The common air of the atmosphere at sea is purer than on shore, which gives to a sea life a very great advantage over a life at land. This advantage is still greater in the tropical regions, where the land air, especially such as proceeds from woods and marshes, is so fatal, and where the heat is also considerably less at sea than on shore. But this superior purity of the air at sea is more than counterbalanced by the artificial means of propagating diseases on board of a ship. Since a sea life, however, has this great natural advantage to health, the causes of disease peculiar to it are chargeable rather to the mismanagement of men than to any thing unavoidable in nature; and we are from this encouraged to exert our endeavours in removing them. The effects of land air, however, are not to be neglected by those who are studious of preserving the health of a ship’s company, for seamen are exposed to it in various ways while they are in harbour; and this is what we shall first treat of. SECT. I. Of the noxious Effects of LAND AIR in particular Situations. All the diseases incident to a fleet, except the scurvy, are more apt to arise in a harbour than at sea, and particularly the violent fevers peculiar to hot climates. There are generally woods and marshes adjacent to the anchoring places in the West Indies, and the men are exposed to the bad air proceeding from thence, either in consequence of the ship’s riding to leeward of them, or of people’s going on shore on the duties of wooding and watering. Instances of this, without number, might be adduced from the accounts of voyages to all the tropical countries. Our fatal expeditions to the Bastimentos, and to Carthagena, in former wars, are striking proofs of it; and we have seen the same effects, though in a much less degree, while the fleet was at Jamaica in 1782. I have known a hundred yards in a road make a difference in the health of a ship at anchor, by her being under the lee of marshes in one situation, and not in the other[40]. Where people at land are so situated, as not to be exposed to the air of woods and marshes, but only to the sea air, they are equally healthy as at sea. There was a remarkable instance of this on a small island, called Pidgeon Island, formerly described, where forty men were employed in making a battery, and they were there from June to December, which includes the most unhealthy time of the year, without a man dying, and with very little sickness among them, though they worked hard, lived on salt provisions, and had their habitations entirely destroyed by the hurricane. During this time near one half of the garrison of St. Lucia died, though in circumstances similar in every respect, except the air of the place, which blew from woods and marshes.