The Ghost Map: The Story of London's Most Terrifying Epidemic--and How It Changed Science, Cities, and the Modern World

by Steven Johnson

Surgeons prided themselves on their speed above all else, since extended procedures were unbearable for both doctor and patient.

In October of 1846, at Massachusetts General Hospital in Boston, a dentist named William Morton gave the first public demonstration of the use of ether as an anesthetic.

Snow quickly hypothesized that the unreliability of ether was likely a problem of dosage, and embarked on a series of interlinked experiments to determine the best mechanism for delivering the miracle gas.

Not only had Snow detected one of the fundamental properties of the gas within two weeks of first seeing it applied, he had also engineered a state-of-the-art medical device to deliver it.

By the end of 1848 he had published a seminal monograph on the theory and practice of anesthesia: On the Inhalation of the Vapour of Ether in Surgical Operations.

He became the most sought-after anesthesiologist in the city, assisting with hundreds of operations a year.

Snow was not interested in individual, isolated phenomena; he was interested in chains and networks, in the movement from scale to scale.

We don’t know exactly what sequence of events turned John Snow’s interest toward cholera in the late 1840s.

Certainly, the outbreak of 1848–1849, the most severe British outbreak in more than a decade, made cholera one of the most urgent medical riddles of its time.

But in 1848, the dispute was largely divided between two camps: the contagionists and the miasmatists.

Either cholera was some kind of agent that passed from person to person, like the flu, or it somehow lingered in the “miasma” of unsanitary spaces.

One survey of published statements from U.S. physicians during the period found that less than five percent believed the disease was primarily contagious.

the foul inner-city air was widely believed to be the source of most disease.

Even the contagionists—who embraced the idea that the disease was transmitted from person to person—failed to see merit in the waterborne scenario.

Snow’s detective work into cholera began when he noticed a telling detail in the published accounts of the 1848 epidemic.

the time the epidemic wound down, two years later, 50,000 people were dead.

The same doctor attended both Harnold and Blenkinsopp,

And yet he remained free of the disease.

In fact, the most puzzling element of the disease was that it seemed capable of traveling across city blocks, skipp...

Snow grasped that solving the mystery of cholera would lie in reconciling these two seemingly contradictory facts.

Snow embarked on a torrid stretch of inquiry: consulting with chemists who had studied the rice-water stools of cholera victims, mailing requests for information from the water and sewer authorities in Horsleydown, devouring accounts of the great epidemic of 1832.

Cholera, Snow argued, was caused by some as-yet-unidentified agent that victims ingested, either through direct contact with the waste matter of other sufferers or, more likely, through drinking water that had been contaminated with that waste matter.

Cholera wasn’t something you inhaled. It was something you swallowed.

The layout of the Thomas Street flats provided Snow with an ingenious control study for his inquiry.

Londoners living south of the Thames were far more likely to drink water that had originated in the river as it passed through Central London.

Londoners living north of the river drank from a variety of sources:

But the South London Water Works drew its supply from the very stretch of the river where most of the city’s sewers emptied.

of the 7,466 deaths in the metropolitan area during the 1848–1849 epidemic, 4,001 were located south of the Thames.

the same pattern repeated itself: the cholera seemed to segment itself around shared water supplies.

The reaction to Snow’s argument was positive but skeptical.

There was a correlation between water supply and cholera—that much Snow had convincingly proved. But he had not yet established a cause.

The Gazette did suggest one scenario that might settle the matter convincingly:

The experimentum crucis would be, that the water conveyed to a distant locality, where cholera had been hitherto unknown, produced the disease in all who used ...

When word arrived of a terrible outbreak in Golden Square, not ten blocks from his new offices on Sackville Street, he was ready.

So many casualties in such a short stretch of time suggested a central contaminated water source used by large numbers of people.

Snow and Whitehead shared one other common experience that night. They both spent those last ruminating hours in the company of water drawn from the Broad Street pump.

Whitehead began to hear talk spreading among his parishioners blaming the outbreak on the new sewers that had been constructed in recent years.

The residents were whispering that the excavations had disturbed the corpses buried there during the Great Plague of 1665, releasing infectious miasma into the neighborhood’s air.

The irony was that the terrified residents of Golden Square had it half right: those new sewers were in fact partly responsible for the outbreak that was devastating the city.

Newspapers were the only source of daily information about the wider state of the city, but for some reason the Broad Street outbreak went unmentioned for nearly four days in the city’s main papers.

Whitehead found himself musing on an old saying that invariably surfaced during plague times: “Whilst pestilence slays its thousands, fear slays its tens of thousands.”

Bethnal Green, the average life expectancy for the working poor was sixteen years. These numbers are so shockingly low because life was especially deadly for young children. The 1842 study found that 62 percent of all recorded deaths were of children under five.

The literature—both public and private—of the nineteenth century is filled with many dark emotions: misery, humiliation, drudgery, rage.

But when the Fertile Crescent’s proto-farmers began planting fields of cereal grains, they dramatically increased the energy available to their settlements,

more people working the fields increased the food supply, which allowed more people to work the fields, and so on.

Three related developments had triggered an unprecedented intensification of the energy flowing through the capital.

First, the “improvements” of agrarian capitalism,

second, the energy unleashed by the coal and steam power of the Industrial Revolution;

third, the dramatic increase in the portability of that energy thanks to the railway system.

human societies appeared to cycle through comparable phase transitions, as the energy harnessed by the society increased: moving from the gaseous state of roaming hunter-gathers, to the more settled configuration of agrarian farming, to the crystalline density of the walled city.