The course of the investigation had planted one additional objection in Whitehead’s mind. In November, the Paving Board had undertaken an examination of the Broad Street pump, looking for some connection to the sewer lines that might have contaminated the well water with waste matter. Their verdict had been definitive: the investigators found the well “free from any fissures or other communication with drains or sewers by which such matters could possibly be conveyed into the waters.” They also ran chemical and microscopy tests on the water itself, all of which failed to detect anything out of the ordinary.
John Snow’s research would be critical in helping Whitehead find a way around his first objection, but it would be Whitehead himself who would solve the mystery posed by the other two. During these winter months, Snow had been revising his book on cholera, integrating both the data from his South London water supply survey and an account of the Broad Street epidemic. At some point early in 1855, he gave Whitehead a copy of the monograph. In reading through Snow’s version of the previous September’s events, the curate was surprised to find that Snow had not blamed the outbreak on a “general impurity in the water.” Snow’s theory had assumed that the original case was a “special contamination… from the evacuations of cholera patients” that had leaked into the well from a sewer or cesspool. So the general quality of the water wasn’t relevant to Snow’s theory. Whatever agent had caused the cholera had come from the outside in.
When Whitehead expressed his gratitude for the book, he offered Snow one “a priori objection” to the contamination theory: if a specific case of cholera had started the outbreak, then shouldn’t the cholera’s rapid diffusion through the surrounding population have made the water increasingly deadly over the course of the week, as more and more rice-water evacuations passed into the well water? If Snow’s theory was correct, Whitehead continued, the pattern of the outbreak should have been a gradual upward slope, rather than a sudden spike followed by a steady decline. And then there was the matter of the contamination route. The Paving Board had found no communication between the Broad Street well and the local sewers. The idea of a cesspool contaminating the well seemed even more ludicrous to Whitehead. As far as the curate knew, all the cesspools had been eliminated since the passing of the Nuisances Act.
But Snow’s monograph and the growing stockpile of data had pushed Whitehead closer and closer to accepting the waterborne theory. If Snow was right, there had to be, in the language of modern epidemiology, an index case, an original cholera victim whose evacuations had somehow found their way into the Broad Street well. Assuming an incubation period of a few days—enough time for the V. cholerae to find its way into the well and then into the small intestines of the first wave of sufferers—patient zero should have fallen ill sometime around the twenty-eighth of August. Whitehead went back and studied the Weekly Returns for the weeks before the outbreak, and found only two cases in the neighborhood: one death on the twelfth, and one on the thirtieth. On further investigation, both cases turned out to have transpired too far from the Broad Street well to have had any likely connection to the water there.
For several weeks, Whitehead was at an impasse. All the evidence that he had compiled pointed to the existence of an index case that would confirm, once and for all, the very theory that he had so long resisted. He was now almost convinced that the well had been contaminated, and that the famously pure waters of the Broad Street pump had been responsible for the devastation in his parish. But who had done the contaminating?
When Whitehead wasn’t performing his duties at St. Luke’s or interviewing the dispersed former residents of Broad Street, he could often be found sifting through the files at the Registrar-General’s Office. The broad-brush statistics of the Weekly Returns had long since lost their utility for Whitehead; he needed the additional specificity that the original records offered. During one visit, while searching for some other stray detail, a record from the Broad Street files caught his eye: “At 40, Broad Street, 2d September, a daughter, aged five months: exhaustion, after an attack of diarrhoea four days previous to death.”
Whitehead was already familiar with the sad story of baby Lewis. Her death had long been included in his chronology of the outbreak. What caught his eye this time was the commentary at the end: “… after an attack of diarrhoea four days previous to death.” It had never occurred to Whitehead that an infant could have survived for more than a day or two with a disease that had killed many a grown adult in a matter of hours. But if baby Lewis had been sick for four days, that meant her illness would have predated the outbreak by at least a day. He knew at a glance that the address—40 Broad—put baby Lewis as close to the pump as anyone in the neighborhood.
Whitehead immediately dropped his other inquiry and rushed back to Broad Street, where he found Mrs. Lewis at home and willing to entertain further questions from the curate. She told him that her daughter had in fact been attacked a day earlier than Farr’s record suggested: on the twenty-eighth, five days before her eventual demise. When Whitehead asked how she disposed of the baby’s soiled diapers, she said the cloths were steeped in pails of water, some of which were then tossed into a sink in the backyard. But some she had dumped into a cesspool that lay in the basement at the front of the house.
The Reverend Whitehead could feel the chain of events click into place. The case of baby Lewis matched the profile of the index case perfectly: an attack of cholera that occurred three days before the first wave of the general outbreak, where the victim’s evacuations were deposited a matter of feet from the Broad Street well. It was exactly as John Snow had predicted. Whitehead convened the Vestry Committee immediately, and the men reached an easy agreement. The Broad Street well would be examined once again.
A local surveyor by the name of York was assigned the task of overseeing the second excavation of the Broad Street well. But this time the cesspool at the base of 40 Broad would be examined, too. Number 40 had a waste pipe connecting to the sewer, but the design was flawed on a number of levels. The cesspool at the front of the house had been intended to function as a trap, but in practice it served as a dam that blocked the normal flow into the sewer. Whitehead would later say that York had found there “abominations, unmolested by water, which I forebear to recite.” The walls of the cesspool were lined with bricks that were so decayed that they could be “lifted from their beds without using the least force.” Two feet and eight inches from the outer edge of the brickwork lay the Broad Street well. At the time of the excavation, the water line in the well was eight feet below the cesspool. Between the cesspool and the well, York reported finding “swampy soil” saturated with human filth.
The original excavation had missed all this because, guided by Benjamin Hall’s dictates, it had examined only the interior of the well, and focused much of its inquiry on the quality of the water. The miasmatists from the Board of Health weren’t interested in transmission routes, in flows. They didn’t see the outbreak as a relay network the way John Snow did. They were looking for a general property of uncleanliness in the neighborhood, not an index case. If the well had been partly responsible for the outbreak, then the flaw was surely to be found inside the well itself. It never occurred to the Board of Health that the well, though sound, could have “caught” the disease from another source. And so the Board’s inspectors merely peered down the well and sampled the water. They never bothered to look beyond those decaying walls, never bothered to see the connections.
But York’s excavation had unearthed the gruesome truth. The contents of a cesspool were seeping into the Broad Street well. Anything living in the intestinal tracts of the residents at 40 Broad had direct access to the intestines of about a thousand other human beings. That was all the V. cholerae had needed.
As the Vestry Committee put the final touches on its report, Whitehead stumbled across the explanation for his final objection to Snow’s theory. If the Broad Street well had been contaminated by the neighborhood’s waste, why didn’t t
he well get even deadlier as more and more of the neighborhood came down with the cholera? Why didn’t the epidemic follow an exponential growth pattern, with each new case making the contamination worse? York’s excavation had offered half an explanation, by narrowing the focus to 40 Broad. Cholera victims living elsewhere in the neighborhood weren’t emptying their pails into the Broad Street well, and so their illness had no effect on the quality of the water there. But five people had died at 40 Broad alone, including some of the very first cases: the tailor, Mr. G, and his wife. Why hadn’t their evacuations drained back into the well water at the height of the epidemic, thus fanning the flames even higher?
The answer turned out to be a simple matter of architecture. Only the Lewis family had ready access to the cesspool at the front of the house. The other residents, living on the upper floors, tossed their waste out the windows into the squalid courtyard at the back of the house. There was, no doubt, a vast colony of V. cholerae lying in wait in the dark earth behind 40 Broad, passed on from the intestines of the newly dead. But no one ever tried to drink from the courtyard’s foul soil, and so the chain of infection stopped there. The population of V. cholerae in Soho was exploding at unthinkable rates, but the connection between the bacteria and the Broad Street well had been cut off after baby Lewis died, because Mrs. Lewis had nothing left to deposit in the cesspool at the front of her house.
As Whitehead shared his discoveries with Snow over those early months in 1855, a quiet but profound friendship bloomed between the two men. Many years later, Whitehead recalled the “calm, prophetic” manner in which Snow described the future of their mutual investigation. “You and I may not live to see the day,” Snow explained to the young curate, “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 the knowledge of the way in which the disease is propagated which will cause them to disappear.”
WITH THE INDEX CASE IDENTIFIED, THE VESTRY COMMITTEE was now ready to issue its report, and it would be a thorough vindication of Snow’s original hypothesis. They began by methodically debunking the other popular explanations that had circulated in the months since the outbreak: meteorological conditions, sewer air, the lingering blight of the pesthouse fields. The pestilence had not leveled a disproportionate blow against any specific industry, nor had it singled out an economic class: both upstairs and downstairs had been devastated. Sanitary houses had suffered as readily as unsanitary ones.
Only one explanation had withstood the committee’s extensive probe:
The Committee is unanimously of the opinion that the striking disproportionate mortality in the “cholera area”… was in some manner attributable to the use of the impure water of the well in Broad Street.
In embracing the waterborne theory, the committee went out of their way to take a pointed swipe at the miasma hypothesis. The sentences are formal Victorian, suitable prose for a serious committee report on a deadly event. But they are fighting words, nonetheless:
The weight of both positive and negative evidence appears to be clearly and unmistakable in one direction viz.—to show that the water had some preponderating influence in determining an attack.… If it be urged, in explanation of an atmospheric influence, that Cholera might be conveyed exclusively to some by a partial distribution of an impure air, it may be replied that no consideration of the streets, local levels, sewergrates, house drains, or direction of the wind, will explain the existence of such partial atmospheric impurity, whereas the individual use of the water has been actually traced, and its consequences may not be unreasonable inferred.
The Vestry Committee’s report on the Broad Street epidemic was, technically, the second institutional victory for Snow’s waterborne theory, but it felt like the first. Snow had convinced the parish’s Board of Governors to remove the pump handle, though they had hardly been persuaded by his argument. Yet his case against the pump had genuinely won over the Vestry Committee. Snow’s theory had even withstood the assault of a committed debunker. The Reverend Whitehead had actively set out to disprove the theory, but he had been so thoroughly convinced by Snow’s argument that he ended up supplying the evidence that ultimately closed the case. The prosecutor had turned out to be the defense’s star witness.
SURELY HERE IS WHERE THE FOG OF MIASMA SHOULD LIFT, and science finally win out over superstition for good. But science rarely lands such decisive blows, and the Broad Street case was no exception. Within a few weeks of the Vestry Committee report, Benjamin Hall’s team issued their account of the St. James cholera epidemic. Its verdict on Snow’s theory was unequivocal—and unequivocally dismissive:
In explanation of the remarkable intensity of this outbreak within very definite limits, it has been suggested by Dr. Snow, that the real cause of whatever was peculiar in the case lay in the general use of one particular well, situate at Broad Street in the middle of the district, and having (it was imagined) its waters contaminated with the rice-water evacuations of cholera patients.
After careful inquiry, we see no reason to adopt this belief. We do not find it established that the water was contaminated in the manner alleged; nor is there before us any sufficient evidence to show, whether inhabitants of the district, drinking from that well, suffered in proportion more than other inhabitants of the district who drank from other sources.
We see no reason to adopt this belief. Of course the Board of Health Committee saw no reason. Their field of vision had been framed by the boundaries of miasma months before, when Benjamin Hall first outlined the committee’s objectives. This blanket dismissal of Snow’s theory seems like a colossal folly to us now, but these were not unreasonable men. They were not hacks, working surreptitiously for Victorian special-interest groups. They were not blinded by politics or personal ambition.
They were blinded, instead, by an idea.
That such local uncleanliness prevailed most intensely throughout the suffering districts, is evident from the reported results of house-to-house visitation. The exterior atmosphere was offensive with effluvia from ill-conditioned sewers; the houses were almost universally affected in the same manner, partly from the same source, partly from their own extreme defects of drainage and cleanliness, partly from unregulated slaughtering and other offensive trades; the inhabitants were overcrowded, perhaps to the greatest degree known even in London, and the general architecture of the locality was such as to render it almost insusceptible of ventilation.
On the principle to which we have referred, and which we believe to be commonly recognised as presenting the most probable theory of choleraic irruptions, it will be obvious that the locality, notwithstanding its high level, contained every predisposing condition which (given the exciting cause) should render it prone to a violent epidemic explosion; and we believe that any person conversant with the laws of disease might have predicted its extreme liability to suffer what afterwards befell it.
Here is the logic of the Cholera Commission’s report, paraphrased in plain English: “Cholera thrives in unventilated, crowded spaces where unsanitary conditions and noxious smells abound. We have examined the Broad Street area, and found it to be an unventilated, crowded space where unsanitary conditions and noxious smells abound. What more do you need?”
If there weren’t human lives at stake, the Cholera Commision’s report would be almost comical reading, capturing in excruciating detail the Gradgrindian overanalysis of utterly meaningless data. The first hundred pages read like a weather almanac, with dozens of tables documenting every atmospheric variable known to science. The section headings read as follows:
Atmospheric Pressure
Temperature of the Air
Temperature of the Thames Water
Humidity of the Air
Direction of the Wind
Force of the Wind
Velocity of the Air
Electricity
Ozone
Rain
Clouds
Comparison o
f the Meteorology of London, Worcester, Liverpool, Dunino, and Arbroath
Wind
Ozone [again]
Progress of the Cholera in the Metropolitan Districts in the Year 1853
Atmospheric Phenomena in the Year 1853
Atmospheric Phenomena in relation to Cholera in the Metropolitan Districts in the Year 1854
This litany makes it clear why the committee found no reason to believe Dr. Snow’s theory. They were not, strictly speaking, investigating Dr. Snow’s theory. Perhaps if they had spent a little more time investigating the patterns of water consumption on Broad Street, and a little less time compiling data on the meteorology of Dunino, they might have found Snow’s argument more compelling.
The only concession the committee made to Snow’s theory was a brief reference to the case of Susannah Eley. It was impossible to avoid the conclusion that the Broad Street water had been the vehicle of contamination in that instance. But the experimentum crucis was apparently not crucial enough for the miasmatists on the committee:
The water was undeniably impure with organic contamination; and we have already argued that if, at the times of epidemic invasion there was operating in the air some influence which converts putrefiable impurities into a specific poison, the water of the locality, in proportion as it contains such impurities, would probably be liable to similar poisonous conversion.
This is circular argumentation at its most devious. The committee begins with the assertion that cholera is transmitted via the atmosphere. When it discovers evidence that contradicts this initial assertion—a clear case that cholera has been transmitted by water—the counter-evidence is invoked as further proof of the original assertion: the atmosphere must be so poisoned that it has infected the water as well. Psychologists call this type of faulty reasoning “confirmation bias”: the tendency to force new information to fit one’s preconceptions about the world. For Benjamin Hall’s committee, the confirmation bias toward miasma was so strong that it literally blinded them to the patterns that Snow and Whitehead perceived so clearly—blinded them on two fundamental levels. Hall’s initial biases had structured the inquiry in such a way that most of the relevant data never came before the committee. And when a few telltale patterns did slip through the cracks, the committee was so conceptually mired in the prevailing model that it turned the waterborne theory’s experimentum crucis into yet another testament to the power of miasma.
The Ghost Map Page 17
