tial chemistry ever made.' He was the first to obtain a photograph of the fixed lines in the spectra of stars, and he continued the work until he had obtained impressions of the spectra of more than one hundred stars.
When the commission was created by Congress for the purpose of observing the transit of Venus, in 1874, Professor Draper was intrusted with the charge of the photographic department. He spent much time in the preparations, for which he declined to receive any compensation. So signal was the success of his disinterested exertions, that the commissioners had a gold medal struck in his honor at the Philadelphia Mint, bearing the inscription, though in an extinct tongue, "He adds luster to ancestral glory." In 1878 he went to the Rocky Mountains to observe the total eclipse of the sun, and there successfully photographed the spectrum of the solar corona. For the last two or three years he had been much engaged in the difficult work of photographing nebulas, and he startled the scientific world by the announcement that he had succeeded in getting a fine photograph of the great nebula in Orion and of its spectrum.
Professor Draper was not a prolific author, like his father, and only wrote one book; but he died in the prime of life, and had he lived would undoubtedly have given to the world the results of his ripened investigations in enduring treatises. He, however, wrote much for the scientific periodicals, describing the results of his work. He contributed several papers to the "American Journal of Science and Arts" and to "Nature." He published in 1864 a "Text-Book of Chemistry," and a paper on the "Philosophic Use of Silvered Glass Reflecting Telescopes." The paper was published in "The Philosophical Magazine." In the same year he published a pamphlet on "Silvered Glass Telescopes and Celestial Photography." "The Quarterly Journal of Science," in 1865, published his views of "Petroleum, its Importance and its History," and "American Contributions to the Spectrum Analysis." The Smithsonian Institution, in its "Contributions, vol. xiv., of 1864," published a paper on "Construction of Silvered Glass Telescopes, Fifteen and a Half-Inch Aperture, and their Use in Celestial Photography." The following papers have been published in "The American Journal of Science and Arts": "On the Diffraction Spectrum Photography," in 1872; "Astronomical Observations on the Atmosphere of the Rocky Mountains," and "Spectra of Venus and α Lyræ," in 1877; "Discovery of Oxygen in the Sun by Photography, and a New Theory of the Solar Spectrum," which was followed by another paper on the same subject, entitled "On the Coincidence of the Bright Lines of the Oxygen Spectrum with Bright Lines in the Solar Spectrum," in 1877; "Eclipse of the Sun in July, 1878," in 1878; "Photographing the Spectra of the Stars and Planets," in 1879; "Photograph of Jupiter's Spectrum," and "Photograph of the Nebula in Orion, on September 30, 1880," in