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In a constant deviation spectrometer, the collimator and telescope are fixed in place, and the observed wavelength is varied by rotating the prism or diffraction grating in the central box. The “ADAM HILGER LTD / LONDON / ENGLAND” inscription on the eyepiece of this example identifies the manufacturer. The “JAMES G. BIDDLE / PHILADELPHIA, U.S.A.” inscription on a brass plate identifies the firm that brought the instrument into the United States.
Adam Hilger, Ltd. introduced its first constant deviation spectrometer in 1904, noting that the prism was designed by Messrs. Pellin & Broca, and described in the Journal de Physique in 1899. The form proved remarkably successful, and remained on the market for decades. This example, made between 1914 and 1926, is a Modified Wavelength Spectrometer. Here, the arm between the collimator and the prism is designed to hold one of three high-resolution, multiple-beam interferometers: a Michelson echelon diffraction grating, a Lummer-Gehrcke parallel plate, and a Fabry-Perot etalon.
Ref: Arthur H. Thomas Company, Laboratory Apparatus and Reagents (Philadelphia, 1914), p. 495.
Noah Rindos, “A Constant Deviation Wavelength Spectrometer Made by Adam Hilger, Ltd.,” Rittenhouse 12 (1998): 25-29.
Charlotte Bigg, “Adam Hilger, Ltd and the Development of Spectrochemical Analysis,” in Peter J. T. Morris, ed., From Classical to Modern Chemistry. The Instrumental Revolution (London, 2002), pp. 111-129.
Currently not on view
Object Name
spectrometer, constant deviation
date made
Adam Hilger, Ltd.
place made
United Kingdom: England, London
overall: 34.5 cm x 60.5 cm x 63 cm; 13 19/32 in x 23 13/16 in x 24 13/16 in
overall: 13 9/16 in x 22 3/4 in x 21 1/2 in; 34.44875 cm x 57.785 cm x 54.61 cm
ID Number
catalog number
accession number
Science & Scientific Instruments
See more items in
Medicine and Science: Physical Sciences
Data Source
National Museum of American History
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