John Snow's Ghost Map

In this episode of Stuff You Missed in History Class, Katie and Sarah discuss Dr. John Snow's famous "ghost map" and work tracing a cholera outbreak in Victorian London.

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Episode Transcript

Speaker 1 (00:00):
Welcome to Stuff You Missed in History Class from how
Stuff Works dot Com. Hello and welcome to the podcast.
I'm Katie Lamberg, joined by Sarah Dowdy. How are you, Sarah?
I'm great, Katie, How are you? He won't be as
great once we start talking about what we're talking about.

(00:21):
Which was a listener request Janie from d C wanted
to hear all about John Snow and the cholera outbreak
in Victorian London. I don't know. I'm kind of a
fan of slummy Victorian London, so I think I'm going
to enjoy this one. John Snow was born in eighteen
thirteen in Yorkshire, England, and he was actually the son
of a coal yard laborer, but quickly gets into the

(00:45):
medical field at fourteen, when he starts three consecutive apprenticeships
and first encounters cholera. Not that long after, while visiting
coal miners in eighteen thirty one, he gets, you know,
his first exposure to contagious disease. He doesn't begin his
formal medical education until eighteen thirty six, but he gets

(01:05):
his m d in eighteen forty four from the University
of London and by eighteen forty nine He is a
licensed specialist of the Royal College of Physicians of London,
which was a really elite organization. Yeah, this guy gets
big fast. Um. He kind of enters the realm of
what today we'd probably call a celebrity doctor, especially when

(01:25):
he treats Queen Victoria. That's because he learned about ether
being used in America but pioneered how it was dispensed. Right,
So he helps Queen Victoria through her childbirth, on the
birth of Prince Leopold and Princess Beatrice, and makes the
public more accepting of the process at all if Victoria

(01:47):
is into it, whether it's Christmas trees or big white
weddings or ether. The Kingdom likes to trends center Victoria.
But we don't think of him today for his work
in anesthesia. We think about him for is pioneering work
in germ theory. And to do that will give a
little background first about Victorian London, which was really disgustingly dirty.

(02:10):
The life expectancy for a gentleman in Victorian London was
forty five, but if you were a tradesman it was
your mid twenties. So I would be killed off by now,
and so would you say, and London was really really stinky,
like known worldwide for being stinky. It was the biggest
city in the world. But sewage was just piled up everywhere.

(02:33):
Toilets drained into basement sesspits, so there would just be
piles and piles of sewage in your basement, stinking too
high heaven, and the sus pits were flushed into the
river if they were cleaned, which of course is where
everyone got their water. Maybe you can see where this
is going. So needless to say, London, overcrowded, dirty, stinky,

(02:54):
a good place for diseases to spread. And at the time,
it was thought of that diseases came from my asthma
or bad air from decayed organic matter, so bad smells
meant disease, and when the entire city stinks, people thought
you were getting sick from the sewage. There's also a

(03:16):
moral element to the whole myasthma theory, uh that stinky
people were you know, unclean and more prone to disease,
not just because they were poor and destitute and living
in overcrowded pubbles. They were morally unsound, so too bad
for you poor people to Victoria in London, everyone thought

(03:38):
your illness was your own darn fault. So Snow doesn't
buy this though. He thinks that diseases are caused by
some agent, not by a smell, right, So they started
calling that germ theory. And so we've got these two
philosophies that are kind of going head to head, and

(03:59):
they go head to head for for decades, surprisingly enough
to to us, who you know, my asthma sounds like
such a bad idea, um, But people aren't quick to
buy germ theory. So there have been a few outbreaks
of cholera in London. The eighteen forty eighteen forty nine
Color outbreak killed fifty thousand people. And this is where

(04:22):
John Snow wants to figure out how this is happening.
Color is not a pretty disease. You die from basically
diarrhea that's unstoppable, and various digestive ills. You die from
dehydration because your body doesn't have any fluid left, and
you can die really quickly, like within a day. So
John Snow wants to figure out this germ theory and

(04:42):
see if he can prove it. But in that particular outbreak,
there weren't a public death records and he couldn't figure
out who was giving water to witch households, so this
wasn't a good test case for him. And in the
summer of eighteen fifty four, another collar outbreak happens. Seven
people are dead in two weeks, and this is when
he starts his experimentation and runs around testing water and

(05:03):
interviewing people and trying to figure out where this is
coming from so he can stop it. And he performed
two classic experiments during this eighteen fifty four outbreak UM.
The first was the Broad Street Pump outbreak experiment, which
is my favorite. He's like Sherlock Holmes of medicine and
it's pretty amazing. So UM, in the Soho district of London,

(05:27):
where he's actually based his medical offices are actually based,
there is a sudden case of cholera. Seventy fatalities within
a twenty four hour period, most of them within five
square blocks UM, and all of these fatalities are based
around the Broad Street Pump, which is a free water

(05:51):
pump for the poor. It draws the water from a
well underneath the Golden Square, which has some of London's porous,
most overcrowded people. So in the last week of August
eighteen fifty four, all the residents of Golden Square start dying.
And it starts with an upset stomach and then goes
to vomiting and severe cramps in the gut, and then

(06:14):
to diarrhea and thirst, and then, like we said, death
from dehydration, and it's fast to kill. Some people are
dying within twelve hours after it starts, and it's really
fast to spread. So the medical authorities are pretty quick
to identify this as cholera, and Snow moves in to
start studying what's happening, and he takes a really multidiscipline approach.

(06:36):
He looks at water samples and sees, you know, what
he can find in the water, but he also starts
looking at the maps of London dead or the weekly
statistics about who's dying of cholera in London, looking for
geographical patterns, and he draws a ghost map that showed
a correlation between cholera cases in this neighbor hood and

(07:00):
the Broad Street pump. Basically, if you lived within walking
distance of the Broad Street pump, if that was your
nearest water source, you were very likely to come down
with cholera. And it's really intense. You can find a
bunch of them online, of the ghost maps, but they're
just black lines everywhere showing people. They're very disturbing, little

(07:22):
stacks of black lines. And you'll see the pump location
in the houses immediately adjacent to the pump just have
these huge stacks of black lines coming from them. And
this is part of the reason he's called the father
of modern epidemiology and starts right here. Um So, after
about a week he goes to the local Board of

(07:43):
Guardians of St. James Parish with his findings with this
ghost map, and Um convinces them to shut down the
Broad Street pump, to take the literally take the handle
off the pump so people can't use it. And they're
not totally into it, though, are They know, they're still
thinking about the whole myasthma thing. So they're engaged in

(08:03):
this pursuit to spread lime all over the streets because
that'll kill the snows. That will kill it. But they decide, okay,
so let's go ahead and take the pump handle off,
and surprise, surprise, the outbreak ends. But what's so great
about Snow's experiment here is he doesn't just look at

(08:24):
the overwhelming evidence on the side of if you, you know,
drink this water, you very well might get sick. He
looks at kind of the statistical outliers. Yes, he's very thorough.
I love this. Yeah he um. There's some school children
who don't live near the pump who end up dying.
He reasons that they passed by the pump on their

(08:46):
way to school. And my favorite, there's a widow in
West End Hampstead and her niece in Isilington and they
got sick, but neither of them had been anywhere near
so how So he did some investigation, did some interviewing
and discovered that the widow had once lived on Broad
Street and liked the taste of the well water so
much that she had a servant go to Soho every

(09:07):
day and bring her back a bottle of it to drink.
It's like when you go to Florida, South Georgia and
you like, bring your Atlanta water. Um. So yeah, And
he actually finds the last bottle of water that the
widow had gotten was from August thirty one, which is
the start of the epidemics, So bad bad timing there.

(09:27):
There's also an army officer living in St. John's Woods,
who dies after dining in Water Street where he had
drunk in a glass of water from the Broad Street well.
And he also, in his thoroughness looks at the people
who didn't get sick. So the people at the Poland
Street workhouse are just around the corner from the Broad
Street pumps. So I mean, if you're thinking about it,

(09:49):
they should have been sick, but they weren't. And so
he went and looked into that. And that's because the
workhouse had its very own water source. They weren't using
a Broad Street pimp. And that's also a good case
against the maas a theory. These people are in the workhouse,
they're dirty, they're more likely to be morally corrupt, but
here they are, you know, safe from cholera. Also, the

(10:11):
Broad Street Brewery, which you know, right down the street
from the pump um no deaths because the workers are
given a daily beer allowance, so they don't need to
drink water. I feel like there's a lesson in there
somewhere for my bosses. He also has the help of
Reverend Henry Whitehead, who's the vicar of St. Luke's Church,

(10:33):
and Whitehead actually wasn't originally on his side. He thought
the outbreak was caused by God's intervention, and he started
a report to prove it, but it actually only ended
up confirming John Snow's study. But he was man enough
to come to a minute to Snow and admit, you know,
my research is the same as years, and he actually
helps Snow track down the source of the local outbreak

(10:57):
of sick child at number four the broad Street, right
near the pump um had had his diapers washed and
the water was dumped into a cesspool. It's only a
few feet away from the well, and after the child died,
no more diaper pail water had been dropped in that
cesspitse so people stopped getting sick. So later in the

(11:18):
year our Sherlock Holmes John Snow conducts a grand experiment
and he compares the London neighborhoods who are receiving water
from two different companies, and one company uses water that
comes from the Upper Thames and the other uses water
that comes from the heart of London. And interestingly, Parliament
had actually required the Metropolitan water companies to improve the

(11:41):
quality of their intake, but not all of them had complied.
And of course sewage is being dumped into the Thames.
The sanitation commissioner named Edwin Chadwick believed in the miasma thing,
and he thought that if you dumped sewage in the river,
you were keeping bat air away from people. So he
thought what he was doing was actually really good. But
of course he's dumping sewage into water that's then getting

(12:04):
turned into drinking water. But this dual water company thing
kind of presents the perfect opportunity for an experiment for
Snow because the companies were rivals and it had at
one point competed head to head. So some houses had
mans from one company while their next door neighbor had
a man from the other company. So essentially you had

(12:26):
this controlled experiment. Everything was the same in this neighborhood
except for the water where they got their water from.
And it turned out for people who got the London
sourced water, they had a much higher chance of contracting cholera.
And Snow is overjoyed because he thinks, wow, he's finally

(12:47):
proved it. The ratio of people who died from one
source of water versus the other was something ridiculous like
seventy five to five. I mean, if that's not proof,
you know, what is, and he suggests intervention strategies to
control epidemics extend. He's thinks that he's proven that contaminated
water is what gets people, but it didn't seem to stick. No,

(13:07):
people are still stuck on the miasma theory and it's
not sadly, it's not really until the eighteen eighties when
germ theory is, you know, golden people, people go with
that when the causative organism of cholera fabrio cholera is

(13:29):
actually finally understood. So when John Snow died in eighteen
fifty eight, people still thought it was my asthma, and
no one accepted all the things he'd worked out so hard.
Chadwick was still suggesting ridiculous things. At one point he
was quoted as saying, all smell is if it be intense,
immediate acute disease. And in the eighteen nineties he suggested

(13:51):
bringing down fresh air from places like the Eiffel Tower
and distributing it. We're discussing how that would actually be done,
Like how how do you get to the air and
then distribute it. I can't ask Mr Chadwick. The Great
Stink of eighteen fifty eight, which is my favorite name

(14:12):
of anything that has ever happened. Ever is what starts
to change things. Because this summer was incredibly hot and
sewage was everywhere in London. The flush toilets were overflowing
the basement cesspits which are going into the street drains,
and I mean it was so bad. No one wanted
to be in the city. It was so horrible. The

(14:33):
people in the House of Commons were draping their curtains
and soaking them in cloride of lime just so they
wouldn't be smelling the sewage. And so a committee was
set up to figure out how to fix the stink.
And this is where the modernization of the sewage system
in London started to happen. So even though sanitation is
much better in London today, it's still a problem in

(14:56):
a lot of places in the world, and cholera is
actually still causing a lot of deaths. Diarrhea is one
of the leading causes of death for kids in the
developing world. There's a treatment for it today, oral rehydration salts,
which you know, basically keep you from dying of dehydration
in twelve hours twenty four hours, and it's um it's

(15:19):
estimated that it's prevented forty million death since nineteen So
today we'd like to give thanks to John's Snow and
his amazing investigative work, and we recommend the book The
Ghost Map if you hadn't picked it up. And if
you'd like to learn more about infectious diseases and safe
water supply, come to how stuff Works and also check

(15:39):
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