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John Snow’s Pump
You know quite a lot John Snow
Soho is not known as a centre of medical innovation but, in August 1854, it became the focus of one of the most remarkable breakthroughs in the history of science.
John Snow was a Northern doctor who had spent much of his early life in Yorkshire and County Durham. Whilst practising in these new, crowded, Northern Cities he came face to face with one of the deadliest diseases that humanity has been inflicted with. Remarkably, Cholera still affects an estimated 3 to 5 million people a year (of which it kills between 28,000 and 130,000). The disease made its mark fully in the Nineteenth Century where a growth of international travel, an increase in population density and general squalor led to worldwide outbreaks. Even worse, the transmission of the disease was not understood and treatment was, at best, poor. An English outbreak in 1848 killed 52,000 alone and this toll was replicated in cities across the globe.
Even though the disease was not understood, it was clear that it often affected those within the poorest communities and John Snow consequentially had an interest as those communities contained his typical patients. With a naturally enquiring mind and statistical analysis that feels much more at place in our age of data analysis, he mapped the outbreak in his local area by noting the deaths in Soho on a map (the outbreak had killed 550 in two weeks). It was this that lead him to challenge the commonly held belief that the disease was passed through the air (via “miasma”).
Looking at the map, Snow could see that most of the deaths were centred around a water pump on Broad Street. More crucially, a group of houses at the centre of the district had very few deaths. The common factor with these exempted households being that the men in these buildings worked at the local brewery and drank their body weight in beer (which was boiled). Perhaps even more tellingly, a lady at the centre of the outbreak admitted that she “didn’t like the taste” of the Broad Street Pump so got one of her children to bring her water from a location some distance away. No one in her household got ill.
Putting two and two together, John Snow persuaded the local council to remove the handle from the Broad Street pump and the disease began to burn itself out almost immediately. An investigation of the pump found it was flooded with human waste from a nearby cesspit which begs the question why it was just that particular lady that didn’t like the “taste”.
More importantly, John Snow had convincingly demonstrated that the disease was waterborne (although it would take years before his findings were accepted). This discovery was all the more remarkable because the existence of micro-organisms and germ theory didn’t develop for another 10 to 20 years. Snow had effectively worked out what was happening without understanding the mechanics of how.
Today, somewhat brilliantly, the pump still exists. Originally moved around the corner, it has been restored to almost its original location (which is marked by a pink flag stone on the floor). It is well worth a visit and a toast to this pioneer of epidemiology in the excellent pub next to it (fittingly, although somewhat ironically considering he was a teetotaller, called The John Snow).
John Snow’s grave in Brompton Cemetery