The Weekly Reflektion 32/2024

Collecting data, and analysing it to find the causes behind an incident is one of the keys to a good investigation. Jumping to immediate conclusions may be easy and cheap in the short term, but is not likely to provide the learning required in the long term.

Do you have the stamina to challenge established truths?

John Snow (1813 – 1856) together with his map of Soho cholera victims

One of the most feared diseases 200 years ago was cholera which had a 50% mortality rate, killing often within 24 hours. Scientists of the time were convinced that cholera was transmitted via ‘bad air’ termed ‘miasma’. John Snow, trained as a physician and focused on medical hygiene, was unconvinced of the miasma theory. He drank no alcohol, was a vegetarian, and drank only distilled water, very unusual for this period. Being trained in Newcastle, England, his area of responsibility covered mining towns where he noticed that miners, who spent significant time underground away from this ‘bad air’ also died at the same rate as town dwellers. He started to develop a theory that the source may be connected to the water supply.

Snow transferred to London, Soho, which was struck by a cholera epidemic when he was there. In true investigative fashion, Snow collected data on the cholera deaths, going door-to-door interviewing the next-of-kin of the victims and mapped the results. Most of the victim’s homes were clustered around a water source, the Broad Street water pump, but there were anomalies that he tried to understand. There was a victim in Hampstead, some distance to the north of Soho which initially appeared not to support his initial theory. After interviewing the victim’s family, it found out that the victim’s niece brought water from the same Broad Street water pump because it ‘tasted sweeter’. 

There were also some anomalies where, in some areas, no victims were located very close to the water pump. The Poland Street workhouse had no victims but had a water source in their own well within the workhouse grounds, that did not use the public water pump. The local brewery also had no victims among their workers, where most people drank beer rather than water. 

Snow approached the local health commission with his evidence, and they removed the pump handle from the Broad Street pump. Cholera cases stopped. Further investigation found a crack connecting the water well to an adjacent cesspit,further confirming Snow’s theory. The miasma lobby,however, was very powerful and discredited Snow’s theory, and the pump handle was replaced. The cholera cases began to reappear.

In memory of this incident, an annual Pumphandle Lecture is held where members of the John Snow Society remove and replace a pump handle to symbolise the continuing challenges for advances in public health. There is also a John Snow pub in Soho, a strange memorial for one who didn’t touch alcohol.

John Snow’s persistence in collecting data and using it to prove or disprove theories is something we can learn from. The correct finding may not be the popular one especially if there are vested interests and when the pride of the people protecting their theories is greater than the truth. How persistent are you in the face of resistance?