This is one of a collection of phototubes from the University of Wisconsin that represents the efforts of the staff of the Department of Astronomy there, led by Joel Stebbins, to develop photoelectric sensor technology for astronomy in the first half of the 20th century. This is an example of a Tykociner cell, named for its creator Josef Tykociner. Tykociner worked at the University of Illinois to develop photoemissive surfaces expanding of the work of Jakob Kunz after Kunz's death in 1938. Tykociner developed tubes like this one specifically to meet the unique needs of astronomers. While at the University of Illinois, Stebbins first used selenium photoresistors in conjunction with physicist F.C. Brown in 1907. Stebbins’s early work with photoemissive devices was done in close coordination with Kunz, however after Kunz's death Stebbins worked with Tykociner to continue the development of these cells. Tykociner developed different methods for formulating and applying the emissive metal coating and while his designs delivered much greater sensitivity in the short run, they tended to lack the stability of Kunz's initial work. Photoemissive devices like those pioneered at Wisconsin did not come into widespread use in astronomy until after the Second World War, but later astronomical detectors combined the concept of Stebbins's early photometers with more advanced commercial photocells to make important observations on large telescopes like the 100 inch reflector at Mount Wilson. The University of Wisconsin donated this set of objects to the Museum in 2017.