The Later Years

In the year 1848 Dr. Snow, in the midst of his other occupations, turned his thoughts to the questions of the cause and propagation of cholera. He argued in his own mind that the poison of cholera must be a poison acting on the alimentary canal by being brought into direct contact with the alimentary mucous surface, and not by the inhalation of any effluvium. In all known diseases, so he reasoned, in which the blood is poisoned in the first instance, there are developed certain general symptoms, such as rigors, headaches, and quickened pulse; and these symptoms all precede any local demonstration of disease. But in cholera this rule is broken; the symptoms are primarily seated in the alimentary canal, and all the after-symptoms of a general kind are the results of the flux from the canal. His inference from this was, that the poison of cholera is taken direct into the canal by the mouth. This view led him to consider the media through which the poison is conveyed, and the nature of the poison itself. Several circumstances lent their aid in referring him to water as the chief, though not the only, medium, and to the excreted matters from the patient already stricken with cholera, as the poison. He first broached these ideas to Drs. Garrod and Parkes, early in 1848; but feeling that his data were not sufficiently clear, he waited for several months, and having in 1849 obtained more reliable data, he published his views in extenso in a pamphlet, entitled "The Mode of Communication of Cholera."  During subsequent years, but specially during the great epidemic outbreak of the disease in London in 1854, intent to follow out his grand idea, he went systematically to his work.  He labored personally with untiring zeal. No one but those who knew him intimately can conceive how he labored, at what cost, and at what risk.  Wherever cholera was visitant, there was he in the midst. For the time he laid aside as much as possible the emoluments of practice; and when even, by early rising and late taking rest, he found that all that might be learned was not, from the physical labor implied, within the grasp of one man, he paid for qualified labor. The result of his endeavors, in so far as scientific satisfaction is a realization, was truly realized, in the discovery of the statistical fact, that of 286 fatal attacks of cholera, in 1854, occurring in the south districts of the metropolis, where one water company, the Southwark and Vauxhall, supplied water charged with the London fecal impurities, and another company, the Lambeth, supplied a pure water, the proportion of fatal cases to each 10,000 houses was to the Southwark and Vauxhall Company's water 71, to the Lambeth 5.

There was, however, another fact during this epidemic, which more than the rest drew attention to Dr. Snow's labors and deductions. In the latter part of August 1854, a terrific outbreak of cholera commenced in and about the neighborhood of Broad Street, Golden Square. Within two hundred and fifty yards of the spot where Cambridge Street joins Broad Street, there were upwards of five hundred fatal attacks of cholera in ten days. To investigate this fearful epidemic was at once the self-imposed task of Dr. Snow.  On the evening of Thursday, September 7th, the vestrymen of St. James's were sitting in solemn consultation on the causes of the visitation. They might well be solemn, for such a panic possibly never existed in London since the days of the great plague. People fled from their homes as from instant death, leaving behind them, in their haste, all which before they valued most. While then the vestrymen were in solemn deliberation, they were called to consider a new suggestion. A stranger had asked, in modest speech, for a brief hearing. Dr. Snow, the stranger in question, was admitted, and in few words explained his view of the "head and front of the offending."  He had fixed his attention on the Broad Street pump as the source and center of the calamity. He advised the removal of the pump-handle as the grand prescription. The vestry was incredulous, but had the good sense to carry out the advice. The pump-handle was removed, and the plague was stayed. It was my privilege, during the life of Dr. Snow, to stand on his side. It is now my duty, as a biographer who feels that his work will not be lost, to claim for him not only the entire originality of the theory of the communication of cholera by the direct introduction of the excreted cholera poison into the alimentary system; but, independently of that theory, the entire originality of the discovery of a connection between impure water supply and choleric disease. The whole of his inquiries in regard to cholera were published in 1855, in the second edition of his work on the "Mode of Communication of Cholera" -- a work in the preparation and publication of which he spent more than 200 pounds in hard cash, and realized in return scarcely so many shillings.

In 1856, he made a visit to Paris in company with his uncle, Mr. Empson, who having personally known the emperor many years, had on this occasion special imperial favors shown to him, in which the nephew participated. During the visit Dr. Snow lodged a copy of his work on Cholera at the "Institute, in competition for the prize of 1,200 pounds offered for the discovery of a means for preventing or curing the disease. The decision of the judges has since been published, but with no notice of Dr. Snow's researches.

The Medical Society of London, reformed under that name in 1849-50, by amalgamation with the Westminster Medical, was at this time the principal scene of Dr. Snow's scientific exertions. In 1852, the Society elected him as Orator for the ensuing year; and at the eightieth anniversary of the Society, held on March 8th, at the Thatched House Tavern, he delivered an admirable oration on "Continuous Molecular Changes, more particularly in their Relation to Epidemic Diseases." He made no claim to the orator's gown; but the address was too forcible not to call forth the enthusiasm of the audience. He spent nearly twelve months in the preparation of this oration, in which he endeavored to convey, in the most pleasing manner at his command, a broad view of his observations on the communication of certain spreading diseases. He advanced, on this occasion, the idea that the poison of intermittent fever, and perhaps yellow fever, is carried direct, like the poison of cholera, into the alimentary system.

Two years after this event, having, meantime, passed the office of vice-president, the Society elected him to the highest honor it can confer, --to the presidential chair. He took his place as President, in his unassuming manner, on March 10th, 1855, delivering a short address. Throughout the year he carried out the duties of his office with great success. One of his presidential acts was peculiarly graceful. One evening, while presiding, Dr. Clutterbuck -- then the father, or oldest member of the Society -- came into the meeting. The venerable and distinguished old man, then long past his eightieth year, had lately been a stranger to the assembly, and was known but to few of the members. The President, as Dr. Clutterbuck entered the room, rose, and in a way that was irresistible in its simple courtesy resigned his chair to the veteran Esculapian. "It is near fifty years,"  said Dr. Clutterbuck with emotion, as he took the proffered seat, "since I last occupied this honorable position."  At the next anniversary meeting, held on March 8th, 1856, Dr. Clutterbuck came to his last meeting, and to see his friend the President play also his last part in presidential duties. At the anniversary dinner on that same day, the President reviewed, in feeling terms, his own career in the professional strife, and expressed that his success in life had originated in his acquaintance with the Society.

In addition to the fellowship of the Medical Society, Dr. Snow belonged to the Royal Medical and Chirurgical, Pathological, and Epidemiological societies, and to the British Medical Association. The Medical Society, from its old associations, was, however, that in which he took the most active part. Next to this, the Epidemiological Society, founded by the late Mr. Tucker, of Berners Street, claimed his regard.

The position which 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. He contended, in regard to true epidemic disorders, distinguished by specific symptoms, that they are due to a specific poison, which is propagated by certain fixed laws; which attains its progression and increase in and through animal bodies; which is communicated from one animal body to another; and, which is the same in its essence from first to last. This was his position, and he adhered to it. No mere emanation arising from evolution of foul smelling gases can, per se, according to his views, originate a specific disease, such as small-pox or scarlet fever; as well expect that the evolution of such gases should plant a plain with oaks or a garden with crocuses. The smallpox may occur over a cesspool as an oak may spring up through a manure heap; but the smallpox 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.

In 1855 Dr. Snow gave evidence before the select committee on the "Public Health and Nuisances Removal Bill," in which evidence he strove to convey the impressions condensed above. Feeling that he had not been correctly understood, he afterwards wrote a letter to Sir Benjamin Hall, in which he set forth the whole of his argument very distinctly and sensibly. He indicated in this letter that he was no defender of nuisances, but that whereas a bad smell cannot, simply because it is a bad smell, give rise to specific disease, so an offensive business conducted in a place where it ought not be, should be proceeded against by ordinary law as a nuisance, without applying to it the word pestiferous, or otherwise dragging in and distorting the science of medicine.

In relation to public health Dr. Snow contributed many other observations. In the first number of my Journal of Public Health and Sanitary Review, he communicated a valuable paper, previously read at the Epidemiological Society, on the "Comparative Mortality of Town and Rural Districts;" and, previous to his decease, he was busily occupied in investigating the question of adulteration of bread with alum. He made several analyses of different specimens of bread, but his papers merely leave a brief record of the fact, without any comments or results.

I return for a few moments to some further points connected with his researches on inhalation. In addition to his experiments with volatile narcotics, he carried out for a long time a series of inquiries with other medicinal substances, and administered many remedies by inhalation at the Brompton Hospital, during a period of twenty months. In 1851, he recorded the result of this experience at the Medical Society of London, and explained the modes of administering various agents. Some, as morphia and stramonium, were inhaled with the aid of heat; others, as hydrocyanic acid and conia, were inhaled at the ordinary temperature. The particulars of these experiments will be found in a short paper in the London Journal of Medicine for January 1851.

He continued steadily to investigate the effects of various volatile agents for the production of insensibility, performing a variety of experiments with carbonic acid, carbonic oxide, cyanogen, hydrocyanic acid, Dutch liquid, ammonia, nitrogen, amylovinic ether, puff-ball smoke, allyle, cyanide of ethyle, chloride of amyl, a carbo-hydrogen from Rangoon tar, a carbo-hydrogen coming over with amylene, and various combinations of these. His grand search was for a narcotic vapor which, having the physical properties and practicability of chloroform, should, in its physiological effects, resemble ether in not producing paralysis of the heart.

First he ascertained the boiling-point of the substance under investigation; then the point of saturation of air with the vapor at different temperatures; next the effects of inhalation of the vapor by inferior animals; and finally the quantity required to be inspired, with the air breathed, to produce insensibility. When he had obtained any substance which would produce insensibility favorably on animals, he pushed it, in one or two experiments, to its extreme in animals of different kinds. Then having produced death by the inhalation, both by giving rapidly a large dose, and by giving a small dose for a long period, he observed the mode of death, whether it occurred primarily by cessation of the heart, or by cessation of the respiration. If the agent seemed to promise favorably from these inquiries, he commenced to try it on man; and the first man was invariably his own self.  His friends, knowing his unflinching courage in the ardor of his inquiries, often expostulated with him in regard to the risks he ran. It was of no avail. He felt the personal trial a duty, and he did it. I do not believe, as some have supposed, that these personal experiments had any effect in producing his early death; but it is certain that he underwent many risks in the performance of his investigations, and that he held his own life of least value when the lives of others were under consideration.

There is yet another trait in his character which I cannot but notice, and which I would respectfully commend to all physiological inquirers.  While he held it as a necessity to use inferior animals for the purpose of experiment, he never touched living thing with the physiologist's finger without having before him some definite object; and never performed experiment on any animal without providing with scrupulous care against the infliction of all unnecessary suffering. The interests of humanity were, he thought, best advanced by the universal practice of humanity.

By his earnest labors Dr. Snow soon acquired a professional reputation, in relation to his knowledge of the action of anesthetics, which spread far and wide, and the people, through the profession, looked up to him from all ranks, as the guide to whom to entrust themselves in "Lethe's walk." On April 7th, 1853, he administered chloroform to Her Majesty at the birth of the Prince Leopold.  A note in his diary records the event. The inhalation lasted fifty-three minutes. The chloroform was given on a handkerchief, in fifteen, minim doses; and the Queen expressed herself as greatly relieved by the administration. He had previously been consulted on the occasion of the birth of Prince Arthur, in 1850, but had not been called in to render his services. Previous to the birth of Prince Leopold he had been honored with an interview with His Royal Highness the Prince Albert, and returned much pleased with the Prince's kindness and great intelligence on the scientific points which had formed the subject of their conversation. On April 14th, 1857, another note in the diary records the fact of the second administration of chloroform to Her Majesty, at the birth of the Princess Beatrice. The chloroform again exerted its beneficent influence, and the Queen once more expressed her satisfaction.

Inquisitive folk often overburthened Snow, after these events, with a multitude of questions of an unmeaning kind. He answered them all with good-natured reserve.  "Her Majesty is a model patient,"  was his usual reply: a reply which, he once told me, seemed to answer every purpose, and was very true. One lady of an inquiring mind, to whom he was administering chloroform, got very loquacious during the period of excitement, and declared she would inhale no more of the vapor unless she were told what the Queen said, word for word, when she was taking it. "Her Majesty," replied the dry doctor, "asked no questions until she had breathed very much longer than you have; and if you will only go on in loyal imitation, I will tell you everything."  The patient could not but follow the example held out to her. In a few seconds she forgot all about Queen, Lords, and Commons; and when the time came for a renewal of hostilities, found that her clever witness had gone home, leaving her with the thirst for knowledge still on her tongue. 


Later years of A Biographical Memory of John Snow

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