This is the biography of a man who made his greatest contribution to science in his reorganization of the U.S. Coast Survey. Alexander Dallas Bache was appointed superintendent in 1843, and the Survey increased its scope and improved its methods in the study of winds, tides, currents, and harbors under his charge Grandson of Benjamin Franklin, Bache was also active in education. Elected first president of Girard College when he was thirty, he visited European educational institutions in order to study their methods. And it may well be that, because of the admiration felt for his great ancestor, he was received in Europe with more attention than even his scholarship and personality merited. His survey of European educational institutions resulted in his monumental "Report on Education in Europe," which exerted a profound influence on educational methods in the United States. At heart, however, Bache was primarily a scientist and he became a significant figure in the development of American scientific institutions in general, and of Philadelphia in particular. An indefatigable worker, he also served as Superintendent of Weights and Measures in the United States, as a member of the Lighthouse Board, a Regent of the Smithsonian Institution, and Secretary of the American Philosophical Society.