Physician John Snow famously figured out the cause of a cholera outbreak using maths and statistics. James Grime tells us what happened, walking those very same streets. | Royal Institution of Great Britain

In 1854 a doctor removed a single pump handle and slowed a deadly cholera outbreak. In 1854, London was struck by a severe cholera outbreak that killed families within days. Most officials believed the disease spread through “bad air,” but physician John Snow suspected contaminated drinking water — a radical idea for the time. Snow mapped cholera cases in the neighborhood surrounding Broad Street and noticed they clustered around one public pump. He interviewed families, traced infection pattern