Modern history

Friday, September 8



ON THURSDAY NIGHT, THE BOARD OF GOVERNORS OF ST. James Parish had held an emergency meeting to discuss the ongoing outbreak and the neighborhood’s response. Halfway into the meeting, they received notice that a gentleman wished to address them. It was John Snow, armed with his survey of the past week’s devastation. He stood before them, and in his odd, husky voice told them that he knew the cause of the outbreak, and could prove convincingly that the great majority of cases in the neighborhood could be traced to its original source. It is unlikely that Snow went into the intricacies of his broader case against the miasma theory—better to go straight to the telling patterns of death and life, leave the philosophizing for another day. He explained the dismal ratios of survival among the people living near the pump, and the unusual exemptions granted to people who had not drunk the water. He told the Board of Governors of deaths that had transpired far from Golden Square, connected to the area only by the consumption of Broad Street water. He may have told them of the brewery of the workhouse on Poland Street. Death after death after death had been linked to the water at the base of the Broad Street well. And yet the pump remained in active use.

The members of the Board were skeptical. They knew as well as any other locals how highly regarded the Broad Street water was—particularly as compared to the other nearby pumps. But they also knew firsthand the smells and noxious fumes that were rampant in the neighborhood; surely these were more responsible for the outbreak than the reliable Broad Street water. Yet Snow’s argument was persuasive—and, besides, they had few other options. If Snow was wrong, the neighborhood might go thirsty for a few weeks. If he was right, who knew how many lives they might save? And so, after a quick internal consultation, the Board voted that the Broad Street well should be closed down.

The following morning, Friday, September 8, exactly a week after the outbreak had first begun its awful rampage through Soho, the pump handle was removed. Whatever menace lay at the bottom of the well would stay there for the time being.

The deaths in Soho would continue for still another week, and the final reckoning of the assault of the Broad Street well on the neighborhood would not be calculated for months. The removal of the pump handle was generally ignored by the newspapers. On Friday, the Globe had published an upbeat—and typically miasmatic—account of the present state of the neighborhood: “Owing to the favourable change in the weather, the pestilence which has raged with such frightful severity in this district has abated, and it may be hoped that the inhabitants have seen the worst of the visitation. Yesterday there were very few deaths, and this morning no new cases were reported.” On the following day, however, the news appeared to be less encouraging:

We regret to announce that after the account was written which appeared in The Globe of yesterday, there were several severe and fatal cases of cholera, and that seven or eight were reported on Saturday morning, although the wisest precautions were adopted to arrest the progress of the disease. The neighbourhood of Golden-square presented… a most melancholy and heart-rending appearance. There was scarcely a street free from hearses and mourning coaches, and the inhabitants of the district, appalled by the calamity which has visited them, crowded the streets to witness the last sorrowing act of duty towards their neighbours and friends. A vast number of the tradespeople left their shops and fled from the place, the closed shutters bearing the announcement that business had been suspended for a few days. Messers Huggins, the brewers, with praiseworthy forethought, have issued an announcement that the poor… may obtain any quantity of hot water for cleansing their dwellings, or other purposes, at any hour of the day or night, an act of humanity and kindness of which a large number have availed themselves.

Dozens would die over the next week, but clearly the worst was over. When the final numbers were tallied, the severity of the outbreak shocked even those who had lived through it. Nearly seven hundred people living within 250 yards of the Broad Street pump had died in a period of less than two weeks. Broad Street’s population had literally been decimated: ninety out of 896 residents had perished. Among the forty-five houses extending in all directions from the intersection of Broad and Cambridge streets, only four managed to survive the epidemic without losing a single inhabitant. “Such a mortality in so short a time is almost unparalleled in this country,” the Observer noted. Past epidemics had produced higher body counts citywide, but none had killed so many in such a small area with such devastating speed.

THE REMOVAL OF THE PUMP HANDLE WAS A HISTORICAL turning point, and not just because it marked the end of London’s most explosive outbreak. History has its epic thresholds where the world is transformed in a matter of minutes—a leader is assassinated, a volcano erupts, a constitution is ratified. But there are other, smaller, turning points that are no less important. A hundred disparate historical trends converge on a single, modest act—some unknown person unscrews the handle of a pump on a side street in a bustling city—and in the years and decades that follow, a thousand changes ripple out from that simple act. It’s not that the world is changed instantly; the change itself takes many years to become visible. But the change is no less momentous for its quiet evolution.

And so it was with the Broad Street well that the decision to remove the pump handle turned out to be more significant than the short-term effects of that decision. Yes, the Broad Street outbreak would burn itself out over the next few days, as the last victims died off and other, more fortunate, cases recovered. Yes, the neighborhood would slowly return to normalcy in the weeks and months that followed. These were real achievements that arose from that pump handle being removed, even if the water in the well had potentially been purged of V. cholerae by the time Snow made his case to the Board of Governors. But the pump handle stands for more than that local redemption. It marks a turning point in the battle between urban man and Vibrio cholerae, because for the first time a public institution had made an informed intervention into a cholera outbreak based on a scientifically sound theory of the disease. The decision to remove the handle was not based on meteorological charts or social prejudice or watered-down medieval humorology; it was based on a methodical survey of the actual social patterns of the epidemic, confirming predictions put forward by an underlying theory of the disease’s effect on the human body. It was based on information that the city’s own organization had made visible. For the first time, the V. cholerae’s growing dominion over the city would be challenged by reason, not superstition.

But learning to listen to reason takes time, particularly among the general public of Broad Street, who had heard nothing but superstition from the authorities for as long as cholera had been in London. When the Board of Governors removed the handle on Friday morning, the act was met with open jeering and derision by the passersby who chanced to witness it. Their bafflement is not hard to understand. For many survivors, Broad Street water had been their primary medicine. And now the authorities were going to cut off the supply? Were they trying to wipe out the entire neighborhood?

It was not just the Soho locals who were deaf to Snow’s reason. The very day that the local Board of Governors removed the handle, the president of the national Board of Health, Benjamin Hall, issued directives for the three-man committee he had formed to investigate the Broad Street outbreak. The inspectors were asked to perform a house-to-house survey through the entire neighborhood and report back on a long list of environmental conditions. It is worth quoting the directives in their entirety, since the list captures perfectly the miasmatic obsessions of the Board of Health:

Structural peculiarities of the Streets as regards Ventilation.

Nuisances, slaughter-houses, noxious trades, etc.

Smells in the streets and their source, gully grates, gutters, etc; whether the gully grates trapped, whether cases and deaths more numerous in houses near gully grates.

Smells in houses and their source, such smells worse during the night, or in the morning before the houses or shops were opened.

Whether the house had privy, or water-closet or cesspool and the position of these; whether complaints of smells from them; whether they were in good condition; whether the water-closets were well supplied with water; whether the house drainage stopped.… This district has been lately drained. Ascertain how many of the houses have drains connected with the new sewers; whether the house drains pass under the house to reach the sewer; the structure of the house drains, pipe or brick drains, and their condition; whether subject to stoppage, or smells from them.

Examine the basements as to the depth of the floor below the level of the street; whether there had been any accumulations of house refuse in these basements, or in the adjoining cellars before the outbreak. Consider the effect of these conditions on the general ventilation of the house, especially at night….

Examine the houses as to their general cleanliness and means of ventilation. Examine also the back yards, and inquire what was their condition before the epidemic. Note if they be flagged or filthy.

Examine whether the disease occurred in the upper or lower flats. Get, if possible, the proportion of cases in the flats.

Estimate as closely as you can the condition of the inhabitants as to overcrowding, personal cleanliness, habits, diet, etc.

Get the number of cases in each house, and the number of deaths of persons who lived in each house.

Examine the water supply as to its source, quality, amount, whether drawn from pipes or water-butts, and the condition of the butts.

Note the general condition of the streets and courts, and inquire what was the state of the cleansing before the outbreak.

Examine whether the disturbance of the ground in making a sewer through the old burial ground in Little Marlborough Street, or the filtrations from it into the sewer, or the drainage of any nuisance into the general sewerage of the district had had any effect, or whether the sewers had accumulations in them that might have been injurious.

Hall’s instructions for his cholera committee offer a brilliant case study in how dominant intellectual paradigms can make it more difficult for the truth to be established, even if the people involved are smart and attentive and methodical in their research. Hall’s list is a kind of straitjacket for an eventual document. You can tell from just scanning the instructions what kind of document they will ultimately produce: a rich and impossibly detailed inventory of the smells of Soho circa 1854. Half of the categories specifically mention smell and ventilation, and the few directives that might potentially be relevant to the waterborne theory of the disease—such as the condition of the cesspools—are specifically colored by Hall’s concern about smell in each instance.

In all, Benjamin Hall delivered about fifty specific instructions to his committee. Only two of them—regarding the quality and source of the water supply—were essential to proving or disproving Snow’s waterborne theory. But of course, on their own, those two variables were close to meaningless. Snow himself had detected nothing unusual in the water on Monday morning, at the height of the epidemic. Analyzing the quality of the water using the available technologies of the day couldn’t shed light on the mystery either way: there was nothing to see. Pacini had caught a glimpse of the bacteria in his microscope that year, but he would be alone in his discovery for three decades. The most reliable way to “see” the cholera was indirectly, in the way the drinking habits of the neighborhood mapped onto the patterns of disease and death that Farr had captured in the Weekly Returns. If you failed to superimpose those two data sets, the power and clarity of the waterborne theory disappeared. But Hall never asked his committee to investigate the drinking habits of the population, much less compare those habits to the overall distribution of deaths.

It’s crucial to note that Hall was not blind to the basic epidemiological principles that governed Snow’s work—that the cause of a disease can be deduced by observing statistically unusual patterns in the course of an epidemic. Hall requested that the investigators report on whether the cholera deaths were concentrated around gully gates or the site of the plague burial ground. But the waterborne theory did not rise to that level of scrutiny. Despite the fact that Snow had published on the subject, and despite Snow’s numerous conversations with William Farr about cholera and the water supply, the president of the Board of Health did not find it necessary to determine whether there was an unusual concentration of deaths around any of the neighborhood’s sources of drinking water. Hall’s instructions had rigged the game against Snow’s theory from the very outset.

But Hall’s task force would not be the only one investigating the Broad Street epidemic. In the weeks and months that followed the outbreak, another group would probe the neighborhood, piecing together the story, looking for clues. And at its center would be the one man who probably knew the neighborhood as intimately as anyone in Soho: Henry Whitehead.


NEWS OF THE PUMP HANDLE’S REMOVAL HAD STRUCK WHITEhead as being particularly foolish. When he first heard the contaminated-pump theory that Friday, he reacted with a quick dismissal, siding with the jeering throngs on Broad Street. This will be easy enough to disprove, he thought. And Whitehead was uniquely equipped to do the disproving. Snow’s two-day investigation couldn’t compete with the bedside hours Whitehead had logged since the outbreak first erupted on Friday. The young curate had already been constructing arguments against other prevailing theories. Now he would add the waterborne theory to the list. The Board of Governers might have been easily swayed by Dr. Snow’s demographic sleight of hand, but they didn’t know the neighborhood as well as Whitehead did; they hadn’t seen a girl drink seventeen quarts of pump water and survive. It would take some additional research, Whitehead knew, but he was confident that the pump would be exonerated in time.

“Every limit is a beginning as well as an ending,” George Eliot would write a few years later in Middlemarch. So it is with the story of the pump handle’s removal. It was the end of the Broad Street well’s assault on Golden Square, and the beginning of a new era of public health. But it does not offer the easy closure of the detective story. The remaining residents did not gather around Dr. Snow to celebrate his solving the mystery of Broad Street; Benjamin Hall did not drop his miasma obsessions overnight; even the Board of Governers remained unimpressed with Snow’s theory, though they followed his advice. And Henry Whitehead was so unconvinced by the case against the pump that he vowed to disprove it. So the true narrative arc of the Broad Street outbreak turns out to have a dialectical twist at its end: in persuading the otherwise incompetent Board of Governers to follow his advice, Snow awakened the one adversary who possessed more local knowledge of the outbreak than himself. In overcoming one opponent, Snow created an even more daunting challenge for his waterborne theory. Snow still had a long list of potential converts to win over: Benjamin Hall and his miasma-addled investigators; William Farr; the editors of The Lancet. But in the short term, his primary nemesis would be the Reverend Henry Whitehead.

WHITEHEAD HAD BEEN INFORMALLY ASSEMBLING CLUES FROM the very outset. On that Friday, before receiving word of the pump handle’s removal, he had ascended to the pulpit at St. Luke’s to give the daily sermon. Standing in front of his haggard parishioners in the half-empty church, he noted the disproportionate number of poor, elderly women in the pews. He congratulated them on their “remarkable immunity from the pestilence.” But even as he spoke the words, he wondered: How can this be? What kind of pestilence spares the old and the destitute?

In the months that followed, Whitehead and Snow explored Broad Street on separate but parallel tracks. Snow began integrating the data from his investigation into a new version of his cholera monograph from 1849, while writing a handful of articles for the medical journals that addressed the outbreak. The section of the monograph devoted to Broad Street began with these dramatic lines:

The most terrible outbreak of cholera which ever occurred in this kingdom, is probably that which took place in Broad Street, Golden Square, and the adjoining streets, a few weeks ago. Within two hundred and fifty yards of the spot where Cambridge Street joins Broad Street, there were upwards of five hundred fatal attacks of cholera in ten days. The mortality in this limited area probably equals any that was ever caused in this country, even by the plague; and it was much more sudden, as the greater number of cases terminated in a few hours. The mortality would undoubtedly have been much greater had it not been for the flight of the population. Persons in furnished lodgings left first, then other lodgers went away, leaving their furniture to be sent for when they could meet with a place to put it in. Many houses were closed altogether, owing to the death of the proprietors; and, in a great number of instances, the tradesmen who remained had sent away their families: so that in less than six days from the commencement of the outbreak, the most afflicted streets were deserted by more than three-quarters of their inhabitants.

That fall, Whitehead quickly wrote and published a seventeen-page monograph titled The Cholera in Berwick Street. It was the first comprehensive look at the outbreak written for a general audience. Most of Whitehead’s inquiries over those initial weeks were aimed at taking stock of the outbreak’s reach and its duration. He began his monograph with a terse inventory:

Dufour’s Place. —Houses, 9; population 170; deaths, 9; houses without any deaths, 4. Rumour sadly exaggerated the mortality in this place.

Cambridge Street. —Houses, 14; population, 179; deaths, 16; deaths on the west side, 10; east, 6, of which 3 were in one house. Five houses escaped.

Whitehead described the strange lack of connection he had observed at the height of the outbreak between the sanitary conditions and the mortality rates in each residence. He noted that the model home on Peter Street—the very one that had been commended by the authorities several years back for its cleanliness—had suffered twelve deaths, the largest number of any residence in the neighborhood. He traced the devastation that the outbreak had leveled against the neighborhood’s families: “There were no less than 21 instances of husband and wife dying within a few days of each other. In one case, besides parents, 4 children also died. In another both parents and 3 of their 4 children. In another, a widow and 3 of her children.” Not fifteen yards from the front steps of St. Luke’s Church stood four houses that had, between them, lost thirty-three people.

Reading Whitehead’s monograph, you can sense the young curate grappling with the theological implications of the outbreak. A visitation of plague had to be, on some level, an expression of divine will, and in this case the divinity appeared to have singled out the parish of St. Luke’s for the most severe retribution imaginable. It must have been a vexing reality to face as a man of the cloth: of all the parishes in London, over the many years that cholera had ravaged the country, God had seen fit to subject Whitehead’s own small community to the most explosive epidemic attack in the history of the city. In the monograph, Whitehead initially professes an inability to explain such an event in terms of divine will, but then he offers a half-formed theory, one that itself follows a markedly dialectical logic:

God’s ways are equal, man’s ways are unequal; and another fact, less difficult to be accounted for, presents itself to our notice, even the unequal accumulation of filth and dirt, the overcrowding together of human beings, the culpable sufferance of ill-constructed streets and ill-ventilated houses, indifference to first principles of drainage and sewage, aggravating the pestilence in particular localities, but attracting little attention and exciting little alarm, till here and there a mine explodes, revealing to the startled population of an ill-managed city the peril of a position which admits of any one street or parish, and that none of the lowest and filthiest, becoming a huge charnel-house in a day or an hour.

Till here and there a mine explodes. The outbreak, as brutal as it was, nonetheless shed light on the poverty and despair of inner-city life, illuminating everyday suffering with the bright light of extraordinary despair. Whitehead had the story half right: the terrifying visibility of the outbreak did in fact sow the seeds of a cure. But it was not divine providence that drove the process. It was density. Crowd a thousand people into three city blocks and you create an environment where epidemic disease will flourish; but in flourishing, the disease reveals the telltale characteristics of its true nature. Its efflorescence points the way to its ultimate defeat. The Broad Street pump was a kind of urban antenna, sending out a signal through the surrounding neighborhood, a signal with a detectible pattern that allowed humans to “see” V. cholerae without the aid of microscopes. But without those thousand bodies crowded around the pump, the signal would have been lost, like a sound wave dissipating into silence in the vacuum of space.

In the weeks after the outbreak, Whitehead had observed enough of these patterns to debunk a number of prevailing theories in his monograph. His account of the devastation at Peter Street exposed the fallacy of the sanitary hypothesis; and he offered numerous cases of brave parishioners falling ill to combat the “fear kills” platitudes. He tabulated the ratio of deaths on upper and lower floors to demonstrate that the cholera had attacked both classes evenly. But despite his initial derision at the the pump handle’s removal, the Broad Street well goes unmentioned in the monograph. Perhaps Whitehead simply felt he hadn’t accumulated enough evidence against Snow’s case to include the waterborne theory in the text. Or perhaps his early inquiries had started to change his mind.

Either way, the monograph was only the beginning. Whitehead would end up pursuing details of the Broad Street outbreak further than he ever imagined in the coming months—further, indeed, than John Snow himself would venture. In late November, the vestry of St. James’ voted to form a committee to investigate the Broad Street outbreak, initially planning to produce a report based on a questionnaire circulated through the neighborhood, augmented by the data assembled by the Board of Health committee. But when the vestry approached Benjamin Hall, the Board’s president declined to share his committee’s findings—“principally on the ground that investigations of this kind were more valuable when independent.” The snub turned out to be fortuitous. Faced with limited returns from their questionnaire, and with no contribution from the Board of Health, the vestry recognized that they would have to assemble a team of their own investigators. On the merits of his recently published monograph, and recognizing the value of his knowledge of the community, they asked the Reverend Whitehead to join the committee. They also invited that local doctor who had been so agitated about the state of the Broad Street pump. Snow and Whitehead may not have agreed on the cause of the outbreak, but they were now working on the same team.

WHITEHEAD BEGAN HIS ASSAULT ON THE PUMP-CONTAMINATION theory by examining a crucial absence in Snow’s original survey of the neighborhood. Snow had focused almost exclusively on the Soho residents who had perished in the outbreak, detecting that an overwhelming majority of them had consumed Broad Street water before falling ill. But Snow had not investigated the drinking habits of the neighborhood residents who had survived the epidemic. If that group turned out to have drunk from the Broad Street pump at the same rate, then the whole basis for Snow’s theory would dissolve. The connection between pump drinking and cholera would be meaningless if most of the neighborhood—the dead and the living—were drinking from the pump. Most of the dead had probably also strolled down Broad Street at some point in the days leading up to the epidemic, but that didn’t mean that strolling down Broad Street caused cholera.

Whitehead’s local knowledge gave him a crucial edge in this investigation, in that he was uniquely able to track down the hundreds of residents who had fled the neighborhood in the weeks after the outbreak. Snow would have intuitively understood the importance of surveying the pump-drinking rates among the survivors, but the great majority of the survivors were unreachable to him that first week of September. And so Snow had been forced to build his case against the pump on his survey of the dead, augmented by a few odd cases of unlikely survival (the workhouse, the brewery). Whitehead, on the other hand, could draw upon the extensive social network he’d long ago established in the neighborhood to track down the émigrés from Golden Square. His investigation took him throughout the Greater London area in the months that followed his appointment to the committee; when he learned of former residents who had moved outside the city, he sent inquiries by post. In the end, he tracked down information on 497 residents of Broad Street, more than half the population that had lived there in the weeks before the outbreak.

As he threw himself into the investigation, sometimes visiting the same flat five separate times to pursue new leads, Whitehead felt his resistance to the pump-contamination theory fade. Again and again, the recollections of cholera survivors would eventually turn up some forgotten connection to the Broad Street pump. A young widow whose husband died on the first had originally told Whitehead that the couple had not been Broad Street drinkers. But several days later, a memory came back to her: on the night of the thirtieth her husband had asked her to fetch some water from the pump to drink with dinner. She herself had not consumed any. One woman whose husband and daughter had come down with the cholera (eventually surviving it), denied forthrightly that anyone in the house had ever favored the Broad Street water. But when she relayed the details of her curious interview with the Reverend Whitehead to the rest of the family, the daughter recalled that, no, she had in fact drunk from the Broad Street well in the days before the outbreak.

This last case was typical of the stories that Whitehead unraveled: the children turned out to offer the missing link to the pump. In performing his analysis of the neighborhood’s drinking customs, Whitehead noted how often the young people were asked to fetch water for their families. A visit to the Broad Street pump was a commonplace chore for any child over the age of six or seven, and their familiarity with the well meant that a number of neighborhood children had drunk from it without their parents’ knowing. As he listened to these accounts, Whitehead’s mind returned to the image of all those widows gathered at St. Luke’s on the day the pump handle was removed. At last he had a potential explanation for their immunity. It wasn’t that the ladies were somehow morally superior to the dead; it wasn’t that they possessed sturdier constitutions or more hygienic lifestyles. What united them all as a group was that they were old and infirm and living alone, with the result that they didn’t have anyone to fetch water for them.

As Whitehead tabulated his initial numbers, the case against the pump looked powerful indeed. Among the pump-water-drinking population, the rates of infection were along the lines that Snow had outlined in his original survey: for every two Broad Street drinkers who were not affected, there were three who fell ill. That ratio seemed even more striking when you compared it to the infection rates among those who had not drunk from the well: only one in ten of that group had been seized with the cholera. As much as he had resisted the waterborne theory, Whitehead found himself confronting the stubborn fact that choosing to drink from the well increased your odds of infection sevenfold.

Still, three objections to the pump-contamination theory continued to trouble Whitehead. Snow lived in Soho but he was not exactly a Broad Street regular, and Whitehead felt that his theory didn’t square with the Broad Street well’s long track record of supplying unusually pure water to the neighborhood. If a local watering hole was going to be infected with some kind of infectious agent, it was much more likely to be the foul-smelling supply at the Little Marlborough Street pump.

And then there were the survivors. The raw numbers made the case against the well look convincing, but Whitehead had a hard time shaking his firsthand observations: watching his parishioners drink gallons of Broad Street water from their seeming deathbeds—and then subsequently recover. Whitehead had his own survival in mind as well; he had drunk from the well at the very height of the outbreak, after all. If the well was truly poisoned, why had he been spared?

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 the 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





Comparison of the Meteorology of London, Worcester, Liverpool, Dunino, and Arbroath


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.

And so the miasma theory did not crumble immediately after the Broad Street outbreak, though its days were numbered. Eventually, Snow’s and Whitehead’s parallel investigations would be seen as the turning point in the battle against cholera. But it would take yet another outbreak—more than a decade later—for that narrative to take hold for good.

It is not known if Sarah Lewis ever learned that the final days she spent tending to her daughter had triggered the most devastating outbreak in the history of London. If so, the weight of the news must have been unbearable, because the outbreak she had unwittingly set in motion eventually killed her husband as well. Thomas Lewis had fallen ill that Friday, September 8, within hours of the pump handle’s removal. He fought the disease much longer than most, surviving for eleven days. The young policeman finally succumbed on the nineteenth of September, leaving a childless widow alone in a ruined neighborhood. The outbreak had begun at 40 Broad Street, and it ended there as well.

The timing of Thomas Lewis’ illness suggests one chilling alternative history. The Broad Street outbreak had subsided in part because the only viable route between the well and the neighborhood’s small intestines had run through the cesspool at 40 Broad. When baby Lewis died, the connection had died with it. But when her husband fell ill, Sarah Lewis began emptying the buckets of soiled water in the cesspool all over again. If Snow had not persuaded the Board of Governors to remove the handle when he did, the disease might have torn through the neighborhood all over again, the well water restocked with a fresh supply of V. cholerae. And so Snow’s intervention did not just help bring the outbreak to a close. It also prevented a second attack.

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