In 1854, London physicians believed cholera was a poison carried in the air, a ‘miasma’ rising from rot and filth. But Dr. John Snow, a respected anesthetist, had a different theory. Five years earlier, he published a pamphlet arguing the disease must be swallowed, not inhaled. He reasoned that cholera’s terrible symptoms began in the digestive system, not the lungs. The poison, he suspected, was a microscopic living cell that multiplied inside the gut. His idea was almost completely ignored by the established medical community, including the Royal College of Physicians. For them, the foul smells of the city were the obvious culprit. But Snow was waiting for a chance to prove his waterborne theory was correct.
John Snow and the Broad Street Pump
In 1854, London's cholera was blamed on bad air. This is the story of how Dr. John Snow used a map to trace the killer to a single water pump.
Chapter 1
A Radical Idea
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Frequently Asked Questions
What did people think caused cholera before John Snow?
Before John Snow, the dominant medical theory was that cholera was caused by 'miasma,' or poisonous air. People believed that foul smells from sewage, garbage, and other decaying organic matter were toxic and spread disease when inhaled.
Why was the Broad Street pump water so popular?
Residents reported that the water from the Broad Street pump was colder and had a more pleasant, 'sparkling' taste than water from other pumps. This was ironically due to the carbonation from the decaying organic matter, including sewage, that was contaminating it.
Was John Snow's theory accepted after he removed the pump handle?
No, his theory was not widely accepted for many years. The Board of Health officially rejected his findings in 1855, and prominent medical journals criticized him. His waterborne theory of cholera was only officially vindicated in 1866, eight years after his death.
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