CHOLERA AND THE WATER SUPPLY IN THE SOUTH DISTRICTS OF LONDON IN 1854. BY JOHN SNOW, M.D. _Reprinted from the_ JOURNAL OF PUBLIC HEALTH _for October 1856_. LONDON: PRINTED BY T. RICHARDS, 37, GT. QUEEN STREET. In the summer of 1849, I published certain conclusions at which I have arrived with regard to Asiatic cholera, and the facts and reasonings which had led to them. The following is a very brief outline of these views. The cholera commences as an affection of the alimentary canal, and not with general illness; there is no evidence of poisoning of the blood in this disease, except in some cases where secondary fever occurs; there is conclusive evidence that cholera may be communicated from person to person, and it follows, therefore, that the morbid matter which produces the disease is applied to the interior of the alimentary canal, where it increases and multiplies during the period of so-called incubation, and passes off, during the attack, to cause fresh cases when suitable opportunities occur. Various circumstances connected with the propagation of cholera seemed in accordance with the above view of its pathology. Thus, it was observed to pass frequently from person to person in the crowded habitations of the poor, who eat, drink, cook, and sleep in the same apartment, and pay little or no regard to cleanliness, who live, in fact, under circumstances where the sudden and copious evacuations of cholera, soiling the bed and body linen, would not fail to contaminate the hands of the patient and his attendants, and be thence transferred to any food they might touch. The absence of colour and odour in the evacuations could not help to favour this result. The social visitor who came to see the poor patient, or attend his funeral, frequently suffered, whilst the medical man, and others who partook of no food in the apartment, and who washed their hands when requisite, escaped. The mining districts of this country have suffered excessively from cholera in each epidemic, an event which might be explained by the following circumstances when taken in connexion with the above view of the cause of the disease. The miners stay eight or nine hours at a time in the pits, and take food with them, which they eat invariably with unwashed hands, and without knife and fork, whilst the pits are without privies, and are generally extremely foul and dirty. The entire absence of daylight must also cause the workmen to take much more dirt with their food than they are aware of. It occurred to me, as soon as I began to entertain the above opinions, that if the cholera excreta could reproduce the disease in the way just mentioned, they might also do so when diffused in water taken as drink, and that unless this were the