Diffraction Grating
notes: label: Description
content: Concave speculum metal diffraction grating with 15,000 lines per inch and a 21-foot radius of curvature, that was used with the large Wadsworth spectrograph at the National Bureau of Standards, also in the collection. The plate was probably figured by John A. Brashear in Pittsburgh, and the ruling done on the Rowland engine at the Johns Hopkins University.
label: Description
content: Ref: W. F. Meggers and Kievin Burns, “Notes on Standard Wave Lengths, Spectrographs, and Spectrum Tubes,” <i>Scientific Papers of the Bureau of Standards</i> 18 (1922): 185-199.
label: Location
content: Currently not on view
setName: label: See more items in
content: Medicine and Science: Physical Sciences
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.328727.04
label: catalog number
content: 328727.04
label: accession number
content: 275807
objectType: label: Object Name
content: concave grating
physicalDescription: label: Measurements
content: overall: 2 1/2 in x 7 3/8 in x 7 1/4 in; 6.35 cm x 18.7325 cm x 18.415 cm