But Fessenden’s innovation had the most transformative effect on dry land, where ultrasound devices, using sound to see into a mother’s womb, revolutionized prenatal care, allowing today’s babies and their mothers to be routinely saved from complications that had been fatal less than a century ago. Fessenden had hoped his idea—using sound to see—might save lives; while he couldn’t persuade the authorities to put it to use in detecting U-boats, the oscillator did end up saving millions of lives, both at sea and in a place Fessenden would never have expected: the hospital.
Of course, ultrasound’s most familiar use involves determining the sex of a baby early in a pregnancy. We are accustomed now to think of information in binary terms: a zero or a one, a circuit connected or broken. But in all of life’s experiences, there are few binary crossroads like the sex of your unborn child. Are you going to have a girl or a boy? How many life-changing consequences flow out of that simple unit of information? Like many of us, my wife and I learned the gender of our children using ultrasound. We now have other, more accurate, means of determining the sex of a fetus, but we found our way to that knowledge first by bouncing sound waves off the growing body of our unborn child. Like the Neanderthals navigating the caves of Arcy-sur-Cure, echoes led the way.
There is, however, a dark side to that innovation. The introduction of ultrasound in countries such as China with a strong cultural preference for male offspring has led to a growing practice of sex-selective abortions. An extensive supply of ultrasound machines was introduced throughout China in the early 1980s, and while the government shortly thereafter officially banned the use of ultrasound to determine sex, the “back-door” use of the technology for sex selection is widespread. By the end of the decade, the sex ratio at birth in hospitals throughout China was almost 110 boys to every 100 girls, with some provinces reporting ratios as high as 118:100. This may be one of the most astonishing, and tragic, hummingbird effects in all of twentieth-century technology: someone builds a machine to listen to sound waves bouncing off icebergs, and a few generations later, millions of female fetuses are aborted thanks to that very same technology.
The skewed sex ratios of modern China contain several important lessons, setting aside the question of abortion itself, much less gender-based abortion. First, they are a reminder that no technological advance is purely positive in its effects: for every ship saved from an iceberg, there are countless pregnancies terminated because of a missing Y chromosome. The march of technology has its own internal logic, but the moral application of that technology is up to us. We can decide to use ultrasound to save lives or terminate them. (Even more challenging, we can use ultrasound to blur the very boundaries of life, detecting a heartbeat in a fetus that is only weeks old.) For the most part, the adjacencies of technological and scientific progress dictate what we can invent next. However smart you might be, you can’t invent an ultrasound before the discovery of sound waves. But what we decide to do with those inventions? That is a more complicated question, one that requires a different set of skills to answer.
But there’s another, more hopeful lesson in the story of sonar and ultrasound, which is how quickly our ingenuity is able to leap boundaries of conventional influence. Our ancestors first noticed the power of echo and reverberation to change the sonic properties of the human voice tens of thousands of years ago; for centuries we have used those properties to enhance the range and power of our vocal chords, from cathedrals to the Wall of Sound. But it’s hard to imagine anyone studying the physics of sound two hundred years ago predicting that those echoes would be used to track undersea weapons or determine the sex of an unborn child. What began with the most moving and intuitive sound to the human ear—the sound of our voices in song, in laughter, sharing news or gossip—has been transformed into the tools of both war and peace, death and life. Like those distorted wails of the tube amp, it is not always a happy sound. Yet, again and again, it turns out to have unsuspected resonance.
4. Clean
In December 1856, a middle-aged Chicago engineer named Ellis Chesbrough traveled across the Atlantic to take in the monuments of the European continent. He visited London, Paris, Hamburg, Amsterdam, and a half dozen other towns—the classic Grand Tour. Only Chesbrough hadn’t made his pilgrimage to study the architecture of the Louvre or Big Ben. He was there, instead, to study the invisible achievements of European engineering. He was there to study the sewers.
Chicago, in the middle of the nineteenth century, was a city in dire need of expertise about waste removal. Thanks to its growing role as a transit hub bringing wheat and preserved pork from the Great Plains to the coastal cities, the city had gone from hamlet to metropolis in a matter of decades. But unlike other cities that had grown at prodigious rates during this period (such as New York and London), Chicago had one crippling attribute, the legacy of a glacier’s crawl thousands of years before the first humans settled there: it was unforgivingly flat. During the Pleistocene era, vast ice fields crept down from Greenland, covering present-day Chicago with glaciers that were more than a mile high. As the ice melted, it formed a massive body of water that geologists now call Lake Chicago. As that lake slowly drained down to form Lake Michigan, it flattened the clay deposits left behind by the glacier. Most cities enjoy a reliable descending grade down to the rivers or harbors they evolved around. Chicago, by comparison, is an ironing board—appropriately enough, for the great city of the American plains.
Building a city on perfectly flat land would seem like a good problem to have; you would think hilly, mountainous terrain like that of San Francisco, Cape Town, or Rio would pose more engineering problems, for buildings and for transportation. But flat topographies don’t drain. And in the middle of the nineteenth century, gravity-based drainage was key to urban sewer systems. Chicago’s terrain also suffered from being unusually nonporous; with nowhere for the water to go, heavy summer rainstorms could turn the topsoil into a murky marshland in a matter of minutes. When William Butler Ogden, who would later become Chicago’s inaugural mayor, first waded through the rain-soaked town, he found himself “sinking knee deep in the mud.” He wrote to his brother-in-law, who had purchased land in the frontier town in a bold bet on its future potential: “You have been guilty of an act of great folly in making [this] purchase.” In the late 1840s, roadways made out of wood planks had been erected over the mud; one contemporary noted that every now and then one of the planks would give way, and “green and black slime [would] gush up between the cracks.” The primary system for sanitation removal was scavenging pigs roaming the streets, devouring the refuse that the humans left behind.
With its rail and shipping network expanding at extraordinary speed, Chicago more than tripled in size during the 1850s. That rate of growth posed challenges for the city’s housing and transportation resources, but the biggest strain of all came from something more scatological: when almost a hundred thousand new residents arrive in your city, they generate a lot of excrement. One local editorial declared: “The gutters are running with filth at which the very swine turn up their noses in supreme disgust.” We rarely think about it, but the growth and vitality of cities have always been dependent on our ability to manage the flow of human waste that emerges when people crowd together. From the very beginnings of human settlements, figuring out where to put all the excrement has been just as important as figuring out how to build shelter or town squares or marketplaces.
The problem is particularly acute in cities experiencing runaway growth, as we see today in the favelas and shantytowns of megacities. Nineteenth-century Chicago, of course, had both human and animal waste to deal with, the horses in the streets, the pigs and cattle awaiting slaughter in the stockyards. (“The river is positively red with blood under the Rush Street Bridge and past down our factory,” one industrialist wrote. “What pestilence may result from it I don’t know.”) The effects of all this filth were not just offensive to the senses; they were deadly. Epidemics of cholera and dysentery erupted regu
larly in the 1850s. Sixty people died a day during the outbreak of cholera in the summer of 1854. The authorities at the time didn’t fully understand the connection between waste and disease. Many of them subscribed to the then-prevailing “miasma” theory, contending that epidemic disease arose from poisonous vapors, sometimes called “death fogs,” that people inhaled in dense cities. The true transmission route—invisible bacteria carried in fecal matter polluting the water supply—would not become conventional wisdom for another decade.
But while their bacteriology wasn’t well developed, the Chicago authorities were right to make the essential connection between cleaning up the city and fighting disease. On February 14, 1855, a Chicago Board of Sewerage Commissioners was created to address the problem; their first act was to announce a search for “the most competent engineer of the time who was available for the position of chief engineer.” Within a few months, they had found their man, Ellis Chesbrough, the son of a railway officer who had worked on canal and rail projects, and who was currently employed as chief engineer of the Boston Water Works.
It was a wise choice: Chesbrough’s background in railway and canal engineering turned out to be decisive in solving the problem of Chicago’s flat, nonporous terrain. Creating an artificial grade by building sewers deep underground was deemed too expensive: tunneling that far below the surface was difficult work using nineteenth-century equipment, and the whole scheme required pumping the waste back to the surface at the end of the process. But here Chesbrough’s unique history helped him come up with an alternate scenario, reminding him of a tool he had seen as a young man working the railway: the jackscrew, a device used to lift multiton locomotives onto the tracks. If you couldn’t dig down to create a proper grade for drainage, why not use jackscrews to lift the city up?
Ellis Chesbrough, Chicago, circa 1870
Aided by the young George Pullman, who would later make a fortune building railway cars, Chesbrough launched one of the most ambitious engineering projects of the nineteenth century. Building by building, Chicago was lifted by an army of men with jackscrews. As the jackscrews raised the buildings inch by inch, workmen would dig holes under the building foundations and install thick timbers to support them, while masons scrambled to build a new footing under the structure. Sewer lines were inserted beneath buildings with main lines running down the center of streets, which were then buried in landfill that had been dredged out of the Chicago River, raising the entire city almost ten feet on average. Tourists walking around downtown Chicago today regularly marvel at the engineering prowess on display in the city’s spectacular skyline; what they don’t realize is that the ground beneath their feet is also the product of brilliant engineering. (Not surprisingly, having participated in such a Herculean undertaking, when George Pullman set out to build his model factory town of Pullman, Illinois, several decades later, his first step was to install sewer and water lines before breaking ground on any of the buildings.)
Amazingly, life went on largely undisturbed as Chesbrough’s team raised the city’s buildings. One British visitor observed a 750-ton hotel being lifted, and described the surreal experience in a letter: “The people were in [the hotel] all the time coming and going, eating and sleeping—the whole business of the hotel proceeding without interruption.” As the project advanced, Chesbrough and his team became ever more daring in the structures they attempted to raise. In 1860, engineers raised half a city block: almost an acre of five-story buildings weighing an estimated thirty-five thousand tons was lifted by more than six thousand jackscrews. Other structures had to be moved as well as lifted to make way for the sewers: “Never a day passed during my stay in the city,” one visitor recalled, “that I did not meet one or more houses shifting their quarters. One day I met nine. Going out on Great Madison Street in the horse cars we had to stop twice to let houses get across.”
The result was the first comprehensive sewer system in any American city. Within three decades, more than twenty cities around the country followed Chicago’s lead, planning and installing their own underground networks of sewer tunnels. These massive underground engineering projects created a template that would come to define the twentieth-century metropolis: the idea of a city as a system supported by an invisible network of subterranean services. The first steam train traveled through underground tunnels beneath London in 1863. The Paris metro opened in 1900 followed shortly by the New York subway. Pedestrian walkways, automobile freeways, electrical and fiber-optic cabling coiled their way beneath city streets. Today, entire parallel worlds exist underground, powering and supporting the cities that rise above them. We think of cities intuitively now in terms of skylines, that epic reach toward the heavens. But the grandeur of those urban cathedrals would be impossible without the hidden world below grade.
Raising the Briggs House—a brick hotel in Chicago— circa 1857.
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OF ALL THOSE ACHIEVEMENTS, more than the underground trains and high-speed Internet cables, the most essential and the most easily overlooked is the small miracle that sewer systems in part make possible: enjoying a glass of clean drinking water from a tap. Just a hundred and fifty years ago, in cities around the world, drinking water was effectively playing Russian roulette. When we think of the defining killers of nineteenth-century urbanism, our minds naturally turn to Jack the Ripper haunting the streets of London. But the real killers of the Victorian city were the diseases bred by contaminated water supplies.
This was the—literally—fatal flaw in Chesbrough’s plan for the sewers of Chicago. He had brilliantly conceived a strategy to get the waste away from the streets and the privies and the cellars of everyday life, but almost all of his sewer pipes drained into the Chicago River, which emptied directly into Lake Michigan, the primary source of the city’s drinking water. By the early 1870s, the city’s water supply was so appalling that a sink or tub would regularly be filled with dead fish, poisoned by the human filth and then hoovered up into the city’s water pipes. In summer months, according to one observer, the fish “came out cooked and one’s bathtub was apt to be filled with what squeamish citizens called chowder.”
Workmen make progress on the Metropolitan Line underground railway works at King’s Cross, London.
Upton Sinclair’s novel The Jungle is generally considered to be the most influential literary work in the muckraking tradition of political activism. Part of the power of the book came from its literal muckraking, describing the filth of turn-of-the-century Chicago in excruciating detail, as in this description of the wonderfully named Bubbly Creek, an offshoot of the Chicago River:
The grease and chemicals that are poured into it undergo all sorts of strange transformations, which are the cause of its name; it is constantly in motion, as if huge fish were feeding in it, or great leviathans disporting themselves in its depths. Bubbles of carbonic gas will rise to the surface and burst, and make rings two or three feet wide. Here and there the grease and filth have caked solid, and the creek looks like a bed of lava; chickens walk about on it, feeding, and many times an unwary stranger has started to stroll across, and vanished temporarily.
Chicago’s experience was replicated around the world: sewers removed human waste from people’s basements and backyards, but more often than not they simply poured it into the drinking water supply, either directly, as in the case of Chicago, or indirectly during heavy rainstorms. Drawing plans for sewer lines and water pipes on the scale of the city itself would not be sufficient for the task of keeping the big city clean and healthy. We also needed to understand what was happening on the scale of microorganisms. We needed both a germ theory of disease—and a way to keep those germs from harming us.
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WHEN YOU GO BACK to look at the initial reaction from the medical community to the germ theory, the response seems beyond comical; it simply doesn’t compute. It is a well-known story that the Hungarian physician Ignaz Semmelweis was roundly mocked and criticized by the medical establishment when he first
proposed, in 1847, that doctors and surgeons wash their hands before attending to their patients. (It took almost half a century for basic antiseptic behaviors to take hold among the medical community, well after Semmelweis himself lost his job and died in an insane asylum.) Less commonly known is that Semmelweis based his initial argument on studies of puerperal (or “childbed”) fever, where new mothers died shortly after childbirth. Working in Vienna’s General Hospital, Semmelweis stumbled across an alarming natural experiment: the hospital contained two maternity wards, one for the well-to-do, attended by physicians and medical students, the other for the working class who received their care from midwives. For some reason, the death rates from puerperal fever were much lower in the working-class ward. After investigating both environments, Semmelweis discovered that the elite physicians and students were switching back and forth between delivering babies and doing research with cadavers in the morgue. Clearly some kind of infectious agent was being transmitted from the corpses to the new mothers; with a simple application of a disinfectant such as chlorinated lime, the cycle of infection could be stopped in its tracks.
There may be no more startling example of how much things have changed in our understanding of cleanliness over the past century and a half: Semmelweis was derided and dismissed not just for daring to propose that doctors wash their hands; he was derided and dismissed for proposing that doctors wash their hands if they wanted to deliver babies and dissect corpses in the same afternoon.
How We Got to Now: Six Innovations That Made the Modern World Page 10