John Snow (1813-1858) was one of the first anaesthetists – he even chloroformed Queen Victoria! – but today he is famous for his investigation of the 1854 Broad Street cholera outbreak in Soho, London. By mapping the cases of cholera he was able to link transmission of the illness to contaminated water consumed from the Broad Street pump. This hammered a nail in the coffin of the “miasma” theory of cholera transmission (sorry, Egerton!), and heralded the birth of the new science of epidemiology.
Map 1. Published by C.F. Cheffins, Lith, Southhampton Buildings, London, England, 1854 in Snow, John. On the Mode of Communication of Cholera, 2nd Ed, John Churchill, New Burlington Street, London, England, 1855.
As John Snow himself said:
On proceeding to the spot, I found that nearly all the deaths had taken place within a short distance of the [Broad Street] pump. There were only ten deaths in houses situated decidedly nearer to another street-pump. In five of these cases the families of the deceased persons informed me that they always sent to the pump in Broad Street, as they preferred the water to that of the pumps which were nearer. In three other cases, the deceased were children who went to school near the pump in Broad Street… With regard to the deaths occurring in the locality belonging to the pump, there were 61 instances in which I was informed that the deceased persons used to drink the pump water from Broad Street, either constantly or occasionally… The result of the inquiry, then, is, that there has been no particular outbreak or prevalence of cholera in this part of London except among the persons who were in the habit of drinking the water of the above-mentioned pump well.John Snow, “The Cholera Near Golden Square, and at Deptford”, Medical Times and Gazette 1854; 9: 321-22
Steven Berlin Johnson has written a truly enthralling book called”The Ghost Map” about John Snow and the Broad Street outbreak, highlighting the importance of sanitation and public heath in the evolution of the modern city, as well as the fascinating characters involved. I recommend reading it. Here he is talking about it at TED: