The Ghost Map

by Steven Johnson

  Radcliffe and Whitehead, along with other investigators, quickly uncovered a number of negligent practices at the East London company that had allowed the nearby River Lea to contaminate the groundwater around the company’s reservoir at Old Ford. Eventually, the index cases at Bromley-by-Bow were tracked down; the doomed couple’s water closet turned out to empty into the River Lea less than a mile from the Old Ford reservoir. In the end, the link to the East London water supply proved to be even more statistically pronounced than the link to the Broad Street pump had been in 1854. Ninety-three percent of the dead were eventually found to be East London Water customers.

  This time, the verdict was nearly unanimous, and Snow’s visionary research was widely acknowledged. Farr himself delivered some of the most powerful words in testimony before Parliament the year after the outbreak. He began in a satiric mode, deriding the commercial interests that sustained the miasma theory despite so much evidence to the contrary:

  As the air of London is not supplied like water to its inhabitants by companies, the air has had the worst of it both before Parliamentary Committees and Royal Commissions. For air no scientific witnesses have been retained, no learned counsel has pleaded; so the atmosphere has been freely charged with the propagation and the illicit diffusion of plagues of all kinds; while Father Thames, deservedly reverenced through the ages, and the water gods of London, have been loudly proclaimed immaculate and innocent.

  Of course, one man had in fact served as “learned counsel” for the atmosphere, in much reviled testimony ten years before. And in turn, Farr acknowledged John Snow’s defining role:

  Dr. Snow’s theory turned the current in the direction of water, and tended to divert attention from the atmospheric doctrine.… The theory of the East wind with cholera on its wings, assailing the East End of London, is not at all borne out by experience of previous epidemics.… An indifferent person would have breathed the air without any apprehension; but only a very robust scientific witness would have dared to drink a glass of the waters of the Lea at Old Ford after filtration.

  Farr’s conversion to Snow’s doctrine was so complete that he literally rewrote history to make it appear as though Snow’s ideas had more initial success than they had actually enjoyed. In the introduction to his report on the 1866 outbreak, Farr, alluding to the investigation into the Broad Street case, delivers this stunning account of the Board of Health committee’s findings:

  The final report of the scientific committee proved conclusively the extensive influence of water as a medium for the diffusion of the disease in its fatal forms.… Dr. Snow’s view that the cholera-stuff was distributed in all its activity through water was confirmed. The special report… inculpated the Broad-street pump to some extent in the terrible outbreak of the St. James district. But the subject was further and more conclusively investigated by a committee, aided by Dr. Snow and by the Rev. Henry Whitehead.

  Either Farr was willfully distorting the record, or—like so many subsequent accounts—his memory of the Vestry Committee’s investigation had suppressed the Board of Health report. Recall the exact wording of the Board of Health’s “confirmation” of Snow’s theory: “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.” With confirmations like that, who needs criticisms?

  Still, the waterborne hypothesis had at long last entered the dominant scientific paradigm. It pleased Whitehead to know that he had once again helped his old friend’s ideas find a larger audience. Even The Lancet came around, editorializing in the weeks after the 1866 outbreak:

  The researches of Dr. Snow are among the most fruitful in modern medicine. He traced the history of cholera. We owe to him chiefly the severe induction by which the influence of the poisoning of water-supplies was proved. No greater service could be rendered to humanity than this; it has enabled us to meet and combat the disease, where alone it is to be vanquished, in its sources or channels of propagation.… Dr. Snow was a great public benefactor, and the benefits which he conferred must be fresh in the minds of all.

  Apparently Dr. Snow found a way out of that “gully-hole” after all.

  BY THE LAST DECADES OF THE NINETEENTH CENTURY, THE germ theory of disease was everywhere ascendant, and the miasmatists had been replaced by a new generation of microbe hunters charting the invisible realm of bacterial and viral life. Shortly after discovering the tuberculosis bacillus, the German scientist Robert Koch isolated Vibrio cholerae while working in Egypt in 1883. Koch had inadvertently replicated Pacini’s discovery of thirty years earlier, but the Italian’s work had been ignored by the scientific establishment, and so it was Koch who won the initial round of acclaim for identifying the agent that had caused so much trauma over the preceding century. History would come around to the Italian, though. In 1965, Vibrio cholerae was formally renamed Vibrio cholerae Pacini 1854.

  Even these advances were not enough to convince a few remaining stalwarts—like Edwin Chadwick, who went to his grave in 1890 an unrepentant believer in the disease-causing powers of miasma. But most public-health institutions reoriented themselves around the new science. Establishing sanitary water supplies and waste-removal systems became the central infrastructure project of every industrialized city on the planet. The appearance of the electrical grid, around the turn of the century, tends to attract more attention, but it was the building of the invisible grid of sewer lines and freshwater pipes that made the modern city safe for the endless consumer delights that electricity would bring. Bazalgette’s project was a model for the world to emulate. By 1868, the pumping station at Abbey Mills was finally completed, which meant the northern branch of Bazalgette’s grand sewer system was fully operational. By the mid-1870s, the entire system was online. Sewage continued to be pumped into the eastern end of the Thames until 1887, when the city began dumping waste into the open sea.

  The changes ushered in by the sewer system were manifold: fish returned to the Thames; the stench abated; the drinking water became markedly more appetizing. But one change stood out above all the others. In all the years that have passed since Henry Whitehead helped track down the Old Ford reservoir contamination in 1866, London has not experienced a single outbreak of cholera. The battle between metropolis and microbe was over, and the metropolis had won.

  Cholera would continue to terrorize Western cities into the first decades of the twentieth century, but with London’s successful engineering project as a model, the outbreaks usually prodded the local authorities into modernizing their civic infrastructure. One such outbreak hit Chicago in 1885, after a heavy storm flushed the sewage collecting in the Chicago River far enough into Lake Michigan that it reached the intake system for the city’s drinking water. Ten percent of the city’s population died in the ensuing outbreak of cholera and typhoid, and the deaths ultimately led to the city’s epic effort to reverse the flow of the Chicago River, sending the sewage away from the water supply. Hamburg had built a modern sewage system in the 1870s, modeled largely on London’s, but the design had been flawed, and in 1892 cholera returned to claim nearly ten thousand lives out of a population one-seventh that of London. Because the major cholera epidemics of the preceding sixty years had all jumped the English Channel from Hamburg, Londoners waited anxiously as news of the German outbreak came over the wires. But their concern was unwarranted. Bazalgette’s defenses held, and the cholera never appeared on British shores.

  By the 1930s, cholera had been reduced to an anomaly in the world’s industrialized cities. The great killer of the nineteenth-century metropolis had been tamed by a combination of science, medicine, and engineering. In the developing world, however, the disease continues to be a serious threat. A strain of V. cholerae known as “El Tor” killed thousands in India and Bangladesh in the 1960s and 1970s. An outbreak in South America in the early 1990s infected more than a million people, killing at least ten thousand. In the summer of 2003, damage to the water-supply system from
the Iraq War triggered an outbreak of cholera in Basra.

  There is a fearful symmetry to these trends. In many ways, the struggles of the developing world mirror the issues that confronted London in 1854. The megacities of the developing world are wrestling with the same problems of uncharted and potentially unsustainable growth that London faced 150 years ago. In 2015, the five largest cities on the planet will be Tokyo, Mumbai, Dhaka, São Paulo, and Delhi—all of them with populations above 20 million. The great preponderance of that growth will be driven by so-called squatter or shantytown developments—entire sprawling cities developed on illegally occupied land, without any traditional infrastructure or civic planning supporting their growth. The scavenger classes of Victorian London have been reborn in the developing world, and their numbers are truly staggering. There are a billion squatters on earth now, and some estimates suggest that their numbers will double in the next twenty years. It’s entirely possible that a quarter of humanity will be squatters by 2030. All the characters of the Victorian underground economy—the mud-larks and toshers and costermongers—may have largely disappeared from cities in the developed world, but everywhere else on the planet their numbers are exploding.

  Squatter cities lack most of the infrastructure and creature comforts of developed metropolitan life, but they are nonetheless spaces of dynamic economic innovation and creativity. Some of the oldest shantytown developments—the Rocinha area in Rio de Janeiro, Squatter Colony in Mumbai—have already matured into fully functioning urban areas with most of the comforts we’ve come to expect in the developed world: improvised wood shacks giving way to steel and concrete; electricity; running water; even cable television. The main road in the squatter village of Sultaneyli in Istanbul is lined with six-story buildings, bustling with the commerce of ordinary city life: banks, restaurants, shops. And all of this has been accomplished without title deeds, without urban planners, without government-created civic infrastructure, on land that it is, technically speaking, illegally occupied. The squatter communities are not, by any measure, sinkholes of poverty and crime. They are where the developing world goes to get out of poverty. The writer Robert Neuwirth puts it best in his mesmerizing account of squatter culture, Shadow Cities: “With makeshift materials, they are building a future in a society that has always viewed them as people without a future. In this very concrete way, they are asserting their own being.”

  But that hope needs to be tempered with caution. The squatters still face significant obstacles. Arguably the most pressing obstacle is the one that confronted London a century and a half ago: the lack of clean water. Over 1.1 billion people lack access to safe drinking water; nearly 3 billion—almost half the planet—do not possess basic sanitation services: toilets, sewers. Each year 2 million children die from diseases—including cholera—that result directly from these unsanitary conditions. And so the megacities of the twenty-first century will have to learn all over again the lessons that London muddled through in the nineteenth. They’ll be dealing with 20 million people, instead of 2 million, but the scientific and technological wisdom available to them far exceeds what Farr and Chadwick and Bazalgette had at their disposal.

  Some of the most ingenious solutions now being proposed take us back to the waste-recycling visions that captivated so many Victorian minds. The inventor Dean Kamen has developed two affiliated machines—each the size of a dishwasher—that together can provide electricity and clean water to rural villages or shantytown communities that lack both. The power generator runs off a readily available fuel—cow dung—though Kamen says it will run off “anything that burns.” Its output can power up to seventy energy-efficient bulbs. The ambient heat from the generator can be used to run the water purifier, which Kamen nicknamed Slingshot. The device accepts any form of water, including raw sewage, and extracts the clean water through vaporization. Kamen’s prototype includes a “manual” featuring a single instruction: just add water. Just as the pure-finders once roamed London, recycling dog excrement for the leather tanners, the squatters of tomorrow may end up solving the sanitation problems of their community by using the very substances—animal and human waste—that cause the problems in the first place.

  One cannot be unduly optimistic about how these megacities will face their potential crises in the coming years. There may be new technologies that enable the squatter communities to concoct public health solutions on their own, but governments will obviously need to play a role as well. It took industrial London a hundred years to mature into a city with clean water and reliable sanitation. The scavenger classes that Mayhew analyzed with such detail no longer exist in London, but even the wealthiest cities in the developed world continue to face problems of homelessness and poverty, particularly in the United States. But the developed cities no longer appear to be on a collision course with themselves, the way London did in the nineteenth century. And so it may take the megacities of the developing world a century to reach that same sense of equilibrium, and during that period there will no doubt be episodes of large-scale human tragedy, including cholera outbreaks that will claim far more lives than were lost in Snow’s time. But the long-term prospects for urban life, even in these vast new sprawling “organisms,” are solid ones. It’s likely the megacities will mature faster than London did, precisely because of all the forms of expertise that were in embryo during the Broad Street events: epidemiology, public infrastructure engineering, waste management and recycling. And of course all that expertise has been greatly amplified by the connective powers of the Web, linking institutional knowledge with the local knowledge of amateurs to an extent that Snow and Whitehead could never have imagined.

  It has never been easier for that local knowledge to find its way onto a map, making patterns of health and sickness (as well as less perilous matters) visible to experts and laypeople in new ways. The descendants of Snow’s Broad Street map are now ubiquitous on the World Wide Web. Instead of Snow and Whitehead knocking on doors, and William Farr tabulating physicians’ reports, we now have far-flung networks of health providers and government officials reporting outbreaks to centralized databases, where they are automatically mapped and published online. A service called GeoSentinel tracks infectious diseases among travelers; the CDC publish a weekly update on the current state of influenza in the United States, along with a near-endless array of charts and maps documenting the different strains of flu circulating through the national bloodstream. The popular ProMED-mail e-mail list offers a daily update on all the known disease outbreaks flaring up around the world, which surely makes it the most terrifying news source known to man. The technology has advanced dramatically, but the underlying philosophy remains the same: that there is something profoundly enlightening about seeing these patterns of life and death laid out in cartographic form. The bird’s-eye view remains as essential as it was back in 1854. When the next great epidemic does come, maps will be as crucial as vaccines in our fight against the disease. But again, the scale of the observation will have broadened considerably: from a neighborhood to an entire planet.

  The influence of the Broad Street maps extends beyond the realm of disease. The Web is teeming with new forms of amateur cartography, thanks to services like Google Earth and Yahoo! Maps. Where Snow inscribed the location of pumps and cholera fatalities over the street grid, today’s mapmakers record a different kind of data: good public schools, Chinese takeout places, playgrounds, gay-friendly bars, open houses. All the local knowledge that so often remains trapped in the minds of neighborhood residents can now be translated into map form and shared with the rest of the world. As in 1854, the amateurs are producing the most interesting work, precisely because they have the most textured, granular experience of their community. Anyone can create a map that shows you where streets intersect and where hotels are; we’ve had maps like that for centuries. The maps now appearing are of a different breed altogether: maps of local knowledge created by actual locals. They’re street-smart. They map the intangibles: blocks
that aren’t safe after dark, playgrounds that could use a renovation, local restaurants that have room for strollers, overvalued real estate offerings.

  Even ordinary Web pages can be explored geographically now. Both Yahoo! and Google have established a standard convention for “tagging” a given piece of information—a blog post, say, or a promotional website—with geographic coordinates that are automatically interpreted by search engines. Someone writes into an online community forum with a complaint about a local park and tags the message with the park’s exact location; someone writes up a mini-review of a new restaurant; someone posts a notice about a summer sublet that they’re offering. Up to now, all of those individual pieces of data possessed a location in the information space of the Web, in that they were associated with a URL—a “uniform resource locator.” Now those items can possess a location in real-world space as well. In the near future, we’ll use these geo-tags as we explore a new city, in much the way that we use search engines to explore the space of the Web today. Instead of looking for Web pages associated with a keyword or phrase, we’ll look for pages associated with the streetcorner we’re standing on. We’ll be able to build instantly the kind of bird’s-eye view of a neighborhood that Snow and Whitehead stitched together by hand over months of investigation.