A clear, non-technical discussion of the basis of all industrial progress is "Power", by Charles E. Lucke (1911), which discusses the general principle of the substitution of power for the labor of men. Many of the references given in "Colonial Folkways", by C. M. Andrews ("The Chronicles of America", vol. IX), are valuable for an understanding of early industrial conditions. The general course of industry and commerce in the United States is briefly told by Carroll D. Wright in "The Industrial Evolution of the United States" (1907), by E. L. Bogart in "The Economic History of the United States" (1920), and by Katharine Coman in "The Industrial History of the United States" (1911). "A Documentary History of American Industrial Society", 10 vols. (1910-11), edited by John R. Commons, is a mine of material. See also Emerson D. Fite, "Social and Industrial Conditions in the North During the Civil War" (1910). The best account of the inventions of the nineteenth century is "The Progress of Invention in the Nineteenth Century" by Edward W. Byrn (1900). George Iles in "Leading American Inventors" (1912) tells the story of several important inventors and their work. The same author in "Flame, Electricity and the Camera" (1900) gives much valuable information.