and least crowded of any. This, I think, can only be attributed to the proximity of the Montfaucon. Indeed, when the wind blows from that direction, which it often does for several months in the year, the effluvium is most odious.” As an instance of a similar influence of another species of effluvium, not observed by the healthy inhabitants of a district, it is stated that at a large infirmary in this country, when the piece of ornamental water, which was formerly stagnant in front of the edifice, had a greenish scum upon it, some descriptions of surgical operations were not so successful as at other times, and a flow of fresh water has been introduced into the reservoir to prevent the miasma. The immediate contrasts of the apparent immunity of adults to conspicuous attacks of epidemics, may perhaps account for the persuasion which masters and workmen sometimes express, that they owe an immunity from epidemics to their occupation, and that the stenches to which they are exposed actually “purify” the atmosphere. Numbers of such witnesses have heretofore been ready to attest their conviction of the preservative effect, and even the positive advantages to health, of the effluvia generated by the decomposition of animal or of vegetable matter, or of the fumes of minerals, of smoke, soot, and coal gas. But though they do not peculiarly suffer from epidemics, it is usually found that they are not exempted. In a recent return of the state of health of some workmen engaged in cleansing sewers, whilst it appeared that very few had suffered any attack from fever, nearly all suffered bowel attacks and violent intestinal derangement. If the effects of such emanations invariably appeared in the form of acute disease, large masses of the population who have lived under their influence must have been exterminated. In general the poison appears only to be generated in a sufficient degree of intensity to create acute disease under such a conjunction of circumstances, as a degree of moisture sufficient to facilitate decomposition, a hot sun, a stagnant atmosphere, and a languid population. The injurious effects of diluted emanations are constantly traceable, not in constitutional disturbance at any one time; they have their effect even on the strong, perceptible over a space of time in a general depression of health and a shortened period of existence. This or that individual may have the florid hue of health, and may live under constant exposure to noxious influences to his sixtieth or his seventieth year; but had he not been so exposed he might have lived in equal or greater vigour to his eightieth or his ninetieth year. A cause common to a whole class is often, however, not manifest in particular individuals, but is yet visible in the pallor and the reduced sum of vitality of the whole class, or in the average duration of life in that class, as compared with the average duration of life of another