A heliostat throws sunlight where it might be used for photography or scientific observations. This example is based on the form devised by Leon Foucault in 1862. It has a rectangular mirror measuring 10 x 5 inches (25 x 12.5 cm), a latitude arc, a declination arc, a clock drive, and a heavy tripod with leveling screws. The “WM. GAERTNER & CO. / MAKERS / CHICAGO” signature refers to a firm that was established in 1896, that worked closely with physicists and other scientists at the University of Chicago, and that became The Gaertner Scientific Corp. in 1923. The “R. L. 1565” mark on one leg screw refers to the Ryerson Laboratory at the University of Chicago.
Currently not on view
Object Name
date made
early 20th century
Gaertner Scientific Corporation
overall: 18 in x 9 in x 15 in; 45.72 cm x 22.86 cm x 38.1 cm
place made
United States: Illinois, Chicago
ID Number
accession number
catalog number
Science & Scientific Instruments
Science & Mathematics
See more items in
Medicine and Science: Physical Sciences
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
University of Chicago

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