Ships of war are exposed to infection chiefly by receiving such men as have been raised by pressing, who are frequently confined in guardships, under such circumstances of bad air and bodily filth as tend to generate the most virulent infection. The service also requires sometimes that men be received from jails, and they are either criminals delivered over by the civil jurisdiction of the country, or captives who have been restored by the enemy after a course of confinement in their prisons. It may happen too, as we have seen[43], that the enemy, who are made prisoners at sea, may have infection about them, and will communicate it the more readily that they are strangers.

There are few fevers but what are infectious at some stage or other of the disease; but it is not necessary that fever should actually exist in order to create infection. In the most violent and pestilential fevers, such as have sometimes originated in the jails of England, the persons who communicated them were not affected with it themselves[44]. Infection, like some other poisons, does not affect those who are accustomed to it, and therefore those who are in the habit of being exposed to it frequently escape its bad effects, especially if it is gradually applied, as must be the case with those about whose persons it is generated. For the like reason, physicians and nurses are less susceptible than others; and strangers, who are accustomed to a pure air, are the most susceptible of any. It is observed by Dr. Short, that contagious epidemics are more frequent and fatal in the country than in London, and this may probably be accounted for on the same principle; for every person in a great town is exposed to the breath and effluvia of others, and to a variety of putrid exhalations, which are unavoidable where multitudes inhabit together; but they are so used to them, that they are not affected by them; whereas in the country, where people are less accustomed to each other’s company, and less used to impure air in general, they are the more readily affected when infection is introduced among them. It may even admit of a doubt if any society of men, living together, are entirely free from morbid contagion. It certainly sometimes happens, that a ship, with a long-established crew, shall be very healthy; yet, if strangers are introduced among them, who are also healthy, sickness will be mutually produced. This principle in the human constitution, by which the presence of strangers affects it, is well illustrated by a fact[45], founded on the best testimony, that, in one of the small western islands of Scotland, which is so remote, that the inhabitants are frequently without any communication with strangers for several months together; they become so susceptible, in consequence of this long interruption of intercourse, that they are seized with a catarrh when strangers of any description come among them. It was said before, that cleanliness was founded on a natural aversion to what is unseemly and offensive in the persons of others; and there seems also to be implanted in human nature, for the same purpose, an instinctive horror at strangers, as is visible in young children and uncultivated people. In the early ages of Rome, one word signified both a stranger and an enemy[46].

These observations naturally suggest several useful and practical remarks. It would appear that the utmost attention is necessary not only to guard against the actual presence of of disease, but to be jealous of all new draughts of men, especially if they should come from guardships, jails, or tenders, and have been turned over from ships where disease is known to have prevailed; nay, that it is best to avoid mixtures of any kind.

The infection of fevers seems different from most others in this, that it is very various in its degrees of virulence. There is reason to think that the poison of the small pox, and that of the venereal disease, are in their own nature invariable, and that the difference of these diseases, in point of malignancy, depends on the constitution and other circumstances of those affected; whereas that of fevers being of different degrees of activity, and being frequently obscure and latent, is, on that account, the more treacherous, and ought to be watched with the greater circumspection.

The mode of manning the navy by pressing, I take it for granted, is unavoidable; at any rate, it would not become me to arraign a practice which has had the public sanction for ages. It is, however, one of the principal means both of generating and spreading the seeds of disease, in consequence of the indiscriminate seizure of men for the public service, and the confinement that is necessary to secure them. And as the exigences of the service make it necessary to admit persons of every description, there is no other remedy for this evil but to annihilate, if possible, the contagion that may thus be conveyed into ships of war. This is done by stripping and washing the new recruits who may be suspected of importing infection; also by cutting off their hair, clothing them with new clothes, and destroying the old, before they are allowed to mix with the ship’s company in which they are to enter.

Those who have put these methods strictly in practice, have been sensible of their great utility; and the most exact attention is necessary, as a single infected man, or even any part of his clothing, may spread sickness through a whole ship’s company. When we reflect what havock an infectious fever sometimes makes in a ship, it will appear how very important this fort of attention is; and when the cause of the sickliness of particular ships is traced to its source, it will generally be found to have originated from taking on board infected men at Spithead, or wherever else the ship’s company may have been completed.

After the first edition of this part of the work was printed, an excellent institution was established at Portsmouth for the prevention of infection. A ship was appointed for the reception of the recruits of the fleet to which they were carried, to be stripped, washed, and provided with new apparel, before they joined their respective ships. This had a visible good effect on the health of the fleet; and it was planned and executed by Sir Charles Middleton, Comptroller of the Navy, whole unwearied assiduity, as well as integrity and ability in that important post, claim the highest praise and gratitude from his country.

It follows farther, from the preceding observations, that there is a sort of risque in mixing two different sorts of men, even when there is no actual disease or suspicion of infection; for, whether it is from dormant infection, or merely from the circumstance of change of air, such mixtures are known from experience to be sometimes productive of sickness. The late Admiral Boscawen was so sensible of this, that he avoided it, unless when some evident utility or necessity of service made it proper; and upon this principle he used to resist the solicitation of captains when they requested to carry men from one ship to another upon changing their commands.

One probable reason, among others, for ships of the line being more sickly than frigates or smaller ships is, that in greater numbers there is a greater chance of men of various descriptions and modes of life being mixed together.

2. Means of preventing the Production of Infection.