkin:

Oh, were pushed out.

Kozai:

Yes. That is why University of Tokyo as well as other national universities do not want to have any outside advisers. However, Inter-University Institutes like National Astronomical Observatory should have advises from other scientists to operate them.

DeVorkin:

I see.

Kozai:

Now it is different. Outside people should have some power. I suspect the University of Tokyo didn't like this idea, just as the astronomers or scientists outside the University of Tokyo didn't have much regard for the University.

DeVorkin:

Were you the one who pushed for a National Observatory?

Kozai:

Yes.

DeVorkin:

Who did you have to convince? Who did you have as allies in this?

Kozai:

Oh, we discussed it with various people. For example, Sachio Hayakawa, you didn't mention Hayakawa B

DeVorkin:

No, I didn't.

Kozai:

Hayakawa died several years ago. He was president of the University of Nagoya. Also Hayashi was very cooperative.

DeVorkin:

So you had people who you worked with.

Kozai:

Yes.

DeVorkin:

Did you go to the Ministry of Education?

Kozai:

Oh, of course.

DeVorkin:

And were they the ones who finally made the decision?

Kozai:

No, we decided because the University of Tokyo didn't want pressure from the outside.

DeVorkin:

"We" being —?

Kozai:

At the beginning, the Tokyo Astronomical Observatory.

DeVorkin:

The staff. The staff of the observatory.

Kozai:

Yes. And the first thing was to persuade people in the University of Tokyo. Without their co-operation we could little.

DeVorkin:

Oh, I see. So you persuaded the University of Tokyo first.

Kozai:

Yes.

DeVorkin:

I see. And the staff of the observatory generally agreed with you?

Kozai:

Yes, they generally agreed. Of course there were some people who were against, but, in any case, we didn't take a vote.

DeVorkin:

Didn't take a vote.

Kozai:

No, vote.

DeVorkin:

Okay. And so when again was it made a national observatory?

Kozai:

It was 1988.

DeVorkin:

1988. And who was it who proposed the Subaru telescope?

Kozai:

Kodaira.

DeVorkin:

Oh, Kodaira did.

Kozai:

Now he is the director of National Astronomical Observatory, Japan. He was in charge of the large telescope project before he became the director.

DeVorkin:

You were director still in 1988 when you made —

Kozai:

Yes. I was nominated the first director of the National Observatory and stayed six years, up to 1994.

DeVorkin:

And by then you were also president of the IAU.

Kozai:

Yes, that's right.

DeVorkin:

I know that Japanese astronomers have been vice presidents of the IAU, but are you the first to become president?

Kozai:

Yes, I think so.

DeVorkin:

Was that an important thing in Japan? Were you recognized for it?

Kozai:

[laughs] No. [laughs] For example, I know that Sahade while he was the president of IAU, the university or government gave him one big secretary, who was a professor of English. [laughs]

DeVorkin:

That made sense. Let me ask also about the large reflector. Not the Subaru, but during your time, didn't you built a 74 inch?

Kozai:

No, this was under Dr. Hagihara's directorship.

DeVorkin:

Oh, Hagihara did.

Kozai:

Yes.

DeVorkin:

But were you involved in deciding who would manufacture the telescope? Who would actually build the telescope, the 74-inch?

Kozai:

It was Grubb-Parson.

DeVorkin:

Do you know how that decision was made? Why Grubb-Parson?

Kozai:

I don't know. I was too young to be involved. Two or three years ago an article appeared in Vistas in Astronomy about the history of Grubb-Parson.

DeVorkin:

About Grubb-Parson. Yes?

Kozai:

The 74-inch telescope in Japan was mentioned. It was ten years after the war, and they discussed whether Japan's business would be accepted or not, since Japan had been an enemy.

DeVorkin:

Yes. But I am interested in why Japan decided to go outside.

Kozai:

At that time we couldn't build. Also, 74-inch telescopes were around the world.

DeVorkin:

There were a lot of them. Right.

Kozai:

Australia, Egypt, and so on.

DeVorkin:

Right. So you wanted one, but you didn't have the company. There was no Japanese company that could built it.

Kozai:

No. And also at that time there were very few Japanese astronomers who had experience in using big telescopes, except for Professor Fujita.

DeVorkin:

Okay. Well, it's about 12:15, and we'd better stop now and get a bit of lunch. I think it would be a good idea. I want to thank you very much for this interview. I was delighted with it. We will have it transcribed in maybe two months, and we'll send it to you. I want to make sure I have your full address. I just want to mention also that the AIP, the American Institute of Physics, is very interested to make sure people like you know that your personal correspondence and your scientific correspondence with other astronomers and your working files and notes are very important, and to try to encourage you to save them.

Kozai:

No, I have already thrown out.

DeVorkin:

You already threw them out?

Kozai:

As you know Japan is very small. So when I left the observatory I found that there was no space in the house.

DeVorkin:

Oh, that's too bad.

Kozai:

And so I sent my books and journals to Vietnam.

DeVorkin:

To Vietnam?

Kozai:

Yes.

DeVorkin:

Oh, that's good.

Kozai:

People in Japan would be happy to have these books, but people in Vietnam even more so.

DeVorkin:

So you threw out all of your personal letters and things?

Kozai:

Yes, most of them.

DeVorkin:

Oh. Well, anything that's still left, make sure it goes to the University of Tokyo, the archives, or wherever you think is appropriate. And if you wanted to talk to anybody about it, you know, we would be interested in helping. Okay, thanks again.