Oral History Transcript — Dr. Yu-Che Chang
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Yu-Che Chang; August 18, 1979
ABSTRACT: Short interview centering around Changís training and influences - upon his career during his graduate years at the University of Chicago and Yerkes Observatory in the late l920s. Some discussion of science education and the growth of astronomy in China and activities of the Purple Mountain Observatory in Nanking where Chang was director for many years. The effects of the war for the Liberation are identified, and there is some discussion of astronomy during the Japanese occupation. Other topics include contact with Bart Bok, visits to Yerkes after World War II, and research in astronomy in China.
DeVorkin: Dr. Chang, what is your first name?
Chang: Yu Che Chang.
DeVorkin: When were you born and where were you born?
Chang: I was born in 1902 in Fukien province, Fuchow.
DeVorkin: What did your family do, your father and mother?
Chang: My father was a merchant. My mother just stayed at home.
DeVorkin: Did you have brothers and sisters?
Chang: Oh yes. I have four brothers and two sisters. But at the present there are only two left, the oldest one and the youngest one. My oldest brother is 94 years of age. He is 16 years older than I am.
DeVorkin: Did any of your brothers or sisters go into science?
Chang: I should say, none.
DeVorkin: What did they do? What were their occupations?
Chang: Some did secretarial work, and some were employees in certain institutions of the government.
DeVorkin: Iím very interested in how you became a scientist and an astronomer. What kind of education did you have when you were a child?
Chang: I went through my education in primary school and in high school. Then I entered what we call Tsing Hua College, which is supported by the Boxer Indemnity Fund. This was to be given to the United States but the United States gave it back to support the college. I graduated from there. Then they sent me to the United States to continue study.
DeVorkin: Were you interested in astronomy in China?
Chang: Well, in the beginning, I was not interested. I came to United States and for half a year I studied mechanical engineering, and then I studied architecture. Finally, I went to University of Chicago to study physics and mathematics.
DeVorkin: Why did you decide to go to University of Chicago finally?
Chang: Well, it just happened. A friend of mine was there and in our correspondence, he recommended it.
DeVorkin: Who was the friend?
Chang: Well, his name was Hsu.
DeVorkin: And he was at the University of Chicago?
DeVorkin: What did he do there?
Chang: He studied physics.
DeVorkin: What type of science did you have when you were still taking college courses in China? Did you have any science courses?
Chang: Oh yes. We had mathematics and physics and chemistry, all one-year courses.
DeVorkin: Did you have laboratory experience?
Chang: Oh yes.
DeVorkin: Approximately what year did you take your physics courses?
Chang: I entered Tsing Hua College at the year 1919. And I graduated in 1923 I took my physics in what I would call my sophomore or junior year.
DeVorkin: What kind of physics? Do you remember at all of you were exposed or did they teach to you anything about modern physics, or was it all classical?
Chang: No, all classical.
DeVorkin: All classical physics. When did you first hear about modern physics?
Chang: I think it was after I came to United States.
DeVorkin: When you were at the University of Chicago, whom did you take courses from? What interests did you have? How did they develop?
Chang: I studied mathematics and dynamics, optics and electricity.
DeVorkin: Do you remember your teachers, their names?
Chang: Some of them, I remember. Slaught was our professor in mathematics. And I attended courses on physics with Michelson and theoretical mechanics under Macmillan.
DeVorkin: When did you become interested in taking astronomy?
Chang: I told you that at first I took engineering and then architecture. But I didnít stick to this kind of work. I thought it over and over. One day I remember I read some popular astronomy. I found it very interesting and thought ďMaybe I should go and continue my study in astronomy.Ē
DeVorkin: Did you read this when you were in the United States?
Chang: Yes. It was a book I still remember that was by Jacoby.
DeVorkin: What interested you most about astronomy? Was it the mathematics in it maybe?
Chang: Yes. Iím interested more in mathematics -- in the computation of orbits and the prediction of position in the heavens, because at that moment that was my conception of astronomy.
DeVorkin: This was celestial mechanics?
Chang: Well, you can say, part of celestial mechanics.
DeVorkin: What astronomers did you have contact with at Chicago?
Chang: At Chicago? I studied under Professor W. D. MacMillan.
DeVorkin: Did you have any courses with F.R. Moulton?
DeVorkin: What was your contact with Moulton?
Chang: I took his course in celestial mechanics. The course on general astronomy, I took under Walter Bartky.
DeVorkin: Now, as you were taking these courses, when did you decide that you really wanted to do a career in astronomy, to work in astronomy?
Chang: I also took courses under a professor Laves of German origin. I worked for George van Biesbroeck later. I wrote my doctorís thesis under his direction.
DeVorkin: The German was the one that got you interested in astronomy?
Chang: I think he had a great influence, to lead me toward astronomy as my career.
DeVorkin: Did you feel at that time that you were going to return to China? To do astronomy?
DeVorkin: Did you know that you would be able to get a job or position?
Chang: I didnít think about that. I didnít think about that question. I remember once I was in a train together with Chandrasekhar and he asked me where should he work, should he stay in the United States, or he should go back to India?
I think I said, ďOf course you should stay in United States because you can make a contribution to astronomy while there. As for me, I am not so talented as you are. I will go back to China to teach astronomy.Ē Thatís what I told him.
DeVorkin: How did he feel about that? He took your advice.
Chang: And I took my own advice. I went back to China and taught for many years there.
DeVorkin: Letís stay with your research. You went to Yerkes Observatory.
DeVorkin: And there you worked only with van Biesbroeck, or did you work with other astronomers?
Chang: Well, only with van Biesbroeck. I made observations of minor planets and comets and I computed orbits with him.
DeVorkin: Which telescopes did you use at Yerkes?
Chang: The telescope was the 24-inch reflecting telescope.
DeVorkin: Was this the first telescope that you ever used?
DeVorkin: How did you like it? Was it fun?
Chang: Well, itís all right.
DeVorkin: You did photography?
Chang: Photography, yes. At that time, Professor Struve also used that telescope, making some observations of asteroids, but when I talked with him, he said, ďNowadays itís astrophysics that is on the frontier.Ē
He persuaded me to follow his direction. I had the conceived idea that the way an astronomer works is computing orbits and making predictions about eclipses and so forth, so I didnít think I should follow his direction.
DeVorkin: He tried to influence you.
Chang: Yes. But maybe itís because Iím rather conservative.
DeVorkin: Well, you do like mathematics.
Chang: Yes. But I couldnít understand the advanced branches of mathematics. I understand up to calculus and the theory of differential equations and so forth, but thatís the limit.
DeVorkin: I see. But thatís enough, more than enough. I know that van Biesbroeck was working on many different things. Did you ever use the 40-inch refractor, the big one?
Chang: Not really, just when Professor van Biesbroeck used it, I went there and visited him.
DeVorkin: What year did you get your PhD?
DeVorkin: At that point, Struve had just barely come to Yerkes then, a little before that, wasnít it?
DeVorkin: So he was very new also. Did you meet Professor Frost?
Chang: Oh yes. When I first went there, he was the Director of the observatory. He took me around the observatory; you remember he was blind. He would count the steps up to the landing and sometimes he asked me to look up something. Heíd say, ďThat is in the Ephemeris, on page so and so.Ē
DeVorkin: And you would look it up for him.
DeVorkin: That is interesting, he knew where things were.
Chang: And in the evening, sometimes he asked me to read, to read something for him. When I made mistakes in pronunciation, heíd correct me. In that way my English improved.
DeVorkin: Itís very good now. Did you learn English in China?
Chang: Yes. But in Tsing Hua College, there were many American teachers.
DeVorkin: I see.
Chang: We spoke English in the class room. But even, you see, in Tsing Hua College they have Middle School and High School. In Middle School, people come after graduation from the primary school. They can take an examination and enter the Middle School of the Tsing Hua College. But I joined it at the college stage, so when I first came there, I noticed that other students could speak English fluently. At first I was surprised, astonished.
DeVorkin: Then you must have worked very hard on English.
Chang: Yes. Some teachers called the roll by number, you understand. Some called by name. I had to be very attentive, so as not to miss when my name was called.
DeVorkin: Did you become very positive about coming to the United States to advance your training after Tsing Hua College? Did you feel as if it would be a very positive thing?
Chang: To come to United States to study has been my aim in life. At least at that moment, because my brother, my second one, not the one that is still alive, the second one, studied banking in United States. Then, the Revolution took place, so he had to come back home and so he studied only for two years. At that time, what we called the ďreturned studentĒ was very much sought after, so he took a position with a good salary. So I think: ďoh, I must go to United States.Ē But seeing my brother do this was the step by which I came to the United States.
DeVorkin: So, going back to Yerkes in 1929, what was your thesis topic?
Chang: The topic was given to me by Professor van Biesbroeck. It was on the orientation of the orbital plane of double stars. For many double stars, the orbit is known, but the inclination might be this way or that way two possibilities. Only for certain double stars, which have spectroscopic observations, can we settle the question. We chose this kind of star. There were not very many at that time, only a little over one dozen. I used that material to determine the direction of the axis, so that I can find out whether there is a certain spatial relationship; whether the orbital planes are parallel or not. That conclusion I got from this, through examples, was that there was not any regularity.
DeVorkin: This was your thesis?
Chang: Yes, it appeared in the ASTRONOMICAL JOURNAL.
DeVorkin: That means that we can find it very easily. With your PhD, what were your plans for the future? What did you want to do after your PhD?
Chang: I planned to return back to China. There wasnít observatory, so I taught in the university there.
DeVorkin: Which university?
Chang: We called it the Central University. It was in Nanking. At that time, the seat of government was there. And this was the major university in Nanking.
DeVorkin: And how did you get this job?
Chang: Well, a friend of mine, K.C. Fong, was in Chicago. He was returning to China. He recommend me to stay at the room where he had been staying in Chicago. This man went back to China and taught at the Central University. So he asked me to come.
DeVorkin: And what did he do? What was his area?
DeVorkin: So you were asked to Nanking to the Central University.
DeVorkin: Was there any astronomy there, before you started teaching?
DeVorkin: So you were the first teacher of astronomy?
DeVorkin: What kinds of courses did you teach?
Chang: I taught physics and I gave a course on general astronomy, and theoretical mechanics, these kinds of courses.
DeVorkin: Did you use textbooks?
Chang: Oh yes.
DeVorkin: Which textbooks did you use?
Chang: GENERAL ASTRONOMY by Russell et al, THEORETICAL MECHANICS by Jeans. All texts were in English.
DeVorkin: Who were some of your first students who became astronomers?
Chang: Iím afraid, none of them.
DeVorkin: What did they usually become? What kinds of students did you have?
Chang: Well, they became teachers and some became prominent officials in the government.
DeVorkin: So this was a college to teach teachers and politicians and people like that, rather than a school to teach scientists?
Chang: Yes, primarily.
DeVorkin: Were there other astronomers in China that you communicated with at that time?
Chang: At that time, I should say that there were not any in China who could be called an astronomer. At that time, the only observatory was run by French Catholic Fathers. (pause)
DeVorkin: You indicated that there was one observatory run by Jesuits?
DeVorkin: What observatory was that?
Chang: They called it Zo Se Observatory. It was near Shanghai.
DeVorkin: Did you have contact with them, did you correspond?
DeVorkin: Not at all?
Chang: No, not until after the Liberation. Then we went over to take control of the observatory.
DeVorkin: What kinds of instruments did they have?
Chang: They had a doublet that I think was about 40 centimeters.
DeVorkin: So, a double astrograph.
DeVorkin: Did you initiate the programs there?
Chang: No. We took that observatory over, and then someone else went there to work.
DeVorkin: I see. Were these other people trained by you or ?
Chang: Not by me.
DeVorkin: They were astronomers?
Chang: They were astronomers.
DeVorkin: Who were they?
Chang: Li Hen. He returned from studying in France.
DeVorkin: So he was educated in France?
DeVorkin: When did you first have astronomy students, or did you ever have them?
Chang: No. I was a teacher, a professor at Central University starting from 1929, and then we had war with Japan. Our observatory was moved to the interior to Kunming in Hunnang Province in southwest of China. I stopped teaching. I worked in the observatory. At that time we had very few instruments for observation.
DeVorkin: What observations did you do?
Chang: We had only a camera for observing variable stars, and I used that sometimes to observe comets. I determined orbits of comets.
DeVorkin: I see, so you were still able to do orbital observations. Did you search for new comets?
DeVorkin: Just when one was found, you took pictures?
DeVorkin: How long were you in the interior at the observatory?
Chang: From 1941 to 1945. That was after the surrender of Japan.
DeVorkin: Right. Then after that?
Chang: We moved back to Nanking, to the Purple Mountain Observatory at Nanking.
DeVorkin: Now, when did the Purple Mountain Observatory start? Did you start that?
Chang: No. Oh no. It was completely constructed by Dr. Chin-sung Yu before the Japanese invasion. It was completed from 1929 to 1934.
DeVorkin: Professor Yu built the observatory?
DeVorkin: Was he an astronomer too?
Chang: Sure, he was an astronomer. When he was a student in the United States, he studied civil engineering at Lehigh University. So he knew something about the construction of an observatory.
DeVorkin: What kind of instrument did he put into the observatory?
Chang: We had a 24-inch reflecting telescope, with optics from Zeiss in Germany. We had a Meridian Circle, and a camera for variable stars, a camera, thatís the only instrument we took to Kunming. There also was a spectrohelioscope.
DeVorkin: With all these instruments, there must have been other people using them?
DeVorkin: You observed with them a bit? Did others?
Chang: No, at that time I wasnít connected. I was just a sort of honorary member in the observatory. I taught at the Central University in Nanking.
DeVorkin: Dr. Yu was the director of the observatory?
DeVorkin: Who else was there along with him to observe?
Chang: There were a few others working with him together. One was his student from Amoy University. Amoy is in the southeastern part of China, near the seashore.
DeVorkin: Yet Purple Mountain was relativity close to Nanking?
Chang: Yes itís in the northeastern suburb of Nanking, very near. From where I live in the city, I can walk up to the mountain in one hour and when I come down, only 45 minutes would be enough for me.
DeVorkin: In the city of Nanking, when you were a Professor of Astronomy, did you popularize astronomy? Was the public interested in astronomy?
DeVorkin: How were they interested? Did you write for the newspaper?
Chang: I occasionally wrote articles for the newspaper.
DeVorkin: Did you have public lectures?
Chang: No. I donít give any public lectures. Sometimes the students from the astronomy department of Nanking University came to Purple Mountain, and I talked to them.
DeVorkin: I understand that when you were in the United States, you met Dr. Bart Bok, is this true?
DeVorkin: When did you meet Dr. Bok?
Chang: That should be Ď46 to Ď48. I met him that year in the house of Professor van Biesbroeck. Once we had a dinner together.
DeVorkin: So you traveled back to the United States after the war?
DeVorkin: What kind of visit was this, a research visit?
Chang: Yes. I was sent over by our government, and the funding was given by United States, especially for this kind of travel.
DeVorkin: How long were you here?
Chang: One and a half years.
DeVorkin: Where did you stay and what did you do?
Chang: At that time, van Biesbroeck kept a boarding house. I stayed there, in their house. At that time I met many well-known astronomers, such as Oort, Stromgren, of course Chandrasekhar was there, and K.A. Strand; I met him at a meeting. I met quite a number who were at Yerkes Observatory at that time.
DeVorkin: You continued your research with Dr. van Biesbroeck? Did you continue orbit work at Yerkes?
Chang: No, not exactly. Professor Struve asked me what kind of work I wanted to do. I said: ďThis time I would like to do something in the line of astrophysics.Ē And so at that time, McDonald Observatory in Texas was under the direction of Yerkes Observatory. He would send astronomers over to make observations, and then after about six weeks they would come back and he would send some others over. Professor Struve sent me over to observe with the 82-inch telescope.
DeVorkin: What did you observe?
Chang: I observed the spectrum of two spectroscopic binaries.
DeVorkin: When you observed the spectroscopic binaries, did you do the orbit reductions too?
DeVorkin: What were your particular interests? Masses of the stars?
Chang: The purpose was from the spectrum to calculate the orbit. I had two stars. I didnít get any useful result for one star but for the other I got a very accurate orbit. And at a meeting of the American Astronomical Society, Struve asked me to present this paper. And so I did.
DeVorkin: Where was the meeting?
Chang: If I remember correctly, it was at Madison.
DeVorkin: Madison, Wisconsin. While you were here at that time, you met Dr. Bok?
Chang: Yes, at that time I met him at Professor van Biesbroeckís house.
DeVorkin: Weíve talked to Dr. Bok about his history and his life, and he remembered meeting with you.
Chang: Yes. He quoted the time as about 1950 or something and thatís wrong. He invited me to a lunch today and he state that. I said I was in the United States for the second time from 1946 to 1948. He said that he thinks he remembers it wrong.
DeVorkin: He was very interested in cooperation.
DeVorkin: How did this idea of cooperation develop? Did you get interested in it at that time? Did you take this idea back to your observatory in China?
Chang: No I was so busy teaching and so forth, I didnít have time for this.
DeVorkin: So when you went back in 1948, did you continue research while you taught, or did you simply teach? What were your activities?
Chang: Our government gave me a certain amount of money, the sum for the trip to the United States, and then for every month gave me about $300, for the year. I told you that from 1941, I left the university and became astronomer and director of the observatory in Kunming.
DeVorkin: But that was only until 1945?
DeVorkin: Then after Ď45 you went to United States, Ď46 to í48.
DeVorkin: Then when you went back to China where did you go?
Chang: I think that by the time of Liberation, 1949, the establishment of the Peopleís Republic of China, I was in Nanking. But when the victorious army of our Communists were near Nanking, our government wanted us to go southward, either to Canton or to Formosa, but we didnít want to go. But we couldnít tell our government we wanted to stay there to wait for the Peopleís Republic, so I said ďWe go but we have first to go to Shanghai, then from Shanghai we go to Formosa or to Canton.Ē The fact is, we knew that all the institutes in Shanghai agreed not to leave Shanghai. So when we went there, we acted in unison. We acted together in Solidarity.
DeVorkin: So you decided then that you could stay at Shanghai.
Chang: Stay there, yes.
DeVorkin: All right. How long were you in Shanghai?
Chang: In Shanghai about nine months, you see. The fighting there lasted about two weeks. Then the new government came. We stayed there. As a matter of fact, Nanking was liberated before Shanghai. We went to Shanghai because they said it would be safer in Shanghai, because of the extraterritorial right there. But this time itís different. In Nanking the fighting was only one day, and itís over. In Shanghai it lasted about two weeks.
DeVorkin: Were you close to the fighting? Were you in danger?
Chang: Well, not in danger. But the fighting was near. Of course it depends upon the trend.
DeVorkin: Did any of the scientists and scholars take part in the fighting?
Chang: No, none of them.
DeVorkin: What did you do after the fighting stopped? Did you do any teaching in Shanghai or you were just waiting to return?
Chang: No. At that time it was very difficult. It was sort of inflation. When we got our salary, at once we went to buy Chinese silver dollars. Otherwise, tomorrow, you would get less. The value became less and less.
DeVorkin: After Shanghai, did you go back to Nanking?
DeVorkin: To the university?
Chang: No, not to the university. I was already on the observatory staff, so I went back to the observatory.
DeVorkin: This is Purple Mountain?
DeVorkin: What was your position there?
DeVorkin: You were the director.
Chang: At first, our observatory was called the Institute of Astronomy but after the Liberation, it was called Purple Mountain Observatory. The name changed.
DeVorkin: I see how that changed. Now, with you as the new director of the Purple Mountain Observatory, what was your program? What did you decide to do?
Chang: At that time, we had only a small telescope, 12-inch diameter, that could be used. The 60-centimeter reflector, and the big dome, were damaged and couldnít be used.
DeVorkin: It was damaged in the war of liberation.
DeVorkin: I see, or earlier, by the Japanese?
DeVorkin: When the Japanese came?
DeVorkin: I see. Did you feel that there should be some practical use for the Purple Mountain Observatory? Did you apply it to time service? Did you have a time service?
Chang: Yes. Gradually we had.
DeVorkin: What kinds of instruments did you use for the time service?
Chang: We have what we called a transit instrument. The transit, at first it was manual and later we made it automatic.
DeVorkin: In the beginning, just after the Liberation, when you began the time service, was this the only time service in China?
Chang: No. I think Shanghai had one also.
DeVorkin: How did you distribute the time service information? By telegraphy? By radio?
Chang: By radio broadcasting.
DeVorkin: Was the radio broadcasting station there at the observatory?
Chang: In Shanghai. There was no broadcasting at the observatory, but the broadcasting station had a sort of wire connection with the observatory.
DeVorkin: I see. So you had a time service and you had a small 12-inch telescope.
DeVorkin: What did you do with the 12-inch telescope?
Chang: Observed asteroids and comets.
DeVorkin: Was there ever any question that you might not be able to continue research?
Chang: No. The new government had a heavy emphasis on the scientific work. They got engineers from Zeiss to come over and repair the 60-centimeter reflecting telescope.
DeVorkin: I see, so they supported science.
Chang: Yes, so we can make a start with the bigger instrument. And afterwards, we got a twin astrograph of 40-centimeter diameter .Thatís most suited for the observation of comets and minor planets.
DeVorkin: You built up a staff of astronomers.
DeVorkin: Where did most of them get their education?
Chang: A number of them were graduates from Nanking University astronomy department, and we also took students of physics and students of engineering.
DeVorkin: When you became director at Purple Mountain, who taught astronomy at Nanking?
Chang: The head of the department was W.S. Tai.
DeVorkin: Where did he get his education?
Chang: He studied in England.
DeVorkin: Do you know, at which university?
Chang: I couldnít say exactly. He was a student of Professor Stratton.
DeVorkin: So he must have been at Cambridge. So, you were building up a staff, and your 60-centimeter telescope was being fixed. When was it back into operation?
Chang: I couldnít remember exactly which year, it was about in 1956.
DeVorkin: Well, how did things progress? You mentioned before that you had a spectroheliograph at the observatory.
Chang: That we left. We couldnít take that.
DeVorkin: I see. Did you have any astrophysic instruments, spectroscopes, spectrographs, at Purple Mountain?
DeVorkin: For the 60-centimeter?
DeVorkin: Who used them?
Chang: We had altogether ten sections. There was a section for stellar astronomy, a section for artificial satellites, and a section for planetary work.
DeVorkin: This is now?
Chang: Now, yes.
DeVorkin: When were these sections begun? When did the observatory grow to the point where you needed sections?
Chang: It came gradually. I canít remember which department started which year.
DeVorkin: How did it grow?
Chang: At first, we had the department of Almanac and Ephemeris. And the planetary section, that came early. Afterward, we had an artificial satellite section for observing artificial satellites of Soviet Russia and United States.
DeVorkin: When the satellites first started going up in 1957, the Sputnik and satellites like that, was there interest in China at that time to build satellites?
Chang: Yes. Yes. But not at that time, we didnít even think about building a satellite ourselves.
DeVorkin: Were you interested at all in this idea?
Chang: Oh yes, of course.
DeVorkin: And did you talk to people in the government about it?
DeVorkin: Did you have anything to do with beginning artificial satellites? For China?
Chang: I didnít have anything to do with it.
DeVorkin: So the sections began to build at the Purple Mountain Observatory. I imagine that stellar astronomy must have come in.
Chang: Yes, stellar astronomy, and computation of Almanac and Ephemeris.
DeVorkin: Did you have assistant directors for each division?
DeVorkin: What were some of the first names of people who headed the sections?
Chang: In the planetary section, one of my men was named also Chang, but his initials were C.H. Chang.
DeVorkin: Who was the first section head who was a real spectroscopist; someone who did spectroscopy?
Chang: It is because of the small size of the instrument, we couldnít do much spectroscopy, except with the sun.
DeVorkin: Did you have people working on the sun?
DeVorkin: What kinds of projects did they do?
Chang: They observed flares on the sun, because that influenced the telegraphic communications.
DeVorkin: Absolutely. Thatís very very important.
DeVorkin: We just finished on tape 1 when you mentioned that the spectroscopy that you did was only done on the sun, and this was for purposes of making sure that youíd know when telegraph communication was going to be affected. In your work as director, did you have responsibility for the publication of the Almanac?
Chang: No. That belonged to the section for making Almanacs and Ephemeris.
DeVorkin: How did they communicate with you? What was your role in directing them?
Chang: As a matter of fact, I only directed the planetary section. There were party members; you understand. They controlled the whole thing, all of that. They would review. Please read the report written by Leo Goldberg. He stayed there and he already mentioned this organization of the institution.
DeVorkin: So he describes the Institute. And this is in the article in SKY AND TELESCOPE?
Chang: Yes. He made a report. The article in the SKY AND TELESCOPE was only part of the report. His report is very complete.
DeVorkin: Now, letís ask in the last few minutes some questions about you and your family and some of your own research. Iíd be very interested to know what you think has been the most interesting or satisfying research that you have done in your career.
Chang: Well, what Iíve done in the observation of asteroids and comets, and computing their orbits. One thing, I should say, that was sort of new at that time we were working on it; we observed the relation of brightness of asteroids and the period of it. The period variations of the light intensity implies the period of rotation of the asteroid, because the reflective ability of different portions is different.
Chang: I determined more than a thousand light curves for the brighter asteroids.
DeVorkin: Yes. When did you do this work?
Chang: Thatís in, I couldnít remember offhand, but all the results were published.
DeVorkin: Iíd like to ask you about your personal life. Are you married?
DeVorkin: I would like to know when you were married and who you married, children youíve had, if youíve had children, and what they are doing today.
Chang: I was married in 1933. My wife was my student, as a matter of fact she was born in Kiangsu province, but she was brought up in Peking, because her family went to Peking. She took my course in astronomy. I think thatís the only course she took with me. Maybe she also took the course in dynamics. Maybe you know, the current president of the American Physical Society in the U.S.; a Chinese by name C. H. Wu? You know that two Chinese here worked on a problem and got the Nobel Prize?
DeVorkin: Oh yes.
Chang: She did the experimental side, and she was my student at that time. She could write the answer to my problems correctly, and she has a fine penmanship.
DeVorkin: Was she one of your best students?
Chang: I should say so. My wife was in the class, she was her classmate.
DeVorkin: What was your wife interested in becoming? Was she interested in becoming a scientist?
Chang: Well, no. After she graduated she became a teacher of mathematics in the high school.
DeVorkin: You were married after she graduated?
DeVorkin: How were marriages consummated at that time? Did you have a free choice in marriage?
Chang: Yes. For me itís all right.
DeVorkin: Now, what children, how many children do you have?
DeVorkin: When were they born and what did they do?
Chang: They were born, one in Ď33, and that was a daughter. The younger one was born in 1935. That was a son. My daughter is now in a musical conservatory. She plays piano as accompaniment for singing and other instruments.
DeVorkin: And your son?
Chang: My son was a graduate of Tsing Hua College, Tsing Ha University now, from the department of mechanics.
DeVorkin: And what is he doing?
Chang: He has special interest in the study of fracture. At first he worked in metal -- in steel and so forth. Now he is working in the institute which works with porcelain and such things, the fracture of such material.
DeVorkin: Do your son and daughter live close to you?
Chang: Oh no. No. My daughter is in Peking, while my son is in Shanghai.
DeVorkin: Are you a grandfather?
Chang: Oh yes. My daughter has two children and my son has one daughter.
DeVorkin: What is your position now? Youíre at the Purple Mountain?
DeVorkin: As director.
DeVorkin: What are your hopes for the future? Are you hoping to build new instruments, to take on new projects? What are some of the plans?
Chang: You see, in our country, you are not required to retire at a certain age. If you like work, you can work all the time. If you donít want to work, you can stay at home. But because my health is rather good, I go up to the observatory this year every morning, and I stay at home in the afternoon.
DeVorkin: I see. And itís a one hour walk up to the observatory?
Chang: Oh no. We have a bus service.
DeVorkin: Well, is there anything else that you would like to add to this interview, that you would like to have recorded for posterity?
Chang: At present, I am writing a book on Halleyís Comet, and in collaboration with others, Iím translating of a book called THE AMAZING UNIVERSE that was published in U.S.
DeVorkin: When will it be published?
Chang: Well, I donít know. Very likely it will be in 1980 or 1981.
DeVorkin: When the astronomers from the United States traveled to China, Leo Goldberg and others, and the Chinese astronomers came to United States here, what was your involvement in bringing all the astronomers together, between China and the United States?
Chang: Well, I had nothing to do with that. If you read Goldbergís articles, you will see. There are two institutions, one in China and one in the United States. They made the arrangements, between them.
DeVorkin: Did you want to have something to do with it? You certainly had a longstanding experience of contact with the United States.
DeVorkin: You were always very friendly. But you were happy to let other people do it?
Chang: Well, it was so arranged. I couldnít go there, take part in that. Couldnít do it.
DeVorkin: Did you ask to take part?
Chang: No. No.
DeVorkin: Ok, I see. Well, I want to thank you very much.
Chang: Youíre welcome, but my English becomes rusty after long disuse. So I couldnít express myself very well.
DeVorkin: Itís good English.
Chang: I can make you understand.
DeVorkin: Yes, I should say so. You will be getting a transcript; a typed copy of the tape, and then you can sit down and see if there are things that you would like to make clearer.
Chang: All right.
DeVorkin: All right, thank you very much.
Chang: All right.