John Snow (15 March 1813 – 16 June 1858) was an English physician and a leader in the development of anaesthesia and medical hygiene. He is considered one of the founders of modern epidemiology, in part because of his work in tracing the source of a cholera outbreak in Soho, London, in 1854, which he curtailed by removing the handle of a water pump. Snow's findings inspired the adoption of anaesthesia as well as fundamental changes in the water and waste systems of London, which led to similar changes in other cities, and a significant improvement in general public health around the world. Early life and education Snow was born on 15 March 1813 in York, England, the first of nine children born to William and Frances Snow in their North Street home, and was baptised at All Saints' Church, North Street, York. His father was a labourer who worked at a local coal yard, by the Ouse, constantly replenished from the Yorkshire coalfield by barges, but later was a farmer in a small village to the north of York. The neighbourhood was one of the poorest in the city, and was frequently in danger of flooding because of its proximity to the River Ouse. Growing up, Snow experienced unsanitary conditions and contamination in his hometown. Most of the streets were unsanitary and the river was contaminated by runoff water from market squares, cemeteries and sewage. From a young age, Snow demonstrated an aptitude for mathematics. In 1827, when he was 14, he obtained a medical apprenticeship with William Hardcastle in the area of Newcastle-upon-Tyne. In 1832, during his time as a surgeon-apothecary apprentice, he encountered a cholera epidemic for the first time in Killingworth, a coal-mining village. Snow treated many victims of the disease and thus gained experience. Eventually he adjusted to teetotalism and led a life characterized by abstinence, signing an abstinence pledge in 1835. Snow was also a vegetarian and tried to only drink distilled water that was “pure”. Between 1832 and 1835 Snow worked as an assistant to a colliery surgeon, first in Burnopfield, County Durham, and then in Pateley Bridge, West Riding of Yorkshire. In October 1836 he enrolled at the Hunterian school of medicine on Great Windmill Street, London. Career In the 1830s, Snow's colleague at the Newcastle Infirmary was surgeon Thomas Michael Greenhow. The surgeons worked together conducting research on England's cholera epidemics,