Selenium cell
Astronomy, photometry
Wooden box measuring 10 cm x 8 cm x2.5 cm, flips open to expose selenium cell. Cell measures 3.0 cm by 5.0 cm. Stebbins described the Giltay selenium cells he and Brown used in the selenium photometer as “Two wires are wound close together in a double spiral about a flat insulator, and the spaces on one face are filled with selenium which has been properly sensitized.” A photograph of the Giltay cell was included in the 1911 article in Popular Astronomy, “The measurement of the light of stars with a selenium photometer with an application to the variation of Algol.”
The selenium cell photometer is historically significant and was used by Brown and Stebbins starting in 1907. Stebbins met Brown at a physics department open house where Brown ran a demonstration using a selenium cell to ring a bell. That apparatus, and selenium cells housed in a wooden case, are found for sale in Max Kohl catalogs .
Giltay of Delft, Holland
Replacement: Michael Svec donated in 2021 a selenium cell in a wooden box. The cell measures 3 cm x 5 cm and has approximately 18 wires per centimeter which is consistent with the Giltay cell’s that Stebbins bought and used from AB Porter in Chicago, in July 1907 for $20. Stebbins and Brown used at least two Giltay cells numbered 93 and 94. The original cells are lost. This replacement cell does have a resistance that decreases when exposed to light, so it is function.
Circa 1910
English
physical object
University of Illinois Observatory, Urbana, IL
Kunz Photoelectric cells
Astronomy
photometry
The photocell is hand blown glass or quartz. Within in the cell is an alkali metal (lithium, sodium, or potassium) that covers the inside and is a cathode emitting electrons when illuminated. A well insulated wire forming a ring centered in the bulb acts as an anode for collecting the emitted electrons. The inside of the bulb is filled with an inert gas such as helium, neon or argon.
The cell with number 15 (Wisconsin inventory number) bear Stebbins’ number 54. It is a typical glass tube in almost original condition.
The second cell is number 23 in Wisconsin’s inventory and bears Stebbins’ number QK 37-4 indicating it is a quartz tube with potassium hydride as the photo-cathode material. It was produced in 1937. This tube comes in an original cardboard box labeled with QK-37-1 and QK37-4. The box is also historically significant.
Jakob Kunz, University of Illinois Department of Physics
Observatory
On loan from the University of Wisconsin Department of Astronomy.
1915 and 1937
Englsih
physical object
University of Illinois Observatory, Urbana, Il
DC Voltmeter
Electrical apparatus
Measuring instruments
Wood, metal, paper, glass
Model 45, No. 32664, in oak box measuring 7 7/8 x 5 3/8 x 7 7/8 inches, with leather handle, 2 scales 0-150, 0-15. Paper label dated November 5, 1926. All hardware is nickel-plated brass. The front panel and meter face plate are of heavy cast iron with a fine diamond pattern on the casting. Iron parts have a "japanned" black enamel finish. The binding posts are of black Bakelite. The meter has a mirrored scale
Weston Electrical Instruments Company, Newark, New Jersey
Astronomy Department, University of Illinois, Urbana, Illinois
circa 1926
Michael Svec
Copyright Michael Svec
image/jpg
English
physical object
University of Illinois Observatory Collection A227
University ID 16768
University of Illinois Observatory, Urbana, Illinois
DC Voltmeter
Electrical apparatus
Measuring instrument
Wood, metal, glass
Weston DC voltmeter model #38635, dated September 1, 1923. Two scales 0-15 and 0-150. Box measures 7 ½ x 4 ½ x 7 ½ inches. Scale has mirrored scale.
Weston Electrical Instruments Company, Newark, New Jersey
Astronomy Department, University of Illinois, Urbana, Illinois
circa 1923
Michael Svec
Copyright Michael Svec
image/jpg
English
physical object
University of Illinois Observatory Collection A195
University ID 16727, obs779
University of Illinois Observatory, Urbana, Illinois
Reading telescope
Measuring instrument
Optical instrument
Metal, glass
Eyepiece with crosshairs, 12-inch tall, 11-inch long, tube 1-inch outer diameter, missing an objective lens.
Used with galvanometer to read the reflection off the mirror.
Eastern Supply Company
Astronomy Department, University of Illinois, Urbana, Illinois
circa 1920
Michael Svec
Copyright Michael Svec
image/jpg
English
physical object
University of Illinois Observatory Collection A164
University ID 16774
University of Illinois Observatory, Urbana, Illinois
Reflection galvanometer
Electrical apparatus
Measuring instrument
Model no. 89, no. 18. Box is 8 ¼ x 8 ½ x 12 inches and screwed closed. Unknown date but estimated around 1908. Used with the selenium cell photometer to measure current and with the photoelectric cell photometer. Visible in pictures of transit room. An unpublished photograph in the Jakob Kunz papers, University Archives, from the 1918 eclipse expedition shows this galvanometer sitting on a shelf in the background. A published picture from 1910 and another unpublished photo from 1912 show the same galvanometer.
Weston Electrical Instruments Company, New, New Jersey
Astronomy Department, University of Illinois, Urbana, Illinois
circa 1908
Michael Svec
Copyright Michael Svec
Harvard Collection: http://waywiser.fas.harvard.edu/objects/2183/reflecting-galvanometer-with-moving-coil
image/jpg
English
physical object
University of Illinois Observatory Collection A193
obs52
University of Illinois Observatory, Urbana, Illinois