The circle of knowledge

Essential facts of everyday interest in nature, geography, history, travel, government, science, invention, education, language, literature, fine arts, philosophy, religion, industry, biography, human culture, and universal progress. Easy to read, easy to understand, easy to retain

Editor-in-chief: Henry W. Ruoff, M.A., Litt.D., D.C.L., editor of "The century book of facts," " The capitals of the world," "Leaders of men," "The standard dictionary of facts," "Masters of achievement," " The volume library," "The human interest library," etc. Numerous text illustrations, maps, tables, duotone and color plates