What did john snow do to prove the pump a was the source of the cholera.?

 By charting the incidence of the disease, he showed that over 500 cases occurred within 10 days over a radius of some 250 yards centered on London's Broad Street. He looked for some poison which he believed came from the excreta of cholera patients and swallowed by the new victims. A common factor was their use of water from the Broadstreet pump. By the methodical process of elimination, he proved his point: A workhouse in that area had its own private well, and there were only 5 deaths among its 535 inmates. A brewery on Broad Street likewise never used the water from the Broad Street pump. Its workers drank beer and it had no cases among its 70 workers.
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