This is a centennial study of Yerkes Observatory, built a century ago by the University of Chicago as one of America's first big science centres. The text describes the changing fortunes of the Observatory under its first three directors, and is illustrated with many archival photographs. Under its founder and first director, George Ellery Hale, Yerkes pioneered the new science of astrophysics. E.B. Frost, Hale's successor, allowed Yerkes to decline from 1904 to 1932, although it still trained rising young astromers such as Edward Hubble. Finally, with the support of Robert M. Hutchins, the University of Chicago's boy president , the boy director Otto Struve presided over Yerkes' revitalization in the 1930s and 1940s.