That year, the British physician John Snow, who was working in a poor area of London, identified contaminated water as the means of transmission of the disease. After the 1854 Broad Street cholera outbreak he had mapped the cases of cholera in the Soho area in London, and noted a cluster of cases near a water pump in one neighborhood. To test his theory, he convinced officials to remove the pump handle, and the number of cholera cases in the area immediately declined. His breakthrough helped eventually bring the epidemic under control. Snow was a founding member of the Epidemiological Society of London, formed in response to a cholera outbreak in 1849, and he is considered one of the fathers of epidemiology.