First man to find that cholera was caused by dirty water
He found that people who drank from board street pump (where there was a cholera outbreak, in London) often became ill and died where as the workers from the nearby brewery all survived (they only drank beer)
Snow demonstrated this on a map where he marked where cholera death occurred
Snow then removed the handle from the pump and the outbreak stopped, Snow was ignored at first but after his death Louis Pasteurs Germ Theory proved he was correct
