Physical apparatus


Physical apparatus


In addition to equipment attached to the telescope, astronomers, especially in the "new astronomy," often had laboratory equipment that could be found in a physics laboratory. Much of this equipment at Illinois was related to the development of photoelectric photometry. The photometer turned the star's light into electric current and much of this equipment was need to measure the electrical output of the photometer.


Department of Astronomy

Collection Items

Reflection galvanometer
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. …

Reading telescope
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.

DC Voltmeter
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.

DC Voltmeter
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…

Kunz Photoelectric cells
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…

Selenium cell
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…
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