• The Brewery Insight: His observation that workers at a nearby brewery, who drank beer instead of water, were largely spared from the outbreak further supported his waterborne hypothesis. This provided a control group, even if it was not intentional.
• Questioning and interviews: Snow went further than simply mapping. He interviewed the residents of the area, and discovered that those who lived further away, but sent for water from the Broad street pump, also contracted cholera.
• Questioning and interviews: Snow went further than simply mapping. He interviewed the residents of the area, and discovered that those who lived further away, but sent for water from the Broad street pump, also contracted cholera.
The Removal of the Pump Handle and the Decline of the Outbreak:
Snow's compelling evidence persuaded the local authorities to remove the handle of the Broad Street pump. This decisive action led to a rapid decline in new cholera cases, providing strong circumstantial evidence that the pump was indeed the source of the outbreak.
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