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The
photoelectric photometer was a great invention that improved the the
field of astronomy by leaps and bounds. It started when Joel Stebbins’s
wife (May) decided she wanted him home earlier, so she suggested
Stebbins make use of electricity. As Stebbins searched for a better
method recording star magnitudes, he met and became friends with F.C
Brown. Brown was a physicist, who, at a demonstration, used a lamp to
illuminate a selenium cell. When the lamp was on, a bell would ring.
Turn it off, and the bell would stop. Brown and Stebbins continued to
work together to make an improved selenium cell.
After
Brown left to pursue a fellowship at Princeton, Stebbins met Jakob Kunz, a colleague also working at Illinois. Kunz was developing his own
photoelectric cell, and the collaboration of the two would result in
Kunz’s photoelectric cells being put inside Stebbins’s photometer. From
1913 until his death, Kunz would provide Stebbins with ever new and
improved photoelectric cells. According to Stebbins, these cells were
far better than any other procurable at the time. Kunz’s cells provided
greater sensitivity and faster operation to the selenium ones Stebbins
was using.
This
collaboration resulted in the measurement of many previously unrecorded
stars, as well as several increases in photoelectric technology.
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Joel Stebbins with his invention: the Photoelectric Photometer, circa 1925
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Department portrait of Jakob Kunz, signed by him, University of Illinois, date unknown.
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Click Below to find out more about who was involved:
Joel Stebbins
Jakob Kunz
F.C. Brown
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Jakob Kunz was born in Brittnau, Switzerland, on November 3rd, 1874. He was educated in the public schools there until he attended Zurich Polytechnikum, where he gained both his B.S. and Ph.D.
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| Department portrait of Jakob Kunz, signed by him, University of Illinois, date unknown. |
After serving in various universities and laboratories abroad, Kunz came to United States in 1908. He worked at the University of Michigan for one year before being offered the role of assistant professor of mathematical physics at the University of Illinois, where he remained for the rest of his life, working up through associate professor to professor.
For years Kunz was practically solely responsible for the whole of graduate courses in mathematical physics. However, he never taught undergraduate courses, with friends noting that he probably did not like the “immature and almost passive attitude” of American undergraduate students.
Kunz was renown for his clear and thorough lectures on classical theoretical physics, but he never reconciled to more “modern” notions as could be found in relativity and quantum mechanics. Indeed, a colleague noted “as he was himself thoroughly familiar with the mathematical structure of these theories, his objections and criticisms were occasionally very penetrating; and indeed troublesome to any who had a tendency to accept them on faith or authority”.
However, Kunz is most famous for his work with photoelectric cells. Photoelectric cells are devices whose electrical characteristics (voltage, etc) vary when subjected to light. Being among the first to work with them in the country, he developed a specially sensitized alkali photoelectric cell. This cell, free from dark current, was far superior for certain astronomical purposes than anything else available at the time. An example of such astronomical purposes was studying the intensity of the sun’s corona during an eclipse.
Kunz was enthusiastic about many subjects, and often attended seminars conducted in the fields of chemistry, mathematics, and engineering. Though often in poor health during the last part of his life, he maintained an active presence in both teaching and research up until a few weeks before his death on July 18th, 1938.
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Works Cited:
Loomis, F.W. (1938). “Jakob Kunz”. Obituary Draft. Found in University Archives Series No. 11/10/ 25, Box 2.
“Portrait of Jakob Kunz” (Unknown). Found in University Archives Series No. 11/10/ 25, Box 2.
