by Sonia Shah
For Snow that could mean only one thing: cholera must be something that victims swallowed.15 Snow collected potent evidence in support of his theory. During a cholera outbreak in Soho in 1854, Snow went door-to-door interviewing local residents. He found, by plotting his results on a map, that nearly 60 percent of the residents who drew water from a popular drinking-water pump, on Broad Street, had sickened with cholera, compared to only 7 percent of those who didn’t. He even found out how the water got contaminated. With the help of a local priest named Henry Whitehead, he located a woman named Mrs. Lewis, who lived at 40 Broad Street near the well. They learned she had washed her cholera-infected baby’s diapers in a partially blocked cesspool situated less than three feet away from the pump’s shaft.
Finally, Snow correlated death rates with London residents’ drinking-water sources. Some of the city’s water companies distributed contaminated downstream water, while others tapped upstream waters, out of reach of the city’s sewers. In 1849, when both a water company called Lambeth and another called Southwark and Vauxhall drew water from the contaminated lower Thames, Snow found, both of the districts they served suffered equal numbers of cholera deaths. But after the Lambeth Company moved its intake pipes farther upstream, the death rate among its customers dropped to one-eighth that of the customers of the Southwark and Vauxhall Company.16
Snow had mustered a masterful case that dirty water, not miasmas, caused cholera. The trouble was that his findings undermined the fundamental tenet in miasmatic theory. It was as if he’d told a bunch of biologists that he had found life on the moon. Accepting such a seditious claim required disavowing principles that had governed medicine and medical practice for centuries.
The medical establishment responded much as the subjects of the anomalous card experiment did. They tried to call a red six of spades a black six of spades, assimilating and submerging Snow’s claims into the edifice of miasmatism. A committee was convened by the board of health to consider Snow’s findings. However agitated they may have felt, they did not reject them outright, most likely because although Snow was an outsider in terms of his expertise, he was an eminent figure among medical elites, who’d administered chloroform to the laboring queen and served as the president of the London Medical Society. And so, in their voluminous report—more than 300 pages, including a 352-page appendix with 98 tables, 8 figures, and 32 color plates—the committee agreed that cholera could indeed spread in water. But, they reported, that did not mean that Hippocratic principles were mistaken. Cholera could grow in either air or water, they said, and of the two modes, air played the decisive role. “It is not easy to say which of these media may have been the chief scene of poisonous fermentation,” the committee wrote. But on the whole, “it seems impossible to doubt that the influences … belong less to the water than to air.”17
This convoluted yet unmistakable dismissal might have discouraged some scientists, but not Snow. He continued to insist that miasmatic theory was wrong. Finally, the medical establishment was forced to denounce him outright. Not long after the committee issued its report, Snow testified in a parliamentary hearing against a board of health bill cracking down on industries that emit miasmas. The parliamentarians railed against his antimiasma stance. “Are the Committee to understand, taking the case of bone-boilers, that no matter how offensive to the sense of smell the effluvia that comes from bone-boiling establishments may be, yet you consider that it is not prejudicial to the health of the inhabitants of the district?” parliamentarians demanded. He assented. “You mean to say,” they followed up, “that the fact of breathing air which is tainted by decomposing matter, either animal or vegetable, will not be highly prejudicial to health?”
When Snow refused to budge, an edge of hysteria crept into the parliamentarians’ line of questioning. “Do you not know that the effect of breathing such tainted air is to produce violent sickness at the time?… Have you never known blood poisoned by inhaling putrid matter?… Do you not know that the effect of a very strong offensive smell is to produce vomiting?… Do you dispute the fact that putrid fever and typhus fever hang about places where there are open sewers?”18
The Lancet, Britain’s leading medical journal, reviewing Snow’s unflinching testimony against the bill, accused him of betraying the public’s health. “Why is it … that Dr. Snow is singular in his opinion? Has he any fact to show in proof?” the journal’s editors fumed. “No! But he has a theory, to the effect that animal matters are only injurious when swallowed!… The well whence Dr. Snow draws all sanitary truth is the main sewer … In riding his hobby very hard, he has fallen down through a gully-hole and has never since been able to get out again.”19
Rebuking Snow, Parliament passed the health board’s anti-stinky-fumes bill in July 1855. Other than convincing the local parish in Soho to remove the handle of the contaminated Broad Street pump (which probably didn’t have much effect on the cholera outbreak, since it had collapsed by then anyway), Snow’s findings on cholera left hardly a ripple on miasmatism’s imperturbable surface.
In 1858, Snow abandoned the study of cholera to write his magnum opus on anesthesia, On Chloroform and Other Anaesthetics. On June 10, as he wrote the final sentences, a paralyzing stroke catapulted him off his chair and onto the floor.20 He died six days later. The Lancet, still miffed at Snow’s disavowal of miasmatism, printed an abbreviated obituary, which pointedly didn’t mention his incendiary work on cholera.21
* * *
With cholera’s subversive cures squashed, nineteenth-century doctors continued to administer their Hippocratic treatments and interventions. These kept long-held principles comfortably intact.
They also made cholera much worse.
Nineteenth-century treatments for cholera increased its death toll from 50 to 70 percent.22 Since they considered cholera patients’ vomiting and diarrhea therapeutic, doctors treated patients with compounds that intensified the very symptoms that were killing them. They administered the toxic mercury compound mercurous chloride, or “calomel,” which induced vomiting and diarrhea.23 (Calomel, the eighteenth-century American physician and surgeon general Benjamin Rush wrote, was a “safe and nearly universal medicine.”)24 Physicians literally poisoned their patients with it, considering treatment complete only when the patient salivated excessively, his mouth turned brown, and his breath started to smell metallic—all signs that physicians today would recognize as mercury toxicity.25
They drained their cholera patients’ blood. “Bloodletting” had long been a cure-all therapy, enthusiastically endorsed by Galen himself. Each spring, people would line up to go to the doctor to be bled, just as they had since medieval times.26 The thinking behind the practice was that the removal of blood would restore the four “humors” whose interactions within the body and the environment shaped health status. Physicians considered it especially salutary for cholera patients, because it got rid of their strangely dark, thick blood (which Stevens had tried to rectify and which is now understood to be a sign of dehydration.27 “All the practitioners who have seen much of, and have written upon, this disease agree upon one point,” remarked Dr. George Taylor in The Lancet in 1831, “the immense advantage of bleeding at the commencement of the disease.”28
Most egregiously, they promoted the dumping of human waste into the drinking-water supply. According to miasmatic theory, the flush toilet, or “water closet,” improved human health by rapidly ridding human habitations of bad smells. People in London started installing them in the late eighteenth century. Because they considered the smells dangerous but the actual excreta harmless, they cared little about where the waste was dumped, so long as it was distant enough to save their noses from the odors. Thus they sent their waste through the sewers into the most convenient dump site, the Thames River, which ran through the city. The more excreta they deposited in the river, the safer they felt. Preventing cholera and other diseases required, as The Times put it, ensuring that there was “no filth in the sewers,” which carrie
d toilet waste, and “all in the river.” The city’s sewer commissioners proudly noted the huge volume of human waste the city’s toilets efficiently deposited into the river: twenty-nine thousand cubic yards in the spring of 1848, and eighty thousand cubic yards by the winter of 1849.29 They even discerned a correlation between mortality and the filthiness of the river. London’s death rate had declined, The Times reported in 1858, as “the Thames has grown fouler.”30
In fact, it was just the opposite, since London relied upon the Thames for its drinking water. Twice a day, when the tide in the North Sea rose, reversing the Thames’s downstream current, the plume of filth they dumped into the river flowed as far as fifty-five miles upstream into the intake pipes of the city’s drinking-water companies. Nevertheless, under the powerful influence of miasmatism, when cholera struck, Londoners believed it was not because too many flush toilets dumped human waste into the river but because too few did. Flush toilet sales, in the years after the 1832 epidemic in London, enjoyed “rapid and remarkable” growth, according to an 1857 report. Flush toilet sales enjoyed another spike after an 1848 outbreak of cholera. So many Londoners installed flush toilets over the 1850s that the city’s water use nearly doubled between 1850 and 1856.31
Hippocratic medicine, in other words, was a boon to Vibrio cholerae. It had probably played a similarly helpful role to other pathogens, too. Over its long tenure, historians judge Hippocratic medicine to have harmed more people than it helped. Nevertheless, as a system of thought it was remarkably resilient. It explained health and disease more effectively than the earlier ideas—that health and disease were the work of the gods—that it replaced. As Thomas Kuhn observes, “To be accepted as a paradigm, a theory must seem better than its competitors, but it need not, and in fact never does, explain all the facts with which it can be confronted.”32 That was certainly true of Hippocratic medicine. And once it was accepted as a paradigm, it took on its own momentum, helped along by the cognitive biases of its practitioners. Hippocratic principles themselves were “wonderfully versatile as an explanatory system,” as the historian Roy Porter has written. Its conception of the body as ruled by four bodily fluids (blood, phlegm, black bile, and yellow bile) could be correlated with all manner of external phenomena, such as the four seasons, the four stages of human development (infancy, youth, adulthood, old age), and the four elements (fire, air, water, earth). Physicians had been making correlations and adding nuance to Hippocratic principles for centuries, enriching it with layers of depth and meaning.33
And it was able to maintain an illusion of success. The kind of group-to-group comparisons that could have revealed the uselessness of its treatments were rarely undertaken, because Hippocratic medicine considered patients as “unique as snowflakes,” as one epidemiologist put it. There was no point in grouping them together and comparing their outcomes. If, in general, patients treated with mercury fared poorly compared to patients treated with other remedies, Hippocratic physicians would never have known.34 Furthermore, although some Hippocratic treatments were harmful, many were probably just useless. These could have seemed beneficial, thanks to placebo effects, by which medical interventions work simply because patients believe they will. (Experts suggest that the placebo effect may be responsible for a third of the apparent effectiveness of modern medicine.)35 Thus, while “for 2,400 years patients have believed that doctors were doing them good,” the historian David Wootton writes, “for 2,300 years they were wrong.”36
* * *
In a serendipitous twist, Parliament decided to start resewering London, a project that ultimately ended cholera transmission in the city, the very year that John Snow died. The fact that the resewering commenced so soon after Snow’s death has often led casual observers to conclude that the British medical establishment had accepted Snow’s insights. On the contrary, the resewering had nothing to do with John Snow and everything to do with miasmas.
The medical establishment had been agitating for a new sewer system for years before Snow made his claims about cholera. The social reformer Edwin Chadwick had advocated for new sewers in his hugely popular report, “On an Inquiry into the Sanitary Condition of the Labouring Population of Great Britain,” in 1842.37 The reason Chadwick and others wanted to resewer the city was to get rid of miasmas, more specifically, the gases that arose from the sewers. High tides regularly prevented the sewers from dumping their loads in the river, forcing the sewage inside the pipes to back up into the city. Miasmatists didn’t consider that in itself a problem, except that the backups allowed stinky sewer gases to escape and waft into unsuspecting Londoners’ nostrils, which they considered a serious public-health hazard. Stories of men who’d entered the sewers and been instantly suffocated by sewer gases abounded.38
But while miasmatic experts agreed on the value of resewering the city, they disagreed about just how to do it. Chadwick thought a whole new network of sewers should be built, to flush the gases (and the waste) into distant waterways and farms. Others, such as the surgeon and chemist Goldsworthy Gurney, thought sewers could simply be ventilated of their gases. The gases could then be passed through a steam bath and burned to render them odorless, and thus harmless. With the city unable to resolve the dispute, neither plan moved forward until a confluence of strange weather events made the stench of the sewers impossible to ignore.39
A heat wave hit the city in the summer of 1858. This followed a period of drought that had lowered the water level in the Thames River, exposing the thick layer of excreta that blanketed its banks. As the mercury climbed to over 100° Fahrenheit, a powerful stench started to emanate from the dried-up, waste-covered banks of the river.40
Newspapers dubbed the odor “the Great Stink.”
For people who believed that smell caused disease, the Great Stink augured catastrophe. Panic set in. “What is to become of us Londoners in the year of grace 1858?” the British Medical Journal asked. “Is this vast metropolis to be devastated by the plague?” “Everyone is crying out that something must be done!” the Medical Times and Review wrote. “We know that the stench from the mud-banks and from the water itself is so great,” wrote The Lancet, “that strong and healthy become faint, and even vomit, and that it produces fever.”41 People were being “struck down with the stench,” added the Journal of Public Health and Sanitary Review, “and of all kinds of fatal diseases, upspringing on the river’s banks.” “It stinks,” the City Press wrote, “and who so once inhales the stink can never forget it and can count himself lucky if he live to remember it.”42
The Thames had never been as stinky. More important, never before had the most powerful people in the city been as exposed to its odors. Thanks to a recent reconstruction, the Palace of Westminster where members of Parliament congregated enjoyed more than eight hundred feet of riverfront.43 And the elaborate ventilation system, which had been devised to protect their chambers from miasmas—and which would have sealed their chambers from the odors of the river—had been dismantled. That ventilation system had drawn in fresh air from the top of one of the palace’s three-hundred-foot towers, filtered the air through damp sheets and sprayed it with water, then forced it into the chambers of Parliament through thousands of tiny holes drilled in the floor. To minimize drafts, a rough horsehair carpet blanketed the floor holes. The system then extracted the “used” air through raised panels built into a glass ceiling. The windows in Parliament’s chambers, which opened into London’s stinky air, were never opened.44
But when parliamentarians complained of bouts of dizziness in 1852, the ventilation system was blamed and its designer (whom The Times called an “aerial Guy Fawkes”) dismissed.45 Goldsworthy Gurney—the man who believed that London’s sewers could continue to dump their loads into the river, so long as the sewer gases were combusted—took over the job of protecting Parliament from miasmas. One of his first acts was to pry open the windows, allowing the most powerful men in London to become intimately acquainted with the sights, sounds, and odors emanating from
the river below.
Thus, as the Great Stink rose from the river, it drifted into the open riverfront windows of Parliament’s chambers.46 Legislators fled the library and their meeting rooms, for fear of “being destroyed by the present pestilential condition of the River Thames,” as The Times noted. The leader of the house escaped while holding a handkerchief over his nose. The lords abandoned their committee rooms. There was worried talk of moving Parliament elsewhere. The stink interrupted the Court of Queen’s Bench, as physicians warned that “it would be dangerous to the lives of the jurymen, counsel and witnesses” if anyone remained in the reeking chambers. With the Great Stink enveloping the palace, by the end of June, Gurney sent notice to his bosses that he could no longer be responsible for the health of the House of Parliament.47
In fear of a plague, parliamentarians introduced legislation to speed the process of resewering the city. Their options were now more clear. With Gurney in disgrace, they adopted an alternative plan, that of the engineer Joseph Bazalgette. He proposed to build a system of intercepting sewers, which would divert all of London’s gases—and its waste—farther downstream of the city. And so, what John Snow’s map could not accomplish, Goldsworthy Gurney’s open windows did. By 1875, the new sewers had been built, Bazalgette had been knighted, the Thames was sewage-free, and cholera had been banished from London forever.