Two of the most influential urban medical maps of the 19th century were those in Dr John Snow’s essay On the mode of communication of cholera, 2nd edition, 1855. Snow was convinced that cholera was carried by contaminated water, and his report contained a map (a facsimile of which is shown above) that plotted the location of the water pumps in the Soho area and the distribution of fatal cholera cases surrounding them. The pattern of data revealed a great concentration of cases around the Broad Street pump, thereby pinpointing this location as a source of cholera.
Snow (himself a teetotaller) is remembered today in the name of the John Snow public house in Soho, on the site of the original Broad Street pump.
This is an edited extract from James Elliot’s chapter ‘Medical and social mapping’ first published in Elliot’s The City in Maps (British Library: London, 1987), pp. 78–81.