John Snow was a British physician of the Victorian era who helped introduce the use of anesthesia in surgery; he also attempted to show, in 1854, that cholera was a water-borne disease. His careful mapping of the distribution of cholera cases in London is the first known example of epidemiological research.

Snow was born in York, England, on March 15, 1813, the oldest of nine children. His father was an unskilled laborer and the family lived in one of the poorest sections of York, an industrial shipping area along the River Ouse. Snow was educated until the age of 14 at a common day school for the poor. In June of 1827 he arrived in Newcastle, 80 miles from his home, to begin a six year apprenticeship in medicine under William Hardcastle. Hardcastle taught him the day-to-day business of running a medical practice and dispensing medicine. During his apprenticeship, Snow also attended lectures at...