The editors of The Lancet (the long-running British journal of medicine) issued a correction this week for several rude statements and a rather terse obituary that it published in the 1850s. All of these relate to John Snow, the epidemiologist famous for figuring out that cholera was spread by contaminated water. The trouble with this: Snow’s evidence-based arguments stepped on the toes of a former Lancet editor who believed strongly that such diseases were caused by bad air — and who had, as a consequence, led an initiative to ban tanners, soap makers, and other smelly professions from the city of London. Snow had testified before Parliament that bad air could not possibly cause disease. A feud ensued.