John Snow
By talking to local residents, he found the source of the outbreak was the public water pump on Broad Street (now Broadwick Street). Snow's chemical and microscope examination of a water sample from the Broad Street pump did not conclusively prove its danger. However, his studies of the pattern of the disease were convincing enough. The local council disabled the well pump by removing its handle. This action is usually credited with ending the outbreak, but Snow saw that the epidemic may have already been in rapid decline: