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Potassium hydride cell that Jakob Kunz made in the 1920s. Attached to the 12-inch refracting telescope at the Lick Observatory, it used by Joel Stebbins, by Gerald Kron, and by Mary Elizabeth Cummings.
Jakob Kunz (1874-1938) was an important pioneer in the development of photoelectric cells. Born and trained in Switzerland, he began teaching physics at the University of Illinois in 1909. Two years later, he convinced Joel Stebbins, director of the astronomical observatory on campus, to use one of his photocells to chart the fluctuating magnitudes of eclipsing binary stars. The experiment was indeed a success. In the words of Gerald Kron, an astronomer who would later work with Stebbins—and who gave this example to the Smithsonian—Stebbins "furnished the continuity that lead to the permanent establishment of photoelectric photometry as one of the most important tools of modern astronomers."
Currently not on view
Science & Scientific Instruments
National Museum of American History
Kunz, Jakob
overall in box: 4 1/2 in x 10 1/4 in x 4 1/8 in; 11.43 cm x 26.035 cm x 10.4775 cm
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Medicine and Science: Physical Sciences
place made
United States: Illinois, Urbana
Object Name
quartz potassium-hydride photocell
ID Number
catalog number
accession number