In the 1830s, Snow's colleague at the
Newcastle Infirmary was surgeon
Thomas Michael Greenhow. The surgeons worked together conducting research on England's
cholera epidemics, both continuing to do so for many years. In 1837, Snow began working at the
Westminster Hospital. Admitted as a member of the
Royal College of Surgeons of England on 2 May 1838, he graduated from the
University of London in December 1844 and was admitted to the
Royal College of Physicians in 1850. Snow was a founding member of the
Epidemiological Society of London which was formed in May 1850 in response to the cholera outbreak of 1849. By 1856, Snow and Greenhow's nephew,
E. H. Greenhow were some of a handful of esteemed medical men of the society who held discussions on this "dreadful scourge, the
cholera". After finishing his medical studies in the
University of London, he earned his MD in 1844. Snow set up his practice at 54 Frith Street in Soho as a surgeon and general practitioner. John Snow contributed to a wide range of medical concerns including
anaesthesiology. He was a member of the
Westminster Medical Society, an organisation dedicated to clinical and scientific demonstrations. Snow gained prestige and recognition all the while being able to experiment and pursue many of his scientific ideas. He was a speaker multiple times at the society's meetings and he also wrote and published articles. He was especially interested in patients with respiratory diseases and tested his hypothesis through animal studies. In 1841, he wrote,
On Asphyxiation, and on the Resuscitation of Still-Born Children, which is an article that discusses his discoveries on the physiology of neonatal respiration, oxygen consumption and the effects of body temperature change. In 1857, Snow made an early and often overlooked contribution to epidemiology in a pamphlet,
On the adulteration of bread as a cause of rickets.
Anaesthesia (detail), 1847, private collection Snow's interest in
anaesthesia and breathing was evident from 1841 and beginning in 1843, he experimented with
ether to see its effects on respiration. Snow published an article on ether in 1847 entitled
On the Inhalation of the Vapor of Ether. A longer version entitled
On Chloroform and Other Anaesthetics and Their Action and Administration was published posthumously in 1858. Although he thoroughly worked with ether as an anaesthetic, he never attempted to patent it; instead, he continued to work and publish written works on his observations and research.
Obstetric anaesthesia Snow's work and findings were related to both anaesthesia and the practice of childbirth. His experience with obstetric patients was extensive and used different substances including ether,
amylene and chloroform to treat his patients. However, chloroform was the easiest drug to administer. He treated 77 obstetric patients with chloroform. He would apply the chloroform at the second stage of labour and controlled the amount without completely putting the patients to sleep. Once the patient was delivering the baby, they would only feel the first half of the contraction and be on the border of unconsciousness, but not fully there. Regarding administration of the anaesthetic, Snow believed that it would be safer if another person that was not the surgeon applied it. This led to wider acceptance of obstetrical anaesthesia. followed by a more detailed treatise in 1855 incorporating the results of his investigation of the role of the water supply in the
Soho epidemic of 1854. By talking to local residents (with the help of
Henry Whitehead), he identified the source of the outbreak as the public water pump on Broad Street (now
Broadwick Street). Although Snow's chemical and microscope examination of a water sample from the
Broad Street pump did not conclusively prove its danger, his studies of the pattern of the disease were convincing enough to persuade the local council to disable the well pump by removing its handle (
force rod). This action has been commonly credited as ending the outbreak, but Snow observed that the epidemic may have already been in rapid decline: of cholera cases in the London epidemic of 1854, drawn and lithographed by
Charles Cheffins. Snow later used a
dot map to illustrate the cluster of cholera cases around the pump. He also used statistics to illustrate the connection between the quality of the water source and cholera cases. He showed that homes supplied by the
Southwark and Vauxhall Waterworks Company, which was taking water from sewage-polluted sections of the
Thames, had a cholera rate fourteen times that of those supplied by
Lambeth Waterworks Company, which obtained water from the upriver, cleaner
Seething Wells. Snow's study was a major event in the history of public health and geography. It is regarded as the founding event of the science of
epidemiology. Snow wrote: ,
Soho Researchers later discovered that this public well had been dug only from an old
cesspit, which had begun to leak faecal bacteria. The cloth nappy of a baby, who had contracted cholera from another source, had been washed into this cesspit. Its opening was originally under a nearby house, which had been rebuilt farther away after a fire. The city had widened the street and the cesspit was lost. It was common at the time to have a cesspit under most homes. Most families tried to have their raw sewage collected and dumped in the Thames to prevent their cesspit from filling faster than the sewage could decompose into the soil.
Thomas Shapter had conducted similar studies and used a point-based map for the study of cholera in
Exeter, seven years before John Snow, although this did not identify the water supply problem that was later held responsible.
Political controversy After the cholera epidemic had subsided, government officials replaced the Broad Street pump handle. They had responded only to the urgent threat posed to the population, and afterward they rejected Snow's theory. To accept his proposal would have meant indirectly accepting the fecal-oral route of disease transmission, which was too unpleasant for most of the public to contemplate. It was not until 1866 that
William Farr, one of Snow's chief opponents, realised the validity of his diagnosis when investigating another outbreak of cholera at
Bromley by Bow and issued immediate orders that unboiled water was not to be drunk. Farr denied Snow's explanation of how exactly the contaminated water spread cholera, although he did accept that water had a role in the spread of the illness. In fact, some of the statistical data that Farr collected helped promote John Snow's views. Public health officials recognise the political struggles in which reformers have often become entangled. During the annual
Pumphandle Lecture in England, members of the
John Snow Society remove and replace a pump handle to symbolise the continuing challenges for advances in public health. == Personal life ==