Rowland Diffraction Grating

Description
This is one of the earliest concave metal gratings made on the ruling engine devised by Henry A. Rowland, professor of physics at The Johns Hopkins University in Baltimore. 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." The reference here is to Samuel Pierpont Langley, the director of the Allegheny Observatory and professor of astronomy at the Western University of Pennsylvania (now the University of Pittsburgh). Langley became the third Secretary of the Smithsonian Institution in 1887. The grating measures 4 inches x 4.5 inches, and is marked "Rowland's concave grating Baltimore, May 12, 1882. 3610 lines to inch, radius 64".
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.
Location
Currently not on view
Object Name
diffraction grating
date made
1882
maker
Rowland, Henry A.
Measurements
overall: 10 in x 7 in x 3 1/2 in; 25.4 cm x 17.78 cm x 8.89 cm
place made
United States: Maryland, Baltimore
ID Number
PH*316865
catalog number
316865
accession number
228767
subject
Science & Mathematics
See more items in
Medicine and Science: Physical Sciences
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Smithsonian Astrophysical Observatory

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