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01 / 05
Heroes of Progress, Pt. 45: John Snow

Blog Post | Sickness & Disease

Heroes of Progress, Pt. 45: John Snow

Introducing the English physician considered by many to be the father of epidemiology, John Snow.

Today marks the 45th installment in a series of articles by HumanProgress.org titled Heroes of Progress. This bi-weekly column provides a short introduction to heroes who have made an extraordinary contribution to the well-being of humanity. You can find the 44th part of this series here.

This week, our hero is John Snow. Snow was a 19th century English physician, and is considered by many the father of epidemiology. Following a series of cholera outbreaks in London, Snow was the first person to use maps and data records to track the spread of a disease back to its source. Snows work provided a foundation for the science of epidemiology. As such, he improved the way humanity confronts public health emergencies.

Snow was born on March 15, 1813 in York, England. His father was a coal-yard laborer and Snow was the oldest of eight siblings. Snow was raised in one of the citys poorest neighborhoods. As a child, he was exceptionally bright, with a strong aptitude for mathematics. His mother, recognizing Snows academic talents, used a small amount of money that she inherited to send him to a nearby private school.

Snow excelled at school. In 1827, aged 14, Snow attained an apprenticeship under Dr. William Hardcastle in Newcastle — about a hundred miles away from York. In 1831, a cholera epidemic began to spread across Europe. By 1832, a nearby coal-mining village was severely afflicted with the disease. With Hardcastle overwhelmed by patients, Snow was sent out to the village to attempt to treat the victims.

Cholera causes its victims to suffer from severe diarrhea and vomiting, which leads to rapid dehydration. It can be fatal within just a few hours. Unfortunately, there was little that Snow could do to help the cholera-stricken miners. The typical medical treatments of the day included laxatives, opium, brandy, and peppermint, were all hopelessly ineffective. A few months later, the epidemic ended. In total, the outbreak killed more than fifty-thousand Britons. The early experience of helplessness in combatting cholera left a significant impact on Snow.

Later in 1832, Snow began to work as an assistant to a colliery surgeon in Country Durham. In 1836, he enrolled in the Hunterian School of Medicine in London. A year earlier, Snow signed an alcohol abstinence pledge and became a supporter of teetotalism. He also became a vegetarian and would only drink water that had first been boiled, so that it was pure.”

In 1837, Snow started working at the Westminster Hospital and a year later he was admitted as a member of the Royal College of Surgeons of England. In 1844, Snow received his Doctorate in Medicine from the University of London. After graduation, Snow began to work as a surgeon and general practitioner.

For several years, Snow meticulously studied the effects of different anesthetics. In Snow’s day, it was typical for a surgeon to use either too little anesthetic and the patient would wake up mid-surgery, or too much anesthetic, which could cause death. Snow was one of the first physicians to study and calculate the dosages of ether and chloroform needed for use in surgery. For many years, Snow tested the effects of ether and chloroform on himself. By taking notes on how long he was unconscious after different dosages, he was eventually able to work out the optimal amount of anesthetic that patients could handle.

After creating an anesthetic inhaler and publishing his findings in 1847 in a textbook titled On the Inhalation of the Vapour Ether in Surgical Operations, Snow quickly gained fame as Britains most accomplished anesthetist. Snows stardom eventually led him to administer chloroform to Queen Victoria during the birth of her last two children, Prince Leopold and Princess Beatrice.

Despite Snows impressive accomplishments in the field of anesthesiology, his most important work came a few years later, following a series of cholera outbreaks in London. In the mid-19th century, most physicians thought that diseases such as cholera or the plague were caused by miasmas” or air pollution. The germ theory of disease had yet to be developed, but Snow theorized that diseases were likely caused by invisible tiny parasites.

In 1848, a new outbreak of cholera struck London and Snow decided to track the disease to its source to find out how it spread. After examining many patients, Snow realized that their first symptoms had nearly always been digestive problems. Snow theorized that the disease must have been ingested through food or water. If the disease had been spread from polluted air, as the supporters of the miasmatic theory believed, then the first symptoms should logically appear in the nose or lungs.

Moreover, Snow reasoned that the severe diarrhea, which was caused by cholera, might be the mechanism by which the germs spread. Put differently, if dangerous germs were present in the diarrhea and the diarrhea contaminated the water supply, the germs could then spread to countless new victims. In 1849, Snow decided, at his own expense, to publish a pamphlet that outlined his thoughts on how cholera was spread. It was titled On the Mode of Communication of Cholera. Although Snows work had little effect on his colleagues’ thinking, he pushed on with his research regardless.

In August 1854, another cholera outbreak occurred in the Soho neighborhood in London. Snow found that, of the seventy-three cholera victims, sixty-one had drunk water from a single pump that was located on Broad Street. Snows microscopic examination of the water from the Broad Street pump proved inconclusive. Undeterred, Snow plotted the number and location of cholera cases on maps of the area, to highlight the correlation between cholera infections and use of the Broad Street pump. The following month Snow showed his evidence to the authorities and recommended that they remove the pumps handle, so that no more water could be drawn from the infected source. Although the authorities were not convinced by Snows argument, they obliged. Subsequently, the local cholera outbreak quickly ended.

Researchers would later discover that the Broad Street well had been dug just 3 feet away from an old cesspit, which had begun to leak fecal bacteria – a discovery that helped lend credence to Snows theory.

Later in 1854, Snow began another project that he called his Grand Experiment.” Snow began to compare the cholera death rates from households that had their water supplied by two different companies: the Southwark & Vauxhall Company, and the Lambeth Company.

Snow found that the Southwark & Vauxhall company relied on water from sewage-polluted sections of the River Thames. In contrast, the Lambeth Company used water from inlets in the upper Thames – which was located miles from urban pollution. Snow created dot maps and used statistics to highlight the correlation between the quality of the water supplied to different households and incidences of cholera.

Snow enlarged his original 1848 pamphlet into a larger book that included intricate details of all his studies. In 1855, he published the second edition of On the Mode of Communication of Cholera. Today, Snows studies are considered to be major events in the history of public health, as it was the first time that maps and data records were used to accurately track the spread of a disease back to its source. As such, many consider Snows 1855 book as the foundation of epidemiology. However, despite the works historical significance, Snows critics and public health officials remained unimpressed, arguing that the enormous quantity of water in the Thames was large enough to dilute any waterborne poison.

Snows foresight wasnt truly appreciated until the 1860s, when our 19th Hero of Progress, Louis Pasteur, successfully proved the germ theory of disease. Unfortunately, Snow never got to see his work become widely accepted, since he died from a stroke on June 16, 1858. He was just 45 years old.

John Snow was one of the great physicians of the 19th Century. During his short life, he wrote over a hundred books, pamphlets and essays on a variety of medical topics. He is widely considered to be the founder of epidemiology. Snows methods have been copied all over the world and have been used to quell, or at least slow down, a number of potentially-catastrophic outbreaks of deadly diseases, thus likely saving untold millions of lives. For these reasons, John Snow is our 45th Hero of Progress.

Wall Street Journal | Water & Sanitation

New Tech to Prevent the World from Running Out of Clean Water

“For decades, desalination has been the only reason that many places, from the Caribbean to the Emirates, have been habitable. But it’s always been a solution of last resort, for one big reason…

Up on land, engineers would literally boil the ocean, creating steam that would become drinking water and, on its way, drive some power-generating turbines to pay back a bit of its cost. It was so energy intensive that in the 1960s, some proposed using nuclear power to do it. The world’s largest desalination plant, in Ras al-Khair, Saudi Arabia, produces much of its water through evaporation.

Around the year 2000, reverse-osmosis changed everything, says Pankratz. In this process, water is forced across a plastic membrane with holes so tiny only water molecules fit through, leaving behind salt and other impurities. This process requires about half the energy, making it a credible option for Trinidad, which in 2002 got a plant that now produces 40 million gallons of water a day, and Israel, which got one in 2005 that now produces 85 million gallons of water daily. Many more plants followed, and this is now the standard way to desalinate water…

Oslo-based Flocean, Netherlands-based Waterise and Bay Area-based OceanWell are among the companies that seized on this idea of desalination—then submerged it to a depth of at least 400 meters.

The principle is easy to grasp: Instead of expending huge amounts of energy to pump seawater onto land, and then pressurize it inside a plant, why not take advantage of the ocean’s extreme natural pressure? At depth, seawater naturally wants to cross a desalination membrane, so long as the fresh water on the other side of it is being pumped to the surface. The result is a net energy savings of up to 40%.”

From Wall Street Journal.

Blog Post | Water & Sanitation

Grim Old Days: Robert Muchembled’s Cultural History of Odours in Early Modern Times

Putrid smells were a defining feature of the past that is now largely forgotten.

Summary: The preindustrial world was anything but fresh and clean, as historian Robert Muchembled reveals in his cultural history of odors. From the stench of slaughtered animals and overflowing latrines to suffocating city air and dubious perfumes made from animal secretions, early modern life was defined by overwhelming, often toxic smells. Despite their constant exposure, people did not become desensitized to the filth, and their desperate attempts to mask or combat foul odors often led to bizarre, ineffective, or even dangerous solutions.


French historian Robert Muchembled’s Smells: A Cultural History of Odours in Early Modern Times, as translated by Susan Pickford, describes what the preindustrial past smelled like in frightening detail.

Some entertain the idea that before industrialization and its “dark Satanic Mills“ belching smoke, the air was sweet and pristine. In reality, an “apocalyptic stench . . . formed the olfactory backdrop to many people’s lives.”

Air pollution is not a modern phenomenon. “The good old days are a myth. The towns and villages of Europe stank horribly in the days of yore.” While certain forms of air pollution are relatively recent, “the foul air of medieval towns” was suffocating.

Animals were being killed nonstop for food, hides, quack medicines, entertainment, and more. Hence “the reek of death constantly hung over towns and cities.” Sometimes the poor air quality even prompted appeals for change. “When the air became too grim to breathe,” outrage occurred. In 1363, several scholars and students at the University of Paris complained to the king about how butchers killed animals in their homes:

The blood and waste from the animals is thrown day and night into the Rue Sainte-Geneviéve, and on several occasions the waste and blood of the animals was kept in pits and latrines in their houses until it was corrupted and rotten and then thrown into that same street day and night, until the street, Place Maubert and all the surrounding air was corrupted, foul, and reeking.

Muchembled quotes the French historian Henri Sauval (1623–1676) describing Paris as “black, foul-smelling, its stench unbearable for those from elsewhere; it stings the nostrils from three or four leagues distant.” Many causes of foul odors besmirched the air. “The noisy, dirty, crowded streets were home to more and more polluting trades, well before the Industrial Revolution.” For example:

Certain trades were a major source of noxious emissions for their immediate neighbourhood, including butchers, tripe makers, fishmongers, potters (who deliberately left their clay to sour in cellars in Paris and elsewhere), and painters who used pigments made from metal oxides. The worst were tanners, glove- and purse-makers, and fullers, who made abundant use of toxic plant and animal substances as mordants, like alum, tartar and soda, urine (often collected from humans), chicken droppings and dog excrement, which accelerated the process of fermenting and rotting the fibres they worked with.

Poor storage of human waste and the remains of slaughtered animals alike affected the quality of city air. Only in 1760 were the massive sewage dumps in Faubourg Saint-Germain and Faubourg Saint-Marceau moved some two and a half miles outside Paris to combat the “foul air” they caused. Another Parisian dump site, which remained operational until 1781, was infamous: “Its ten hectares of cesspits full of fermenting sewage and its slaughterhouse piled high with rotting carcasses could almost have been something out of Dante’s Inferno.”

Parisians complained that “noxious emissions from the boats [transporting sewage] were tarnishing and bleaching their silverware, gilding and mirrors.” Many homes abutted towering dung heaps, prompting the Italian physician Bernardino Ramazzini (1633–1714) to observe that “the air they live in must be polluted with the foul vapours that rise constantly.” Many prominent minds were deeply troubled by air quality affected by insufficient sanitation systems. “The noxious vapours of excrement were the main concern of hygienists in the reign of Louis XVI.” The smell of sewage was everywhere. “A French royal edict in 1539 complained of the “‘mud, dung, rubble and other rubbish’ piled up outside people’s doors and blocking the streets, despite earlier royal decrees.”

The night soil men who cleaned the sewer dump sites sometimes even died from the smell. “Fatal suffocation was a real risk on opening a latrine. . . . The rotting excrement released a dangerous, fetid sewer gas called ‘mofette’ . . . or ‘plomb’ (the French term for lead, as the symptoms were thought to be similar to those of lead poisoning). . . . Cases of fatal sewer gas poisoning among night soil men remained a cause for medical research throughout the nineteenth century. . . . In 1777, the king [of France] appointed a commission of chemists to study the effects of mephitism, a disease which struck fear into the hearts of night soil men.” The sewer gases could kill directly or through incineration when they burst into flames. “The gas sometimes caught fire, as in Lyon in July 1749.”

Not to mention the stench of human corpses. “Then there was the smell of bodies buried in and around churches, often in shallow graves, before a 1776 decree banished graveyards to outside urban areas” in France. The situation before that decree was a nightmare. “Before the 1776 order to relocate France’s graveyards out of urban centres,” one writer complained of the “mephitic vapours” emitted by the country’s cemeteries into the surrounding cities.

Outside of cities, the air was not necessarily better. Indeed, the countryside our ancestors knew has been described as “a concentration of bad smells: sweaty livestock, poultry droppings, rotting rat carcases, bodies living together in a single room, rubbish hidden in dark corners, and combustible fumes steaming from the dung heap outside the door.” Bizarrely, rural people sometimes took pride in the filth and used “the height of dung heaps as a measure of wealth.”

One might imagine that noses were dulled from the constant assault on the senses. Yet despite being used to “the terror of omnipresent putrid smells” that did not happen: “In the sixteenth and seventeenth centuries, the extraordinary stench in towns and cities and at court did not weaken people’s sense of smell.” In other words, “The local population’s sense of smell, long accustomed to the urban fug, was triggered afresh by unusual events such as unexpected flooding from the Isére or Drac rivers, which left behind a tide of ‘stinking mud, a mix of latrines and graves,’ as one observer wrote in 1733.”

Not only were our ancestors surrounded by horrific smells, but they themselves were often rather stinky. The frequency with which most ordinary people today bathe, wash their hands, and engage in other bodily cleansing would utterly bewilder their preindustrial ancestors, who often feared contact with water as a threat to health. In 16th-century France, “the culture set little store by cleanliness, water being considered dangerous.” Daily bathing would be seen as eccentric and possibly harmful. “The population should be imagined as filthy, crawling with vermin and scabies-ridden.” Muchembled quotes a French writer who described how in 1764 some people bathed just once a year, in accordance with tradition, while others had adopted the more modern habits of bathing once a week, fortnight, or month. When they did bathe, what passed for soap at the time would not pass muster today. One French work from 1764 contains several pages of “soap recipes liable to lead to rough, even wrinkly skin, being heavy on soda ash, quicklime and olive oil.”

Given their smelly surroundings and lack of basic personal hygiene, preindustrial people were certainly in need of a way to conceal the smell of their unwashed, often diseased bodies and stinking breath. Many turned to what they considered to be perfume, although a person today might not recognize the pungent concoctions as such. Most popular perfumes today smell like flowers, such as rose or jasmine, or other sweet things. The perfumes of the past were rather different and, in many cases, would not readily appeal to modern noses. “Heady perfumes painfully extracted from the sex glands of exotic creatures were used in extravagant quantities to hide the ever-present stink.”

“All sixteenth- and seventeenth-century perfumes were saturated with animal base notes made from glandular secretions.” Consider some of the most popular perfume ingredients. “Ambergris” came from the stomachs of sperm whales, “castoreum” from the abdominal sacs of beavers, “civet” from the anal glands of its namesake wildcat, and “musk” from glands between the navel and genitals of the Asian musk deer. In other words, perfume ingredients were far from sweet-smelling; “civet” in particular carried a fecal odor. “Without the [excrement] of martens, civets, and other animals, would we not be deprived of the strongest and best scents?” asked Sophia the Electress of Hanover (1630–1714) in a letter.

Other ingredients were added to these bases. Some are still beloved today, such as roses; others were less sweet. In 1522, among the perfume ingredients sold by a French apothecary were litharge (a form of lead), verdigris (which is mildly poisonous), asafoetida (colloquially known as “devil’s dung” for its fecal stench), and sulphur, which is commonly considered to smell like rotting eggs. Eau de millefleurs (“water of a thousand flowers”) was a pretty name given to a concoction derived from the urine or dung of a cow, although by the late 18th century, a less-repulsive version of this creation “made from cow pats, was later made from musk, ambergris and civet.”

Pigeon blood and goat bile were also acceptable perfume ingredients. Consider a text from 1686 by the French chemist Nicolas Lémery that advised unscrupulous perfumers on how

to make cheap ‘Western’ musk from small quantities of the original product: in the last three days of the moon, feed the blackest rough-footed pigeons you can then find with spike lavender seed and sprinkle them with rose water. Then feed them on beans and pills for fifteen days. Slit their neck on the sixteenth and catch the blood in an earthenware dish standing on hot ashes. Skim off the top, then crown each ounce with a drachma (one-eighth of an ounce, or 576 grains) of genuine oriental musk dissolved in spirits of wine. Add four or five drops of billy goat bile, leave the mixture to steep in good, hot horse manure, and warm it through again.

Such ingredients were common not only in perfume but also in many mainstream beauty treatments. A facial skin treatment promoted by the writer Pierre Erresalde in 1669 “consisted of calves’ feet, river water, white breadcrumbs, fresh butter and egg whites.” Keep in mind that rivers also often functioned as sewers at the time. Nicolas de Blégny, medical adviser to Louis XIV, the Sun King, recommended that the court women drink a broth that listed ox bile among its ingredients to improve their complexions. Other ingredients used in his recommendations include crushed snails, pearls dissolved in pork fat, frog sperm, and of course, lead. Another popular makeup sometimes made with a form of lead was “virgin’s milk,” which corroded the very skin it was meant to improve. “Virgin’s milk, used to whiten the skin, contained litharge, which was very harsh on the skin and deeply toxic.” Other beautifiers containing lead included “ceruse” and “vinegar of Saturn.”

Minor blemishes “were treated with silver sublimate, white lead and vitriol, while litharge was regularly recommended as a skin whitener. . . . One recipe called for a freshly killed white hen whose blood was to be rubbed on spots or freckles and left on to dry.” One French recipe for preventing a suntan (because pale skin was fashionable) called for “half a dozen whelps mixed with calf’s blood, pigeon droppings, a pigeon with its innards stripped out, the ‘blood of a male hare’ mixed with ‘an equal part of the urine from the person who is to use it’, and ox bile.”

The animal-based scents of ambergris, musk, and civet only fell out of favor around the mid-18th century, when flowery and fruit-based fragrances came into vogue. The preindustrial people’s tendency to douse themselves with “perfumes” consisting of animal secretions, toxins, and stinking ingredients to hide the powerful odor of their own unbathed bodies was not the sole use of perfume. Perfume was also used to fight the bubonic plague.

Many of our preindustrial forebears thought that the plague spread through foul air. In the town of Arras in France, in 1655, a rule banned feeding pigs, whose foul odor was thought to corrupt the air in a way that spread the plague. In 1604, a French physician complained that some peasants tried to prevent the plague by eating “cheese on an empty stomach.” In contrast, “mainstream advice [recommended that people] keep sniffing at a pomander, sprig of herbs or flowers, or a sponge dipped in vinegar and rose water when out walking.” Many ordinary people used pomanders for this purpose. “The fashion for pomanders was by no means limited to the aristocracy or the wealthy. It was perfectly possible to make one simply by sticking cloves into an orange or lemon or even a ball of clay with various scents kneaded into it.” Ordinary people, in other words, often used them.

Other physicians advised rubbing “genuine scorpion oil” over the body on the theory that “one venom or poison often cures or drives out another.” Foul smells were thus thought to offer protection against the plague, which was itself theorized to derive from putrid air. The cures of physicians often closely resembled folk remedies. “The doctor Jean de Renou wrote in 1624 that his colleagues were using rat droppings to treat kidney stones, dog dirt for throat infections, and peacock droppings for ‘falling sickness’ (epilepsy), while human excrement was ‘marvellously suppurative.’ . . . Madame de Sévigné used spirit of urine against rheumatism and the vapours. Some doctors believed that one cure for airborne contagion was breathing in an even fouler smell. . . . This was a serious medical opinion, not folk wisdom; its popularity among the poorest sections of society was doubtless due to the fact it was free.”

Many people seeking to ward off the plague thus “sniffed rotting cheese, drank their own urine, bred goats to keep their homes safe, and breathed in the air from privies first thing in the morning on an empty stomach. One German doctor was still recommending privy sniffing as late as 1680.” In Poland, some “fought the epidemic by throwing the stinking carcases of dogs, horses, cattle, ewes and wolves into the streets on the grounds that ‘the horrible stench drives out the pestilential air.’”

“Garlic and rue were considered to smell vile” and hence to offer protection against the plague. Rue-based perfume actually may have offered some protection because rue naturally repels fleas (a spreader of bubonic plague), but merely sniffing rue occasionally or placing rue in one’s mouth, as was sometimes advised, likely made no difference. The use of garlic, which does not repel fleas, was just as popular as a preventive measure—some physicians advised washing one’s hands and face with “garlic vinegar or rue.” One common concoction meant to drive plague contagion out of the air was “four thieves vinegar,” which counted garlic and rue among its ingredients, along with onion and the pungent asafoetida.

In 1624, the physician Jean de Renou advised, “Not only mainstream protections such as . . . scorpion’s oil” but also “unicorn horn, mercury, viper flesh . . . mummia (a medicine made from powdered mummies), the mythical bezoar” and many other bizarre, dangerous, or simply nonexistent things. (A bezoar is a hard mass of undigested matter sometimes found lodged in the gastrointestinal tracts of animals such as oxen and horses; these objects were widely believed to have magical healing properties in much of the preindustrial world, in areas as diverse as China and Europe). There were worse cures still, such as those offered by the physician Blégny (1652–1722):

Nicolas de Blegny also had several even more astonishing recipes to cure those suffering from the dreadful disease. Take, he wrote, large toads in the hottest July days, hang them upside down by a small fire, then dry them and their vomit in the oven. Grind them to powder to be shaped into small flat medallions. Sprinkle these generously with theriac and apply them over the heart in a pouch. The same result could be obtained by placing large toads in a pot over the fire, dissolving the resulting powder in white wine and drinking the mix in bed in the morning, leading to profuse sweating.

Even royalty were subjected to horrific, unscientific cures. Recall that de Blégny gave medical advice to Louis XIV and consider another recipe that the former recommended:

Dog excrement, ground and soaked in vinegar and plantain water, was, in Blégny’s expert opinion, an excellent remedy for diarrhoea when applied as a hot, if rather smelly, poultice. Nosebleeds needed a liquid blend of donkey droppings that were ground and mixed with plantain syrup, certainly intended to attenuate the taste and smell. Fresh pig’s droppings could also be dried on a fire-shovel, ground, heated and inhaled. It is interesting to think that the king, who hired the imaginative doctor in 1682, might have tried out some of his bold ideas.

Tobacco, with its strong odor, was also considered a miraculous cure for many ailments. Unsurprisingly, then, “tobacco also had a role to play in the fight against the Black Death.” In Europe, tobacco was among the scents frequently sniffed to ward off the bubonic plague and fight the putrid and omnipresent stench of toxic and occasionally lethal sewage gas. “In England, the night soil men described in Daniel Defoe’s 1720 Journal of the Plague Year followed medical advice to the letter, working with garlic and rue in their mouths and smoking scented tobacco.”

The Guardian | Water & Sanitation

Wastewater Sampling Could Warn Early of New Disease Outbreaks

“Wastewater sampling could predict new disease outbreaks and the emergence of new variants of pathogens weeks or months before they become widespread, new research shows.

Pathogen monitoring in sewer systems, including on airplanes, can reveal which viruses and bacteria are present and cause outbreaks, two studies indicate.”

From The Guardian.