Comparator Made by Warner and Swasey for use by S.P. Langley

Comparator Made by Warner and Swasey for use by S.P. Langley

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Usage conditions apply
Smithsonian Institution staff have long used instruments, made in both the United States and abroad, to record and to analyze scientific data. For example, in 1887 astrophysicist Samuel Pierpont Langley (1834 -1906) began working as assistant Secretary at the Smithsonian, while retaining his position as head of the Alleghany Observatory in Pittsburgh. He was promoted to the position of Secretary of the Smithsonian that same year, and a Smithsonian Astrophysical Observatory soon was under construction in Washington. Langley had invented a sensitive instrument called to bolometer to measure the intensity of solar radiation at various wavelengths. It produced records on glass plates 60 cm. long and 20 cm. wide. To measure these, Langley and his associates used this apparatus, called a comparator, and a microscope that moved along the carriage of the comparator (this microscope is not present in the museum object). This particular comparator was made for the Smithsonian by the firm of Warner & Swasey Co. of Cleveland, Ohio.
S. Pierpont Langley, Annals of the Astrophysical Observatory of the Smithsonian Institution, vol. 1, 1900, pp. 64-65.
Donald L. Obendorf, Samuel P. Langley, Solar Scientist, 1867-1891, PhD. Dissertation, Berkeley: University of California, 1969
Currently not on view
Object Name
date made
ca 1900
Warner & Swasey Company
place made
United States: Ohio, Cleveland
Physical Description
metal (overall material)
overall: 17 1/2 in x 36 in x 12 in; 44.45 cm x 91.44 cm x 30.48 cm
ID Number
accession number
catalog number
Credit Line
Transfer from Smithsonian Institution Astrophysical Observatory
See more items in
Medicine and Science: Mathematics
Data Source
National Museum of American History
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