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John Snow

1813 – 1858

All who knew him said he was a quiet man, very reserved and peculiar - a clever man, but not easy to be understood, and very peculiar." - B.W. Richardson, a close friend and writer of a biographical memoir which first appeared in The Asclepiad, London, 1887, and now can be found in Snow on Cholera.

Throughout his life, John Snow devoted himself to the welfare of others; he never married and lived a life of "student loneliness," according to Richardson. However, "with his increased popularity, he became less reserved to strangers, and in the last years of his life he so far threw off restraint as to visit the opera occasionally!"


Ether and Chloroform

Snow's career was dominated by experiments with various procedures regarding inhalation. Two years before Mr. became Dr. in 1848, his first attempt at authorship involved a double air pump for supporting artificial respiration. Only months later, he invented an instrument "for performing the operation of paracentesis of the thorax".

In 1846, news came from America that operations were being performed painlessly under the influence of ether. Surgeons in England, however, remain skeptical of the practice, due to the unsafe method by which the agent was administered. Dr. Snow, upon detecting the cause of the problem, quickly remedied this by developing an improved inhaler.

Soon he was administering ether all over London. In his first book in September 1847, he wrote of all his experiences with etherisation. However, just as the book began to be appreciated, "the discovery of the application of chloroform threw ether into the shade, and the book with it".

Once Dr. Snow was convinced of the effects and the greater practicality of this new agent, he began using it in earnest. He soon developed a professional reputation, and people from all over sought him out as their guide in "Lethe’s Walk." His diary tells us he administered chloroform to the Queen at the birth of Prince Leopold and Princess Beatrice.

The Great Cholera Epidemic

By the time of the London cholera epidemic in 1854, Dr. Snow was ready to test his ideas regarding the transmission of the disease. He had begun his research on cholera in 1848, and contrary to the belief at the time, he was convinced that it was a poison acting not on the respiratory system, but on the alimentary canal. Several circumstances led him to believe that water was the chief medium. So, toward the end of August 1854, when there were more than 500 fatal attacks on cholera in 10 days in the neighborhood of Broad Street, Golden Square, and there was such panic that "people fled from their homes as from instant death, leaving behind them in all their haste, all which they valued most," Dr. Snow offered a new suggestion: Since, he said, the Broad Street pump was the "head and front of the offending," he advised the removal of the pump handle as the "grand prescription." Those who heard him were skeptical of this newfangled approach, but they took his advice, and the plague was stayed.

He published the "Mode of Communication at Cholera" in 1855 - for which "he spent more than £200 in hard cash, and realized in return scarcely so many shillings".


Richardson encapsulates Snow’s epidemiologic ideas thus: "The position he took as an epidemiologist was original, and in opposition to the views of many eminent men who had, in matters relating to public health, considerable scientific and political influence."

It was accepted at the time that an "emanation arising from evolution of foul smelling gases" could produce a specific disease. But according to Snow: "The small-pox may occur over a cesspool as an oak may spring up through manure heap; but the small-pox would never appear over the cesspool in the absence of its specific poison: nor the oak rise from the manure heap in the absence of the acorn which seeded it".


Snow's life was filled with experimentation, often with volatile agents. He first tested them him on animals, and if it proved favorable, he tried it on a human - - himself. He ran great risks, and many suppose they had an effect in bringing about his early death. On June 9, 1858, while at work on a manuscript, he was seized with sudden paralysis just as he had written the word "exit". He died eight days later, at the height of his success.

Source: Excerpted from the introduction to Snow on Cholera, by B.W. Richardson. Cambridge, Harvard University Press, 1949.

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