However, I would not be understood to assert that fresh provisions, plenty of water, and a constant supply of sweet air between decks are matters of no moment: I am, on the contrary, well satisfied that they are all of them articles of great importance, and are doubtless extremely conducive to the health and vigour of a crew, and may in many cases prevent this fatal malady from taking place. All I have aimed at in what I have advanced is only to evince that, in some instances, both the cure and prevention of this malady is impossible to be effected by any management, or by the application of any remedies which can be made use of at sea. Indeed, I am myself fully persuaded that, when it has got to a certain head, there are no other means in nature for relieving the sick but carrying them on shore, or at least bringing them into the neighbourhood of the land. Perhaps a distinct and adequate knowledge of the source of this disease may never be discovered; but, in general, there is no difficulty in conceiving that, as a continued supply of fresh {270} air is necessary to all animal life, and as this air is so particular a fluid that, without losing its elasticity, or any of its obvious properties, it may be rendered unfit for this purpose by the mixing with it some very subtle and otherwise imperceptible effluvia; it may be easily conceived, I say, that the steams arising from the ocean may have a tendency to render the air they are spread through less properly adapted to the support of the life of terrestrial animals, unless these steams are corrected by effluvia of another kind, which perhaps the land alone can afford.