Diffraction Grating


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.

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.

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.”

Date Made: 1884

Maker: Rowland, Henry A.

Location: Currently not on view

Place Made: United States: Maryland, Baltimore

See more items in: Medicine and Science: Physical Sciences, Science & Mathematics


Exhibition Location:

Credit Line: U.S. Military Academy

Data Source: National Museum of American History

Id Number: PH.315760Accession Number: 217544Catalog Number: 315760

Object Name: diffraction grating

Measurements: overall: 3 cm x 12 cm x 12.5 cm; 1 3/16 in x 4 23/32 in x 4 29/32 inoverall: 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

Guid: http://n2t.net/ark:/65665/ng49ca746aa-25ac-704b-e053-15f76fa0b4fa

Record Id: nmah_1183759

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