The Ghost Map

The Ghost Map Chapter 7 Summary & Analysis

Summary
Analysis
On the night of Thursday, September 7, the board of governors of St. James’s Parish had a meeting to discuss how the neighborhood would respond to the cholera outbreak. John Snow spoke at the meeting, insisting that the community needed to remove the pump as soon as possible. The Board was skeptical. They knew that everybody loved Broad Street water, and many of them subscribed to the miasma theory, not Snow’s waterborne theory. But Snow’s arguments were very persuasive, and in the end the Board voted to close down the well.
Snow was able to convince a local administrative board to enact public policy (specifically, performing the symbolic and life-saving act of removing the pump handle). One could argue that the real heroes of the 1854 epidemic were the board members who kept open minds, set aside their biases toward miasma theory, and voted to follow Snow’s recommendations.
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On the morning of Friday, September 8, the Broad Street pump handle was removed. The deaths would continue in Soho for another week, and none of the newspapers reported that the Board had removed the pump handle. Indeed, the Friday paper included a miasmic story about how changes in the weather were going to improve the cholera situation. However, as the days went on, it became clear that the worst of the outbreak was over—few people were contracting the disease. In all, some seven hundred people near the Broad Street pump had died in less than two weeks.
Even after the board of governors agreed to remove the pump handle, the investigation into the cholera epidemic was far from resolved. People continued to die, meaning that, as far as many doctors were concerned, Snow hadn’t proven his theory at all. In reality, these victims had probably already drunk from the Broad Street pump; nevertheless, it was difficult for people to see a clear causal relationship between the removal of the pump and the aversion of further death.
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The removal of the Broad Street pump handle probably didn’t seem like a major event. But it was quietly momentous—a public institution had made an informed intervention in a cholera outbreak, based on “a scientifically sound theory.” Reason triumphed over the disease. However, many people were furious that the pump had been shut down. Meanwhile, Sir Benjamin Hall commissioned an investigation into the Soho neighborhood, attributing the disease to factors such as slaughterhouses and “peculiarities of ventilation.” Hall ordered that researchers should study the pipe system beneath the neighborhood, but overall, his assignment reflected a loyalty to miasma theory, which acted as a kind of intellectual “strait-jacket.” Hall took the waterborne theory of cholera into account, but it wasn’t a priority for him—for months, he and his research team asked the wrong questions about why the outbreak happened.
John Snow’s cholera research—and, just as importantly, his collaboration with the local municipal board—set an important precedent for public health policy. However, the miasma theory of disease continued to reign supreme in England for a long time after Snow’s “victory” in 1854. Benjamin Hall’s mistake was to investigate the wrong factors in the epidemic, focusing on smells, “noxious environments,” and other data that implicitly favored the miasma theory. Put another way, Hall unconsciously posed a series of leading questions that inevitably led his research team to confirm the miasma theory.
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At first, Henry Whitehead thought the pump handle’s removal was a foolish choice. He was so displeased, in fact, that he vowed to disprove the waterborne theory of cholera—and in the end, his opposition to Snow’s theory proved invaluable, since it strengthened Snow’s theory. Whitehead began by interviewing elderly people who’d survived the cholera epidemic—“What kind of pestilence,” he wondered, “spares the old?” Meanwhile, Snow began writing a monograph on cholera, which he published in the fall.
Henry Whitehead, like Benjamin Hall, didn’t believe that the removal of the pump handle played a decisive role in ending the cholera epidemic of 1854. However, unlike Hall, Whitehead kept an open mind and asked a series of important, open-ended questions that didn’t simply confirm his convictions about the disease.
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As Whitehead continued with his research, he became aware of the lack of correlation between sanitary conditions and mortality rates on Broad Street. He then composed his own monograph on the cholera outbreak of 1854; in it, one can see Whitehead struggling with the theological meaning of so many deaths. He claims, for example, that God had a greater plan in mind for London—by sending a plague of cholera, God was drawing mankind’s attention to the problem of poverty. But in addition to his theological musings, Whitehead offered some important data in his monograph.
Johnson doesn’t editorialize about the role Whitehead’s religious faith played in his investigations. In some ways, his faith may have preventing him from seeing the truth about the epidemic; however, one could also argue that it inspired him to keep working long after most people would have given up. Furthermore, in trying to understand God’s “plan” with the 1854 epidemic, Whitehead had to adopt the “bird’s eye view” that Johnson considers so essential to urban planning and epidemiology—instead of seeing Soho as a hodgepodge of individuals, Whitehead’s faith enabled him to see the community more holistically.
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In late November, the St. James Vestry founded a committee to investigate the Broad Street cholera outbreak; however, the committee was weakened by the fact that Sir Benjamin Hall refused to share his Board’s findings with anyone else. Hall’s refusal turned out to be a good thing, though, as it encouraged the committee to hire Henry Whitehead, the only local with an encyclopedic knowledge of the outbreak. On the committee, Whitehead offered a vigorous attack on John Snow’s theory that the Broad Street well was to blame for the outbreak, pointing out that many of the cholera victims who’d survived the outbreak attributed their survival to drinking from the well.
Whitehead’s attempts to disprove John Snow’s waterborne theory perfectly encapsulate why it’s so important for scientific theories to be falsifiable. When a theory is falsifiable, other scientists can attempt to accumulate enough data to refute the theory—and in the end, they either succeed in doing so or, just as often, end up verifying and strengthening the original theory.
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As Whitehead conducted further research, he began to come around to John Snow’s theory. Some of the families who Whitehead interviewed later remembered that their deceased loved ones had drunk from the well, contrary to what they’d told Whitehead initially. In particular, Whitehead realized that young children were the well’s most frequent patrons—many of them had to fetch water from the well as part of their chores. He further realized that many elderly men and women had survived the outbreak not because of their inner constitutions, but simply because they lived alone and hadn’t had anyone bring them water from the well.
In the act of trying to disprove Snow’s theory, Whitehead came to realize how convincing the waterborne theory of cholera really was. Snow’s theory answered Whitehead’s initial question, explaining why the old and infirm had been spared in the epidemic—they hadn’t been able to venture outside and drink the contaminated Broad Street water.
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Whitehead was coming around to John Snow’s theory, but he still had some objections. First, he wondered why the outbreak hadn’t occurred near some other well with a reputation for inferior water. Second, he couldn’t explain why some Soho residents had survived the outbreak after drinking extra water from the well. Finally, Whitehead couldn’t explain why he’d survived the outbreak, considering that he’d drunk Broad Street water. Furthermore, studies had concluded that the Broad Street well wasn’t connected to the sewer lines in any way. Whitehead received a copy of Snow’s monograph, and later wrote Snow a letter listing his objections to Snow’s theory. Whitehead wondered why the cholera outbreak had plateaued so quickly—if the disease was waterborne, and if people were passing rice-water diarrhea, wouldn’t the spread of the disease have accelerated?
In trying to understand Snow’s theory, Whitehead’s biggest weakness was his inability to grasp how certain bodies of water become contaminated. But of course, neither Whitehead nor Snow had a convincing answer for this question, since the germ theory of disease was still in its infancy. Whitehead’s questions about the cholera epidemic were very insightful—notice that Johnson already devoted a lot of space in a previous chapter to answering them (the reason why the epidemic didn’t accelerate, Johnson believes, is either that the cholera germs were swept away from the well or that the epidemic claimed too great a portion of Soho’s population).
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As the data about the cholera outbreak continued to pile up, Whitehead began to believe Snow’s theory. He began searching for an “index case”—i.e., the earliest cholera victim of 1854. While studying the data, he came across the medical report for baby Lewis, who’d experienced diarrhea before dying. Whitehead interviewed Sarah Lewis and learned that she’d thrown soiled diapers into a cesspool. Whitehead realized that the baby’s cholera evacuations must have been deposited near the Broad Street well. He commissioned surveyors to examine the cesspool, and the surveyor found that it had, indeed, leaked into the well. Earlier investigations had missed the cesspool connection, perhaps because they were too focused on miasma. Whitehead realized that the surveyor had answered his objections to Snow’s theory. The reason the cholera body count hadn’t grown exponentially was that only the Lewis family could access the cesspool—therefore, baby Lewis’s waste was the only source of cholera in the well, and the cholera agent wasn’t growing exponentially.
Whitehead came to believe Snow’s theory, even though it couldn't explain every aspect of the cholera epidemic (for example, Whitehead had no way of understanding why he hadn’t died after drinking water with brandy). Whitehead and Snow went from being intellectual opponents to friends and collaborators. Johnson doesn’t provide much information about their personal relationship (How many times did they actually meet? Were they friends? Were they close?), and as he later acknowledges, it’s not clear how well they actually knew each other. Whitehead came to admire Snow’s theory for explaining a complex phenomenon, the cholera epidemic, in terms of one simple factor (water from Broad Street).
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The St. James Vestry Committee issued a report hypothesizing that, just as John Snow had argued, the cholera outbreak was caused by contamination of the Broad Street well. The Committee’s report further attacked the popular miasma theory of the era. And yet, around the same time, Benjamin Hall’s own Committee issued a report on the epidemic concluding that Snow’s theory was unverifiable and unlikely. The Board of Health Committee was so blinded by miasma theory that it couldn’t accept any other explanation for cholera. The Committee’s report on the outbreak analyzed a stunning number of factors (including humidity, wind velocity, and atmospheric pressure), all of which reflected a miasmatic conception of the disease.
In the scientific community, the best idea wins in the long run—in the short term, however, personal bias, a lack of common sense, and sheer arrogance often get in the way of the truth. Here, for instance, the popularity of miasma theory obscured most of its gaping holes. Furthermore, Snow’s theory was weakened by the fact that 1) he didn’t know anything about the contagious agent in cholera, and 2) he couldn’t conduct a scientific experiment on cholera, and instead had to support his findings with correlative data.
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Hall’s Committee’s report hit on one problem on its miasmatic hypothesis: the death of Susannah Eley, miles away from Broad Street. The Committee explained Eley’s death by saying that the water she’d received from her sons was “impure with organic contamination.” However, the Committee stressed that, during an epidemic, contamination in the atmosphere can also contaminate the water. This was “circular argumentation at its most devious.” Thus, miasma theory survived the 1854 outbreak intact.
Miasma theory exemplifies most of the features of a bad scientific theory—above all, its un-falsifiability. Even when Snow offered a persuasive challenge to miasma theorists’ notions of noxious fumes and contaminated environments, miasma theorists performed elaborate mental gymnastics to justify their beliefs—practically agreeing with Snow’s theory in the process!
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Perhaps the last person to die of the 1854 outbreak was Thomas Lewis, who succumbed to his illness on September 19, 1854. After baby Lewis’s death, the Lewis family stopped emptying cholera-infected waste into the cesspool—however, after Thomas took ill, Sarah Lewis began emptying his diarrhea into the cesspool, infecting the Broad Street pump once more. Had Snow not convinced the authorities to remove the pump handle, the outbreak probably would have continued.
John Snow died before his theory of cholera became universally accepted, but his contributions to epidemiology surely saved lives. In the 1854 epidemic alone, he may have prevented a second cholera outbreak by preventing additional people from drinking from the Broad Street pump.
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