LOCKE 711 LOGAN He received his M. D. from Yale College in 1819, and that year delivered his first public lectures in Portland, Maine, also in Boston, Salem and at Dartmouth College. After graduation he began practice, but abandoned it, not from want of patients, but from their neglect to pay. Discouraged, he accepted a position as assistant in a Female Academy in NVindsor, Vermont. In Tune, 1821, he went West and established a school for girls in Lexington, Kentucky, in 1822 going to Cincinnati, Ohio, where he found a friend, one Ethan Stone, who introduced him to a number of the most influential citi- zens, with whose assistance he established a school for girls which soon became popular, even famous. Dr. Locke's method of instruc- tion was largely conversational. In 1835 he was elected professor of chem- istry in the Medical College of Ohio but found the place wanting in the necessary means of illustration, so, to meet every possible demand, he visited Europe, and purchased many thou- sand dollars worth of apparatus. Dr. Locke held this position until the session of 1849- ."iO, when he was displaced, but at the solicitation of friends he resumed and held the chair un- til 1853. In 1854 he accepted the position of principal in the academy at Lebanon, Ohio. The following year he returned to Cincinnati. He had a most accurate knowledge of geol- ogy, and in 1838 was engaged in a state geo- logical survey of Ohio, his report on the "Geological Structure of the Southwestern Portion of the State," being regarded as a paper of greatest value. Later he was called into the service of the United States for the survey of the mineral lands of the Northwest in connection with David D. Owen. Dr. Locke invented a number of scientific instruments ; among them the thermoscopic galvanometer described in the American Jour- nal of Sciences, vol. xxxiii. The object was, "to construct a thcrmoscope so large that its indications might be seen on the lecture table, and at the same time so delicate as to show extremely small changes of temperature. In volume xxiii of the American Journal of Sciences is a description of a microscopic com- pass invented by him. His greatest achievement was the invention of the "Electric Chronograph," or "Magnetic Clock." Lieut. Maury, in an official letter to the Hon. John Y. Mason, secretary of the navy, dated National Observatory, Washing- ton, January 5, 1849, says : "I have the honor of making known to you a most important dis- covery in astronomy, by Dr. Locke, of Ohio." After his observations in magnetism had been published, the English government presented to him a complete set of magnetic instruments. After his return to Cincinnati in 1855, he broke down completely. For rest he went to Virginia to examine some coal lands, but re- turned with his infirmities greatly aggravated. He married, in Cincinnati, October 25, 1825, Miss Mary Morris, of Newark, New Jersey. He was the author of "The Outlines of Botany" (1829) ; A sub-report on "The Sur vey of the Mineral Lands of Iowa, Illinois and Wisconsin," published by Congress (1840) ; sub-report on "The Geology of Ohio," published by the state (1838) ; and text-books on botany and English grammar. He died in Cincinnati, July 10, 1856. A. G. Drury. From an address on the Life and Character of Prof. John Locke, M. B. Wright, M.D., 1857. Applcton's Cyclop. Amer. Biog., N. Y., 1887. Logan, Cornelius Ambrose (1832-1899) Cornelius Ambrose Logan, physician, editor and diplomat, was born in Deerfield, Massa- chusetts, August 24, 1832. He came of a fam- ily distinguished as journalists, dramatists and actors. His father, Cornelius Ambrose Lo- gan (1806-1853), was author of "Yankee Land" 1834), "The Wag of Maine," "The Wool Dealer" and other plays ; his mother was Alice Eliza Blunden. _Hcr sisters, Eliza (1829- 1872) and Olive (1839-1909), were actresses and writers, and another sister, Celia (1837- 1904), was a journalist and dramatist. Dr. Logan's boyhood was passed in Cincin- nati, Ohio, to which his parents moved in 1840, and where he received his early education. In 1849 he began to study medicine under John T. Shotwell (q.v.) and in 1850 under R. D. Mussey (q.v.) ; he graduated at the Miami Medical College in 1853 and was appointed resident physician at St. John's Hospital, Cin- cinnati, and assistant in chemistry at Miami. He later moved to Indiana where he remained one 3'ear, then in 1856 settled in Leavenworth, Kansas, and practised his profession, at the same time being interested in the political life of the state. When the Civil War broke out he was appointed by the governor of Kan- sas chairman of the State Board of Medical Examiners and held this position till the end of the war; he took part in the Battle of Westport. In 1865 he was appointed a member of the Geological Corps of the State and made a "Report on the Sanitary Relations of the State of Kansas" (1866). In 1868 he was a founder of the Leavenworth Medical Herald, of which he was editor also. He wrote "On the Clim- atology of the Missouri Valley;" "Physics of
