John Snow

• 1. Introduction

  ›

  John Snow removed a pump handle on Broad Street and changed how the world thinks about disease. The year was 1854, and cholera was killing people across London's Soho. Snow, an English physician, suspected the water rather than the air. He found that nearly all the deaths had clustered within a short distance of one public well. By talking to the families of the dead, he learned which households drank from that pump. The local council pulled the handle. What kind of man arrives at such an idea decades before germ theory exists? How does a labourer's son from York end up giving chloroform to a queen and tracing a killer to a leaking cesspit? And why did the officials he persuaded turn around and reject him?

• 2. A York Childhood

  ›

  On the 15th of March 1813, Snow was born in York, the first of nine children of William and Frances Snow. The family lived in a North Street home in one of the poorest neighbourhoods in the city. He was baptised at All Saints' Church, North Street. His father worked as a labourer at a coal yard by the River Ouse, replenished by barges from the Yorkshire coalfield, and later farmed in a small village to the north of York. The neighbourhood sat in constant danger of flooding because of its closeness to the Ouse. Streets ran unsanitary, and the river carried runoff from market squares, cemeteries and sewage. A child raised among that contamination would spend his career studying what happens when water and waste mix. At 14, in 1827, Snow left for a medical apprenticeship with William Hardcastle near Newcastle-upon-Tyne.

• 3. The First Cholera

  ›

  In 1832, working as a surgeon-apothecary apprentice, Snow met cholera for the first time in Killingworth, a coal-mining village. He treated many victims and gained hard experience with the disease. Between 1832 and 1835, he worked as an assistant to a colliery surgeon, first in Burnopfield in County Durham, then in Pateley Bridge in the West Riding of Yorkshire. In October 1836 he enrolled at the Hunterian school of medicine on Great Windmill Street in London. His colleague at the Newcastle Infirmary, the surgeon Thomas Michael Greenhow, joined him in research on England's cholera epidemics, and the two continued that work for many years. The disease Snow first faced in a mining village would follow him to London and become the puzzle that defined his life.

• 4. A London Practice

  ›

  In 1837, Snow began working at the Westminster Hospital. He was admitted as a member of the Royal College of Surgeons of England on the 2nd of May 1838. He graduated from the University of London in December 1844, earning his MD that year, and was admitted to the Royal College of Physicians in 1850. He set up practice at 54 Frith Street in Soho as a surgeon and general practitioner. A member of the Westminster Medical Society, he spoke many times at its meetings and published articles, building prestige while pursuing his own scientific ideas. Patients with respiratory diseases drew his particular interest, and he tested his ideas through animal studies. In 1841 he wrote On Asphyxiation, and on the Resuscitation of Still-Born Children, examining neonatal respiration, oxygen consumption and the effects of body temperature change. He was a founding member of the Epidemiological Society of London, formed in May 1850 in response to the cholera outbreak of 1849.

• 5. Measuring The Breath

  ›

  From 1841, Snow's interest in anaesthesia and breathing was already plain, and in 1843 he began experimenting with ether to see its effects on respiration. Ether had reached Britain only the year before when, in 1847, he published On the Inhalation of the Vapor of Ether as a guide to its use. Within two years of ether's arrival he was the most accomplished anaesthetist in Britain, and London's principal surgeons suddenly wanted his help. He was one of the first physicians to study and calculate dosages for ether and chloroform as surgical anaesthetics. That precision let patients undergo surgical and obstetric procedures without the distress and pain they would otherwise face. He designed an apparatus to administer ether safely and a mask to administer chloroform. A longer work, On Chloroform and Other Anaesthetics and Their Action and Administration, was published after his death in 1858. Though he worked thoroughly with ether, he never tried to patent it, choosing instead to keep publishing his observations.

• 6. The Danger Of Chloroform

  ›

  Chloroform was introduced in 1847 by James Young Simpson, a Scottish obstetrician, and Snow saw at once that it was far more potent than ether. It demanded more attention and precision in its administration. He learned this through Hannah Greener, a 15-year-old patient who died on the 28th of January 1848 after a procedure to cut her toenail. She was given chloroform by a cloth dipped in the substance and held over her face, lost her pulse quickly, and died. After investigating her death and several that followed, Snow concluded the drug had to be administered carefully and published his findings in a letter to The Lancet. His obstetric work was extensive, using ether, amylene and chloroform, though chloroform proved the easiest to administer. He treated 77 obstetric patients with it, applying it at the second stage of labour and controlling the dose so the patient felt only the first half of a contraction without falling fully unconscious. He believed it safer if someone other than the surgeon applied the anaesthetic.

• 7. A Queen Says Yes

  ›

  Many physicians, and even the Church of England, viewed chloroform during childbirth as unethical. That resistance broke on the 7th of April 1853, when Queen Victoria asked Snow to administer chloroform during the delivery of her eighth child, Leopold. He repeated the procedure for the birth of her daughter Beatrice in 1857. Royal approval pushed obstetrical anaesthesia toward wider acceptance. The same physician who calmed a queen's labour would also stake his reputation on an idea that disgusted the public, that disease could travel through what people drank.

• 8. The Broad Street Pump

  ›

  Snow was a skeptic of the dominant miasma theory, which held that cholera and bubonic plague came from pollution or a noxious form of bad air. Germ theory did not yet exist, so he could not explain the mechanism of transmission, but the evidence led him to discount foul air. He first published his theory in an 1849 essay, On the Mode of Communication of Cholera, then expanded it in an 1855 treatise drawing on the Soho epidemic of 1854. With the help of Henry Whitehead, he questioned local residents and traced the outbreak to the public water pump on Broad Street, now Broadwick Street. His chemical and microscope examination of a water sample did not conclusively prove the danger, but his study of the disease pattern persuaded the council to disable the pump by removing its handle. Snow himself doubted this ended the outbreak, noting the attacks had already diminished before the water was stopped. He later drew a dot map showing the cluster of cases around the pump. Homes supplied by the Southwark and Vauxhall Waterworks Company, drawing from sewage-polluted parts of the Thames, had a cholera rate fourteen times that of homes served by the Lambeth Waterworks Company, which drew cleaner water upriver from Seething Wells. Researchers later found the well had been dug only 3 ft from an old cesspit leaking faecal bacteria, into which a baby's cholera-contaminated nappy had been washed. Thomas Shapter had used a point-based map for cholera in Exeter seven years earlier, though he never identified the water supply as the cause.

  After the epidemic subsided, government officials replaced the Broad Street pump handle. They had acted only against the urgent threat, and afterward they rejected Snow's theory. Accepting it would have meant accepting the fecal-oral route of disease transmission, too unpleasant for most of the public to contemplate. Not until 1866 did William Farr, one of Snow's chief opponents, accept the validity of his diagnosis while investigating another outbreak at Bromley by Bow. Farr then ordered that unboiled water was not to be drunk. He still denied Snow's account of exactly how the contaminated water spread cholera, though he conceded water played a role, and some of the statistical data Farr collected ended up promoting Snow's views. The John Snow Society now marks these struggles each year at the Pumphandle Lecture, where members remove and replace a pump handle.

  Snow swam as a hobby for exercise and never married. He became a vegetarian at 17 and a teetotaller, joining the temperance movement in 1830 and the York Temperance Society in 1845. He followed a lacto-ovo vegetarian diet, adding dairy and eggs to his vegetables for eight years, then became a vegan in his thirties. When his health declined and he developed a renal disorder he blamed on the vegan diet, he returned to meat and, around 1845, took a little wine to aid digestion. Throughout his adult life he drank only pure water, boiled before drinking. He lived at 18 Sackville Street in London from 1852 until his death. On the 10th of June 1858, while working in his London office, he suffered a stroke at the age of 45. He never recovered and died six days later, on the 16th of June 1858, and was buried in Brompton Cemetery. Some have speculated his early death was tied to his frequent exposure to anaesthetic gases, among them ether, chloroform, ethyl nitrate, carbon disulfide, benzene, bromoform, ethyl bromide and dichloroethane, now known to carry adverse health effects.

  A plaque on Broad Street, now Broadwick Street, marks the place of the 1854 study, showing a water pump with its handle removed, and the spot where the pump stood is covered with red granite. A nearby public house was named the John Snow in his honour, where the John Snow Society regularly meets and where the annual Pumphandle Lecture is delivered each September by a leading authority in public health. In York, a blue plaque on the Park Inn in North Street commemorates him, and in 2017 the York Civic Trust raised a memorial near his birthplace in the form of a handle-less pump. Snow is one of the heraldic supporters of the Royal College of Anaesthetists, alongside fellow anaesthesia pioneer Joseph Thomas Clover. In 2003, readers of Hospital Doctor magazine in the United Kingdom voted him the greatest doctor of all time. In 2013, The Lancet printed a correction to its 1858 obituary, accepting that readers may wrongly have inferred it failed to recognise his visionary work in deducing the mode of transmission of epidemic cholera. The handle that once vanished from a Soho street is lifted and replaced every September, a working reminder that the case Snow made was won long after he could see it.