A Discourse on the Plague by Richard Mead (early readers txt) 📕

Intempestivis pluviisque et solibus icta[46].

Now if we compare this last Remark of the Intemperance of the Climate in Æthiopia, with what the Arabian Physicians[47], who lived near these Countries, declare, that Pestilences are brought by unseasonable Moistures, Heats, and want of Winds; I believe we shall be fully instructed in the usual Cause of this Disease. Which from all these Observations compared together, I conclude to arise from the Putrefaction so constantly generated in these Countries, when that is hightened and increased by the ill State of Air now described; and especially from the Putrefaction of animal Substances.

It is very plain, that animal Bodies are capable of being altered into a Matter fit to breed this Disease: because this is the Case of every one who is sick of it, the Humours in him being corrupted into a Substance which will infect others. And it is not improbable, that the volatile Parts with which Animals abound, may in some ill States of Air in the sultry Heats of Africa be converted by Putrefaction into a Substance of the same kind: since in these colder Regions, we sometimes find them to contract a greater Degree of Acrimony than most other Substances will do by putrefying, and also more dangerous for Men to come within the reach of their Action; as in those pernicious, and even poysonous Juices, which are sometimes generated in corrupted Carcasses: Of which I have formerly given one very remarkable Instance[48], and, if it were necessary, many more might be produced, especially in hydropic Bodies, and in cancerous Tumors. Nay more, we find animal Putrefaction sometimes to produce in these Northern Climates very fatal Distempers, though they do not arise to the Malignity of the true Plague: For such Fevers are often bred, where a large Number of People are closely confined together; as in Goals, Sieges, and Camps.

And perhaps it may not be here amiss to remark, that the Egyptians of old were so sensible how much the Putridness of dead Animals contributed towards breeding the Plague, that they worshipped the Bird Ibis for the Service it did in devouring great Numbers of Serpents; which they observed did hurt by their Stench when dead, as well as by their Bite when alive[49].

But no kind of Putrefaction is ever hightened in these European Countries to a degree capable of producing the true Plague: and we learn from the Observation of the Arabian Physicians, that some Indisposition of the Air is necessary in the hottest Climates, either to cause so exalted a Corruption of the forementioned Substances, or at least to enforce upon Mens Bodies the Action of the Effluvia exhaled from those Substances, while they putrefy. Both which Effects may well be expected from the sensible ill Qualities of the Air before described, whenever they continue and exert their Force together any considerable time.

What I have here advanced of the first Original of the Plague, appears to me so reasonable, that I cannot enough wonder at Authors for quitting the Consideration of such manifest Causes for Hidden Qualities; such as Malignant Influences of the Heavens; Arsenical, Bituminous, or other Mineral Effluvia, with the like imaginary or uncertain Agents.

This however I do not say with design absolutely to exclude all Disorders in the Air, that are more latent than the intemperate Heat and Moisture before mentioned, from a Share in increasing and promoting the Infection of the Plague, where it is once bred: for I rather think this must sometimes be the Case; like to what is observed among us in relation to another infectious Distemper, namely, the Small-Pox, which is most commonly spread, and propagated by the same manifest Qualities of the Air as those here described: Notwithstanding which, this Distemper is sometimes known to rage with great Violence in the very opposite Constitution of Air, viz. in the Winter during dry and frosty Weather. But to breed a Distemper, and to give force to it when bred, are two different things. And though we should allow any such secret Change in the Air to assist in the first Production of the Disease; yet it may justly be censured in these Writers, that they should undertake to determine the Specific Nature of these secret Changes and Alterations, which we have no means at all of discovering: Since they do not shew themselves in any such sensible manner, as to come directly under our Examination; nor yet do their Effects, in producing the Plague, point out any thing of their Specific Nature.

All that we know, is this, that the Cause of the Plague, whatever it be, is of such a Nature, that when taken into the Body, it works such Changes in the Blood and Juices, as to produce this Disease, by suddenly giving some Parts of the Humours such corrosive Qualities, that they either excite inward Inflammations and Gangrenes, or push out Carbuncles and Bubo’s; the Matter of which, when suppurated, communicates the like Disease to others: But of the manner how this is done, I shall discourse in the following Chapter.

I Have been thus particular in tracing the Plague up to its first Origine, in order to remove, as much as possible, all Objection against what I shall say of the Causes, which excite and propagate it among us. This is done by Contagion. Those who are Strangers to the full Power of this, that is, those who do not understand how subtile it is, and how widely the Distemper may be spread by Infection, ascribe the Rise of it wholly to the malignant Quality of the Air in all Places, wherever it happens; and, on the other hand, some have thought that the Consideration of the infectious Nature of the Disease must exclude all regard to the Influence of the Air: Whereas the Contagion accompanying the Disease, and the Disposition of the Air to promote that Contagion, ought equally to be considered; both being necessary to give the Distemper full force. The Design therefore of this Chapter, is to make a proper Balance between these two, and to set just Limits to the Effects of each.

For this purpose, I shall reduce the Causes, which spread the Plague, to three, Diseased Persons, Goods transported from infected Places, and a corrupted State of Air.

There are several Diseases, which will be communicated from the Sick to others: and this not done after the same manner in all. The Hydrophobia is communicated no other way than by mixing the morbid Juices of the diseased Animal immediately with the Blood of the sound, by a Bite, or what is analogous thereto; the Itch is given by simple Contact; the Lues Venerea not without a closer Contact; but the Measles, Small-Pox, and Plague are caught by a near Approach only to the Sick: for in these three last Diseases Persons are render’d obnoxious to them only by residing in the same House, and conversing with the Sick.

Now it appears by the Experiments mentioned in the Preface, of giving the Plague to Dogs by putting the Bile, Blood or Urine from infected Persons, into their Veins, that the whole mass of the animal Fluids in this Disease is highly corrupted and putrefied. It is therefore easy to conceive how the Effluvia or Fumes from Liquors so affected may taint the ambient Air. And this will more especially happen, when the Humours are in the greatest Fermentation, that is, at the Highth of the Fever: as it is observed that fermenting Liquors do at the latter end of their intestine Motion throw off a great Quantity of their most subtile and active Particles. And this Discharge will be chiefly made upon those Glands of the Body, in which the Secretions are the most copious, and the most easily increased: such are those of the Mouth and Skin. From these therefore the Air will be impregnated with pestiferous Atoms: which being taken into the Body of a sound Person will, in the Nature of a Ferment, put the Fluids there into the like Agitation and Disorder.

The Body, I suppose, receives them these two ways, by the Breath, and by the Skin; but chiefly by the former.

I think it certain that Respiration does always communicate to the Blood some Parts from the Air: Which is proved from this Observation, that the same Quantity of Air will not suffice long for breathing, though it be deprived of none of those Qualities, by which it is fitted to inflate the Lungs and agitate the Blood, the Uses commonly ascribed to it. And this is farther confirm’d by what the learned Dr. Halley has inform’d me, that when he was several Fathom under Water in his Diving Engine, and breathing an Air much more condensed than the natural, he observed himself to breath more slowly than usual: Which makes it more than probable, that this conveying to the Blood some subtile Parts from the Air, is the chief Use of Respiration; since when a greater Quantity of Air than usual was taken in at a time, and consequently more of these subtile Parts received at once by the Blood, a less frequent Respiration sufficed.

As to the Skin, since there is a continual Discharge made thro’ its innumerable Pores, of the matter of insensible Perspiration and Sweat; it is very possible that the same Passages may admit subtile Corpuscles, which may penetrate into the inward Parts. Nay it is very plain that they do so, from what we observe upon the outward Application of Ointments and warm Bathings: which have their Effects by their finest and most active Parts insinuating themselves into the Blood.

It is commonly thought, that the Blood only is affected in these Cases by the morbific Effluvia. But I am of opinion, that there is another Fluid in the Body, which is, especially in the beginning, equally, if not more, concerned in this Affair: I mean the Liquid of the Nerves, usually called the Animal Spirits. As this is the immediate Instrument of all Motion and Sensation, and has a great Agency in all the glandular Secretions, and in the Circulation of the Blood itself; any considerable Alteration made in it must be attended with dangerous Consequences. It is not possible that the whole Mass of Blood should be corrupted in so short a Time as that, in which the fatal Symptoms, in some Cases, discover themselves. Those Patients of the first Class, mentioned in the beginning of this Discourse, particularly the Porters who opened the infected Bales of Goods in the Lazaretto’s of Marseilles, died upon the first Appearance of Infection, as it were by a sudden Stroke; being seized with Rigors, Tremblings, Heart-Sickness, Vomitings, Giddiness and Heaviness of the Head, an universal Languor and Inquietude; the Pulse low and unequal: and Death insued sometimes in a few Hours.

Effects so sudden must be owing to the Action of some Corpuscles of great Force insinuated into, and changing the Properties of, another subtle and active Fluid in the Body: and such an one, no doubt, is the Nervous Liquor.

It is not to be expected that we should be able to explain the particular manner by which this is brought about. We know too little of the Frame