BARKER, George Frederic, physicist, born in Charlestown, Massachusetts, 14 July 1835. He received an academic education and was apprenticed to a manufacturer of philosophical apparatus in Boston, with whom he remained until he became of age. In 1856 he entered the Yale, now Sheffield, Scientific School, and was graduated two years later. While in his final year he was made assistant in chemistry under Professor Silliman, and during the winters of 1858-'9 and in 1860-'1 he was assistant to Dr. John Bacon, professor of chemistry in Harvard Medical College. In 1861 he became professor of natural sciences in Wheaton (Illinois) College. A year later he was acting professor of chemistry in Albany Medical College, where he remained for several years, and at the same time pursued a course of medical studies, being graduated in 1863. He was then called to the chair of natural sciences in the Western University of Pennsylvania at Pitts-burg. In 1865 he became demonstrator of chemistry in the medical department of Yale College, occupying Professor Silliman's chair during his absence in :[866-'7, and in 1867 was placed in charge of the department of physiological chemistry and toxicology at the same institution. Since 1873 he has been professor of physics at the University of Pennsylvania, Philadelphia. He was one of the commissioners of the United States to the International Electrical Exhibition in Paris in 1881, and a delegate to the International Congress of Electricians held at that time. The French government conferred on him the decorations of the Legion of Honor, with the rank of commander. In 1884 he was appointed by the president a member of the U.S. Electrical Commission. Professor Barker has frequently been called upon to testify in important patent cases, and he was requested by the department of justice to act as one of the government experts in the suit against the American Bell Telephone Company. The toxicological and chemical evidence given by him in the Lydia Sherman poisoning case in 1872 was remarkable for its clearness, and has been inserted as a typical case in Wharton's and Stille's "Medical Jurisprudence." During the winter of 1859 he gave a series of public lectures in Pittsburghh, Pennsylvania, and his "Lecture on the Forces of Nature," delivered in 1863 before the chemical society of Union College, has been published. In December 1871, his lecture "On the Correlation of Vital and Physical Forces," before the American Institute of New York, attracted universal attention, and it was afterward republished in France. In 1859 Professor Barker was elected a member of the American Association for the Advancement of Science, and he has filled the offices of vice-president (1872) and president (1879). In 1876 he was elected a member of the National Academy of Sciences. His published papers have appeared principally in the "American Journal of Science and Arts," the "American Chemist," and more recently in the "Proceedings of the American Philosophical Society." Besides the lectures mentioned, his two presidential addresses before the American Association for the Advancement of Science are valuable contributions to scientific literature. For many years he has been one of the editors of the "American Journal of Science," and in 1874-'5 he was editor of the "Journal of the Franklin Institute." For several years he also has edited the annual record of progress in physics published in the Smithsonian reports. Professor Barker is the author of a "Text-Book of Elementary Chemistry" (New Haven, 1870), which has passed through eight editions, and has been translated into French and Japanese.