Rutherfurd diffraction grating on glass
Date1877
Inventory Number2047
ClassificationDiffraction Grating
Subject
Attributed to
Daniel C. Chapman
1826 - 1894
Attributed to
Lewis M. Rutherfurd
1816 - 1892
Owner
Theodore Lyman IV
1874 - 1954
User
Department of Physics, Harvard University
founded 1884
Cultural Region
Place of Origin
Dimensions4.3 × 4.3 × 0.5 cm (1 11/16 × 1 11/16 × 3/16 in.)
Material
Accessorieswooden box
DescriptionFlat diffraction grating, made of glass, with 5,765 lines per inch. There is no radius of curvature since it is flat. It is stored in a box.
Signedunsigned
Inscribedetched: March 18 1877 / 5765 per inch / Ther. 68.5° / A
etched: Began 703/4 rev. of screw
Curatorial RemarksThe attribution to Chapman is due to the date and the similarity with other gratings made by him on the Rutherfurd ruling engine.
FunctionA diffraction grating is a glass or mirror that has regularly spaced microscopic interruptions to the passage of light (lines) such that light passing through or reflected by it experiences interference phenomena, magnifying its magnitude at some angles and cancelling it at others. As this effect depends on the wavelength of light, a diffraction grating is an effective method of decomposing light into its constituent wavelengths, that will be transmitted at different angles (short wavelengths -- bluer -- are deflected less than longer -- redder -- ones). If one knows the line density (lines per inch) and the angle of deflection (with a spectrometer), one can deduce the exact wavelengths.
Diffraction gratings like this one were often used in astronomy to produce spectra of celestial objects. Begun in 1882, Rowland's gratings were more than an order of magnitude larger and more accurate than any previous one. With these, for instance, it became possible to measure the wavelength of light emitted by atoms to unprecedented accuracy. Rowland himself was able to draw a new and more accurate map of the solar spectrum.
For more information go to the following website.
Diffraction gratings like this one were often used in astronomy to produce spectra of celestial objects. Begun in 1882, Rowland's gratings were more than an order of magnitude larger and more accurate than any previous one. With these, for instance, it became possible to measure the wavelength of light emitted by atoms to unprecedented accuracy. Rowland himself was able to draw a new and more accurate map of the solar spectrum.
For more information go to the following website.
ProvenanceFrom the Department of Physics, Lyman Laboratory, Harvard University.
Historical AttributesOwned and used by Theodore Lyman IV.
Lewis M. Rutherfurd
Date: 1879
Accessories: box
Object number: 2049
Lewis M. Rutherfurd
Date: 1877
Accessories: leather case
Object number: 2044
Henry A. Rowland
Date: circa 1884
Accessories: wooden box; key
Object number: 2031
Robert W. Wood
Date: 1928
Accessories: wooden box
Object number: 2022