Diffraction Grating

Description:

This is one of the earliest concave metal diffraction gratings made on the ruling engine devised by Henry A. Rowland, professor of physics at The Johns Hopkins University. It measures 4 inches x 4.5 inches. The inscription reads "Rowland's concave grating Baltimore, May 12, 1882. 3610 lines to inch, radius 64". According to Rowland, it "was made for Professor Langley's experiments on the ultra-red portion of the spectrum, and was thus made very bright in the first spectrum. The definition seems to be very fine, notwithstanding the short focus and divides the 1474 line with ease."

At the time this grating was made, Samuel Pierpont Langley was serving as the director of the Allegheny Observatory and professor of astronomy at the Western University of Pennsylvania (now the University of Pittsburgh). He apparently brought this grating to Washington in 1887 when he became the third Secretary of the Smithsonian Institution. And he apparently left it at the Smithsonian Astrophysical Observatory, an organization he established soon thereafter.

Ref: Henry A. Rowland, "Preliminary Notice of the Results accomplished in the Manufacture and Theory of Gratings for Optical Purposes," Philosophical Magazine 13 (1882): 469-474.

Date Made: 1882

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:

Exhibition Location:

Credit Line: Smithsonian Astrophysical Observatory

Data Source: National Museum of American History

Id Number: PH.316865Catalog Number: 316865Accession Number: 228767

Object Name: diffraction grating

Measurements: overall: 10 in x 7 in x 3 1/2 in; 25.4 cm x 17.78 cm x 8.89 cmoverall; case: 10 in x 7 1/8 in x 4 in; 25.4 cm x 18.0975 cm x 10.16 cm

Guid: http://n2t.net/ark:/65665/ng49ca746aa-3ab3-704b-e053-15f76fa0b4fa

Record Id: nmah_1184623

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