I. John, an American naturalist, born near Shrewsbury, N. J., Feb. 22, 1784, died in Philadelphia, Nov. 21, 1860. He entered the corps of United States engineers in 1813, and was early employed in various important surveys and fortifications. He always manifested a taste for the natural sciences, to which he contributed many important papers in the departments of botany and zoology. His principal publications are: "Monographs of the North American Species of Utricularia, Gratiola, and Ruellia" (in the "Annals of the New York Lyceum of Natural History," vol. i.); "Observations of the North American Species of Viola" (ibid., vol. ii.); "Descriptions of the Species of North American Tortoises" (ibid., vol. iii.); "A Monography of North American Histeroides " (Boston " Journal of Natural History," vol. v.); and "Descriptions of Three New Species of Arvicola, with Remarks upon other North American Rodents" (" Proceedings of the Academy of Natural Sciences of Philadelphia," vol. vi.).
II. John Lawrence, an American naturalist, son of the preceding, born in New York, May 13, 1825. He graduated at the New York college of physicians and surgeons in 1846, and while a student made several scientific journeys to the western states. He has since travelled extensively in North and Central America, for the purpose of scientific investigation, and has contributed many memoirs to the transactions of scientific societies and to journals, mostly upon the coleoptera of North America. Lists of these memoirs are given by Agassiz, Bibliographies Zoologies, and by Hagen, Bibliotheca Entomologica, etc. The principal ones are: " Catalogue of Geodaphagous Coleoptera of the United States " ("Annals of the New York Lyceum of Natural History," vol. iv.); "On the Pselaphidae of the United States " (Boston "Journal of Natural History," vol. vi.); " On the Classification of the Carabidse of the United States" ("Transactions of the American Philosophical Society," vol. x.); "Attempt to Classify the Longicornia of the United States " ("Journal of the Academy of Natural Sciences of Philadelphia," new series, vols. i. and ii.); and "Synopsis of the Melonthidae of the United States" (ibid., vol. iii.). The Smithsonian miscellaneous collections include his " Classification of the Coleoptera of North America " (1861-'2) and " List of the Coleoptera of North America" (1863-'6). In 1862 he entered the army as surgeon of volunteers, and was soon promoted to medical inspector in the regular army, in which capacity he served until that grade ceased to exist on the termination of the war.
In 1873 he was elected president of the American association for the advancement of science.
I. John, an American physicist, born in Liberty co., Ga., Dec. 4, 1818. He is a descendant of a French Huguenot who near the close of the 17th century emigrated to New Rochelle, N. Y. His grandfather removed to Georgia before the revolution. His father, Louis Le Conte, was a graduate of Columbia college, and became a diligent student of the natural sciences. John graduated at Franklin college, Athens, Ga., in 1838. In 1841 he received the degree of M. D. from the New York college of physicians and surgeons, and in 1842 settled in Savannah. He contributed largely to medical periodical literature, and from 1846 to 1855 was professor of natural philosophy in Franklin college, in 1855 lecturer on chemistry in the New York college of physicians and surgeons, and from 1856 to 1869 professor of natural and mechanical philosophy in South Carolina college, now the university of South Carolina. In 1869 he accepted the chair of physics and industrial mechanics in the university of California, which he still holds (1874). Among his more important papers are those on " Experiments on the Seat of Volition in the Alligator;" "Observations on the Exudation of Ice from the Stems of Vegetables, and the Protrusion of Icy Columns from Earth;" " Observations on the Freezing of Vegetables;" " Researches on the alleged Influence of Solar Light on Combustion;" " On the Influence of Musical Sound on a Gas Flame;" and " On the Discrepancy between the computed and the observed Velocity of Sound in Air and Gases." A treatise on " General Physics," nearly completed by him, was destroyed in the burning of Columbia, S. C, in 1865.
II. Joseph, an American physicist, brother of the preceding, born in Liberty co., Ga., Feb. 26, 1823. He graduated at Franklin college, Ga., in 1841, and at the New York college of physicians and surgeons in 1845. In 1848 he settled as a physician in Macon, Ga., and in 1850 went to Cambridge, Mass., to complete a course of studies in natural history and geology under Agassiz, whom he accompanied in 1851 on an exploring expedition to Florida. After graduating at the Lawrence scientific school in Cambridge, he held for one year the chair of natural sciences in Oglethorpe university. He was then for four years professor of natural history and geology in Franklin college, and from 1856 to 1869 of chemistry and geology in South Carolina college. Since 1869 he has been professor of geology and natural history in the university of California. Among the more important of his scientific papers are: "On the Agency of the Gulf Stream in the Formation of the Peninsula and Keys of Florida;" "On the Correlation of Vital Force with Physical and Chemical Forces;" a series of papers "On the Phenomena of Binocular Vision and the Theory of Binocular Relief;" "A Theory of the Formation of the Great Features of the Earth's Surface;" "On some of the Ancient Glaciers of the Sierras;" "On the great Lava Flood of the Northwest;" and "On the Structure and Age of the Cascade Mountains." Among his literary productions are several essays on education and on the nature and uses of fine art.
He has also published " The Mutual Relations of Religion and Science."