Draper. I. John William, an American chemist and physiologist, born at St. Helens, near Liverpool, England, May 5, 1811. He received his early education in the Wesleyan Methodist school at Woodhouse Grove, and was then placed under private instructors, devoting much attention to chemistry and natural philosophy. The higher mathematics were also a part of his early training. He subsequently went to the university of London, where he prosecuted his chemical studies. Some of his ancestors had been attracted to America before the revolution, a greater part of his family connections followed, and in 1833 he joined them. He continued his chemical and medical studies at the university of Pennsylvania, where he took the degree of M. D. in 1836, with the rare distinction that his thesis was selected for publication by the medical faculty. A few weeks later he was appointed professor of chemistry, natural philosophy, and physiology in Hampden-Sidney college, Virginia. During his residence there his time was occupied in chemical and physiological investigations, many of the latter appearing in the "American Journal of Medical Sciences." In 1839 he was called to the chair of chemistry and natural history in the academic department of the university of the city of New York, where, besides instruction in those branches, he delivered lectures to the advanced undergraduates on physiology.

In 1841 he was appointed professor of chemistry in the university medical college, and in 1850 physiology was added to the chair of chemistry. He is now (1874) president both of the scientific and the medical department of the university. Although his researches have been mostly experimental, involving great labor and cost, he has written voluminously and with high reputation. Besides contributions to various other scientific journals, he furnished to the "London and Edinburgh Philosophical Journal "and to the "American Journal of Science and Arts" between 1837 and 1857 about 40 memoirs, principally on topics previously little understood. For an account of some of these investigations, see Actinism, Ac-tinometer, and Photography. He is the author of many literary works, reviews, etc, the latter for the most part published anonymously; of a " Treatise on the Forces which produce the Organization of Plants " (4to, New York, 1844); of a popular "Text Book on Chemistry " (12mo, 1846), and another on "Natural Philosophy" (8vo, 1847), which consist of excerpts from his courses of lectures; and of a treatise on "Human Physiology, Statical and Dynamical, or the Conditions and Course of the Life of Man" (8vo, 1856), many editions of which have been published.

His " History of the Intellectual Development of Europe" appeared in 1862, and shortly afterward in England. It has been translated into French, German, Italian, Polish, Russian, etc. In 1865 four lectures that he had given before the New York historical society were collected in a volume under the title of " Thoughts on the future Civil Policy of America;" and between 1867 and 1870 appeared in three volumes his "History of the American Civil War." In the preparation of this work he enjoyed singular advantages from the friendship and assistance of officers, both civil and military, who had taken a conspicuous part in the events. This work too has been largely translated. To him is due the discovery of many fundamental facts of spectrum analysis; and among his latest papers are "Experimental Examinations of the Distribution of Heat and of Chemical Force in the Spectrum." II. John Christopher, son of the preceding, born in Prince Edward co., Va., March 31, 1835. He graduated in the medical department of the university of the city of New York in 1857, and from 1858 to 1860 was professor of physiology in the same institution.

For three years he was professor of chemistry in the Cooper union, and he is now (1874) professor of chemistry in the university medical college, and professor of physiology and natural history in the college of the city of New York. He has published a treatise " On Respiration " (8vo, New York, 1856), and a "Text Book on Anatomy, Physiology, and Hygiene" (8vo, 1856); and has contributed freely to English and American medical and scientific journals. III. Henry, brother of the preceding, born in Prince Edward co., Va., March 7, 1837. He graduated in the medical department of the university of the city of New York in 1858, and since 1860 has been professor of physiology there, and is also professor of physiology and analytical chemistry in the scientific department. He has made, at Hastings on the Hudson, the largest telescope (28 inches aperture) in the United States, and has devoted much attention to photographic and spectroscopic examination of the moon and other heavenly bodies. He has published a memoir " On the Construction of a Silvered Glass Telescope " (4to, Smithsonian institution, 1864), and " Text Book of Chemistry " (12mo, New York, 1864); and has been a frequent contributor to scientific periodicals.