. Bulletin - United States National Museum. Science. Figure 16.—Polishing lenses in the Alvan Clark & Sons factory. From cover of Scientific Ameri- can, 24 September 1887. Henry Draper, although an outstanding instrument maker him- self, purchased several pieces of apparatus from the Clarks. A Clark sider- ostat on the roof, and secondary mirror, directed sunlight to all corners of his New York City This laboratory was used primarily for photographing and studying the spectra of the elements. Around 1879, to verify the existence of oxygen emission lines in the solar spec- tru
. Bulletin - United States National Museum. Science. Figure 16.—Polishing lenses in the Alvan Clark & Sons factory. From cover of Scientific Ameri- can, 24 September 1887. Henry Draper, although an outstanding instrument maker him- self, purchased several pieces of apparatus from the Clarks. A Clark sider- ostat on the roof, and secondary mirror, directed sunlight to all corners of his New York City This laboratory was used primarily for photographing and studying the spectra of the elements. Around 1879, to verify the existence of oxygen emission lines in the solar spec- trum, Draper ordered from the Clarks a spectroscope which would "give the dispersion of twenty heavy flint prisms and . . bear high magni- fying power".70 Draper used both reflecting and refracting telescopes at his observatory at Hastings-on-Hudson. He made the reflectors himself, but relied on the Clarks for the refractors. In 1875 he bought a Clark telescope of 12 inches aperture. Alvan Clark thought this objective one of the best he 75 George F. Barker, "Memoir of Henry Draper," Biographical Memoirs, National Academy of Sciences, vol. 3 (1895), pp. 113-1 14. 76 Henry Draper, "On the Coincidence of the Bright Lines of the Oxygen Spectrum with Bright Lines in the Solar Spectrum," American Journal of Science, vol. 18 (1879), p. 268. 57. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original United States National Museum; Smithsonian Institution; United States. Dept. of the Interior. Washington : Smithsonian Institution Press, [etc. ]; for sale by the Supt. of Docs. , U. S. Govt Print. Off.
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