92."The case of fissure of the sternum"

Source: Snow, John. Lancet 2, 7 July 1855, p.17 [Letter to Ed.].

To the Editor of the Lancet.

Sir,--I shall be obliged if you will allow me to make a few remarks on the case of fissure of the sternum, to which you have called the attention of the profession in the last two numbers of the Lancet. This case has been under the notice of several medical men of eminence in Paris and Strasbourg, who have expressed their opinions in the medical journals of those towns. These opinions, however, differ widely from each other; for whilst M. Forget and M. Jules Béclard consider that the phenomena connected with the heart in this case support the ancient and usual doctrine of the action of that organ, Dr. F. A. Aran believes that they confirm the extra-ordinary doctrine that the impulse of the heart against the walls of the chest is caused by the penetration of the blood from the auricles into the ventricles, and that, in fact, what is considered to be the systole of the ventricles is the diastole. All the observers agree, however, in believing that the pulsation which is seen through the integuments, in the centre of the fissure, is caused by the alternate dilation and contraction of the right auricle--that is to say, by its being alternately filled with blood from the two venæ cavæ, and emptied by its own contraction.

When M. Groux, the subject of the malformation, called on me, on the 18th ult., I formed a very different opinion respecting the cause of the pulsation; and on seeing him again, on the 28th, I became confirmed in my conclusion, which is as follows: When the ventricles contract, the portion of blood which is at their entrance is necessarily driven back into the auricles before the closing auriculo-ventricular valves, and the moment the ventricles become relaxed the blood in the auricles is drawn onwards again into them. It is the wave of blood so driven back into the right auricle by the tricuspid valve, as it is closed by the contraction of the right ventricle, which causes the pulsation seen and felt in the situation of the right auricle, in the case of M. Groux; whilst the relaxation of the ventricle causes the sudden subsidence of the tumour.

The following circumstances, as I consider, prove the above view of the case:--When the hand is placed over the situation of the right auricle, it is felt to pulsate with a force nearly equal to that of the aorta, which can be found by pressing deeply a little higher up in the fissure; but it is impossible that the blood should be propelled from the cavæ into the auricle with a force of this kind. Again, the pulsation, or filling out of the tumour, takes place from below upwards, and slightly from the left side towards the right, whether M. Groux be upright or lying, but this is exactly the direction from the ventricle into the auricle, and not that from the two cavæ. The subsidence of the tumour takes place of course exactly in the opposite direction. Thirdly, the filling of the tumour caused by the right auricle seems to be exactly synchronous with the first sound of the heart and the pulsation of the aorta.

I believe the contraction of the right auricle is not apparent in the case under consideration. I did, indeed, on one occasion, observe a slight motion for a few moments in the intervals between the greater and more apparent ones; but this slight motion, which might have been caused by the contraction of the auricle, disappeared, and I could not again observe it.

It is somewhat curious that there is a difference of opinion amongst the observers of this case, on the other side of the Channel, respecting the exact time when the rise and subsidence of the tumour in the situation of the right auricle takes place; some of the observers stating that the subsidence of the tumour coincides with the impulse of the heart against the wall of the thorax; and Professor Forget stating that the dilation or impulse of the tumour coincides with the impulse of the heart. It is difficult to appreciate a small part of a second of time whilst observing two distinct phenomena at once; but according to the best of my observation, the truth lies between the two opinions. It appeared to me that the impulse or dilation of the tumour occurred just before the impulse of the heart, and the subsidence of the tumour directly after that impulse. The explanation of this is as follows:--the contraction of the ventricles occupies an appreciable part of a second. The closing of the auriculo-ventricular valves, and the impulse in the right auricle above described take place at the beginning of the ventricular contraction, and the impulse of the apex of the heart against the ribs near its conclusion, when the ventricles have injected their blood into the large arteries, and have consequently altered their shape, and are just on the point of relaxing.

There are many interesting points connected with the case of fissure of the sternum that I have not thought it necessary to allude to, as there appears to be no difference of opinion about them. I believe the explanation I have offered above, respecting the chief feature of the case, will remove the cause of disagreement that previously existed, and will show that the phenomena presented by the heart, in this instance, are quite in accordance with the physiology of that organ which is usually taught and received.

I am Sir, your obedient servant,

John Snow, M.D.

Sacksville-street, July, 1855.

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  93."Letter to the right honourable Sir Benjamin Hall, Bart., President of the General Board of Health"

Source: Snow, John. London: Churchill, 12 July 1855.

By John Snow, M.D.

Member of the Royal College of Physicians, and President of the Medical Society of London.

I was ordered, as you are aware, to give evidence before the Select Committee on Public Health Bill and Nuisances Removal Amendment Bill, Of which Committee you were the Chairman. I stated my opinion that certain useful though offensive trades do not cause, or in any way promote the prevalence and mortality of cholera, fevers, and other diseases, which are communicated from person to person, and which, on account of the property of being so communicated, take on very often the form of epidemics. I explained the grounds of my opinions as well as the opportunity permitted. Although I had published the same opinions on more than one previous occasion, and they had received no notice except of approval, I have been subjected since expressing them to the Select Committee to some rather severe attacks, commencing in the newspaper press, and continued in the medical journals.

The writers of these attacks have assumed and asserted that the opinions I have expressed on the subject of offensive trades are altogether new and peculiar. This error might be excused in the editor of a newspaper, but in the editors of the two medical journals who have given a leader on my evidence it is altogether unpardonable. It is only necessary to quote the following passage from page 635 of Dr. Bancroft's work on Yellow Fever, published in 1811, in order to show that my opinions on this point are at all events not new.

"The following statement is extracted from a letter written to the author by Mr. Lawrence, Anatomical Demonstrator at St. Bartholomew's Hospital; whose character, talents, and professional acquirements, have already, at an early period of his life, greatly and justly advanced him on the road to eminence.

"'In a constant attendance at the dissecting room of St. Bartholomew's Hospital, for more than ten years, I have never seen any illness produced by the closest attention to anatomical pursuits, except such as might be expected to follow from a similar confinement and application to any other employment.

"'When it is considered that most of the students come from the country, and that many spend much time in dissection, being employed also in writing, reading, etc., during the rest of the day, it will not be a matter of surprise that their health should occasionally suffer: but the indisposition has never appeared to derive any peculiar character from the exposure of the subject to putrid effluvia. Of course you will except from this observation, the effects which may arise from the absorption of noxious matter from wounds received in dissection. It has not appeared to me that ill consequences of that description follow more frequently from the dissection of the most putrid, than from that of recent bodies. The following particulars will afford the most complete proof, that the exhalations from decomposing animal substances are not necessarily injurious to the human body. John Gilmore, together with his wife, and two sons, lived for ten years in a room under the anatomical buildings of St. Bartholomew's Hospital. The whole family slept, as well as spent the day, in this apartment, which received a very small quantity of light, inconsequence of its single window opening against a high wall. The room was at the end of a passage, in which several tubs containing bones in a state of maceration were generally placed, and with which other divisions of the cellars communicated, continuing large excavations for receiving the refuse of the anatomical rooms. The latter were not separated from the passage by any door.

"'The animal matters thrown into the receptacles last mentioned, are, I believe, converted into adipocere, and the fetor is consequently not so offensive as if they went through the putrefactive process; but the whole place was constantly filled with a close cadaverous smell, very disagreeable to any persons who went down from the fresh air. During the whole day, Gilmore was employed about the dissecting room, in removing the offals, in cleaning macerated bones; in short, in an almost constant handling of putrid matters. He always enjoyed good health, was fat, and possessed very great bodily strength. He left his situation in consequence of an apoplectic attack, and died lately, at the age of 69, after two other similar affections. His wife survives, enjoying a good state of health. Neither of his sons appears to have suffered from any unwholesomeness of their abode. They are both hearty and strong, although they have been employed some years in attending the dissecting room. But the whole family left the cellar soon after the father's first attack.'"

The above facts, detailed by Mr. Lawrence, agree with the experience of all medical men regarding dissection, and the bearing of these facts on the mischief alleged to arise from other occupations connected with decomposing animal matters must be very evident. I could, indeed, if I had time, quote many passages from trustworthy authorities to prove that skin dressing, bone crushing, and other offensive trades are not perceptibly injurious to health; but I have preferred to select the above passage, because the experience and opinion of Mr. Lawrence, who is well known to you as an eminent member of the Medical Council of the General Board of Health, will naturally have more weight with you, than the opinions and evidence of others who might be strangers.

It is hardly necessary to remark that occupations which are not injurious to those who follow them, cannot, by any stretch of the imagination, be considered to do harm to those who merely live in the neighbourhood in which the occupations are pursued. As the gases given off from putrefying substances become diffused in the air, the quantity of them in a given Space is inversely as the square of the distance. Thus, a man working with his face one yard from offensive substances, would breathe ten thousand times as much of the gases given off as a person living a hundred yards from the spot. Currents of air would make a difference; but this would be the average proportion of the gases inhaled respectively by the two individuals. Therefore, if these gases are supposed to act as ordinary poisons, the health of the workman ought to be injured ten thousand times as much as that of the inhabitant a hundred yards from the factory; or if they are supposed to act as specific poisons, having the power of reproduction, so that the smallest quantity might suffice to set up disease, then the chances of contracting such disease would be ten thousand times greater amongst the workmen, than amongst those living at a distance of one hundred yards.

It is sometimes asserted that workmen become inured by habit to offensive trades, and thus escape the diseases which attack others at a distance; but they who use this argument forget that those at a distance ought by habit to become inured to their minute dose as well as the workmen to the larger quantity; and also that the workmen are not inured by habit when they first enter on their trades, and ought then to be affected by their occupation if it really produced fevers and other epidemic diseases; but this is contrary to experience.

The gases which result from the putrefaction of animal substances are capable of causing death, when they are breathed in a concentrated form, and it is often assumed that this of itself proves that they must be more or less injurious in the most minute quantities. This, however, by no means follows, for carbonic acid gas causes instant death when not much diluted, and yet it is a natural constituent of the atmosphere, and is constantly breathed in all parts of the world. Carbonic acid gas is not so powerful a poison as some of the gases resulting from putrefaction; but then the amount of it always present the air is far greater than that in which the gases from putrefying substances are ever met with in the streets and houses nearest to any kind of offensive factory.

The editors who have attacked me have apparently copied each other's sentiments, and they have assumed that my opinions respecting offensive trades are the consequence of the principles I have endeavoured to establish concerning the mode of communication of cholera, typhoid fever, and some other diseases. But this is an error, for I held the sentiments that I now hold respecting offensive trades, for many years before my opinions were formed, on the mode of communication of cholera, at the latter part of 1848; and in this respect I was in no way singular. One of the most approved and largely circulated works on the Practice of Physic, is Dr. Watson's Lectures, which appeared in the Medical Gazette in 1841-2. The following passage will show Dr. Watson's opinions with respect to the alleged connection between fever and offensive effluvia.

"Again, continued fever has been attributed, with great confidence, to a vitiated state of the air, from the putrefaction of dead animal and vegetable substances. Dr. Bancroft deals with and demolishes this error also, showing that neither the putrid atmosphere of the dissecting-rooms (respecting which you must have some personal experience), nor the noisome effluvia from full and ill-conditioned burial grounds, nor those to which tallow-chandlers, soap-boilers, glue and catgut makers, and the melters of whale-blubber, are exposed, nor the foul air of sewers and privies, have ever been known to produce anything like continued fever. In some parts of Essex, near the coast, where the farmers are in the habit of manuring their fields with shoals of sprats, I have seen large tracts covered with these fish in a state of putrefaction. The stench they occasion is horrible; but no disease results. Dr. Chisholm, in a paper to which I can only refer, but which I would recommend you to look at, in the sixth volume of the Edinburgh Medical and Surgical Journal, brings forward other, and very satisfactory, instances, to the same purpose: from a bone manufactory, near Bitton, in Gloucestershire; from an establishment (now relinquished) on the banks of the Avon, for converting the flesh of dead animals into adipocere; from manufactories for refining sugar, where the blood of slaughtered animals is kept for that use by butchers; from the leather-dressing business; all tending, I say, to the conclusion, that air, contaminated by the decomposition of animal substances, is not necessarily noxious to life; still less productive of that specific disease which we are now considering. The old belief, therefore, was unfounded, that the exhalations from the dead and putrefying bodies of men and horses, lying unburied on the field of battle, are capable of producing a pestilence. Many instances to the contrary are on record; one, of an early date, is thus stated by Diemerbroek:--'Anno 1642, in agro Juliacensi maxima strages facta est, et ad minimum 8,000 militum occisa fuerunt, præter majorem adhuc famulorum, etc., numerum: corpora inhumata sub dio computruerunt, nulla tamen pestis insecuta est.'" [In 1642, the greatest massacre took place in the territory of Juliacensi, and at least 8,000 soldiers were killed, besides a still greater number of servants, etc.: the unburied bodies rotted under the sun, but no plague followed.]--Medical Gazette, 1842, Vol.xxx., p.791.

Although there is sufficient direct evidence to prove that cholera is neither caused nor increased by offensive trades,* that circumstance is very much confirmed by the facts which I have been able to collect in illustration of the mode of propagation of cholera; for it is not reasonable to seek for additional causes of any phenomenon, when a real and adequate cause is known. Thus the itch, owing to its being almost exclusively confined to the poor and dirty, is more confined to neighbourhoods where offensive smells prevail, than typhoid fever is, and very much more so than cholera is; yet no one attributes the itch to the gases given off by decomposing animal or vegetable matters, for the simple reason that the real and sufficient cause of that complaint is known.

(*The Registrar-General's sub-district of Lambeth Church, first part, which extends by the river side from Westminster Bridge to Vauxhall Bridge, and contains most of the manufactories that are Complained of in Lambeth, suffered only a mortality of 29 persons in 10,000, in the epidemic of cholera in 1854, whilst the more genteel, open, and thinly peopled sub-districts of Clapham and Kennington, in which few factories are situated, suffered as follows: Clapham, 103; Kennington, first part, 125; and Kennington, second part,76 deaths from cholera to each 10,000 inhabitants. The sub-district of Saffron Hill, with the open Fleet Ditch flowing through it, and the slaughter-houses, knackers' yards, and cat-gut factories of Sharp's Alley, on its eastern boundary, suffered the lowest mortality from cholera in 1854 of any sub-district in London except one. The mortality of the Saffron Hill sub-district was only 5 in 10,000, whilst that of London altogether was 45, and that of the fashionable Belgrave sub-district was 60 in 10,000.)

It appeared to me that you were not sufficiently aware of the bearing that any facts, which should establish a distinct and adequate cause of cholera, would have on the alleged effect of offensive trades in promoting that malady; for when a member of the Select Committee--Mr. Wilkinson, I think--put a question to me respecting the cause of the outbreak of cholera near Golden-square, you did not allow it to be answered, although, undoubtedly, the late epidemic of cholera was the cause of the bills being framed which are now before Parliament.

The absence or defect of drainage, undoubtedly, assists very much in the propagation of many epidemic diseases, and as defective drainage very often occasions offensive smells, the editors of whom I complain have arrived at the short and easy conclusion that any trade or manufacture, which gives rise to an offensive odour, must also promote disease. The matters, which it is the purpose of drainage to remove, contain all that comes from the sick, as well as the healthy part of the community, and, when they are not properly removed, they permeate the ground, and pollute the pump-wells and other supplies of water and, in this way, as I have elsewhere adduced a good deal of evidence to prove,* several epidemic diseases may be propagated; the morbid matter of each disease reproducing its own specific malady.

(*On the Mode of Communication of Cholera.)

There are also other ways more gross and material than a mere odour, by which the absence of proper drainage aids in the spread of disease. On the other hand, occupations connected with the skins, bones, or fat of dead animals, cannot in any way assist in conveying the morbid matter of disease from the sick to the healthy.

I am, of course, no defender of nuisances, but I consider that if a trade is more offensive than it ought to be, or is conducted in a place where it has no right to be, it might be proceeded against by the ordinary laws as a nuisance, without using the word pestiferous, or otherwise dragging in and distorting the science of medicine.

Some of the manufacturing processes which give rise to offensive smells, are not only a source of wealth in themselves, but are highly useful to agriculture. These are circumstances that would, at one time, have been thought worthy of consideration, but, however desirable it may be that commerce and agriculture should not be injured on mistaken grounds, it is still more important that the real causes which affect the health of the community should be ascertained, and that epidemics should not be attributed to a wrong cause, for I have previously shown that great increase of disease has several times been occasioned by presumed sanitary measures.

I have of course not written this letter in the way of personal complaint against the editors by whom I have been attacked. My reason for writing it is, that I have an impression that the editors in question have really expressed the sentiments of the majority of the persons who have paid little attention to the subject, but are more likely to influence legislation than careful and industrious observers.

I have the honour to be, Sir,

Your obedient servant,

John Snow, M.D.

Sackville Street, July 12th, 1855.

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  95."Further remarks on the mode of communication of cholera; including some comments on the recent reports on cholera by the General Board of Health"

Source: Snow, John. Medical Times and Gazette 11, 28 July 1855, pp. 84-88, Part 2.

Part 2

Another circumstance, which shows very forcibly that the impure water produced its deleterious effects in time of cholera in no other way than by conveying the real material cause of the disease, is, that in the outbreaks caused by the contamination of a pump well, or other local supply of water, nearly all the cases occur together. The water in nearly all these outbreaks had been habitually contaminated for a length of time, and, if it acted as a mere auxiliary cause of cholera, it would increase the prevalence of the malady during the whole time of its existence in the town or neighbourhood, instead of which, without any chemical or physical alteration in the water, a sudden outbreak of cholera takes place among those drinking it; and in most of the instances, as in that at Surrey-buildings, Horseleydown, in 1849, and in that last summer in the neighbourhood of Golden-square, it has been found that the evacuations of a cholera patient were among the impurities which entered the water just before the outbreak. When the cholera is communicated through the medium of a large river, and the pipes of a water company, this sudden kind of outbreak, or increase of the disease, does not of course take place, but the disease gradually increases, as the number of fresh cases add fresh germs or particles of cholera poison to the water, and thereby increase the chances of a person getting one. The time when the epidemic begins to decline is usually that when, on account of a diminution of temperature, persons begin to leave off drinking unboiled water.

Another evidence of the way in which impure water must act in promoting cholera, is the fact itself of cholera being a communicable disease, as is proved by numbers of instances of overwhelming weight. For in itch, syphilis, small-pox, measles, and other communicable diseases, we do not look about for necessary or predisposing causes, but acknowledge in the reproductive morbid material of the disease its sole and sufficient cause. Any circumstance, therefore, which determines the attack of cholera may be presumed to do so by conveying the specific cause of the disease, especially where there is other evidence in favour of this event.

If this point is shown to be established, namely, that impure water increases the prevalence and fatality of cholera, by conveying the morbid poison from one patient to another, then the circumstance of the disease being communicated by swallowing the morbid poison with the food that has been touched with unwashed hands, or otherwise contaminated by the cholera evacuations, is also fully established; for it cannot be supposed that any poison, whether a morbid one or not, could produce active effects when mixed with an almost indefinite quantity of water, and not produce its effects also without the water. If the views I am explaining be correct, we have, therefore, the power of avoiding cholera as easily as one may avoid the itch. Every man may be his own quarantine officer, and go about during an epidemic among the sick almost as safely as if no epidemic were present.

In the recent Report on Cholera to the General Board of Health, by Dr. Sutherland, after saying--"It is believed by some that the water which induces cholera contains the specific poison of cholera in it," and that others consider the impure water only a predisposing cause, continues as follows: "The matter in dispute is really of no practical value, for if it be a fact that the use of impure water is injurious to the public health, the manner of its action is of very secondary importance, at least for practical purposes." P. 40.

It seems very curious that Dr. Sutherland should not have perceived that this question, as to whether or not the water contains the specific cause of cholera, involves the entire question of the cause and prevention of the malady, and also the approval or condemnation of nearly all the so-called sanitary measures which have been adopted with respect to cholera, since it was first expected in 1830.

There are some remarks in Dr. Sutherland's report respecting the south districts of London which require to be noticed, because they refer to the subject of which I am treating, and also because some of them are not quite correct. Quoting from an unpublished report by Dr. Greenhow, Dr. Sutherland says: "After the epidemic of 1849, Christchurch parish was exclusively supplied with the new and comparatively pure water of the Lambeth Company, while St. Saviour's continues to be mainly supplied with the impure water of the Southwark and Vauxhall Company," Now this is an error; Christchurch parish is not entirely supplied with the Lambeth water, as there are some houses in every part of the parish supplied with the water of the Southwark and Vauxhall Company. There is no district or sub-district nearer than Streatham, Norwood, Dulwich, and Sydenham which is supplied exclusively by the Lambeth Company. This is important as regards Christchurch, because there was a very high mortality among the minority having the impure water, and a very low one among the majority having the water from Thames Ditton. St. Saviour's is not mainly but exclusively supplied with water by the Southwark and Vauxhall Company; this error is, however, of less importance than the other. Dr. Sutherland, continuing to speak for Dr. Greenhow, says: "During the late epidemic the mortality in St. Saviour's had advanced from 73 to 97 in 10,000, while the mortality of Christchurch had fallen from 100 in 10,000 to 44 in 10,000, of population." Striking as this difference in the numbers appears, it is much greater when it is known that a great proportion of the deaths in Christchurch occurred in the comparatively few houses having the impure water supply of the Southwark and Vauxhall Company. In the first four weeks of the epidemic there were three deaths from cholera in Christchurch parish, two of which occurred in houses supplied by the Southwark and Vauxhall Company, and one in a house supplied with the water of the Lambeth Company. In the next three weeks twenty-two deaths occurred; nine of the attacks took place in houses supplied by the Southwark and Vauxhall Company, twelve in houses supplied by the Lambeth Company, and one in a house where the inmates begged water all round, as the supply was cut off. Mr. Greenwood, the Registrar of Christchurch, also made an inquiry respecting these eases, and, on comparing our notes, we found that our results coincided respecting the water supply in every instance.

Dr. Sutherland continues as follows:--"This great difference is sufficiently striking; but, while admitting the beneficial results of the purer water, Dr. Greenhow considers it not to be entirely due to the water alone, for Christchurch parish has been improved in other respects of late years, by the covering over of a pestiferous ditch which formerly occasioned a great deal of atmospheric impurity in the neighbourhood, and by other sanitary measures."

Now, leaving out the fact that there are no open ditches in St. Saviour's, with its recent high mortality, if Dr. Greenhow had been aware that the small number of persons in Christchurch who received the impure water of the Southwark and Vauxhall Company suffered as high a mortality as a similar number in 1849, and that the population having the improved water were enjoying only the same amount of immunity as the inhabitants who had the same water in Lambeth Church, first part, amongst the bone-crushers and skin-dressers; or, the ragged, bare-footed people in the streets near the Cornwall-road, in the sub-district of Waterloo-road first part, he would have had no reason to suppose that the ditch had any share in propagating cholera in 1849. I believe that open ditches, which receive the dejections of cholera patients, do sometimes assist in the communication of that disorder, not only when people drink out of them, but also when children can get down to the edge, to pick out their marbles and other toys, and afterwards clean their hands with their tongues before showing themselves at home; but the above circumstances would seem to show that the ditch in Christchurch was not of either of these characters.

Dr. Sutherland proceeds, still quoting from Dr. Greenhow; he says:--"In proof that impure water, though a predisposing cause of cholera, does not act as a specific poison in producing cholera, Dr. Greenhow adduces several instances in which houses supplied by the Lambeth water suffered from cholera, while those supplied by the Southwark and Vauxhall water escaped."

These instances may be correct, notwithstanding Dr. Greenhow's mistake respecting the water supply of Christchurch and St. Saviour's; but I have to submit that the suffering or exemption from cholera in particular houses, whilst it bears on the question of the influence of the water, has no relation to the manner in which the influence is exerted. That is a question which must be decided by other means. The water of the Thames never became as full of the cholera poison as to affect persons in all the 40,000 houses supplied by the Southwark and Vauxhall Company, therefore the exemption of some of these houses was a matter of course; and, as the persons living in houses supplied with the Lambeth water were exposed to at least the same opportunities of taking cholera, as those living in the districts supplied with the New River water, and other water which could have no effect in propagating cholera, it was equally a matter of course that some cases should occur in houses supplied with water by the Lambeth Company. It must also be recollected that the people having this last-mentioned water were not prisoners in their houses. Mixed up as these houses are with others having the impure water of the Southwark and Vauxhall Company, it is not unreasonable to suppose that they would be liable to take the other water. Out of the very few fatal cases occurring in houses supplied with the Lambeth water, in the early part of the epidemic, one was that of a carman who was constantly going about, and took none of his meals at home except his supper, and another was a journeymen baker, who drank no water at home except in his tea, (of course boiled,) but he drank a great deal of cold water when at his work.

I have previously stated that, in the first four weeks of the epidemic, the fatal cases of cholera were fourteen times as numerous in a given number of houses supplied with the Vauxhall water, as in the same number supplied with the Lambeth water from Thames Ditton; and it is by no means improbable that out of every fourteen drinks of water taken at that time, one drink might be of a kind different from that supplied at the house of attack, to say nothing of the use of water for making and adulterating beverages which are vended.

I find from some further quotations which Dr. Sutherland makes, that I have the happiness of agreeing with Dr. Greenhow as to the effect of the impure water, though not as to its mode of action. Dr. Greenhow states that the use of the Southwark and Vauxhall water very greatly aggravated the pestilence; and further he says, "although, doubtless, the unwholesome water has much aggravated the result, it is only one cause among several." I believe no one ever supposed that impure water was the sole cause of cholera, and, for my part, I do not consider it a cause at all, but only a frequent medium or vehicle of the one true cause of the disease, namely, the reproductive cholera poison.

In speaking of sanitary improvements, Dr. Sutherland makes the following remark:--"Mr. Walsh states that Jacob's Island, Bermondsey and its immediate neighbourhood, suffered much less during the late epidemic, notwithstanding its greater severity, than it did during either of the two former visitations, which he says is attributable, without doubt, to the filling up of the foul tidal ditch, since the epidemic of 1849."

Judging from what Mr. Walsh stated on a former occasion in this Society, it is most likely that he would mention in his report the fact of a number of the inhabitants of Jacob's Island and the neighbourhood drinking the water of these ditches in 1849, but if so, Dr. Sutherland has not quoted this in his report; and as the quotation now stands, it would be understood by nearly every reader to imply that the aggravation of cholera in this neighborhood, in 1849, was caused by effluvia from the ditches; and that the improvement in l854 was due to improvement of the air, by the ditches being filled up. I have, however, the results of a statistical inquiry to show that such was not the case. The Metropolitan Commissioners of Sewers caused an inquiry to be made, at the close of the epidemic of 1849, into the effects of using the water of these ditches; and Mr. John Grant, the Assistant Surveyor to the Commissioners for Kent and Surrey, was kind enough to favour me with the result. In Jacob's Island, and the streets immediately surrounding the ditches, there were 7286 inhabitants. Of these there were 865 individuals having no other supply of water than the ditches, and the remaining 6421 had the supply of the Southwark and Vauxhall Watar Company, or were supplied by private pumps. During the first nine months of 1849, 18 deaths took place from cholera, [85/86] and 8 deaths from other causes, amongst the 865 persons having no water supply but that of the ditches; and 95 deaths from cholera, and 46 from other causes, amongst the 6421 persons having another supply. The mortality from cholera was, consequently, at the rate of 208 in 10,000 amongst the persons using the ditch water, and 147 in 10,000 amongst the inhabitants who had the supply of the Southwark and Vauxhall Company, or that of private pumps. The mortality of the population living amongst and around the ditches, but not drinking the water, was, in fact, almost exactly the same as that of the other inhabitants further removed from the ditches; whilst that of the people who were obliged to drink the water was more than one-third higher; as the following figures from the Report of the Registrar-General show. St. James's, Bermondsey, in which Jacob's Island is situated, suffered a mortality from cholera of 142 in 10,000, St. Mary Magdalen, Bermondsey, a mortality of 159 in 10,000, and the Leather Market sub-district of Bermondsey a mortality of 160 in 10,000.

The ditches were of considerable extent, and as wide as an ordinary canal. The water had been formerly used for turning the wheel of a mill, as it flowed back into the river, but of late years the ditches were usually kept full, and only emptied at intervals. During the time of my visits in August and September, 1849, when the cholera was at the worst, they were not emptied at all, and no mud was exposed. The water of the Thames, admitted into these ditches, received the sewage of the surrounding population, either directly, by the privies overhanging the ditches, or through channels and drains. Thames water emits no smell, although the odour of exposed mud, and that from the mouths of sewers, sometimes leads persons to suppose it does.

The water of the ditches around Jacob's Island, although richer in manure than that of the Thames, did not seem offensive, so far as I could perceive; and if the ditches had been filled with black stinking mud, I believe they would not have increased the prevalence of cholera, as it could then have been impossible for the people to drink the water, and thus to imbibe the cholera poison coming from the cases in the neighbourhood. As it was, the water became moderately clear after standing in a vessel for a few hours, as the persons who were obliged to use it generally allowed it to do. Many of the persons having no other supply than that from the ditches, were able to beg water occasionally from their neighbours, otherwise the mortality amongst these people would probably have been still higher. In the recent epidemic, since the ditches were filled up, the mortality in the immediate neighbourhood has been only the same as that in the rest of the sub-district of St. James's, Bermondsey. The proportionate reduction of the mortality being entirely due, as the above facts prove, to the circumstance that none of the people drank worse water than those in the rest of the district. The whole of Bermondsey suffered a higher rate of mortality in 1854 than in 1849. This is the case with nearly all the other districts and sub-districts supplied exclusively by the Southwark and Vauxhall Water Company, and arises from the circumstance that, between 1849 and 1854, a great number of cesspools were suppressed, and water-closets substituted in their stead, throughout London, with the effect, when cholera was re-introduced, of sending the evacuations of the patients more generally and more quickly into the river.

Dr. Sutherland states that, "After the decline of the cholera, the President of the General Board of Health directed Dr. Fraser to make an inspection and inquiry into the condition of Lambeth-square, to ascertain to what extent the epidemic had prevailed among the population. This inquiry was directed in consequence of certain improvements in drainage having been carried out, subsequent to the epidemic of l849."--p. 67.

Dr. Fraser seems to have carried out his inquiry very ably and faithfully according to his instructions, which unfortunately contained no intimation that the supply of water had been altered in any part of Lambeth, and he appears not to have been himself aware of the circumstance, or he would have alluded to it. Lambeth-square contains 35 eight-roomed houses, inhabited by the better class of artisans. There were six deaths from cholera in 1849. In 1852 water-closets were substituted for open privies, and improvements were made in the drainage, and last year there was no death from cholera. The general mortality has also been lower the last two years than during the two years previous to the alterations. An improvement took place in 1852, however, of which Dr. Fraser was not aware. Lambeth-square is the property of one person, and is entirely supplied with water by the Lambeth Water Company, who in that year removed their source of supply from the middle of the sewers of London to Thames Ditton, as was before explained. To show that this was the real cause of the late immunity from cholera, I shall allude to another property, which has all the advantages described by Dr. Fraser as belonging to Lambeth-square, and the additional one of not being surrounded with the offensive smells external to the property, of which the inhabitants of that square still complain; but which has a water supply very similar to that which Lambeth-square had in 1849, namely, the supply of the Southwark and Vauxhall Company. In the Weekly Return of Deaths for September 9, 1854, the Registrar of the Clapham district writes as follows:--

"In consequence of there being a larger number of deaths from cholera this week in the vicinity of Park-road than in any other part of my district, I have inspected Park-crescent and Crescent-road, and found the drainage very good; the houses have recently been built, and there is great credit due to the landlords for the care they have taken to render them in every way comfortable and healthy; there is a water-closet and water laid on to each of them; but when I examined the water I found it in such a filthy state that I advised the inhabitants not to drink any more of it for the present. At most of the houses they had pieces of flannel, two or three thick, to act as filters."

There were only 472 deaths last year in all the 26,107 houses supplied by the Lambeth Water Company, or 1 death to each 56 houses, and therefore it is not surprising that a group of 35 should have escaped having a death.

Dr. Sutherland quotes some remarks respecting the water supplied to different parts of London, by Dr. Hassell, who very truly observes that the most impure is that of the Southwark and Vauxhall Company. He says: "Between it and the water of the Thames, as taken from the river at the spot at which the Southwark and Vauxhall Company obtains its supplies, there is frequently only that amount of difference which would arise from mere subsidence." Dr. Hassell describes the practice, which I have seen in hundreds of instances, of tying folds of flannel or other fabric over the taps through which the water of this company is distributed, and adds: "The quantity of dirt and organic matter obtained in this way in a short time is often perfectly surprising." Just after the above, on the same page (42), Dr. Sutherland quotes a passage from Dr. R. D. Thomson, who says that the water of the Chelsea Company is the most impure that is supplied in London, and that the water of the Southwark and Vauxhall Company comes next. The reader must not suppose, however, that the inhabitants of Belgrave-square and the great mansions round St. James's Park tie folds of flannel over the water taps, and collect a surprising quantity of dirt every time the water comes in, for this is certainly not the case. Dr. Thomson makes an unusual application of the word impurity, an application which would cause the water drunk at many of the fashionable watering places to rank as ten times more impure than that of an ordinary horse-pond. He includes every foreign ingredient in the water, in the term impurity, which may be allowable in a strictly chemical point of view, but practically pure water would, according to this view, be quite inadmissible in London, as it would dissolve the leaden cisterns and service-pipes, and poison the community.

The Chelsea Water Company obtain their supply from the same part of the river as the Southwark and Vauxhall Company, and their customers suffered a higher mortality from cholera in the late epidemic, than those of any other London water company, except the Southwark and Vauxhall. Between the mortality of the population supplied by these two companies, there was, however, a considerable difference. That of the population supplied by the Southwark and Vauxhall Company was 157 in each 10,000 inhabitants, that of the population an p plied by the Chelsea Company was 56, and that of the rest of London was 34 to each 10,000 inhabitants. The reason of the lower mortality in the districts supplied by the Chelsea Company than in those supplied by the Southwark and Vauxhall Company, can be very satisfactorily explained. While the latter company distribute the water nearly as they [86/87] take it from the Thames, the Chelsea Company have very large and expensive filtering beds, by which nearly all the visible dirt is separated from the water. The cholera poison may, much of it, be separated at the same time, but I have several reasons for concluding that the detention of the water reservoirs, which necessarily accompanies the filtration, is more effectual in diminishing the cholera poison than the mere filtration itself.

Whilst the Chelsea Water Company were detaining their water in large open reservoirs, during the hot dry weather of last summer, in order to separate from it as much as possible of what comes down the sewers, it was evaporating, and the relative quantity of sea salt, and of the salts belonging to the water of the river, were necessarily increased; in this way, Dr. Thomson, according to his method of investigating impurity, was able to pronounce this water more impure than that of the Southwark and Vauxhall Company.

Dr. Sutherland quotes a passage from Dr. Thomson, which seems to throw a very unmerited blame on the water of the New River Company. It is as follows:--"In the Soho district a very remarkable circumstance occurred in the houses supplied by the New River Company. In these it was found that the water, although taken on the same day, possessed a totally different composition from that contained in the reservoir at the New River Head; for, while the impurity of the reservoir water was 17.18 degrees, that of the Soho district, obtained from the New River Company, as ascertained by the water receipts, but from what source is unknown, was 30 degrees; the organic impurity being l.5l degrees in the first case, and 2 degrees in the second instance." P. 46.

Now, passing over the fact that the outbreak of cholera in this neighbourhood was confined, almost altogether, to persons who had water from a pump in Broad-street, Golden-square, and that those persons who confined themselves to the use of cistern water remained as free from cholera, throughout the outbreak, as persons in another part of London; there are two circumstances which ought at once to have shown Dr. Thomson that the water in these cisterns could have had nothing to do with the outbreak of cholera. The locality of this outbreak is extremely well defined. It is about a quarter of a mile in diameter, and includes a portion of the Golden-square sub-district, a portion of the Berwick-street sub-district, and a small part, only fifty yards wide, of the adjoining sub-district of St. Ann's, Soho. The outbreak commenced in all parts of the locality on the same day, and, as nearly as can be ascertained, at the same hour. But the New River water extends to only about one half of the locality attacked. It supplies the sub-districts of St. Ann's Soho and Berwick-street, but does not extend into the sub-district of Golden-square, which is entirely supplied with the water of the Grand Junction Company. The districts of these companies have been long fixed, as firmly as the parish boundaries, and there was small reason for the inspectors of the Board of Health to examine the receipts. But, even if the New River Company had supplied all the locality of the outbreak, there is another circumstance which might have shown Dr. Thomson that this water could have no connexion with it. It would be impossible that the company's pipe, after proceeding a certain distance down Wardour-street, should suddenly take up a certain quantity of additional foreign matter or impurity; and that, after proceeding some way, it should as suddenly leave off this foreign matter again, just where the cholera ceased, and that these two processes should take place in nearly all the streets of the locality. A little inquiry also would have shown Dr. Thomson that the kind of water he speaks of extended far beyond the limits of the outbreak. The reason of its differing from that at the New River Head admits of a very easy explanation, but I am treating of cholera, and not of water supply.

Mr. Glover, in his Report on the Common and Model Lodging Houses, recently published, in speaking of the Soho Chambers, 36, Old Compton Street, makes the following remark:--"In the district of Golden-square (in which these chambers are situated), up to October 7th, no less than 267 persons died from cholera alone, exclusive of the mortality from diarrhœa; and yet in these chambers there was not a single case of cholera, and only seven of diarrhœa, none of which proved fatal.* (*Page 27.) Mr. Glover moreover enumerates Compton-street among those in which "the inhabitants were a dying in large numbers daily. "Now, in the first place, Old Compton-street, in which the Soho Chambers are situated, is not in the district of Golden-square, but in the next district but one to it; namely, in the district of St Ann's Soho, the district of Berwick-street lying between the two. In the next place, and what is of still more importance, so far from Compton-street being one of the streets in which the inhabitants were dying in large numbers daily, there was not a single death from cholera in this street, either during the outbreak or for three weeks before or after it. The outbreak extended to a small part of the parish of St. Ann's, Soho, but not into Compton-street, than which there was not a street more free from cholera in London. It is a street containing 53 large houses, nearly all of them divided into tenements, and densely inhabited. The population of this street is probably not less than a thousand persons, and yet not a death from cholera was registered from it, from August 19th to September 30th, inclusive.

Mr. Glover makes it appear that the mortality of cholera in the common and model lodging-houses, during the late epidemic, was only at the rate of 7 to 10,000 inhabitants, whilst in the metropolis generally the mortality was 44 to 10,000. It is but justice to Mr. Glover to state that he makes the following remarks:--"This result is of so startling a character, that some doubts naturally arise as to whether the police return can be taken as actually correct, or merely as an approximation to the actual amount of mortality. It is very probable that many cases originated in the houses which ended fatally elsewhere."--P. 10.

The following circumstances, with which I became acquainted in making an inquiry for a different purpose, prove that Mr. Glover's surmise is correct. During the first seven weeks of the late epidemic there were only six deaths from cholera registered from the common lodging-houses in the parish of St. George, Southwark; but during this period there were seven deaths in the workhouse of persons who were admitted from the common lodging-houses, after being attacked with cholera. In fact, out of thirteen persons admitted into the workhouse, during these seven weeks, with fatal attacks of cholera, seven of them came from the common lodging-houses, as I have stated, and only six from all the other places, including two whose address was unknown, and who might also have been persons who generally lived in these lodging-houses. It is very probable, therefore, that if Mr. Glover had searched the books of all the workhouses and hospitals in London he would have been able to get a much nearer approximation to the real number of fatal attacks of cholera occurring in the common and model lodging-houses than he has done.

Except the distribution of the cholera poison in the water, there is no circumstance which favours its propagation so much as the crowding together of people of uncleanly habits; it is, therefore, very probable that the regulation of the common lodging-houses, and especially the establishment of model ones, has contributed greatly to the mitigation of the recent epidemics; but it is not likely that the inmates of the lodging-houses have enjoyed an immunity from cholera so much exceeding that of the inhabitants of May Fair as was indicated in Mr. Glover's report. As for the entire escape of model lodging-houses whilst the cholera was raging around, which has been so much commented on in the public prints, it did not exist at all. The idea arose out of the error respecting the Soho Chambers, which I have pointed out above.

The only other subject to which I shall allude in connexion with the recent Reports of the Board of Health, is the statement, several times repeated, and implied almost everywhere, that the cholera has been most severe where the air was most impure. That there is an occasional association between cholera and impure air, is what might be expected, according to any view of the pathology of cholera, but that this amounts to anything like a rule, a very few examples, drawn from the last epidemic in London, will serve to prove to every one acquainted with this metropolis. The sub-district of Saffron-hill, with the open Fleet Ditch steaming through it has experienced a lower mortality from cholera in the recent epidemic than any other sub-district in London, except the neighbouring one of St. George the Martyr, Holborn. Saffron-hill had a mortality of 5, and St. George of 4, in 10,000. No one acquainted with the south districts of London would assert that the air at Clapham and Kennington is as impure as in the low-lying districts of Lambeth, crowded with a poor [87/88] population, and containing the bone-boilers, and other offensive trades; yet the following figures, from the reports of the Registrar-General, show how these respective sub-districts were visited by cholera. I have added the London-road sub-district of Southwark, as it contains a very poor population in very dirty streets, and is on a level with Trinity high-water mark.

The reason of the lower mortality in the last four sub-districts, is that they receive a good deal of the new water supply of the Lambeth Company, while Clapham and Kennington 1st Part are chiefly supplied by the Southwark and Vauxhall Company, where the people have not pump-wells. In Kennington 2nd Part the water of the two companies is pretty equally distributed.

Cholera, as I stated before, spreads more readily from person to person in the crowded dwellings of the poor than under other circumstances. Even when the malady is propagated through the water supply, it causes a higher mortality among the poor than among the well-to-do, because, in addition to the cases caused directly by the water, others arise from the disease passing from one member of a family to another. But the poor very generally live in places where the air is impure, therefore, a certain amount of association between cholera and impurity of the air might be expected. A far greater association of this kind than actually exists, would, however, be no proof of any connexion in cause and effect. If an inquiry were set on foot with regard to the itch in London, and other towns, it would be rarely met with except in situations where the air is impure; a far greater association would be found between impure air and itch, than between impure air and cholera, and yet we know that impure air has no share in causing the itch.

Sackville-street.

Return to John Snow Publications

  96."On the employment of chloroform in surgical operations"

Source: Snow, John. Lancet 2, 20 October 1855, pp. 361-63, Part 1.

Part 1

By John Snow, M.D.

I have now been very much occupied in the administration of chloroform for a period of nearly eight years; and I am quite confirmed in the opinion which I long ago expressed, that this agent may be exhibited with propriety in every case in which the patient requires, and is in a condition to undergo, a surgical operation. If it were simply a question of giving chloroform or not giving it, there are, indeed, some patients to whom one would prefer not to give it; but the question lies between exhibiting chloroform or inflicting the pain of an operation, and, according to my observation, the former is always the lesser evil of the two. The affection which is generally thought to be most opposed to the inhalation of chloroform is fatty degeneration of the heart; but from all that I have been able to observe, it is of great advantage, in such cases, to prevent the pain of an operation.

Patients with fatty degeneration of the heart are liable to die suddenly in two distinct ways: first, with the cavities of the heart empty; and, secondly, with the cavities of the heart full of blood. In the latter case, death is caused by the inability of the weakened heart to propel the blood; but, in the former case, where the patient dies by ordinary syncope, such as that occasioned by loss of blood, and where the cavities of the heart are empty, death must be caused by some undescribed condition which accompanies the disease of the heart, and not by that disease itself; for the most healthy heart would be unable to maintain the circulation when the blood no longer reached its cavities from the veins.

The pain of a surgical operation has a tendency to produce both those conditions of the cavities of the heart which are liable to prove fatal, when that organ is affected with fatty degeneration; whilst, on the other hand, chloroform has the effect of keeping the circulation in a more equable state. The ordinary kind of syncope, in which all the cavities of the heart are probably empty, was very common during surgical operations, before the introduction of ether and chloroform, even when the patients were apparently strong, and the operation of a trifling nature. Under the influence of chloroform, however, syncope is extremely rare, even in operations attended with considerable loss of blood. The pain of an operation has a tendency also, in many cases, to cause over-distention of the right cavities of the heart, owing to the patient straining violently, and holding his breath. The following instance, in which I had an opportunity of witnessing a similar operation, in the same patient, both with and without chloroform, shows this effect of pain, and the favourable effect of anæsthesia, in a remarkable manner.

On January the 6th, 1855, Mr. Fergusson performed lithotrity in King's College Hospital, on a man aged fifty-one. He generally directs chloroform to be administered in lithotrity, but in this instance he omitted to do so, as he thought that the bladder was not very irritable, and that the patient would not suffer much. I began to feel the pulse just when the patient saw the lithotrite about to be introduced. It was 120 in the minute. As soon as the instrument was introduced, the pulse increase to 144, and immediately afterwards it became uneven, irregular, and intermitting. I could not count more than three or four beats at a time, and, occasionally, when the pain seemed greatest, and the man was straining and holding his breath, the pulse at the wrist was altogether absent for four or five seconds at a time. In order to ascertain whether the absence of pulse might not depend on the pressure of the muscles of the arm, caused by grasping the table, I applied my ear to the chest, and found that there was no sound whatever to be heard during the intervals when the pulse was imperceptible. It was evident that the patient held his breath till the right cavities of the heart became so distended as to stop the action of that organ till the respiration returned. The man did not complain, or cry out, during the operation. A week afterwards the lithotrity was repeated, but on this occasion I administered chloroform. The pulse was about 120 in the minute, when the patient began to inhale; but it became slower as he was made unconscious, and it was regular and natural during the operation. It was only towards the end of the operation, when the effect of the chloroform was allowed to diminish, and the man began to strain a little, though not yet conscious, that the pulse intermitted slightly, passing over a single beat occasionally. There were none of the long intermissions of the pulse which were observed on the former occasion.

It is very evident, that if this patient had been the subject of any affection of the heart which weakened or embarrassed its action, he would have run a much greater risk from the pain of the first operation than from the inhalation of chloroform in the second one.

I have given chloroform with a favourable result to a great number of patients having all the symptoms of fatty degeneration of the heart, as a weak, intermittent pulse, arcus senilis of the cornea, and liability to faintness. The only patient, indeed, whom I have had the misfortune to lose whilst inhaling chloroform had very extensive fatty degeneration of the heart, the symptoms of which were well marked during life; but I am by no means sure that this patient died from the effects of chloroform, although I thought it best at the time to designate the death as one from this agent. The patient, a gentleman aged seventy-three, died just as he probably would have done, at no distant day, if no surgical or medical interference had taken place. He was making a straining effort, as if he was beginning to feel the pain of the operation, and I was commencing to give him a little more chloroform, when he suddenly expired; and I am quite unable to tell whether it was the effort of straining, or the influence of the chloroform, which caused death to take place at the moment when it did. The quantity of chloroform he was taking at the time was very small indeed, and largely diluted with air, and he had inhaled it several times before. But if it be granted that this death was caused by the chloroform, when I take into account the number of other patients with similar symptoms, to whom I have given it with a favourable result, I do not consider that it furnishes any argument against the use of this agent in such cases. Patients with fatty degeneration of the heart in an advanced stage are, no doubt, very undesirable subjects for a surgical operation under any circumstances; but when it is absolutely necessary to perform one, I am of opinion, both from what I have seen of the effects of pain on the circulation, and from what I have seen of the effects of chloroform in patients of this kind, that it is desirable to let them have the advantage of its administration. Patients with symptoms of fatty disease of the heart sometimes become faint after the conclusion of an operation under chloroform if they are kept in a sitting posture, but I have always found the faintness to subside on placing them horizontally.

Out of the entire number of deaths from chloroform which are recorded, there are very few in which any considerable disease of the heart was found. In fact, the majority of those who are dead from chloroform were healthy persons in the best period of life--that is, from fifteen to thirty-five or forty, and it is most likely that they had, on the average, a sounder state of the heart than the multitude who have inhaled chloroform with impunity. It was not very uncommon occurrence for patients to die on the operating table before the introduction of anæsthesia, either just before the commencement of an operation or during its performance. Dr. Simpson, writing in 1852, says that two deaths had occurred on the operating-table in Edinburgh since the discovery of the effects of chloroform, in cases where the agent was not used. One died directly after the first incision through the skin, in a case of hernia, and the other instantly after the use of an abscess lancet. He also alludes to a case which occurred in Edinburgh just before the introduction of chloroform. Dr. Robertson had shaved the groin of a patient, and was proceeding to perform the operation for hernia, when the patient fainted, and died before any incision was made.

We have no information respecting the state of the heart in the patients who died suddenly on the operating table before the introduction of ether and chloroform, but it is extremely probably that many of them were affected with fatty degeneration of this organ; and I believe that by the careful administration of chloroform during operations on such patients, we not only prevent pain, but may in some cases save life.

The sudden deaths which occasionally took place on the operating table, before the introduction of anæsthesia, have sometimes been alluded to as affording an explanation of the deaths that have occurred during the use of chloroform; but, with a very few exceptions, this is not a correct view of the subject. In the instance at Mr. Robinson's, and in that at St. George's Hospital, the patients appeared to die suddenly from mental emotion, without being affected by the chloroform, which they were only just beginning to inhale; and in three cases on the Continent, where the patients died suddenly, just after great operations, loss of blood was probably the cause of death. With these, and perhaps one or two other exceptions, the deaths that have taken place under the influence of chloroform have nothing in common with those which happened on the operating-table before its introduction. In these latter cases, if the death did not arise from hæmorrhage, it was occasioned either by pain or mental emotion; but as the patient neither feels nor thinks when fully under the influence of chloroform, he cannot die from either of the two latter causes. In speaking of the benefits of chloroform, it is quite allowable to bring forward the sudden deaths which occasionally happened in operations, as a set-off against the deaths from this agent; but to suppose that the patients who have died during the employment of chloroform are the same that would have died without it is undoubtedly a mistake. The late Dr. Richard Mackenzie related a case of sudden death, which, he said, narrowly escaped being imputed to chloroform. He reduced a fracture of the radius, about an inch above the wrist, in a case where there was a good deal of swelling and displacement. He would have used chloroform, but he had none with him. Within five minutes after Dr. Mackenzie left the house, the patient died instantaneously, whilst he was talking freely to those about him. He was a corpulent man, from sixty-five to seventy years of age, who had lived freely, and Dr. Mackenzie thought it probable that he had fatty degeneration of the heart, but there was no examination of the body. The cause of death, in this case, was probably the pain to which the patient had been subjected, and it is not unlikely that the employment of chloroform might have saved his life for a time. At all events, there is no reason to conclude that the patient would have died in the manner he did if chloroform had been administered.

Surgical operations are, I believe, never performed during acute disease of the lungs, and chronic affections of these organs, as phthisis and chronic bronchitis, form no objection to its use. I have administered this agent in a number of operations where one or other of these diseases was present, and there have been no ill consequences in any case. The mucous membrane of the air-passages is always irritable, both in consumption and bronchitis, and the chloroform is apt to excite coughing at first. It is therefore necessary to begin by giving the vapour very gently in these cases, and in a little time the irritability of the mucous membrane is allayed, and insensibility can always be induced in a few minutes. The cough is afterwards relieved, in nearly all these cases, for a time--often for two or three days, in cases of chronic bronchitis.

Affections of the head offer no obstacle to the exhibition of chloroform in surgical operations. I have given it in many cases where more or less paralysis remained, from previous attacks of apoplexy, and no ill effects have followed. In a patient on whom Mr. Robert Wade lately operated--removing a scirrhous tumour of the labium pudenda--there was probably disease of the heart, as well as the remains of an apoplectic clot in the brain. The age of the patient is seventy-two; she is partially hemiplegic, from an apoplectic seizure two years ago; and her pulse, when I saw her, was irregular in the strength of its beats, and also intermitted. She went through the operation very well, and readily recovered her consciousness. I saw Mr. Wade eleven days after the operation, and learned that his patient was going on well. There is often some trouble in giving chloroform to insane patients, for when they cannot be persuaded to inhale it, it has to be given by force. When once they are under its influence, however, the surgeon is enabled to make examinations, and to perform operations that would otherwise be impossible.

I have given chloroform to a number of patients who were reduced to a state of extreme debility, from chronic disease of the large joints, and from various other causes. Chloroform agrees extremely well with such patients; they do not require to inhale so much as stronger persons, but that forms no difficulty, as the administration of this agent does not consist in giving a dose, but in executing a process, and the effects produced are observed as the process goes on.

An objection was raised in the Crimea last autumn to the use of chloroform in operations immediately succeeding to severe gun-shot wounds; but this objection seems to have given way before further experience. According to the letter of a medical officer, quoted in the medical journals, this agent was used with very good effect in such cases in particular where the soldier had the left thigh shattered to pieces, the right hand and wrist joint in the same condition, and a compound fracture of the other arm. Amputation of the thigh and forearm was performed, and, when sent to Sentari, two days afterwards, the patient promised to do well. The writer was of opinion that the soldier could hardly have borne the shock of his wounds and the operation without chloroform. I have not had occasion to give chloroform in operations immediately after gun-shot wounds, but after severe compound fractures from other causes, I have found its action very satisfactory, as well as in strangulated hernia, where there was excessive exhaustion.

I have often administered chloroform during pregnancy and no ill effects have followed in any case. Mr. Fergusson, Mr. Bowman, Mr. Henry Charles Johnson, and Mr. B. Travers, jun., are some of the surgeons for whom I have given chloroform to patients undergoing operation during pregnancy.

Chloroform may be given with propriety to patients of all ages. I have exhibited it to several infants aged from ten days to three weeks, and to one patient nearly ninety. I have notes of the cases of 145 infants under a year old, to whom I have administered this agent. A great number of them were operated on for hare-lip by Mr. Fergusson, who performs this operation at the earliest period of life, if the children are healthy. Chloroform acts very favourably on infants and children. There has, I believe, been no death from chloroform under the age of fifteen years. Chloroform was, indeed, blamed for the death of a child, in Germany, during the removal of a very large nævus on the side of the face, but there is no doubt that the cause of death in that case was hæmorrhage.

The only direction which it is usually requisite to give beforehand to the patient who is to inhale chloroform, is to avoid taking a meal previous to the inhalation; for chloroform is very apt to cause vomiting if inhaled when there is much food in the stomach. The sickness is not attended with any danger, but it constitutes an unpleasantness and inconvenience which it is desirable to avoid. The best time of all for an operation under chloroform is before breakfast; but the customs and arrangements of this country do not often admit of that time being chosen, and it is not advisable to make the patient fast beyond his usual hour. It answers very well to perform an operation about the time when the patient would be ready for another meal, or, if the time of the operation fall two or three hours after the usual time of eating, to request the patient to make only a slender repast at that time, so as just to prevent this feeling of hunger. It is impossible to prevent vomiting, in some cases, with best precautions, for the stomach occasionally will not digest when the patient is expecting a surgical operation, and the breakfast may be rejected in an unaltered state hours after it has been taken. In other cases the patient does not vomit, even when he inhales chloroform shortly after a full meal.

The most convenient position in which the patient can be placed whilst inhaling chloroform, is lying on the back or side, as he is then duly supported in the state of insensibility, and can be more easily restrained if he should struggle whilst becoming insensible. The semi-recumbent posture on a sofa, also, does very well; and there is no objection to the sitting posture, when that is most convenient to the operator. In that case, however, the patient could be placed in a large easy chair with a high back, so that the head as well as the trunk may be supported without any effort, otherwise he would have a tendency to slide and fall when insensible. It has been said, that it is unsafe to give chloroform in the sitting posture, on the supposition that it would, in some cases, so weaken the power of the heart as to render it unable to send the blood to the brain. Observation has proved, however, that chloroform usually increases the force of the circulation; and although the horizontal position is certainly the best for a patient under an operation in all circumstances, I consider that the sitting posture is by no means a source of danger when chloroform is given, if the ordinary precaution be used which would be used without chloroform, that of placing the patient horizontally if symptoms of faintness come on. I have preserved notes of 647 cases in which I have given chloroform to patients sitting in a chair, and no ill effects have arisen in any of these cases.

The person who is about to inhale chloroform is occasionally in a state of alarm, either about the agent itself or the operation which calls for its use. It is desirable to allay the patient's fears if possible before he begins to inhale, as he will then be able to breathe in a more regular and tranquil manner. In a few cases, however, the apprehensions of the patient cannot be removed, and they subside only as he becomes unconscious from the inhalation. It has been said that chloroform ought not to be administered if the patient is very much afraid, on the supposition that fear makes the chloroform dangerous. This is, however, a mistake; the danger, if any, lies in the fear itself. Two cases were alluded to above, in which the patients died suddenly from fear, whilst they were beginning to inhale chloroform, and before they were affected by it; but the probability is, that if they had lived till the chloroform took effect, they would have been as safe as other patients who have inhaled it. If chloroform were denied to the patients who are much afraid, the nervous and feeble, who most require it, would often be deprived of its benefits. Moreover, the patients would either be prevented altogether from having the advantage of surgery, or they would be subjected to the still greater fear of the pain, as well as the pain itself; for whatever undefined and unreasoning fears a patient may have when the moment comes for inhaling chloroform, he has only chosen to inhale it on account of a still greater fear of pain. The practice I have always followed has been to try to calm the patient by the assurance that there was nothing to apprehend from the chloroform, and that it would be sure to prevent all pain; but where it has been impossible to remove the fears of the patient in this way, I have always proceeded to remove them by causing a state of unconsciousness. As soon as this is induced, the pulse, which just before may have been extremely frequent and small, from the effects of fear, generally falls almost to its natural frequency, and resumes its full volume and force.

As a general rule, it is best to place the patient in the position in which the operation will be performed before he inhales the chloroform; but in cases of disease of the large joints, and other instances where motion causes pain, it is an advantage to give the chloroform to the patient in bed before he is removed to the operating-table. It is often desirable also to give it to children in another room, that they may not see any of the preparations for the operation.

[Part 2 appeared in the following issue.]

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  97."On the employment of chloroform in surgical operations"

Source: Snow, John. Lancet 2, 27 October 1855, pp. 383-85, Part 2.

Part 2

By John Snow, M.D.

It is unnecessary to say anything on the propriety and advantage of administering chloroform in lithotomy, in the larger amputations, and the removal of tumours of the breast, for I believe the whole of the profession agree on this point. There is still, however, some difference of opinion as to the propriety of giving it in lithotrity. It has been said that the surgeon requires the assistance of the patient's sensations, to prevent him from seizing the coats of the bladder in the lithotrite; but if this were the case, I believe that the operation could never have been performed at all. Some patients cry out when they are scarcely touched, whilst others will bear the greatest torture without a murmur. I believe there is very little danger, or even possibility of seizing the bladder with the lithotrite, and that, even if this should take place, the surgeon's sense of touch would be the proper guide to prevent mischief. The greatest sensibility of the bladder appears to be at the neck and it may fairly be doubted whether seizing the mucous membrane of the cavity would cause much pain. It has always appeared to me that the operation of lithotrity is one in which chloroform prevents very great suffering, and is of the utmost advantage. I will, however, quote the opinion of one who has had much practice in lithotrity both before the introduction of anæsthetic surgery and since, and is therefore better able to judge. Mr. Fergusson says, in his Practical Surgery,* "I am of opinion that there is not any department in practical surgery in which anæsthesia has been of more service than in this. Since the earliest period of its introduction I have almost invariably used it on such occasions, and with the best possible effects; and now I no more think of performing the operation of lithotrity without this agent than I would that of lithotomy." (*Third edition, p. 800.) Many other surgeons are of the same opinion as Mr. Fergusson, and some of those who are disinclined to use it as a general rule, practically admit its benefits by resorting to its employment in cases where the urinary passages are very irritable, or the patient very intolerant of pain. The operation of lithotrity requires a pretty full dose of chloroform, as, without this, the patient is apt to strain very much and move his legs about.

Some surgeons, and more especially those of Edinburgh, had an objection, at one time, to employ chloroform in large operations about the mouth and nose, and especially in the removal of tumours of the jaw, for fear the blood should flow into the windpipe during the state of insensibility and cause suffocation. However, I have given chloroform in a great number of such cases without any ill effects. Unless the effects of the chloroform are too deep or long-continued, the sensibility of the glottis is not impaired; if a little blood enters the windpipe, it is coughed out again; the patient can hold a little blood in his throat, and breathe through it with a gurgling noise, just as he would in the waking state; and if the quantity of blood begins to embarrass the breathing, the head must be leaned forward to get rid of it, and the same attention paid to the patient which would be paid if chloroform were not used. After the commencement of an operation of this kind, a little chloroform may be given from time to time, on a sponge, as opportunity permits, so as to keep up the insensibility to some extent. I prefer, under these circumstances, to have the chloroform diluted with spirit, in the manner and for the reason that I shall mention further on, in treating of its use on a handkerchief.

A case has been related by Mr. Prescott Hewett, in the Medico-Chirurgical Transactions, (vol. xxxiv., p. 43.) in which a patient died about half an hour after the removal of the greater portion of a tumour of the upper jaw. He was previously much reduced by hæmorrhage from the tumour, and he fainted before the operation was concluded. He remained much exhausted till the period of his death, though quite conscious. The breathing was not embarrassed until he was moribund, at which time a little blood, which was still oozing from the remains of the tumour was drawn into the trachea, as I was informed by a surgeon who was standing by at the time. This circumstance gave rise to some small spots of ecchymosis, which were found in the lungs after death. It was suggested that in this case blood might have got into the lungs during the insensibility from chloroform, and so have been the cause of death. But, in the first place, the symptoms which were observed during the operation, and for some time afterwards, were simply those of syncope, and not of embarrassed breathing; and, again, the amount of blood met with in the lungs was not enough to cause death, or even acute symptoms of any kind.

Extraction of cataract is an operation in which surgeons hesitated for a long time before employing chloroform. They were afraid lest the vomiting which sometimes attends or follows the use of this agent might be injurious to the eye. Mr. George Pollock and Mr. White Cooper were, I believe, the first surgeons who adopted the use of chloroform in the extraction of cataract; and I have since administered this agent also in many operations of this kind for Mr. Lawrence, Mr. Bowman, Mr. Haynes Walton, and others. Several of the patients were considerably over eighty years of age. By taking care not to give the chloroform too soon after a meal, there has very seldom been vomiting; and although a little vomiting has taken place in a very few of the cases, it was not attended by straining, and, as I understand, did not do harm in any case. I have, indeed, been informed of a case, at which I was not present, where chloroform was given, and where the patient vomited and expelled the humours of the eye; but she was a person of bad constitution, and such accidents did occasionally happen before the use of chloroform. In some cases, where the patient is very nervous, and the eye very irritable, I believe that chloroform is essential to the success of the operation, but it is not necessary to use it in all cases. I understand from Mr. Bowman that his practice is to operate without chloroform in cases where the patient does not wish for it, and has resolution to lie still, and keep the eye steady. The operation is said to be not very painful, but it is one which has a great tendency to rouse the patient, if he is not very insensible; it is necessary therefore to induce complete insensibility, and to keep it up till the lens is extracted, as the least movement of the patient might be prejudicial.

Operations about the anus generally require a full dose of chloroform, as the part is very sensitive when in a state of disease, and the patient, if not quite insensible, has a tendency to move his legs, which is very embarrassing to the surgeon, especially if there is no one to hold them. It was feared at one time that there would be a difficulty in operating for hæmorrhoids under chloroform, as the patient is often required to press them down; but it is found that if he do so beforehand, and whilst he is beginning to inhale, the bowel remains down; in fact, there is a great tendency to make a straining effort under the influence of chloroform, when the rectum is the seat of operation. Mr. Salmon thinks that the vessels of the rectum bleed rather more during operations under chloroform than without it, owing to the relaxation or diminished contraction of the sphincter; but I have not heard other surgeons make the same remark.

With respect to the deaths which unfortunately take place, now and then, from chloroform, many medical men have supposed that they are to be avoided by carefully selecting the cases for its administration; and declining to give it in certain affections, especially of the heart; whilst others, remarking that the deaths have often occurred in persons apparently the most healthy, acknowledge that they are not to be avoided by selecting the patients, but consider that they nevertheless depend on some peculiarity in the constitution which is not to be discovered beforehand. This is a more melancholy conclusion than the former, as it invests the chloroform with some amount of danger in all cases. It meets with apparent support at first sight, however, in the circumstance that some patients have died from a very small quantity of chloroform, whilst in numerous instances a large quantity has been used without ill effects. A little further inquiry shows, however, that several of the patients who died from chloroform had inhaled it previously in as great quantity without ill effects; and in the case of Samuel Bennett, which occurred in Westminster, in February, 1849, half an ounce of chloroform was used without causing insensibility, and when a fresh supply was obtained and administered, two hours afterwards, he suddenly expired. But it cannot be supposed that a person would have a peculiarity of constitution at one time which he did not possess at another, especially within the space of two hours.

In two papers which I had the honour to read to the Medical Society of London* a few years ago, it was shown that the deaths which had taken place from chloroform were occasioned by the sudden arrest of the action of the heart by this agent, and this is equally true of the deaths which have since occurred.

(*See Edin. Med. and Surg. Journal, No. 180, and London Journal of Medicine, 1852.)

To stop the action of the heart by the direct action of chloroform, there requires to be a larger proportion of it present in the blood than suffices to arrest the action of the muscles of respiration, and, therefore, if the vapour were always inhaled in a very regular and gradual manner, it would be impossible for it to paralyse the heart by its direct influence; for the breathing would first cease, and the action of the heart would only be brought to a close by the absence of the respiration, as in asphyxia. But as the heart is the first organ which the chloroform reaches after it is taken into the lungs, the coronary arteries being the first branches given off from the aorta, it is possible, if the vapour inhaled be too strong, that the heart may receive an overdose. When animals are made to breathe air containing four or five per cent of vapour of chloroform till death ensues, the breathing ceases first, and the heart continues to beat for a minute or two longer. During this interval life can easily be restored by means of artificial respiration, and the animals sometimes give one or two gasps at the moment when the heart is ceasing to beat, which may restore the action of that organ, and bring about recovery, if the animal have been removed from the chloroform. On the other hand, when animals are made to breathe air, containing eight or ten per cent of the vapour, death takes place suddenly, the motion of the heart ceasing at the same time as the breathing, or even before it. It requires a little contrivance to make the air on all occasions take up as much as eight or ten per cent of vapour of chloroform, and this explains not only how accidents may happen, but also why they happened so rarely, even when no regard is had to the amount of vapour in the air breathed by the patient. According to experiments, which I related on a former occasion, the amount of chloroform required to stop the action of the heart is one-eighteenth part as much as the blood will dissolve, or one part of chloroform to about 5,184 parts of serum of blood. The actual quantity of chloroform, therefore, which, by acting locally on the heart, arrests its motion, and causes a sudden accident, is very little more than a quarter of a minim. Consequently it need excite no surprise that the amount of chloroform which has been used in cases where accidents have occurred has been extremely variable. The danger from chloroform bears very little relation to the quantity used. In fact, to make an adult patient insensible with half a drachm is not so safe as to use a drachm in the process, if it be used judiciously; for in the former case the air must be more highly charged with vapour than in the latter. Exhalation of chloroform is always going on at the same time as inhalation, and to cause insensibility with vapour largely diluted, a larger quantity of it must be used than when it is less diluted.

I have already expressed the opinion that chloroform may be given to every patient requiring an operation without increasing the danger, whatever his condition may be; and have now to add, that the danger from chloroform, when it does exist, is as great to the strong and healthy as to the feeble and diseased. In fact, it is precisely in the most strong and robust persons that, according to my belief, the greatest care is required in giving chloroform. Robust lean persons, accustomed to hard work or athletic sports, require the narcotism of the nervous centres to be carried further than in the feeble, fat, or sedentary, before they will lie still under the use of the knife; and they are also very apt to struggle and become rigid after they are made unconscious, but before being insensible. During this state of struggling and rigidity they often hold the breath for a considerable time, and then suddenly draw a deep inspiration; and, if the vapour of chloroform is not presented in a very diluted form, a large quantity of it may be drawn into the lungs all at ounce, at a time when the pulmonary circulation is probably much retarded from the temporary suspension of respiration. In this way the portion of blood passing through the lungs at the moment may be so overcharged with chloroform as suddenly to paralyse the heart. In a considerable number of the fatal cases of inhalation of chloroform, the patient has expired suddenly whilst he was struggling in an involuntary manner.

The danger which exists in giving chloroform is simply that the patient should be allowed to breathe air too highly charged with vapour; for when the vapour is sufficiently diluted its effects takes place so gradually that no medical man can mistake them, and proceed to give an overdose. A very prevalent error respecting chloroform is to suppose that the patient is safe as long as he gets sufficient air for the purposes of respiration, whilst the truth is that the more air a person breathes the greater is his danger, if the air happens to be over highly charged with vapour. I have not space, in this paper, to enter on mode of operation of narcotic vapours, but, in order to show that narcotics, in a gaseous form, do not produce their effects by mechanically excluding the air, it is only necessary to allude to two or three well known agents of this class. Thus, whilst air containing eight per cent of vapour of chloroform cannot be inhaled without danger, air containing four or five times as much vapour of ether may be breathed with the utmost impunity. Nitrous oxide gas may be breathed when diluted only with the air which is present in the lungs at the beginning of the experiment; whilst the vapour of hydrocyanic acid requires to be diluted with several hundred times its volume of air before it can be inhaled without danger.

The means which I use to prevent the air breathed by the patient being too highly charged with vapour, is an inhaler which I have described on a former occasion. I cannot with a handkerchief regulate the amount of vapour and of air in the manner that is desirable; but I consider that those who prefer to give chloroform on a handkerchief may do so without danger though with no great accuracy, if they dilute the chloroform with rectified spirit. Either two parts by measure of spirit to one of chloroform, as recommended by Dr. Warren, of Boston in America, or equal parts of each, answer very well. Very little of the spirit is inhaled; it remains behind on the handkerchief, but it has the effect of lowering the elastic force of the vapour of chloroform, and thereby diminishing the amount of the vapour that the air will take up under the same physical circumstances.

In whatever way chloroform is given, it is necessary to begin gently at first, in order to accustom the mucous membrane of the air-passages to the pungency of the vapour, and to increase the strength of the vapour by degrees. I usually take two or three minutes in children and about four minutes in the adult to produce insensibility; but in robust, muscular subjects, who struggle much, it is sometimes desirable to proceed so cautiously as to take seven or eight minutes. In giving chloroform, it is best to observe every symptom exhibited by the patient; but the sensibility of the edge of the eyelid is the best test of the general sensibility. When the ciliary border may be touched without causing winking, or with very slight winking, the knife may in nearly all cases be used without causing a flinch or a cry. The state of the breathing is the best guide against carrying the effects of the chloroform too far. If it beings to [384/385] be stertorous, it is advisable to suspend the inhalation. The pulse is of less consequence than many of the other signs; for if the chloroform be properly diluted with air, it cannot seriously affect the pulse, and if it be not the pulse might cease suddenly. Its last beat in some of the accidents which have happened has been equal in strength to any which went before.

It is impossible in a brief space to allude to more than a few of the points connected with the use of chloroform in operations. I have therefore passed over most of those points on which I believe the profession are entirely agreed, and have treated chiefly on those respecting which I considered that my views might differ from those of, at all events, some of my professional brethren, in order that there might be the more room for the expression of opinion and experience.

Sackville-street, October, 1855.

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  98."On the mode of communication of cholera"

Source: Snow, John. Edinburgh Medical Journal 1, January 1856, pp. 668-70, [Letter to Ed.].

To the Editor of the Edinburgh Medical Journal

Sir,--Dr. Alison has called attention in the last number of the Journal to the opinions and facts of Dr Budd of Bristol, respecting the communication of cholera by dejections, and I shall be obliged if you will allow me to make a few additional remarks on the subject, partly on my own account, but chiefly to lay the matter before the reader in what I conceive to be its true aspect. I arrived at the conclusion in the latter part of 1848, that cholera is communicated by the evacuations from the alimentary canal, and in August, 1849, I endeavoured to establish this point by a number of facts, which I published in a pamphlet, On the Mode of Communication of Cholera. In the following month, Dr William Budd published a pamphlet On Malignant Cholera in which he expressed views similar to my own, and made a full and handsome acknowledgment of my priority in more than one place in his essay. I feel sure that Dr Alison was not aware of these circumstances, or he would have mentioned my name in connection with his subject.

In his recent papers in the Association Journal, Dr William Budd attributes a much greater range to the action of the cholera poison through the air, than I am willing to admit, and if he can establish this point, the credit of it will be due to him. In my opinion, the cholera poison only produces its effects through the air when carried by insects, or when the evacuations become dry, and are wafted as a fine dust. I have on several occasions, since the autumn of 1849, alluded to the great mortality from cholera amongst the mining population of this country, as an instance in which the morbid matter of the disease is swallowed with the food. As the miners stay in the pits eight or ten hours at a time, they always take food down with them, which they invariably eat with unwashed hands, and without knife and fork. There are no privies in the pits, and Dr Budd himself alludes to the foul state of the latter. When a case of cholera or choleraic diarrhœa occurs in a pit, it must therefore almost of necessity happen that the hands of many of the workmen would be soiled by the evacuations, minute quantities of which would be swallowed with the food. Dr Budd has alluded to the food of the pitmen being supplied from very different sources, and prepared by different hands; but the hand by which the food is contaminated is as often that from which it is eaten, as that by which it is prepared. This mode of taking minute quantities of poison was pointed out by Dr. Christison long ago as being the way in which house painters of uncleanly habits, sometimes acquire lead colic.

In the very interesting cases which Dr Budd has related of propagation of cholera in the ill kept privies of a large workhouse, the same mode of communication of the disease could not fail to exist. The seats would be soiled by the cholera discharges, and the paupers who came afterwards would have neither the desire nor the opportunity to wash their hands after each visit to the place.

. . . . . . . . . . . . . . . . . . . . . . .

The mode of communication of the disease which I am advocating also, explains many circumstances in the history of cholera, which could not be explained by effluvia from the evacuations. I allude to the spreading of cholera in the crowded habitations of the poor, who cook, eat, and nurse the sick in the same room, and pay little attention to cleanliness, and to its not spreading in the houses of the well-to-do; also to the escape of the medical and clerical visitors, who do not eat or drink in the room of a poor cholera patient, and who carefully wash the hands when required, whilst the social visitor who comes to see the patient, or to attend his funeral, often suffers.

. . . . . . . . . . . . . . . . . . . . . .

Dr Budd entirely agrees with me that the cholera poison is produced only in the alimentary canal, and acts only on that canal, which it reaches by being swallowed. He enforces this point by the same arguments that I had used, adding indeed some additional illustrations; so that in fact there is no difference between us respecting the essential mode of communication of the disease, but only as to the extent to which it is communicated through the air.

. . . . . . . . . . . . . . . . . . . . . .

I would gladly say much more on the pathology of cholera as bearing on the mode of its communication, but I am afraid of making this letter too long. I will only say in conclusion that, should the views I first promulgated be exactly correct, the extension of cholera may be more easily prevented than it would be if the slight modification of these views introduced by Dr Budd were true. In [669/670] the former case all that would be required to prevent the disease would be such a close attention to cleanliness in cooking and eating, and to drainage and water supply, as is desirable at all times.--I am, Sir, your obedient servant.

John Snow, M.D.

18 Sackville Street, London, 14th Dec. 1855.

([Editorial comment:] We regret that from want of space, we have been compelled to abbreviate Dr. Snow's letter. The important points, however, have been retained. His theory that it is chiefly or almost exclusively by swallowing that the poison of cholera is taken in, can scarcely be supposed, notwithstanding his arguments, to be the usual mode of admission of the poison in the numerous cases which he, as well as Dr Budd, seems to suppose to have extended by the people using the same privies. Dr Alison, in former papers, in which he maintained the contagious property of cholera, has, however, expressly said that he gave no opinion as to the mode or modes in which the poison, thrown off by the human body, may be taken into another--only as to the question whether, in one way or another, it may be so thrown off and may be so taken in, and the epidemic extension be thus affected; and, therefore, if as Dr Alison believes, there are different modes of extension, multiplication and absorption of the poison, demanding a certain multiplicity and variety of practical precautions--this will be all in favour of the only practical opinion Dr Alison has given on the subject.)

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