Snow, John (1813–1858)

John Snow has an unusual place in medical history because he is a seminal figure in two medical disciplines—anesthesiology and epidemiology. His contribution to the first field was to establish the chemical and biological principles underlying the administration of consistent dosages of anesthetic gases effectively and with minimal toxicity. In the latter field, he discovered how cholera—and, by extension, every form of intestinal infection—was transmitted. The process by which he discovered the fecal-oral and waterborne routes of disease communication was the first true model of epidemiologic investigation.

Snow's twin accomplishments were not unrelated. As the world's first practicing anesthesiologist, he was intimately familiar with the effects of gases on human physiology. This understanding made him skeptical of the then-reigning dogma that miasmas—hypothesized gaseous emanations from rotting ...