Among the oldest and most enduring of American institutions are those that have been devoted to the encouragement of the arts and the sciences. During the nineteenth century, a great many scientific societies came and went, and a few in individual disciplines achieved permanence. But the century also witnessed the founding of three major organizations with broadly interdisciplinary interests: the Smithsonian Institution in 1846; the Association of American Geologists and Naturalists, which in 1848 became the American Association for the Promotion (later, Advancement) of Science; and the National Academy of Sciences in 1863. The founding of the National Academy of Sciences represented a momentous event in the history of science in the United States. Its establishment in the midst of a great civil war was fortuitous, perhaps, and its early existence precarious; and in this it mirrored the state of science at that time. The antecedents of the new organization in American science were the national academies in Great Britain and on the Continent, whose membership included the principal men of science of the realm. The chartering of academies under the auspices of a sovereign lent the prestige and elements of support and permanence the scientists sought, and in return they made their scientific talents and counsel available to the state. describes the National Academies from inception through the beginning of the space age. The book describes the Academies' work through different periods in history, including the Postbellum years, World War I, the Great Depression, and World War II.