It has been the opinion of some, that fevers do not arise from any putrid _effluvia_, except those of the living human body, or some specific infection generated by it while under the influence of disease. It has been alledged in proof of this, that the putrid air in some great cities is breathed without any bad effects; and a celebrated professor of anatomy[19] used to observe, that those employed in dissecting dead bodies did not catch acute diseases more readily than other people. I believe this may be true, in a climate like Europe, where cold invigorates the body, and enables it to resist the effects of foul air; but I am persuaded it is otherwise in tropical climates. The external heat of the air induces great languor and relaxation, and we cannot breathe the same portion of air for the same length of time in a hot as in a cold climate, without great uneasiness. The want of coolness must, therefore, be compensated by a more frequent change of air, and by its greater purity: any foulness of the air is accordingly more felt in a hot climate; and, according to the modern theory, air, already loaded with putrid phlogistic vapour, will be less qualified to absorb the same sort of vapour from the blood in the lungs, in which, according to this theory, the use of respiration consists. Be this as it will, there is something in purity of air which invigorates the circulation, and refreshes the body; and the contrary state of it depresses and debilitates, particularly in a hot climate; and in this way foul air may induce disease, like any other debilitating cause, independent of infection, or any specific quality. There was no reason to suspect any such infection in the Ville de Paris; for there was no sickness on board of this ship when in possession of the enemy, and the sickness that prevailed after her being captured seemed to proceed from what may be called simple putrefaction. There was an instance of the same kind in one of our own ships of the line, in which a bad fever broke out in the beginning of July, which seemed to be owing to the foul air of a neglected hold; for there was a putrid stench proceeding from the pumps, which pervaded the whole ship. I perceived this very sensibly one day, when visiting some officers who were ill of fevers; and before I left the ship an alarm was given of two men being suffocated in what is called the _well_, which is the lowest accessible part of the hold. This fever was of a very malignant kind, and fell upon the officers more than the men; for six of them were seized with it, of whom three died on the third day after being taken ill.