JOHN WILLIAM DRAPER, M.D., LL.D., President of the Medical and Scientific Faculties of the University of New York, who died January 4, 1882, was an Englishman, having been born at St. Helens, near Liverpool, on May 5, 1811. He was therefore in his seventy-first year. Up to the age of twenty-two he was resident in his native country, receiving his education, first under private tutors, and afterwards studied chemistry in the University College, London, then known as the University of London. In 1832 he emigrated to the States, and continued his studies at the University of Pennsylvania, where, in 1836, he took the degree of M.D. Meantime his talent for original research had manifested itself in the production of several memoirs, which appeared in the pages of the Journal of the Franklin Institution. The first of these (published in 1834) was “On the Nature of Capillary Attraction”; whilst a second was devoted to a discussion of the most eligible method of constructing galvanic batteries of four elements. In 1835 he published an account of some experiments made to detect whether light exhibits any. magnetic actions. Several branches of the science of electricity subsequently claimed his attention. In 1839 he wrote a memoir, which afterwards was reprinted in the Philosophical Magazine, “On the Use of a Secondary Wire as a Measure of the Relative Tension of Electric Currents.” It is instructive to observe in this memoir how Draper's exact mind revolted against the misuse, by writers on electricity, of the words “tension” and “intensity”; and, though he himself employed both terms, he carefully distinguished between them, using “tension” for what we now call “electromotive force,” and “intensity” for the “strength of the current,” agreeing therefore with the practice of many continental authorities. He also made experiments upon electro-capillary motions, and contributed to the science of thermo-electricity, a valuable series of determinations of the thermo-electromotive force of different pairs of metals at different temperatures. In 1837 began the notable series of researches upon the nature of rays of light in the spectrum, with which the name of Draper will always be associated. His paper that year bore the title “Experiments on Solar Light,” but it failed to attract much attention in Europe. He was now devoting himself to photography and photochemistry with great zeal. His paper “On the Discovery of Latent Light,” in 1842, dealt with the images produced by rays of light which are only subsequently developed by some chemical reaction—a process with which the art of photography has made us familiar, but which was then a curious and novel phenomenon. It was Draper who first discovered that in the ultra-violet part of the spectrum there are absorption bands like the Fraunhofer lines in the visible part of the spectrum. To enumerate the works which proceeded from Draper's pen upon the chemical and physical properties of the ultra-violet, or as he styled them, tithonic rays, would be inadmissible here. Suffice it to say that the greater part of the fifty memoirs mentioned in the Royal Society's Catalogue related to this subject, and the most important of them are to be found reprinted in his “Scientific Memoirs,” published in 1878. In this volume may be found the pregnant suggestion for a standard of white light for photometry of a piece of platinum foil of given size and thickness, raised to a white heat by an electric current of specified strength. To guard against fusion he suggested that an automatic short-circuiting apparatus should be constructed by some “skilled artificer.” He thus exactly anticipated Edison's first incandescent lamps: though the satisfactory standard of white light appears to be as far off as ever.
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