 The founding physicians (the "Four Doctors") of the Johns Hopkins School of Medicine included pathologist William Henry Welch (1850–1934), the first dean of the school and a mentor to generations of research scientists; a Canadian, internist Sir William Osler (1849–1919), regarded as the "Father of Modern Medicine", having been perhaps the most influential physician of the late 19th and early 20th centuries as author of "The Principles and Practice of Medicine" (1892), written at the Johns Hopkins Hospital and published for more than a century; surgeon William Stewart Halsted (1852–1922), who revolutionized surgery by insisting on subtle skill and technique, as well as strict adherence to sanitary procedures; and gynecologist Howard Atwood Kelly (1858–1943), a superb gynecological surgeon credited with establishing gynecology as a specialty and being among the first to use radium to treat cancer.The Johns Hopkins School of Medicine, which was finally begun 17 years after its original visionary benefactor Johns Hopkins (1795–1873), died and opened only with the large financial help offered by several wealthy daughters of the city's business elite on condition that the medical school be open equally to students of both sexes, consequently one of the first co-educational medical colleges.The School of Medicine is affiliated with the Johns Hopkins Hospital, its main teaching hospital, as well as several other regional medical centers, including the Johns Hopkins Bayview Medical Center on Eastern Avenue in East Baltimore; the Howard County General Hospital, near Ellicott City, southwest of Baltimore; Suburban Hospital in Bethesda in suburban Montgomery County, (northwest of Washington, D.C.); Sibley Memorial Hospital in Washington, D.C.; and Johns Hopkins All Children's Hospital in St. Petersburg, Florida.