This is the third episode of the series of contents dedicated to the cholera map, created by Dr. John Snow during an epidemiological outbreak that killed hundreds of people within a week in 1854 in the Soho region of London. The previous chapter was The deaths in Soho.
Crime Scene Investigation
As in the crime series, the duo Dr. Snow and Reverend Whitehead tried to retrace the steps of the people who had been victims of the outbreak as a way of understanding what happened.
Even though his first map showed concentration, it wasn't perfect.
They recorded deaths of people who lived in remote places.
This reinforced the miasma theory and discredited their efforts.
Especially in the middle of summer, when the stinks were even more intense and biased the perception that evil was coming through the air.
The investigation would have to go deeper.
Interviews with the families of people who had died showed something in common, these people were moving around the Broad Street region.
Commercial and industrial area of the city, many people had issues to solve there.
Even those who had access to water elsewhere sought to drink and carry some of the water from Broad St, which was famous for its flavor.
This even encouraged the production of beverages in that region, with a nearby brewery, Lion Brewery, coffee shops and pubs.
A coffee shop that used Broad St. water as a decoy saw 9 customers die in 1 day.
Investigations showed that:
- There was a geographical dispersion, but that all people from afar had some relationship with Broad Street
- At two points in the area with the highest concentration of deaths, there was an incredible drop in the rates, they were places that had another source of access to water, such as the Lion brewery and a hostel for homeless people
Here comes the famous map, with which it would be possible to demonstrate that the Broad St. region was a Central Location, an area of concentration of economic activities with a power of attraction over neighboring and even distant regions.
Reports presented by John Snow showed that the water from other wells was already mistrustful on the part of the population.
The amount of waste, some strange smell and taste was remarkable, while the water from Broad St. was considered to be of better quality.
However, microscopic analysis at the time failed to identify water contamination from Broad St.
That unusual success of the Broad bomb. St. further complicated the defense against the miasma theory.
As stated by Edmund Parkes of the Epidemiological Society, claiming¹:
This density in the center, with a circular distribution that decreases as it moves away from the center, demonstrates that airborne transmission is the most likely.
The non-deaths at points within the epicenter were the counterproof. If the transmission were airborne, the contamination would be proportional to the rest of the residents.
In the words of Dr. Snow himself quoted in the book The Ghost Map by Steven Johnson.
The experiment was taking place on the largest possible scale. No less than three hundred thousand people of both sexes, of all ages and occupations and of all levels and positions, from the highest society to the poorest, were inescapably and often unconsciously divided into two groups; one group received contaminated water from London's sewage and, together, whatever came from the victims of cholera; the other, water proven to be free of such impurities.
Continued in the next article, The bomb is banned under protests.
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(1) Could it be that one or more of the Epidemiological Society members made comments along the lines of what Edmund Parkes would write in his review of On the Mode: “On examining a map given by Dr. Snow, it would clearly appear that the centre of the outburst was a spot in Broad-street, close to which is the accused pump; and that cases were scattered all round this nearly in a circle, becoming less numerous as the outside of the circle is approached. This certainly looks more like the effect of an atmospheric cause than any other.
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