John Snow. Portrait of John Snow (1813-58), British physician and anaesthetist. Snow treated victims of the first outbreak of cholera in 1831. He became convinced that contaminated water played a role in the spread of the disease and recommended simple hygiene precautions. During other outbreaks of the disease in 1848 and 1854, he carried out epidemiological investigations and proved that the disease was caused by infected sewage seeping into wells and rivers. Snow was also interested in respiratory physiology. He devised inhalation methods to deliver ether and chloroform anaesthetics to patients. He also divided the stages of anaesthesia into 5 degrees.