John Snow's single case study was not enough to convince the medical community that cholera was spread through the water, but he did not give up. He founded the Epidemiological Society of London in 1850, the first organization dedicated to studying not just cures for disease, but also their causes. And so when cholera returned in 1854, John Snow saw a chance to finally prove his theory and set about studying the patterns of disease. The disease appeared to strike randomly, both rich and poor, but he realized that in his district were two different water companies, one of which he theorized might be contaminated. Finding evidence proved more difficult than he anticipated: going to door to door, he was often met by people who didn't even know what water company supplied their building. He tracked down landlords and even developed a water test to help him identify which water source each house had, but before he had the time to compile and analyze his findings, another terrible outbreak struck in Broad Street.