Pope.
[39] Wherever causes are obscure, superstition naturally ascribes them to some preternatural influence; and what seemed farther to have encouraged this, anciently, was, that violent epidemics occurred most frequently in camps and at sieges where great political conjunctures were likely to arise, in which superior powers were supposed to interest themselves. Thus we read in Homer of fatal diseases being sent as punishments by the gods. But the pestilential diseases so often mentioned by poets and historians as prevailing in cities and armies, were probably nothing else but fevers, produced partly perhaps by the scarcity and bad quality of provisions, but probably still more by corrupted human effluvia, which was very apt to he produced by the want of personal cleanliness, to which the mode of cloathing among the ancients would more particularly subject them, especially in camps and besieged towns.
[40] If the experiments of modern philosophy are to be depended on, they go a certain way to account for the unwholesomeness of air from woods in hot climates, and in wet weather; for Dr. Ingenhousz found that the effluvia of plants in the night time, and in the shade, are more poisonous in hot than in cold weather; but though there is a salubrity in the effluvia in sunshine, the heat of the weather makes no difference with regard to this. He found also that vegetables, when wet, yield an unwholesome air.
It is difficult to ascertain how far the influence of vapours from woods and marshes extend; but there is reason to think that it is to a very small distance. When the ships watered at Rock Fort, they found that if they anchored close to the shore, so as to smell the land air, the health of the men was affected; but upon removing two cables length, no inconvenience was perceived. I was informed of the following fact, in proof of the same, by the medical gentlemen who attended the army in Jamaica:—The garrison of Fort Augusta, which stands very near some marshes, to which it is to leeward when the land wind blows, was yet remarkably healthy; but it became at one time extremely sickly upon the breaking in of the sea in consequence of a high tide, whereby the water which was retained in the hollows of the fort produced a putrid moisture in the soil, exhaling a vapour offensive to the smell, and with all the noxious effects upon health commonly arising from the effluvia of marshes.
[41] Dr. Hendy has lately published an ingenious treatise upon this disease.
[42] See Sydenham’s Works.
[43] [See Part I. Book II. Chap. VI].
[44] We have a proof of this fact in particular, in the account of the jail distemper, which broke out at the Old Bailey in the year 1750.
[45] See Martin’s History of the Western Islands, and Medical Communications, Vol. I. page 68.
[46] There are some contagious diseases which cannot be propagated but by their own peculiar infections, as has been before observed, just as the seeds of vegetables are necessary to continue their several species; so that if the infectious poison were lost, so would the disease. Of this kind are the small pox, and the other diseases to which man is subject but once during life. There are other diseases which produce infection without having themselves proceeded from it. Of this kind are fevers and fluxes.