Spectrometer

A prism or grating split light into colors, and a circle with a telescope measured the angle of each color precisely.

Date: 1873-1881
Maker: William Grunow
Place: United States: New York, New York City
Dimensions: overall: 12 1/2 in x 34 in; 31.75 cm x 86.36 cm; overall: 12 3/4 in x 24 in x 13 1/4 in; 32.385 cm x 60.96 cm x 33.655 cm
Museum: National Museum of American History
Credit line: U.S. Military Academy

This instrument, which could be used with either a prism or a diffraction grating, has a graduated horizontal circle read by microscopes and verniers. The “Wm. Grunow / New York” inscription refers to William Grunow (1830-1917), a German craftsman who, with his brother Julius, came to the United States in 1849 and went to work making microscopes. In 1873, now settled in New York, Grunow announced his willingness “to execute all orders for philosophical instruments.” In 1881 he moved to West Point, and spent the next 36 years as custodian of the astronomical observatory of the U.S. Military Academy.

Ref: D.J. Warner, “Julius & William Grunow,” Rittenhouse 3 (1989): 41-48.

The museum's own record (Smithsonian, National Museum of American History)

Spectrometer

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