An Essay on Contagious Diseases / more particularly on the small-pox, measles, putrid, malignant, and pestilential fevers

Now if to this be added the increased Pressure of the Air, against the internal Surfaces of the Vesicles in Expiration, the Force will be found to be still greater. For supposing the Diameter of the Larynx to be equal to O.5 of an Inch; Supposing also the Pressure of the Larynx in an ordinary Expiration, by which the Force of the expired Air exceeds the Pressure of the Atmosphere, to be two Ounces, as has been found by Experiment [s], the Pressure of the Air in an ordinary Expiration upon the Internal Surface of the Vesicles of the Lungs, will on this Account only be equal to 1844736 Drams, or 19216 lib. Troy weight, which added to the Pressure on the Vesicles by the Weight of the Atmosphere, amounts to 39444401.536 Drams, or 410879.182 + 64/96 Pounds Troy weight. But the Pressure of the Air on all the rest of the Surface of our Bodies amounts but to 39900 lib. Troy, which is to the Pressure upon the Internal Surface of the Lungs, as 1 to 10.297 + 28882/39900, and consequently many more of the Contagious Particles will be communicated this way, than thro' the whole Surface of the rest of the Body. The Weights aforemention'd are indeed prodigious, but that is caused by the great Increase of Surface by the Number of the Vesicles: For it is still to be consider'd, that the Pressure upon each square Inch of the Surface of these Vesicles, amounts to no more than the Pressure on every Inch Square on the Surface of our Bodies, except that Increase which is made by the Force of Expiration, otherwise these Vesicles cou'd in no wise withstand so prodigious a Pressure. This Quantity viz. 75 Cubic Inches or thereabouts seems to be emitted from the Lungs in an ordinary Expiration, for I have found by Experiment, that the Lungs in a large Expiration will emit above 160 Cubic Inches of Air. Having my self fill'd an exhausted Receiver of that Size with Air at one Expiration, of the same Density with that of the Atmosphere.

Now if we likewise consider the exceeding Smallness of the Pulmonary Vessels, and also that the whole Quantity of Blood in the Body must necessarily pass this Organ, in order to its being attenuated and made fit for Circulation; It will necessarily follow, that the Alterations made in the Texture of the Blood by the Poisonous Effluvia, are communicated to it chiefly thro' this Organ. Besides, the Poisonous Particles do not only Enter into the Blood in greater Quantities in this Bowel, but when carried by these Passages, are capable of doing much more Mischief, than if entring in at any other Part of the Body, in Regard that they are more intimately mixt with it in its Comminution. I have insisted the more largely on this Argument, because I find that most who have wrote in this Subject, tho' they do suppose some of the Contagious Particles may be communicated to the Blood this way, yet lay the greatest Stress on the Mixture of these Particles with the Saliva, which being swallowed carries them in common with our Nourishment. 'Tis not Improbable indeed, that many of these Particles may be this way communicated to the Blood; but it is as Probable, that many of them which are by this way Communicated, lose much of their Force by their Mixture with the Bile and other Juices; As we see happens in the Poison of the Viper, which taken at the Mouth is not deadly, but when mixed immediately with the Blood produces the most violent Symptoms. The same may be observed from many other Substances, which may be safely taken into the Body by the common Passages, as most Acids, Spirit of Wine, and other Substances, but when mixed immediately with the Blood, by Injections into the Vessels of living Animals, produce Coagulations, Convulsions, and Death: The principal Reason which has induced Physicians to suppose, that the Poisonous Effluvia are chiefly communicated by these Passages, are those violent Vomitings which frequently accompany it; But this happens equally in many other Fevers, where there cannot be the least Suspicion of Contagion. The only Objection to what I have here advanced seems to be, That if the Contagion was communicated to the Blood chiefly by the Lungs, the Coagulations wou'd be immediately form'd there, and this Bowel totally obstructed. But if we consider, that the Chief Application of the Air to the Pulmonary Vesicles is in Expiration, immediately after which the Blood enters the Vena Arteriosa, whose Branches continually grow wider, and give Space and Time for the Coagulating Particles to act with their full Force, this Objection will of it self fall to the Ground.

The Contagious Particles being by these Means got into the Blood, do there by Coagulating and Inspissating the more gross and tenacious Parts, and highly Volatilising and Attenuating others of the most Subtil, reduce the Blood into the above-mentioned State. Thus we see that Milk, which is the Juice of an Animal, by the Addition of a small Quantity of an Acid Spirit, changes from an equal Texture, to one of a more gross and viscous, as well as more fluid and watry Substance. The like may be observed in the White of an Egg and the Blood of an Animal it self. Analogous to this is that Experiment of Jo. Bapt. Alprunus, who examining the Matter of a Pestilential Bubo by Distillation, found at first a Phlegm, then a more fat and oily Matter, and lastly a Salt ascending into the Neck of the Retort. But what was the most Remarkable in this Experiment, was the prodigious Stench upon opening the Vessels, exceeding as he expresses it a Thousand Wounds exposed to the Summer's Heat, and likewise a Salt so exceedingly Acrid and Pungent, as to equal, if not exceed Aq. Regis it self [s].

I shall not from hence pretend to determine, that an Acid Salt is the immediate Instrument of these Changes in the Animal Oeconomy, since the same may be wrought by Spirit of Wine, and other Liquids [t]; and Experience assures us, that the Effluvia, proceeding from the putrifying Parts of Animal Bodies, abound with a Volatil Alcaline Salt, as appears by Collecting them by the Bell, or in Distillation, by which they afford some Phlegm, a most Fetid Oil, and exceedingly Pungent and Volatil Salt; But this is sufficiently Evident from what has been said, that whatever the determinate Nature of the particular Particles may be, they do not only Coagulate the Animal Juices, and increase the Bulk of the Particles of the Blood, but render the remaining Part exceedingly Acrid and Pungent.

Consonant to this Dr. Hodges has observed a great Affinity between a Pestilential and Scorbutic Habit of Body, and that those whose Blood naturally abounded with Saline Particles, and had the rest Coagulated or Inspissated, as happens in Scorbutic Constitutions, were more grievously affected by the Pestilence; and also that most of those who Recover'd of the late Plague, were very much subject to Scorbutic Diseases: The like I have frequently observed, where the Small-Pox, Measles, &c. seizes those of a Scorbutic Habit.

Nor is the Blood alone affected by its Mixture with these Saline Spiculæ, but the rest of the Animal Juices also in Proportion, and especially the Nervous Fluid, which consisting of the most fine Volatil and Subtil Parts, will be render'd extreamly Acrid and Pungent: Whence Pain, Sickness, Inflammations, &c. must necessarily succeed.

CHAP. V.

The Symptoms accompanying a Pestilential Fever are Yawning, Stretching, Coldness, frequently to the greatest Extremity, Shuddering, suddain Pains in the Head, Giddiness, Loathing, Vomiting, a low unequal Pulse, Trembling, great inward Heat, especially about the Præcordia, Coldness of the Extremities, uncertain Sweats, Inquietude, Stupor, Delirium, Watching, Convulsions, Carbuncles, Buboes, Livid Vesications, Purple Spots, Hæmorrhages, which three last are the certain Forerunners of Death.

But here it is to be observed, that all the preceeding Symptoms do not constantly happen to every individual Person who is affected with a Pestilential Fever, but differ both in Number and Degree according to the Degree of Infection, Virulence of the Contagious Particles, and Constitutions of particular Persons; Thus the more the Blood is stock'd with Acrid and Pungent Salts, and other Parts render'd Glutinous, Coagulated, or Inspissated, the hotter the Season of the Year, the more violent the Symptoms will be, where the Degree of Infection is equal, and vice versa.

Yawning, Stretching Lassitude.

These are the first Signs of the Seisure of the fatal Enemy, and take their Rise from the Slowness of the Motion of the Circulating Fluids. For the Viscosity of the moving Fluids being increased, and the Liquidum Nervorum degenerating in Proportion thereto, the Weight to be moved will bear a greater Proportion to the moving Force than in a Natural State, and consequently the Animal must be affected with Weariness, as we find it is in all Cases where the Spirits are exhausted and weakned, in Proportion to the Circulating Juices. The other two are the necessary Consequence of this, for the Viscosity of the Fluids rendring them unfit to pass the small Capillary Vessels, the Pressure on the Fibres and Vessels will be increased, excite an uneasy Sensation, and stimulate them to more frequent Vibrations, in order to dislodge the Enemy: Whence follows a Contraction of the Muscles, and especially those which serve for Voluntary Motion, and into which the Spirits are most frequently determin'd: Hence then appears the Necessity of such a Method and Medicines as may dilute and dissolve the Cohering Fluids, and especially of such as are taken actually hot, and with large Quantities of Diluters, the great Activity of the Fiery Particles contain'd in them, rendring them much more capable of penetrating into the smallest Recesses of the Body, and disjoining the Coagulated Fluids.

Coldness, Shuddering.

These likewise depend on the too great Cohesion of the sanguineous Particles, on which account the Circulatory as well as the Motion of the intestine Particles of the Blood being diminish'd, and many of the Igneous Particles intangled in the viscous Cohesions, a Sensation of Cold must necessarily ensue, and especially in those Parts where the Motion of the Blood is most slow, and its Cohesion increased as happens in the Extremities. The nervous Juice being likewise for the same reason determin'd Irregularly, and in less Quantity into the Muscles, sometimes one, sometimes another of them will be weakly contracted, or a Shuddering will ensue.

A Low, quick, unequal Pulse.

These arise from the Secretion of a smaller Quantity of Animal Spirits, and those too unfit to actuate the Heart and other Muscles, whence their Contractions will be more weak, and being stimulated by the Acrimony of the Juices more frequent than in a Natural State. The Derivation likewise of the Nervous Fluid into the Fibres of the Heart being irregular, for the Reasons afore-given, the Motion of the Heart, and consequently of the Pulse, must be weak, quick, and unequal.

Loathing, Vomiting.

These are occasion'd partly by the Contagious Particles being drawn in with the Breath, and in their Passage tainting the Saliva, which when swallowed Irritates the Nervous Filaments of the Stomach, and partly by the Secretion of a more Pungent and Acrid Matter by its Glandulous Coat; as appears from their spontaneous Ceasing as soon as a Sweat can be procured, and the Discharge of these Acrid Particles promoted by the Perspirable Glands [u], and seldom otherwise.

Diarrhœa.

A Diarrhœa is likewise oftentimes a Concomitant of these Fevers, and ever of most dangerous Consequence in the Beginning of the Disease, inasmuch as it exhausts the Strength of the Patient, and prevents the regular Expulsion of the Perspirable Matter, by which Experience assures us that these Contagious Particles are most effectually discharg'd. These then indicate such Medicines as cleanse the Primæ Viæ from the Contagious Particles, and other Crudities lodged in them, blunt the Acrimony of the Saline Particles, and promote the Regular Expulsion of the Perspirable Matter.

Coldness of the Extremities.

This is occasion'd by the weak Contraction of the Heart, and greater Viscosity of the Blood in the Extream Parts of the Body, for the Circulating Fluids being prest on every Side by the containing Vessels, the more thin and liquid Part will pass into such Vessels as arise nearest the Heart, and leave the rest more Viscous and unfit for Motion. The Force of the Heart in the extream Parts being also much diminish'd, thro' the numerous Ramifications of the Vessels, the Motion of the Blood will be more slow, the Cohesion of the Particles of the Blood greater, and the Obstructions in the Capillaries more fixt than in other Parts of the Body. Now the Heat of the Body depending in a great Measure on the Attrition of the Particles against each other, this being diminish'd in the Extream Parts of the Body, the other must be lessen'd in Proportion.

Great inward Heat especially about the Præcordia.

This is occasion'd by the greater Intestine Motion and Colluctation of the Particles of the Blood, and the Expansive Particles of Heat being in greater Proportion in these than other Parts of the Body, from the more numerous Ramifications and Obstructions of the Vessels, and their Proximity to the Heart, as appears by Prop. 2.

Inquietude Watching.

These arise from the same Cause as the Preceeding, the great inward Heat being a constant Stimulus to the nervous Parts, and obliging the Sick to seek continual Change of Place and Posture, in order to abate this uneasy Sensation. These therefore indicate the use of such Medicines as specifically correct the Acrid and Stimulating Particles, restrain the inordinate Effervescence of the Circulating Fluids, and attenuate the Viscous Cohesions, of which kind are diluting and attenuating Acids, temperate Cordials and Anodynes, in such Doses and Proportions as are agreeable to the Age, Strength, and other Circumstances of the Patient.

Delirium.

This arises from the Inordinate Influx of the Liquidum Nervorum, occasioned from its Acrimony, Viscosity, and Quantity, different from those in a healthful State. Whence the Reflux of the Spirits to the Brain will be altogether irregular, and the Representations brought by them Irrational and Inconsistent. As this Symptom may arise as well from the increased as lessen'd Quantity, and different Texture of the Fluids, and Springyness of the Solids; so Regard must be had to the particular State of the Solids and Fluids in every Individual, for the abating of this Symptom.

Stupor.

This Symptom necessarily supposes the Flux of the Spirits thro' the Brain and Nerves in some Measure intercepted or diminished, and consequently as the preceeding may arise from different and even contrary Causes, but generally in these Cases shews a greater Degree of Coagulation in the Juices than the former, and consequently of greater Danger from the more numerous Obstructions in the Capillary and Nervous Vessels. Agreeable to which is that Observation of Dr. Hodges, That they who were attended with this Symptom rarely recover'd.

Trembling, Faultering in the Speech.

These depend on the same Cause as the former, viz. On the Diminution or Obstruction of the Liquidum Nervorum, whereby the Muscles are involuntarily and weakly contracted. As these suppose a more torpid Motion and greater Viscosity of the Fluids, and less Degree of Elasticity in the solid Parts, so the Method taken herein ought to be more active and stimulating than in any of the foregoing Symptoms. Whence Epispasticks, and the most Volatil Attenuating Medicines are more necessarily required, and ought to be oftner repeated, than in preceeding Symptoms.

Pain in the Head.

This is Occasioned by the Obstruction of some of the Capillary Vessels of the Brain by the Coagulated Part of the Blood, and the wounding of the Nervous Filaments by the Poisonous Saline Spiculæ. Whence the Blood being resisted in its Motion, must press more strongly against the Sides of the Vessels, and distend them beyond their Natural Diameters, and produce a shooting and throbbing Pain; and if the Obstruction continue or increase, a Phrensy, Inflammation, Suppuration, and Gangreen of the Part affected. Why this Symptom should be one of the first, as well as a constant Attendant thro' the whole Course of the Disease, appears from Prop. 2.

Carbuncles, Buboes, &c.

Hence likewise appears the Reason of Carbuncles, Boboes, Vesications, and the like, which take their Rise from the same Cause, and are different only in Proportion to the Viscosity or Acrimony of the obstructing Matter, and the Situation and Structure of the Part affected.

Purple spots, Hemorrhages

These show the greatest Corrosion and Acrimony imaginable in the Circulating Fluids, so as to be able to break and destroy the very Vessels themselves, and consequently certain Signs of a speedy Dissolution of the whole Animal Oeconomy.

Dissections of such as have died of Malignant and Pestilential diseases.

The Dissections of such as have died of these Diseases are a farther Confirmation of the foregoing Theory, inasmuch as they demonstrate a greater Acrimony and Coagulation in the Juices than other Diseases, by the numerous Obstructions Inflammations, and Mortifications of different Parts of the Body. Thus the Stomach and Intestines are commonly highly Inflamed, and frequently Gangreen'd. The Lungs, Diaphragm, and several of the Viscera inflamed, obstructed, and beset with Carbuncles and Purple Spots. The Arteries of the Dura and Pia Mater obstructed, and stuff'd with Grumous Blood, and often mortified. The Arteries of the whole Body in general fuller than ordinary, the Veins more empty. The Vessels about Præcordia much obstructed, highly inflamed, and often Gangreen'd. The membranous Parts of the Body in general more dry and rigid than in most other Diseases.

CHAP. VI.

Of the Small-Pox.

From what has been said of the Nature of Malignant and Pestilential Diseases it will follow, that the Contagious Matter producing the Small-Pox does likewise Coagulate the Blood, and increase the Bulk of its constituent Particles, and that in such a Proportion as are capable of obstructing only the ultimate and perspirable Vessels, as appears, in that it principally, if not solely affects the membranous Parts of the Body, as well External as Internal. Now these Parts being formed of such Vessels, the Pustules could not happen in these more than other Parts of the Body, were not their Vessels thus obstructed, and obstructed they cou'd not be, but from the increased Bulk of the Sanguineous Particles, and that in such a Proportion as renders them capable of penetrating into, but not passing thro' the Cavities of the ultimate Vessels, as appears from the preceeding Propositions, and consequently, the contagious Matter producing the Small-Pox, must be indued with this peculiar Property. And indeed if we allow the different Degrees of Coagulation in these Contagious Diseases, and which appear even to our Senses, it will appear, that the Principal if not the sole Difference proceeds only from the greater or less Bulk and Number of the Coagulated Moleculæ, and Acrimony of the Coagulating Matter. Thus we see that in Pestilential Diseases, where the Degree of Coagulation and Acrimony of the Juices are superior to the rest, the Obstructions happen in the larger Glands, as are those of the Armpits, Groin, &c. The Circulation of the Blood being obstructed, or at lest much retarded in the Capillary Blood Vessels, as appears from the weak Pulse, Coldness of the Extremities, and the like, which constantly accompany it; And consequently the Moleculæ form'd by the Coagulation of the Animal Juices must be larger, than these in the Small Pox, which proceed to the ultimate Vessels before the Obstructions are formed. The Measles are another Confirmation of this Theory, whose Moleculæ are still less than the preceeding, as appears by their Eruption with greater Flatness, and less Extension of the Obstructed Vessels. Thus also we see that in all these Diseases where the Contagious Matter is more Virulent than ordinary, or the Constitution of the Year more productive of these Diseases, or join'd with a Hot Tense and Scorbutic Disposition, Diarrhea's, Dysenteries, Purple Spots, Hemorrhages, Phrensies, Convulsions, Inflammations, &c. equally accompany these as Pestilential Diseases.

From what has been said in this and the foregoing Chapters may be deduced the Reasons of the greater or less Virulency of the Small-Pox, Measles, &c. in some Years more than others; As also why these Diseases shou'd rage with the greatest Violence when join'd with, or immediately preceeding a Pestilential Constitution of the Air. Hence also appears the Reason why Pains of the Head, Stomach, Loins and Back, preceed the Eruption of the Pustules, these Parts as nearest the Heart being soonest obstructed, and the Impetus of the Blood against the obstructed Canals much greater than in the rest of the Body. As also why the Pustules should appear so much sooner in the Face, Neck and Breast, than other Parts of the Body, as appears from Prop. 2.

Hence likewise appears the Reason why the Fever, Vomiting, Pains, &c. preceeding the Eruption of the Pustules should cease or be much diminish'd upon their Appearance; The Moleculæ, by the Force of the Circulating Fluids, being driven into and fixt in the Cutaneous Glands, and Secretory Vessels, whereby the Capillary Arteries being freed from them, a more easy Passage is allowed to the Circulating Fluids. Hence also appears the Reason why the Fever gradually increases with the Augmentation of the Pustules, the Contiguous Vessels being compress'd by their Distention, and the Obstructions in the Secretory Vessels made more Numerous; whence the Quantity of the Perspirable Matter being Diminished, and the Canals streightned, the Vessels will be more full, and the Pulse more strong and frequent. Hence likewise it will follow, that the more numerous the Obstructions are, and more pungent the Contagious Matter, the more Violent the Symptoms will be, and the Matter of the Pustules when suppurated become an Acrid and pungent gleety Substance, or Laudable Pus. As also why the Time of Suppuration shou'd vary in Proportion to the Virulency of the obstructing Matter; and consequently the Reason of the Difference between the Distinct and Confluent Small-Pox. Hence also it will appear, that Bleeding, in the Beginning of the Disease, ought only to be Administred where the Impetus of the Circulating Fluids is so great, that notwithstanding the Diminution of the Force of the Blood by it, the protrusive Force of the Circulating Mass will exceed the Impetus made on the Obstructing Matter by the Vibrations of the Fibres, and likewise why on its imprudent Use in the Beginning of the Disease, the Pustules shou'd disappear, and be driven back into the sanguineous Vessels. Hence also may be deduced the Reason of the Flux by the Salival Glands, the Swelling of the Face, Hands, and Feet, in the height of the Disease, the Vessels being at this time Turgid by the Suppression of the perspirable Matter; And likewise the Necessity of such Evacuations, as may reduce the Pressure of the Fluids upon them to such a Proportion, as the Tone of the Fibres may be able to resist; And why where this is neglected, a Peripneumonia, Phrensy, Delirium, &c. do frequently succeed.

Lastly, Hence may be deduced the Reason why the Small-Pox shou'd rarely seize those twice, who have had a Competent Number of them. For the Ultimate Perspirable Vessels being distended much beyond their Natural Tone, by the Bulk of the Obstructing Moleculæ, the Secretory Vessels must be left wider than before, and consequently less subject to be obstructed by Particles of this Size; Agreeable to this is that Observation of Dr. Sydenham and others, That in those Constitutions of the Air where the Small-Pox were very Epidemic, many (especially such as attended the Sick) who before had been affected with this Disease, were seized with a Fever in all Respects the same with that attending the Small-Pox, except only the Eruption of the Pustules, and the Symptoms which necessarily attend on them.

THE
APPENDIX.

The Pressure of the Atmosphere on the internal Surface of the Lungs, as computed in the foregoing Pages, so much exceeding that made by the ingenious Dr. Kiel, in the last Edition of his Book of Animal Secretion, it may not be amiss for the farther Illustration of it, to show that the Weight computed by that Learned Author is not really the whole Pressure of the Atmosphere, but the Force of the Lungs in Expiration, by which they exceed the Pressure of the Air upon them. For let the Tube A B be inserted into the Vessel C D E F of any given Dimension, and both the Tube and Vessel fill'd with Water or any other Fluid, it is evident from the Writers in Hydrostatics, that the Vessel C D E F will be pressed upon on every Part of its Internal Surface equal to the Basis of the Tube, by the Weight of a Column of the contained Fluid of the same Height with the Fluid, and whose Base is equal to that of the Tube, and consequently every Inch Square on the Internal Surface of the Lungs will be pressed upon by a Column of Air, whose Height is equal to that of the Atmosphere, and base one Inch Square, which will amount to the aforesaid Sum. Vide Pag. 34 & 35. Now if we suppose the Tube X inserted into the Neck of the Bladder Y and the Air forced into the Bladder in Expiration, to an equal Density with that of the incumbent Atmosphere, it is evident that the Air will not go out by the Tube without some external Force, being in Æquilibrio with the Atmosphere, and consequently the Force by which it is expressed thro' the Tube, must be that by which it exceeds the Pressure of the Atmosphere, upon the Orifice of the Tube.

If any one think that I have allowed too large a Quantity of Air to be taken into the Lungs in an Ordinary Inspiration, That is sufficiently recompensed by supposing the Diameter of the Larynx equal to O.5 and its Orifice O.19 which is more than it can be, for the Diameter does not exceed O.4, and consequently its Orifice will be but O.12. Now it being demonstrated by the Writers in Hydrostatics, that Weights forcing equal Quantities of the same Fluid out of the same Orifice, are to each other as the Squares of the Times in which the Fluid is forced out, and that in equal Times and Quantities of the same Fluid forced thro' unequal Orifices, the weights are Reciprocally as the Orifices; The Powers forcing an equal Quantity of Air thro' the Orifices O.19 and O.12 must be to each other in a Reciprocal Proportion, compounded of the Squares of the Times and Orifices of the Tubes; Which will be found sufficient to answer any Objection of this kind, by any who will give himself the Trouble to compute it.

FINIS.

Some Books Printed for Francis Hildyard Bookseller in YORK.

Tractatus de Podagra in quo de ultimis Vasis & Liquidis, & Succo Nutritio tractatur, Authore Cliftono Wintringham, 8vo. 2s. 6d.

A Treatise of Endemic Diseases, wherein the different Nature of Airs, Situations, Soils, Water, Diet, &c. are Mechanically explain'd and accounted for, by Clifton Wintringham, 2s.

Sermons on several Occasions, preached at the Cathedral of York, by William Pearson L. L. D. late Chancellor of the Diocess of York, Arch-Deacon of Nottingham, and Residentiary of the Church of York, 4s. 6d.

Antiquities of York-City, and the Civil Government thereof, &c. to the Year 1720, 2s. 6d.

The Church Catechism Explain'd by a Paraphrase, and Confirm'd by Proofs from the Holy Scripture, &c. By Fa. Talbot, D. D. Rector of Spofforth, 8vo. 1s. 6d.

The Praise of Yorkshire Ale, &c. to which is added a Yorkshire Dialogue in its pure Natural Dialect. 1s.