PART I.
OF THE
NATURE
OF
CONTAGION.
That the Reasonableness of any Method, which shall be proposed to prevent the spreading of Contagious Diseases, may the better appear, it is necessary to premise somewhat in general concerning Contagion, and the Manner, by which it acts.
Contagion is propagated by three Causes, the Air; Diseased Persons; and Goods transported from infected Places.
We shall therefore first enquire what alteration of the Air it is, that makes it infectious; and then, by what Means it communicates its noxious Quality to other Bodies.
The ancientest and best Authors of Physick, who lived in a Country more exposed to these Calamities than ours, observed the Constitution of the Air, which preceded Pestilential Fevers, to be great Heats attended with much Rain and Southerly Winds[[1]]: And one of Them takes particular Notice, that no other than a moist and hot Temperament of the Air brings the Plague; and that the Duration of this Constitution is the Measure of the Violence of the Distemper[[2]].
The Natural History of several Countries confirms this Observation; in Africa particularly, if Showers fall during the sultry Heats of July and August, the Plague ensues thereupon, with which whosoever is infected hardly escapes[[3]].
It has besides been remarked in all Times, that the Stinks of stagnating Waters in hot Weather, putrid Exhalations from the Earth; and above all, the Corruption of dead Carcasses lying unburied, have occasioned infectious Diseases.
From hence it appears to be a Concurrence of Causes, that produces Diseases of this Kind; which must not only meet, but exert their Force together for a considerable time. And when this happens, their first effect is a Degree of Stagnation in the Air, which is afterwards followed by Corruption and Putrefaction.
And upon this account it is, that those Countries are chiefly liable to these Calamities, where not only the Heats are very great, and the Weather continues long in the same State; but the Winds (the Use of which is by Motion to purify the Air) do not shift and change so often as they do in Northern Climates.
Indeed Plagues seem to be of the Growth of the Eastern and Southern Parts of the World, and to be transmitted from them into colder Climates by the Way of Commerce. Nor do I think, that in this Island particularly there is any one Instance of a Pestilential Disease among us of great Consequence; which we did not receive from other infected Places.
This I the rather mention, because it is a common Opinion, and propagated by Authors of great Name, that we are usually visited with the Plague once in 30 or 40 Years; which is a mere Fancy without any Foundation either in Reason or Experience: and therefore People ought to be delivered from the Subjection to such vain Fears.
On the contrary, though we have had several Strokes of this kind, yet there are Instances of bad Contagions from abroad being brought over to us, which have proved less malignant here by our Air not being disposed to receive such Impressions.
The Sweating Sickness, called the Sudor Anglicus and Febris Ephemera Britannica, because it was commonly thought to have taken its Rise here, was most probably of a foreign Original, and no other than a Plague abated in its Violence by the mild Temperament of our Climate.
For, we learn from Histories, that the first time this was felt here, which was in the Year 1485, it began in the Army, with which King Henry VII. came from France, and landed in Wales[[4]]; and it was then thought to have been brought into France from the famous Siege of Rhodes by the Turks 3 or 4 Years before. And of the four Returns, which this has made since that Time; two, viz. those in the Years 1527, and 1528, may very justly be suspected to have been owing to the Pestilence, which at those Times raged in Italy, particularly at Florence and Naples[[5]]. And the others were very probably from a Turkish Infection.
I call this Distemper a Plague with lessened Force, because the Symptoms of it were of that kind, though in a less Degree; as great Faintness and Inquietudes, inward Burning, Pain in the Head, a Delirium &c. All which were accompanied with profuse Sweats, and the Disease lasted but 24 hours. And though for want of Care and due Management many died of it; yet, as a learned and wise Historian[[6]] observes, It appeared rather to be a surprize of Nature than obstinate to Remedies, for if the Patient was kept warm with temperate Cordials, he commonly recovered.
And I cannot but take Notice, as a Confirmation of what I have been advancing, that we had here the same kind of Fever in the Year 1713, about the Month of September, which was called the Dunkirk Fever, as being brought by our Soldiers from that Place; where it was indeed a Malignant Disease attended with a Diarrhœa, Vomiting, &c. and probably had its Original from the Pestilential Distemper, which some time before broke out at Dantzick and Hamburgh: But with us was much more mild, beginning only with a Pain in the Head, and by very easy Means went off in large Sweats, after a Day's Confinement.
There being in every Air a greater Disposition to Contagion at one Time than another, we have indeed sometimes felt this Calamity with greater Fury; as particularly the last time in the Year 1665; when it continued in this City about ten Months, and swept away by computation 97306 Persons: But it was generally allowed, that the Contagion came by Cotton imported from Turkey[[7]]; and the long Duration of it, I believe, may justly be charged up the unhappy Management of infected Houses, which was then directed by Publick Authority; as I shall shew anon.
And the History of the most terrible of all the Plagues, that ever were in these Parts of the World, which was that in the Year 1349, gives a manifest Proof from whence all Europe may trace the Origine of these Evils, viz. from Asia: for [[8]]This taking its Rise in China in the Year 1346, advanced through the East Indies to Syria, Turkey, Ægypt, Greece, Africa, &c. In 1347 some Ships from the Levant carried it to Sicily, Pisa, Genoa, &c. In 1348 it got into Savoy, Provence, Dauphiny, Catalonia, Castile, &c. In 1349 it seized England, Scotland, Ireland, and Flanders; and in the next place Germany, Hungary, and Denmark; and in all these Countries made most incredible Havock.
But to return to the Consideration of the Air, which we left in a putrid State: It is to be observed, that Putrefaction is a kind of Fermentation, and that all Bodies in a Ferment emit a volatile active Spirit, of Power to agitate, and put into intestine Motions, that is, to change the Nature of other Fluids into which it insinuates it self.
It were easy to shew from the best Theory of Fevers[[9]], how the Alterations made in the Blood this Way will favour Pestilential Diseases, by rendring the Body obnoxious to them: But the Digression would be too great.
THIS is one step towards Contagion. The next, as it seems to me, proceeds after this Manner. The Blood in all Malignant Fevers, especially Pestilential ones, at the latter End of the Disease, does like Fermenting Liquors throw off a great Quantity of active Particles upon the several Glands of the Body, particularly upon those of the Mouth and Skin, from which the Secretions are naturally the most constant and large. These, in Pestilential Cases, although the Air be in a right State, will generally infect those, who are very near to the sick Person; otherwise are soon dispersed and lost: But when in an evil Disposition of This they meet with the subtle Parts, its Corruption has generated, by uniting with them they become much more active and powerful, and likewise more durable and lasting, so as to form an Infectious Matter capable of conveying the Mischief to a great Distance from the diseased Body, out of which it was produced.
They who know what strange Attractions and Combinations are made by volatile Spirits will understand this Reasoning; especially if they consider, how easily all kinds of Effluvia are diffused in a warm Air, such as we have described an Infectious one to be; and further, of how penetrating a Force the finest Parts of Animal Juices are; of which the strange Stench of a mortified Limb, upon a Body yet living, will convince any one.
A corrupted State of Air is without doubt necessary to give these Contagious Atoms their full Force; for otherwise it were not easy to conceive how the Plague, when once it had seized any Place, should ever cease, but with the Destruction of all the Inhabitants: Which is readily accounted for by supposing an Emendation of the Qualities of the Air, and the restoring of it to a healthy State capable of dissipating and suppressing the Malignity.
On the other hand it is evident, that Infection is not received from the Air it self, however predisposed, without the Concurrence of something emitted from Infected Persons; because, by strictly preventing all Intercourse of Infected Places with the Neighbourhood, it may be effectually kept from spreading: Whereas the least Wind must necessarily convey whatever noxious Quality resides in the Air alone, even to a great Distance. Of this we have had a fresh Proof in the present unhappy Plague in France, which, by keeping careful Guard, was confined for a considerable Time within the Walls of Marseilles; so that none of the adjacent Villages suffered any thing by it; till at length some Persons finding Means to escape carried the Infection along with them. And we find, they have been able, by the like Care, still to restrain it within moderate Bounds.
This is the Manner by which Infectious Effluvia are generated; The Way, by which a sound Person receives the Injury, I suppose most commonly to be this. These Contagious Particles being drawn in with the Air we breath, they taint in their Passage the Salival Juices, which being swallowed down into the Stomach presently fix their Malignity there; as appears from the Nausea and Vomiting, with which the Distemper often begins its first Attacks. Though I make no Question but the Blood is also more immediately affected by hurtful Particles being mixed through Inspiration with it in the Lungs.
The third Way, by which we mentioned Contagion to be spread, is by Goods transported from infected Places. It has been thought so difficult to explain the Manner of this, that some Authors have imagined Infection to be performed by the Means of Insects, the Eggs of which may be conveyed from Place to Place, and make the Disease when they come to be hatched. As this is a supposition grounded upon no manner of Observation, so I think there is no need to have Recourse to it. If, as we have conjectured, the Matter of Contagion be an active Substance, perhaps in the Nature of a Salt, generated chiefly from the Corruption of a Humane Body, it is not hard to conceive how this may be lodged and preserved in soft, porous Bodies, which are kept pressed close together.
We all know how long a time Perfumes hold their Scent, if wrapt up in proper Coverings: And it is very remarkable, that the strongest of these, like the Matter we are treating of, are mostly Animal Juices, as Mosch, Civet, &c. and that the Substances found most fit to keep them in, are the very same with those which are most apt to receive and communicate Infection, as, Furrs, Feathers, Silk, Hair, Wool, Cotton, Flax, &c. the greatest Part of which are likewise of the Animal Kind; which Remark alone may serve to lead Us a little into the true Nature of Contagion.
From all that has been said, it appears, I think, very plainly, that the Plague is a real Poison, which being bred in the Eastern or Southern Parts of the World, maintains it self there by circulating from Infected Persons to Goods; which is chiefly owing to the Negligence of the People in those Countries, who are stupidly Careless in this Affair: That when the Constitution of the Air happens to favour Infection, it rages there with great Violence; That at that Time more especially diseased Persons give it to one another, and Contagious Matter is lodged in Goods of a loose and soft Texture, which being packt up, and carried into other Countries, let out, when opened, the imprisoned Seeds of Contagion: And lastly, That the Air cannot diffuse and spread these to any great Distance, if Intercourse and Commerce with the Place infected be strictly prevented.
