Chapter II: 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.