Cholera and the Broad Street pump. Cholera and the Broad Street Pump. John Snow's classic study of cholera cases in Soho in 1854 (A), and the same data plotted on a modern map of London, with red circles showing 321 individual addresses from Snow's original map and blue squares the locations of 13 neighbourhood water pumps (B). (C) The resulting geoprofile, omitting for clarity the locations of disease cases. (D) The top 1% of the geoprofile, clearly identifying the Broad Street pump.