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Interview of J. Barton Hoag by Dorothy Stevens on 1965, Niels Bohr Library & Archives, American Institute of Physics, College Park, MD USA, www.aip.org/history-programs/niels-bohr-library/oral-histories/4675
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Reminiscences about Albert Abraham Michelson at the University of Chicago when Hoag was a young teacher on Michelson's staff. Topics also include the visible spectrum, vacuum tubes, ultra-violet spectrum, high precision optical measurements, and interferometers.
I am J. Barton Hoag, who went to the University of Chicago in 1921 because of Albert Abraham Michelson, whose fame and reputation reached me in Colorado Springs, Colorado, at my home town in Colorado College and I wanted to study under him. I stayed as a graduate student and as an instructor and as an assistant professor on the staff with your father until he passed on. He retired first and then passed on. I left the University of Chicago in 1940. So I have had a background of intimate contact. I wouldn't say personal contact. But I have known him as my great mentor in my preparation, and he was kind enough to hire me to continue on his staff. There are a number of little stories which I could think of about his life and works. For example, in the faculty club, the Quadrangle Club, in Chicago, there was a going-away dinner. W. F. G. Swann was the toastmaster, and he was calling upon Dr. Michelson to advise Arthur Compton as to what he should do when he went to receive his Nobel Prize. Dr. Michelson said when he was there receiving his award at the dinner, and since he was an optical man and had studied the visible spectrum — the red, orange, yellow, green and blue — so much of his life, they served him wines in the corresponding red, yellow, orange, yellow, blue colors. This, he said, resulted in his giving a wonderful lecture in German, although he didn't know he could speak German — at least not wonderfully. He sat down and W. F. G. Swann rose to introduce Compton. He said, “Now, Arthur, we all know you're an abstemious man, but we want to warn you particularly because the electro-magnetic spectrum has been broadened since Albert's time to include the radio ultra-violet, the infra-red, the X and the gamma ray regions; and so if they serve you wines that will cover the entire spectrum, watch out.” Now, that little story is a true story that is connected with your father, Dorothy.
Heavenly days, that is delightful!
He asked me as a young teacher on his staff one time to explore the mine shafts and tunnels in Colorado for their optical characteristics as a possible use in his velocity of light experiments.
Instead of the vacuum tube?
Instead of the vacuum tube. This is before he had a vacuum tube. And he was considering how to reduce the length of the path by multiple reflections or mirrors at each end, but he needed a certain degree of goodness of the air in the shaft or the tunnel. So on my vacation time one September, I took one of his [???] telescopes, went to Colorado, and one of my friends would hold two flashlights a certain distance apart; I, at the far end of the tunnel, would look through the telescope, and then at synchronized watch times, as the flashlights were moved closer together, I would write down the time and hence the distance between the flashlights when they merged together and lost this ability to resolve or separate the two lights from each other. This measurement was what he needed. I measured with my friends having a wonderful time rambling all over the state. Many of the tunnels and mine shafts came back in my report to Dr. Michelson, and he said, “These measurements are just on the limit of usability, but I don't like the climate. This is just barely usable and not a decimal place better, so I propose that we build a pipeline some place in a nice, warm climate and carry out the experiments with a much better degree… where the light is not subject to the fluctuations of the air so drastically as occurs in mine shafts or tunnels.” Well, that was one little thing we did. After retirement and his giving up the rooms in Byerson(?), Dean Gale, who then was head of the department in his place, and I worked an experiment in ultra-violet spectra in his room. The first day we went in, I looked under the benches and I saw many pieces of apparatus. I said to Dean Gale, “What is this? I have had four courses from Dr. Michelson. He never once mentioned this. I have his reprints. I have his little book on optics, and I have never seen this piece of equipment. What is it?” He said this was a radical, unusual idea that Michelson tried. Dean Gale explained it to me. He said, “It didn't work,” and Mike said, “Well, it didn't work. Let somebody else waste their time on this cockeyed idea like I did. If I tell them all my failures they will get ahead of me.” He was a perfectionist as I knew him. Nothing pleased him. Even a polished surface to the ten-millionth of an inch was still too rough. He was in himself a horribly hard disciplinarian. He just controlled himself; he forced himself to get better and better to find that next decimal place to increase the accuracy of measurements in the world.
What was this equipment that was under the benches?
Frankly, I don’t remember. There was more than one piece. There were about a dozen there which we never wrote up or anything else: I suppose things where he tried to bump light rays after going around square paths, bumped them into each other to see if he could produce a flash of light where they bumped together — crazy schemes. He never talked about those, but I know there were a dozen such pieces amongst many other fine pieces of equipment which just apparently have disappeared. We left them there, and as far as I know, up to 1940 they were there. This loss of his equipment occurred practically entirely during the war years in a [???] metallurgical. Tom O'Donnell has written me letters. He's trying to find and collect these things. I'm ashamed of myself; I haven't answered Tom. I had these notes jotted down to write to him months ago and his first document to me. And so here now I have a chance to sit with my feet up and comfortable, looking at the charming daughter of Dr. Michelson, and tell my story in words.
I bought Tom a tape recording machine like this. This back and forth, and it somebody comes from Chicago that knew father, Tom rushes down with it and gets them down. We're building a library of tapes [???].
I got to know Dr. Michelson quite closely. I remember very definitely a comment he made to me which shocked me terribly. We were talking about the luminescent(?) ether. He said, “Darn it, Hoag, if there is a source of light here and I’m over here and see it and there's vacuum in between, there's got to be something that carries this wave.” You see, he was completely sold on the wave theory of light. This lay a subconscious pattern in his mind and he couldn't change that to conceive of photons(?) and quantum theory and so on. It was not particular to a corpuscular light was a wave to him, and a wave had to have a medium to work in. And he said, “All my life I have been trying to prove the existence of something called the theory.” And the great Albert Abraham Michelson failed in his own eyes at the fundamental thing he was trying to find and prove in life. Of course out of this failure of him to himself as a human being has come the standardization of the world standard of meter(?) bar(?), the interferometer, these high precision optical measurements, this exact determination of the velocity of light, and all the great work he did in his lifetime. But to himself he told me in so many words: “I have not succeeded in the thing I have tried to do all my life.” He tried to measure any property. He said, “Measure the velocity of light in flowing water and try to measure it with the water going one direction compared with the light beam and then in the reverse direction.” He tried every scheme he could think of. He tried to measure rigidity. He said, “If a thing is to be believed in, it must have a physically measurable quantity associated with it. We know nothing of ether.” And finally in desperation he began his ether drift experiments to at least get a relative motion. If he couldn't measure density, color, elasticity or any other physical property, at least he hoped he could find a relative motion. And then with the Michelson-Morley(?) experiment, he had a complete negative result, which, as we all know, let Einstein to his relativity work. But it was a failure for Mike. This man was such a hard man on himself, drove himself hard, failed; and probably because of that failure was probably one of the greatest motivating forces back of him driving him into his work. He was sick one time — I've forgotten what. He was sent to the hospital and a friend and I went down to visit him. He was recuperating and still in bed. We asked him the usual “How are you?” We told him what was going on in the laboratory and so on. He chuckled. He said, “You know, when I was just coming back to consciousness, I thought sitting on the end of this bed” (they were the old-fashioned beds with the iron rails there) “there were a group of monkeys, but it turned out that they were just a bunch of interns standing there looking me over.”
He made a canvas of it.(?)
Did he? I hadn’t known that. I know his paintings, his water color paintings. There are still many of them in the Quadrangle Club in Chicago. I've always wished I had nerve enough in those days to ask him for even one of what he thought was a poor and little one, but I never had the nerve because they were such wonderful things. He was such a perfectionist in all of his work. It was beautifully done. I was playing billiards one day in the Quadrangle Club and he went by. He said, “Did you know the accuracy with which the billiard balls are manufactured? Why, the radius is the same everywhere on this ivory ball.” I think he said a micron(?). This kind of life was life. Accuracy personified care, patience, driving himself for greater perfection. Take the little mirrors he used in his velocity of light workout at Wilson Park(?) earlier or later work. These little rotating mirrors had to be made, say, with the number of sides they had — six, eight; he went up even to twelve-sided…
And 32. Well, before I had reached Byerson, there was an optician working under him by the name of Pettitidy(?). He left before I got there in ‘21. But there is a story handed down about him which I've heard concerning this work on making the opposite faces of the mirror exactly parallel, making the angles all exactly equal, having no humps or hollows on any one face more than a millionth or ten-millionth of an inch — this great optical perfection. The man worked for months on this one little mirror — polishing and polishing, testing with the interferometer techniques until he had it almost finished, and then he scratched it horribly on one surface. He took it off of the polishing bench, grabbed it up in his hands and threw it on the floor. He jumped up and down on that piece of glass he'd worked on for so many months and he said, “Ten thousand damns! Ten thousand damns!” But this accuracy, this need for it, was reflected in his music with his violins, his paintings, and his tennis.
Did you ever play tennis?
Never with him, but I know he licked in his younger days pretty nearly everybody on the faculty at the University of Chicago, and that included Fred Pearson, who later got to be a [???] good tennis player. His perfection of a ruling engine stroke… Gee, I can still see that screw in the lathe out in the shop with the little thread hung over it and the weight on the end of the thread and the rouge solution dripping down over it and the lathe running that polishing thread back and forth for months at a time to make those threads just as smooth as smooth could be; taken down to test with the interferometer every so often, brought back and polished and polished until the men in the shop (I won’t use their language) got darned sick and tired of that screw. But it was the heart of the accuracy of his ruling engines for making gradings. He made the world's finest gradings without a doubt. They learned to make them so that they could control the higher orders; they could eliminate ghosts and with thousands of lines per inch and gradings that were as long as ten and twelve inches long. The world has never seen anything like the perfection of those gradings. At least I don’t know of any mechanical structure that has been moved with such great accuracy and precision. Well, as I said, I had four courses from Michelson while I was working for my doctor's degree. He met us three times a week — Monday, Wednesday and Friday at eleven o'clock in the morning. There were about twenty, twenty-four of us in the room, and everything was absolutely silent while he was lecturing. The chairs would squeak, and that was about the only sound — the writing of the pen on the paper. But Friday he required us to be able to reproduce his lectures of the two preceding days, Monday and Wednesday. And then there was dead silence as he called on one person at a time to come up and present.