Diffraction Grating
date: label: date made
content: 1884
name: label: maker
content: Rowland, Henry A.
notes: label: Description
content: Henry A. Rowland, a professor of physics at The Johns Hopkins University, designed an engine that produced diffraction gratings by ruling a large number of closely spaced lines on a metal surface. The concave speculum metal mirrors for many of these gratings were ground and polished in John A. Brashear's shop in Pittsburgh. The mirrors were sent to Baltimore, where Theodore C. Schneider ruled them with Rowland's engine, and then returned to Pittsburgh for sale to scientists around the world.
label: Description
content: This example was probably used by Peter Smith Michie, the Army Engineer who, in 1871, became Professor of Natural and Experimental Philosophy at the U.S. Military Academy. Michie was also the first American academic to recognize Rowland’s first important scientific paper. And it was he who, in 1875, suggested that Daniel Coit Gilman, recently named founding president of The Johns Hopkins University, consider hiring Rowland to teach physics at the new university.
label: Description
content: The inscription on this example reads “Ruled by Schneider on Rowland's engine 14438 lines per inch Johns Hopkins Univ. Feb 1884 definition good. Ruling third class.”
label: Location
content: Currently not on view
place: label: place made
content: United States: Maryland, Baltimore
setName: label: See more items in
content: Medicine and Science: Physical Sciences
label: See more items in
content: Science & Mathematics
creditLine: label: Credit Line
content: U.S. Military Academy
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: PH.315760
label: accession number
content: 217544
label: catalog number
content: 315760
objectType: label: Object Name
content: diffraction grating
physicalDescription: label: Measurements
content: overall: 3 cm x 12 cm x 12.5 cm; 1 3/16 in x 4 23/32 in x 4 29/32 in
label: Measurements
content: overall: 1 1/4 in x 4 5/8 in x 4 5/8 in; 3.175 cm x 11.7475 cm x 11.7475 cm