A cholera outbreak had struck Broad
Street. The death count mounted and the moans of the sick could be
heard through thin tenement walls. It was down this street,
that John Snow walked. Knocking on door after door after door. But many had already fled and the cold
blue end of cholera had claimed many of those who had not. Again,
John Snow was frustrated in getting the evidence he sought.
But this time, the clock was ticking Every passing minute meant more deaths.
And every passing minute decreased his chances of preventing this
from ever happening again. And so, by noon on Tuesday the
4th of September, 1854, he realised that there'd be only one
place he could quickly and efficiently get the data he so desperately needed;
the office of the Registrar General. He raced from Broad Street to the halls
of the Government, demanding a full list of every death and an address for
everyone the cholera had taken. And so, he began to establish a pattern
of how these things were done. On ground inspection combined with combing
government records to get the data needed not just to treat the disease, but to
fight it. And fight it he would. Right there on Broad Street. He
returned to the epicenter, with its air of suffering and death so
that he could understand what those addresses he now held meant. His boot heels rang out against the
pavers of the abandoned streets as he paced from house to house,
trying to see the connection. Then he had it! Of course! He needed
to think of these deaths as a map. And so he began to craft his map.
plotting the deaths one by one. And as his map filled out with tragedy,
a pattern began to emerge. It really was an epidemic starting at
Broad Street and radiating out, thinning the further it went. But he knew that already. He needed more.
He needed to show that the pump itself was the source. He needed to know not
only how these points of mortality were related to each other, but also how
they related to the neighbourhood wells. So he made what we today know
as a Voronoi diagram. But to him, it was something he was
making up of the top of his head in a desperate attempt to find the fastest
way to understand the problem he faced. He marked the wells on the map, then he
split the map in to sections according to proximity to the wells. Any deaths that
was closer to one specific well than to any other would be grouped together.
The idea being that well water was well water and people were
probably getting their water from whatever pump was convenient. So if you
broke up the map by proximity to wells and you saw a pattern in where the most
deaths occurred, you'd be able to tell if there was a contaminated well.
And there it was clear as day. People who had a shorter walk to the
Broad Street pump than to any other well, were inordinately more likely to die.
But he had been down this road before. He knew this wouldn't Ben enough to
convince the miasmatists. they would just say that some noxious stench hung
around the region of the pump and that the pump itself was coincidental. Nope,
he needed something more. So he poured over his map. There were
a few outliers. There, right there! On Cross Street! There was a clump of
deaths that were closer to the Little Marlborough pump than the
one on Broad Street. He raced to the tenement to see
if he could get some answers, But he was too late. Those had only
been the first deaths marked down in the Registrar General's morning notes.
By afternoon, the entire family had been wiped out. Of all the 84 deaths
he had on record, only 8 more were outside the area he'd marked as
closest to the Broad Street pump. He needed to follow those leads. 3 were tragically children who went to
school near Broad Street and would drink from the well on their way
to and from their education. 3 more were workers who also
regularly stopped at the well. The last 2 he couldn't get data for. This
still left him with clear connections to the pump, even for those who were
outside its range and equally importantly outside the range of any
argument about a miasmatic cloud. But he needed to understand the
other holes in his data as well. On Poland Street there was a massive
workhouse with 535 inhabitants and yet almost no-one there had died. And it
was well within the range of the Broad Street pump. There should be 10
times as many deaths there, at least. He rushed to the workhouse, feeling the
daylight burning as each precious minute slipped away. He had to hurry.
Upon questioning the workhouse director, the answer became glaringly obvious:
The workhouse had its own private water supply. Of course! Snow pressed
the director further: "Where do you get your water from?" and the director
replied: "Grand Junction water works." Snow already knew that Grand Junction water
was safe based on his earlier research. It was all starting to make sense. Next
he had to go to the local brewery. There they told him (teetotaler that he was)
that their men drank nothing but beer. All the pieces fit, he had his case. Now he just had to convince the local
health board to shut down the well. Now this had all happened within the
first 48 hours of Snow's finding out about the outbreak. For 48 hours, he
had trudged through the streets that others had fled. He'd visited the sick,
he'd recorded the statements of the bereaved, for 48 hours he had
mapped, made statistical plots, studied and chased down data. And now
on Thursday night, after a brief rest, he prepared for what might
be an even greater challenge: the meeting of the local health commission. He addressed them with all of the
vigor and certainty of his data. He showed them his maps and his charts.
He let them know the egregious mortality rate of those who had drunk
from the well and the remarkable clemency granted to those who had not. And in
the end after much deliberation they said: "Hmpf, you might know
something, John Snow!" And they agreed to remove the handle
from the pump the following morning. Now, whether or not the outbreak would
have burned itself out over the next few days on its own is up for debate.
But what IS certain is that by Monday, the epidemic had practically passed. But after the epidemic had ended, the
pump handle was returned and life went on. Investigations into the outbreak began.
And most minds of the time went right back to thinking of things in terms
of the miasma theory of disease. But a young curate who was the Minister
to the people of Broad Street and had sat with many of them during
their final hours went further. This man (Henry Whitehead) began
doing a serious investigation of his own to make sense of the whole thing. Deeply
disturbed by why this had happened to his parish, he began writing monographs
on his results and debunking the theories that so many had offered. Especially
about this outbreak being the result of the lax morals of the poor. One of
the theories he thought he would debunk along the way was that silly notion
John Snow had about the pump having something to do with the outbreak.
But he never got around to it. Then, in November, a committee was
formed to really look into the outbreak and both Whitehead and Snow
were invited to be on it. And here, Whitehead really began to test
Snow's results. After all, sure Snow had shown that people who had drunk from
the pump suffered. But what of those who survived? If they had drunk from the
pump and never gotten cholera, would that not put into question the water as
a cause? And as a local prelate, Whitehead could do what Snow could not; reach
out to all of those in the local area that hadn't fallen ill. His knowledge of
the people of the area and their intimate trust of him as their priest actually
allowed him to get the last pieces of data that Snow had needed. And as
that data came in, his doubts about Snow's ideas began to melt away. But
there was one final piece to the puzzle: Why now? The Broad Street pump
had served the people well for years. It was groundwater not water from one
of the contaminated vendors. And when the city had studied it, they'd find no
cracks that might have connected it to a sewage system. He was looking for
a reason, flipping through the records of the office of the Registrar General,
and that's when he found it. The index case, patient zero. An infant
- one who he remembered well - had died in the outbreak. But unlike most
patients, this tiny child had - according to the records in the Registrar's office -
held out for 4 days. That would put her case as predating the epidemic. Immediately he went to the house of this
child's mother, a woman who knew him well from the community. He asked about
those days and she talked about how she had tossed child's diapers into a
cesspool at the bottom of the house. The committee immediately authorized
an examination of the cesspit and a new examination of the well. Sure enough, the cesspool was poorly
built and was seeping as much into the soil around it as into the sewer
to which it was supposed to drain. Two feet away, through that
soil, lay the Broad Street well. With that final piece of data
they had all they needed. The committee would release its report
and that report would be dismissed or ignored by many at the time, but today we
know as a report that changed the world. But perhaps Snow himself put it best.
Talking to Whitehead he said: "You and I may not live to see the day and
my name may be forgotten when it comes, but the time will arrive when great
outbreaks of cholera will be things of the past. And it is knowledge of the
way in which the disease is propagated which will cause them to disappear."
And it is because of the tireless sleuthing of John Snow that that day is
here. History has not forgotten you. You do know something John Snow.
