29414	----	Posner Memorial Collection, Carnegie Mellon University Libraries (http://posner.library.cmu.edu/Posner/) Note: Project Gutenberg also has an HTML version of this file which includes the original illustrations. See 29414-h.htm or 29414-h.zip: (http://www.gutenberg.org/files/29414/29414-h/29414-h.htm) or (http://www.gutenberg.org/files/29414/29414-h.zip) Images of the original pages are available through the Posner Memorial Collection, Carnegie Mellon University Libraries. See http://posner.library.cmu.edu/Posner/books/book.cgi?call=614.4_J54I_1798 AN _INQUIRY_ INTO THE CAUSES AND EFFECTS OF THE VARIOLÆ VACCINÆ. PRICE 7s. 6d. AN _INQUIRY_ INTO THE CAUSES AND EFFECTS OF THE VARIOLÆ VACCINÆ, A DISEASE DISCOVERED IN SOME OF THE WESTERN COUNTIES OF ENGLAND, PARTICULARLY _GLOUCESTERSHIRE_, AND KNOWN BY THE NAME OF THE COW POX. BY EDWARD JENNER, M.D. F.R.S. &c. ----QUID NOBIS CERTIUS IPSIS SENSIBUS ESSE POTEST, QUO VERA AC FALSA NOTEMUS. LUCRETIUS. London: PRINTED, FOR THE AUTHOR, BY SAMPSON LOW, Nº. 7, BERWICK STREET, SOHO: AND SOLD BY LAW, AVE-MARIA LANE; AND MURRAY AND HIGHLEY, FLEET STREET. 1798. TO _C. H. PARRY, M.D._ AT BATH. _My dear friend_, In the present age of scientific investigation, it is remarkable that a disease of so peculiar a nature as the Cow Pox, which has appeared in this and some of the neighbouring counties for such a series of years, should so long have escaped particular attention. Finding the prevailing notions on the subject, both among men of our profession and others, extremely vague and indeterminate, and conceiving that facts might appear at once both curious and useful, I have instituted as strict an inquiry into the causes and effects of this singular malady as local circumstances would admit. The following pages are the result, which, from motives of the most affectionate regard, are dedicated to you, by Your sincere Friend, EDWARD JENNER. Berkeley, Gloucestershire, June 21st, 1798. AN INQUIRY, _&c. &c._ The deviation of Man from the state in which he was originally placed by Nature seems to have proved to him a prolific source of Diseases. From the love of splendour, from the indulgences of luxury, and from his fondness for amusement, he has familiarised himself with a great number of animals, which may not originally have been intended for his associates. The Wolf, disarmed of ferocity, is now pillowed in the lady's lap[1]. The Cat, the little Tyger of our island, whose natural home is the forest, is equally domesticated and caressed. The Cow, the Hog, the Sheep, and the Horse, are all, for a variety of purposes, brought under his care and dominion. There is a disease to which the Horse, from his state of domestication, is frequently subject. The Farriers have termed it _the Grease_. It is an inflammation and swelling in the heel, from which issues matter possessing properties of a very peculiar kind, which seems capable of generating a disease in the Human Body (after it has undergone the modification which I shall presently speak of), which bears so strong a resemblance to the Small Pox, that I think it highly probable it may be the source of that disease. In this Dairy Country a great number of Cows are kept, and the office of milking is performed indiscriminately by Men and Maid Servants. One of the former having been appointed to apply dressings to the heels of a Horse affected with _the Grease_, and not paying due attention to cleanliness, incautiously bears his part in milking the Cows, with some particles of the infectious matter adhering to his fingers. When this is the case, it commonly happens that a disease is communicated to the Cows, and from the Cows to the Dairy-maids, which spreads through the farm until most of the cattle and domestics feel its unpleasant consequences. This disease has obtained the name of the Cow Pox. It appears on the nipples of the Cows in the form of irregular pustules. At their first appearance they are commonly of a palish blue, or rather of a colour somewhat approaching to livid, and are surrounded by an erysipelatous inflammation. These pustules, unless a timely remedy be applied, frequently degenerate into phagedenic ulcers, which prove extremely troublesome[2]. The animals become indisposed, and the secretion of milk is much lessened. Inflamed spots now begin to appear on different parts of the hands of the domestics employed in milking, and sometimes on the wrists, which quickly run on to suppuration, first assuming the appearance of the small vesications produced by a burn. Most commonly they appear about the joints of the fingers, and at their extremities; but whatever parts are affected, if the situation will admit, these superficial suppurations put on a circular form, with their edges more elevated than their centre, and of a colour distantly approaching to blue. Absorption takes place, and tumours appear in each axilla. The system becomes affected--the pulse is quickened; and shiverings succeeded by heat, with general lassitude and pains about the loins and limbs, with vomiting, come on. The head is painful, and the patient is now and then even affected with delirium. These symptoms, varying in their degrees of violence, generally continue from one day to three or four, leaving ulcerated sores about the hands, which, from the sensibility of the parts, are very troublesome, and commonly heal slowly, frequently becoming phagedenic, like those from whence they sprung. The lips, nostrils, eyelids, and other parts of the body, are sometimes affected with sores; but these evidently arise from their being heedlessly rubbed or scratched with the patient's infected fingers. No eruptions on the skin have followed the decline of the feverish symptoms in any instance that has come under my inspection, one only excepted, and in this case a very few appeared on the arms: they were very minute, of a vivid red colour, and soon died away without advancing to maturation; so that I cannot determine whether they had any connection with the preceding symptoms. Thus the disease makes its progress from the Horse to the nipple of the Cow, and from the Cow to the Human Subject. Morbid matter of various kinds, when absorbed into the system, may produce effects in some degree similar; but what renders the Cow-pox virus so extremely singular, is, that the person who has been thus affected is for ever after secure from the infection of the Small Pox; neither exposure to the variolous effluvia, nor the insertion of the matter into the skin, producing this distemper. In support of so extraordinary a fact, I shall lay before my Reader a great number of instances[3]. [Footnote 1: The late Mr. John Hunter proved, by experiments, that the Dog is the Wolf in a degenerated state.] [Footnote 2: They who attend sick cattle in this country find a speedy remedy for stopping the progress of this complaint in those applications which act chemically upon the morbid matter, such as the solutions of the Vitriolum Zinci, the Vitriolum Cupri, &c.] [Footnote 3: It is necessary to observe, that pustulous sores frequently appear spontaneously on the nipples of Cows, and instances have occurred, though very rarely, of the hands of the servants employed in milking being affected with sores in consequence, and even of their feeling an indisposition from absorption. These pustules are of a much milder nature than those which arise from that contagion which constitutes the true Cow Pox. They are always free from the bluish or livid tint so conspicuous in the pustules in that disease. No erysipelas attends them, nor do they shew any phagedenic disposition as in the other case, but quickly terminate in a scab without creating any apparent disorder in the Cow. This complaint appears at various seasons of the year, but most commonly in the Spring, when the Cows are first taken from their winter food and fed with grass. It is very apt to appear also when they are suckling their young. But this disease is not to be considered as similar in any respect to that of which I am treating, as it is incapable of producing any specific effects on the human Constitution. However, it is of the greatest consequence to point it out here, lest the want of discrimination should occasion an idea of security from the infection of the Small Pox, which might prove delusive.] _CASE I._ JOSEPH MERRET, now an Under Gardener to the Earl of Berkeley, lived as a Servant with a Farmer near this place in the year 1770, and occasionally assisted in milking his master's cows. Several horses belonging to the farm began to have sore heels, which Merret frequently attended. The cows soon became affected with the Cow Pox, and soon after several sores appeared on his hands. Swellings and stiffness in each axilla followed, and he was so much indisposed for several days as to be incapable of pursuing his ordinary employment. Previously to the appearance of the distemper among the cows there was no fresh cow brought into the farm, nor any servant employed who was affected with the Cow Pox. In April, 1795, a general inoculation taking place here, Merret was inoculated with his family; so that a period of twenty-five years had elapsed from his having the Cow Pox to this time. However, though the variolous matter was repeatedly inserted into his arm, I found it impracticable to infect him with it; an efflorescence only, taking on an erysipelatous look about the centre, appearing on the skin near the punctured parts. During the whole time that his family had the Small Pox, one of whom had it very full, he remained in the house with them, but received no injury from exposure to the contagion. It is necessary to observe, that the utmost care was taken to ascertain, with the most scrupulous precision, that no one whose case is here adduced had gone through the Small Pox previous to these attempts to produce that disease. Had these experiments been conducted in a large city, or in a populous neighbourhood, some doubts might have been entertained; but here, where population is thin, and where such an event as a person's having had the Small Pox is always faithfully recorded, no risk of inaccuracy in this particular can arise. _CASE II._ SARAH PORTLOCK, of this place, was infected with the Cow Pox, when a Servant at a Farmer's in the neighbourhood, twenty-seven years ago[1]. In the year 1792, conceiving herself, from this circumstance, secure from the infection of the Small Pox, she nursed one of her own children who had accidentally caught the disease, but no indisposition ensued.--During the time she remained in the infected room, variolous matter was inserted into both her arms, but without any further effect than in the preceding case. [Footnote 1: I have purposely selected several cases in which the disease had appeared at a very distant period previous to the experiments made with variolous matter, to shew that the change produced in the constitution is not affected by time.] _CASE III._ JOHN PHILLIPS, a Tradesman of this town, had the Cow Pox at so early a period as nine years of age. At the age of sixty-two I inoculated him, and was very careful in selecting matter in its most active state. It was taken from the arm of a boy just before the commencement of the eruptive fever, and instantly inserted. It very speedily produced a sting-like feel in the part. An efflorescence appeared, which on the fourth day was rather extensive, and some degree of pain and stiffness were felt about the shoulder; but on the fifth day these symptoms began to disappear, and in a day or two after went entirely off, without producing any effect on the system. _CASE IV._ MARY BARGE, of Woodford, in this parish, was inoculated with variolous matter in the year 1791. An efflorescence of a palish red colour soon appeared about the parts where the matter was inserted, and spread itself rather extensively, but died away in a few days without producing any variolous symptoms[1]. She has since been repeatedly employed as a nurse to Small-pox patients, without experiencing any ill consequences. This woman had the Cow Pox when she lived in the service of a Farmer in this parish thirty-one years before. [Footnote 1: It is remarkable that variolous matter, when the system is disposed to reject it, should excite inflammation on the part to which it is applied more speedily than when it produces the Small Pox. Indeed it becomes almost a criterion by which we can determine whether the infection will be received or not. It seems as if a change, which endures through life, had been produced in the action, or disposition to action, in the vessels of the skin; and it is remarkable too, that whether this change has been effected by the Small Pox, or the Cow Pox, that the disposition to sudden cuticular inflammation is the same on the application of variolous matter.] _CASE V._ MRS. H----, a respectable Gentlewoman of this town, had the Cow Pox when very young. She received the infection in rather an uncommon manner: it was given by means of her handling some of the same utensils[1] which were in use among the servants of the family, who had the disease from milking infected cows. Her hands had many of the Cow-pox sores upon them, and they were communicated to her nose, which became inflamed and very much swoln. Soon after this event Mrs. H---- was exposed to the contagion of the Small Pox, where it was scarcely possible for her to have escaped, had she been susceptible of it, as she regularly attended a relative who had the disease in so violent a degree that it proved fatal to him. In the year 1778 the Small Pox prevailed very much at Berkeley, and Mrs. H---- not feeling perfectly satisfied respecting her safety (no indisposition having followed her exposure to the Small Pox) I inoculated her with active variolous matter. The same appearance followed as in the preceding cases--an efflorescence on the arm without any effect on the constitution. [Footnote 1: When the Cow Pox has prevailed in the dairy, it has often been communicated to those who have not milked the cows, by the handle of the milk pail.] _CASE VI._ It is a fact so well known among our Dairy Farmers, that those who have had the Small Pox either escape the Cow Pox or are disposed to have it slightly; that as soon as the complaint shews itself among the cattle, assistants are procured, if possible, who are thus rendered less susceptible of it, otherwise the business of the farm could scarcely go forward. In the month of May, 1796, the Cow Pox broke out at Mr. Baker's, a Farmer who lives near this place. The disease was communicated by means of a cow which was purchased in an infected state at a neighbouring fair, and not one of the Farmer's cows (consisting of thirty) which were at that time milked escaped the contagion. The family consisted of a man servant, two dairymaids, and a servant boy, who, with the Farmer himself, were twice a day employed in milking the cattle. The whole of this family, except Sarah Wynne, one of the dairymaids, had gone through the Small Pox. The consequence was, that the Farmer and the servant boy escaped the infection of the Cow Pox entirely, and the servant man and one of the maid servants had each of them nothing more than a sore on one of their fingers, which produced no disorder in the system. But the other dairymaid, Sarah Wynne, who never had the Small Pox, did not escape in so easy a manner. She caught the complaint from the cows, and was affected with the symptoms described in the 5th page in so violent a degree, that she was confined to her bed, and rendered incapable for several days of pursuing her ordinary vocations in the farm. March 28th, 1797, I inoculated this girl, and carefully rubbed the variolous matter into two slight incisions made upon the left arm. A little inflammation appeared in the usual manner around the parts where the matter was inserted, but so early as the fifth day it vanished entirely without producing any effect on the system. _CASE VII._ Although the preceding history pretty clearly evinces that the constitution is far less susceptible of the contagion of the Cow Pox after it has felt that of the Small Pox, and although in general, as I have observed, they who have had the Small Pox, and are employed in milking cows which are infected with the Cow Pox, either escape the disorder, or have sores on the hands without feeling any general indisposition, yet the animal economy is subject to some variation in this respect, which the following relation will point out: In the summer of the year 1796 the Cow Pox appeared at the Farm of Mr. Andrews, a considerable dairy adjoining to the town of Berkeley. It was communicated, as in the preceding instance, by an infected cow purchased at a fair in the neighbourhood. The family consisted of the Farmer, his wife, two sons, a man and a maid servant; all of whom, except the Farmer (who was fearful of the consequences), bore a part in milking the cows. The whole of them, exclusive of the man servant, had regularly gone through the Small Pox; but in this case no one who milked the cows escaped the contagion. All of them had sores upon their hands, and some degree of general indisposition, preceded by pains and tumours in the axillæ: but there was no comparison in the severity of the disease as it was felt by the servant man, who had escaped the Small Pox, and by those of the family who had not, for, while he was confined to his bed, they were able, without much inconvenience, to follow their ordinary business. February the 13th, 1797, I availed myself of an opportunity of inoculating William Rodway, the servant man above alluded to. Variolous matter was inserted into both his arms; in the right by means of superficial incisions, and into the left by slight punctures into the cutis. Both were perceptibly inflamed on the third day. After this the inflammation about the punctures soon died away, but a small appearance of erysipelas was manifest about the edges of the incisions till the eighth day, when a little uneasiness was felt for the space of half an hour in the right axilla. The inflammation then hastily disappeared without producing the most distant mark of affection of the system. _CASE VIII._ ELIZABETH WYNNE, aged fifty-seven, lived as a servant with a neighbouring Farmer thirty-eight years ago. She was then a dairymaid, and the Cow Pox broke out among the cows. She caught the disease with the rest of the family, but, compared with them, had it in a very slight degree, one very small sore only breaking out on the little finger of her left hand, and scarcely any perceptible indisposition following it. As the malady had shewn itself in so slight a manner, and as it had taken place at so distant a period of her life, I was happy with the opportunity of trying the effects of variolous matter upon her constitution, and on the 28th of March, 1797, I inoculated her by making two superficial incisions on the left arm, on which the matter was cautiously rubbed. A little efflorescence soon appeared, and a tingling sensation was felt about the parts where the matter was inserted until the third day, when both began to subside, and so early as the fifth day it was evident that no indisposition would follow. _CASE IX._ Although the Cow Pox shields the constitution from the Small Pox, and the Small Pox proves a protection against its own future poison, yet it appears that the human body is again and again susceptible of the infectious matter of the Cow Pox, as the following history will demonstrate: William Smith, of Pyrton in this parish, contracted this disease when he lived with a neighbouring Farmer in the year 1780. One of the horses belonging to the farm had sore heels, and it fell to his lot to attend him. By these means the infection was carried to the cows, and from the cows it was communicated to Smith. On one of his hands were several ulcerated sores, and he was affected with such symptoms as have been before described. In the year 1791 the Cow Pox broke out at another farm where he then lived as a servant, and he became affected with it a second time; and in the year 1794 he was so unfortunate as to catch it again. The disease was equally as severe the second and third time as it was on the first[1]. In the spring of the year 1795 he was twice inoculated, but no affection of the system could be produced from the variolous matter; and he has since associated with those who had the Small Pox in its most contagious state without feeling any effect from it. [Footnote 1: This is not the case in general--a second attack is commonly very slight, and so, I am informed, it is among the cows.] _CASE X._ SIMON NICHOLS lived as a servant with Mr. Bromedge, a gentleman who resides on his own farm in this parish, in the year 1782. He was employed in applying dressings to the sore heels of one of his master's horses, and at the same time assisted in milking the cows. The cows became affected in consequence, but the disease did not shew itself on their nipples till several weeks after he had begun to dress the horse. He quitted Mr. Bromedge's service, and went to another farm without any sores upon him; but here his hands soon began to be affected in the common way, and he was much indisposed with the usual symptoms. Concealing the nature of the malady from Mr. Cole, his new master, and being there also employed in milking, the Cow Pox was communicated to the cows. Some years afterwards Nichols was employed in a farm where the Small Pox broke out, when I inoculated him with several other patients, with whom he continued during the whole time of their confinement. His arm inflamed, but neither the inflammation nor his associating with the inoculated family produced the least effect upon his constitution. _CASE XI._ WILLIAM STINCHCOMB was a fellow servant with Nichols at Mr. Bromedge's Farm at the time the cattle had the Cow Pox, and he was unfortunately infected by them. His left hand was very severely affected with several corroding ulcers, and a tumour of considerable size appeared in the axilla of that side. His right hand had only one small sore upon it, and no tumour discovered itself in the corresponding axilla. In the year 1792 Stinchcomb was inoculated with variolous matter, but no consequences ensued beyond a little inflammation in the arm for a few days. A large party were inoculated at the same time, some of whom had the disease in a more violent degree than is commonly seen from inoculation. He purposely associated with them, but could not receive the Small Pox. During the sickening of some of his companions, their symptoms so strongly recalled to his mind his own state when sickening with the Cow Pox, that he very pertinently remarked their striking similarity. _CASE XII._ The Paupers of the village of Tortworth, in this county, were inoculated by Mr. Henry Jenner, Surgeon, of Berkeley, in the year 1795. Among them, eight patients presented themselves who had at different periods of their lives had the Cow Pox. One of them, Hester Walkley, I attended with that disease when she lived in the service of a Farmer in the same village in the year 1782; but neither this woman, nor any other of the patients who had gone through the Cow Pox, received the variolous infection either from the arm or from mixing in the society of the other patients who were inoculated at the same time. This state of security proved a fortunate circumstance, as many of the poor women were at the same time in a state of pregnancy. _CASE XIII._ One instance has occurred to me of the system being affected from the matter issuing from the heels of horses, and of its remaining afterwards unsusceptible of the variolous contagion; another, where the Small Pox appeared obscurely; and a third, in which its complete existence was positively ascertained. First, THOMAS PEARCE, is the son of a Smith and Farrier near to this place. He never had the Cow Pox; but, in consequence of dressing horses with sore heels at his father's, when a lad, he had sores on his fingers which suppurated, and which occasioned a pretty severe indisposition. Six years afterwards I inserted variolous matter into his arm repeatedly, without being able to produce any thing more than slight inflammation, which appeared very soon after the matter was applied, and afterwards I exposed him to the contagion of the Small Pox with as little effect[1]. [Footnote 1: It is a remarkable fact, and well known to many, that we are frequently foiled in our endeavours to communicate the Small Pox by inoculation to blacksmiths, who in the country are farriers. They often, as in the above instance, either resist the contagion entirely, or have the disease anomalously. Shall we not be able now to account for this on a rational principle?] _CASE XIV._ Secondly, Mr. JAMES COLE, a Farmer in this parish, had a disease from the same source as related in the preceding case, and some years after was inoculated with variolous matter. He had a little pain in the axilla, and felt a slight indisposition for three or four hours. A few eruptions shewed themselves on the forehead, but they very soon disappeared without advancing to maturation. _CASE XV._ Although in the two former instances the system seemed to be secured, or nearly so, from variolous infection, by the absorption of matter from sores produced by the diseased heels of horses, yet the following case decisively proves that this cannot be entirely relied upon, until a disease has been generated by the morbid matter from the horse on the nipple of the cow, and passed through that medium to the human subject. Mr. ABRAHAM RIDDIFORD, a Farmer at Stone in this parish, in consequence of dressing a mare that had sore heels, was affected with very painful sores in both his hands, tumours in each axilla, and severe and general indisposition. A Surgeon in the neighbourhood attended him, who, knowing the similarity between the appearance of the sores upon his hands and those produced by the Cow Pox, and being acquainted also with the effects of that disease on the human constitution, assured him that he never need to fear the infection of the Small Pox; but this assertion proved fallacious, for, on being exposed to the infection upwards of twenty years afterwards, he caught the disease, which took its regular course in a very mild way. There certainly was a difference perceptible, although it is not easy to describe it, in the general appearance of the pustules from that which we commonly see. Other practitioners, who visited the patient at my request, agreed with me in this point, though there was no room left for suspicion as to the reality of the disease, as I inoculated some of his family from the pustules, who had the Small Pox, with its usual appearances, in consequence. _CASE XVI._ SARAH NELMES, a dairymaid at a Farmer's near this place, was infected with the Cow Pox from her master's cows in May, 1796. She received the infection on a part of the hand which had been previously in a slight degree injured by a scratch from a thorn. A large pustulous sore and the usual symptoms accompanying the disease were produced in consequence. The pustule was so expressive of the true character of the Cow Pox, as it commonly appears upon the hand, that I have given a representation of it in the annexed plate. The two small pustules on the wrists arose also from the application of the virus to some minute abrasions of the cuticle, but the livid tint, if they ever had any, was not conspicuous at the time I saw the patient. The pustule on the fore finger shews the disease in an earlier stage. It did not actually appear on the hand of this young woman, but was taken from that of another, and is annexed for the purpose of representing the malady after it has newly appeared. _CASE XVII._ The more accurately to observe the progress of the infection, I selected a healthy boy, about eight years old, for the purpose of inoculation for the Cow Pox. The matter was taken from a sore on the hand of a dairymaid[1], who was infected by her master's cows, and it was inserted, on the 14th of May, 1796, into the arm of the boy by means of two superficial incisions, barely penetrating the cutis, each about half an inch long. [Illustration] On the seventh day he complained of uneasiness in the axilla, and on the ninth he became a little chilly, lost his appetite, and had a slight head-ach. During the whole of this day he was perceptibly indisposed, and spent the night with some degree of restlessness, but on the day following he was perfectly well. The appearance of the incisions in their progress to a state of maturation were much the same as when produced in a similar manner by variolous matter. The only difference which I perceived was, in the state of the limpid fluid arising from the action of the virus, which assumed rather a darker hue, and in that of the efflorescence spreading round the incisions, which had more of an erysipelatous look than we commonly perceive when variolous matter has been made use of in the same manner; but the whole died away (leaving on the inoculated parts scabs and subsequent eschars) without giving me or my patient the least trouble. In order to ascertain whether the boy, after feeling so slight an affection of the system from the Cow-pox virus, was secure from the contagion of the Small-pox, he was inoculated the 1st of July following with variolous matter, immediately taken from a pustule. Several slight punctures and incisions were made on both his arms, and the matter was carefully inserted, but no disease followed. The same appearances were observable on the arms as we commonly see when a patient has had variolous matter applied, after having either the Cow-pox or the Small-pox. Several months afterwards, he was again inoculated with variolous matter, but no sensible effect was produced on the constitution. Here my researches were interrupted till the spring of the year 1798, when from the wetness of the early part of the season, many of the farmers' horses in this neighbourhood were affected with sore heels, in consequence of which the Cow-pox broke out among several of our dairies, which afforded me an opportunity of making further observations upon this curious disease. A mare, the property of a person who keeps a dairy in a neighbouring parish, began to have sore heels the latter end of the month of February 1798, which were occasionally washed by the servant men of the farm, Thomas Virgoe, William Wherret, and William Haynes, who in consequence became affected with sores in their hands, followed by inflamed lymphatic glands in the arms and axillæ, shiverings succeeded by heat, lassitude and general pains in the limbs. A single paroxysm terminated the disease; for within twenty-four hours they were free from general indisposition, nothing remaining but the sores on their hands. Haynes and Virgoe, who had gone through the Small-pox from inoculation, described their feelings as very similar to those which affected them on sickening with that malady. Wherret never had had the Small-pox. Haynes was daily employed as one of the milkers at the farm, and the disease began to shew itself among the cows about ten days after he first assisted in washing the mare's heels. Their nipples became sore in the usual way, with blueish pustules; but as remedies were early applied they did not ulcerate to any extent. [Footnote 1: From the sore on the hand of Sarah Nelmes.--See the preceding case and the plate.] _CASE XVIII._ JOHN BAKER, a child of five years old, was inoculated March 16, 1798, with matter taken from a pustule on the hand of Thomas Virgoe, one of the servants who had been infected from the mare's heels. He became ill on the 6th day with symptoms similar to those excited by Cow-pox matter. On the 8th day he was free from indisposition. There was some variation in the appearance of the pustule on the arm. Although it somewhat resembled a Small-pox pustule, yet its similitude was not so conspicuous as when excited by matter from the nipple of the cow, or when the matter has passed from thence through the medium of the human subject.--(See Plate, No. 2.) [Illustration] This experiment was made to ascertain the progress and subsequent effects of the disease when thus propagated. We have seen that the virus from the horse, when it proves infectious to the human subject is not to be relied upon as rendering the system secure from variolous infection, but that the matter produced by it upon the nipple of the cow is perfectly so. Whether its passing from the horse through the human constitution, as in the present instance, will produce a similar effect, remains to be decided. This would now have been effected, but the boy was rendered unfit for inoculation from having felt the effects of a contagious fever in a work-house, soon after this experiment was made. _CASE XIX._ WILLIAM SUMMERS, a child of five years and a half old was inoculated the same day with Baker, with matter taken from the nipples of one of the infected cows, at the farm alluded to in page 35. He became indisposed on the 6th day, vomited once, and felt the usual slight symptoms till the 8th day, when he appeared perfectly well. The progress of the pustule, formed by the infection of the virus was similar to that noticed in Case XVII., with this exception, its being free from the livid tint observed in that instance. _CASE XX._ From William Summers the disease was transfered to William Pead a boy of eight years old, who was inoculated March 28th. On the 6th day he complained of pain in the axilla, and on the 7th was affected with the common symptoms of a patient sickening with the Small-pox from inoculation, which did not terminate 'till the 3d day after the seizure. So perfect was the similarity to the variolous fever that I was induced to examine the skin, conceiving there might have been some eruptions, but none appeared. The efflorescent blush around the part punctured in the boy's arm was so truly characteristic of that which appears on variolous inoculation, that I have given a representation of it. The drawing was made when the pustule was beginning to die away, and the areola retiring from the centre. (See Plate, No. 3.) [Illustration] _CASE XXI._ April 5th. Several children and adults were inoculated from the arm of William Pead. The greater part of them sickened on the 6th day, and were well on the 7th, but in three of the number a secondary indisposition arose in consequence of an extensive erysipelatous inflammation which appeared on the inoculated arms. It seemed to arise from the state of the pustule, which spread out, accompanied with some degree of pain, to about half the diameter of a six-pence. One of these patients was an infant of half a year old. By the application of mercurial ointment to the inflamed parts (a treatment recommended under similar circumstances in the inoculated Small-pox) the complaint subsided without giving much trouble. HANNAH EXCELL an healthy girl of seven years old, and one of the patients above mentioned, received the infection from the insertion of the virus under the cuticle of the arm in three distinct points. The pustules which arose in consequence, so much resembled, on the 12th day, those appearing from the insertion of variolous matter, that an experienced Inoculator would scarcely have discovered a shade of difference at that period. Experience now tells me that almost the only variation which follows consists in the pustulous fluids remaining limpid nearly to the time of its total disappearance; and not, as in the direct Small-pox, becoming purulent.--(See Plate, No. 4.) _CASE XXII._ From the arm of this girl matter was taken and inserted April 12th into the arms of John Marklove one year and a half old, Robert F. Jenner, eleven months old, Mary Pead, 5 years old, and Mary James, 6 years old. [Illustration] Among these Robert F. Jenner did not receive the infection. The arms of the other three inflamed properly and began to affect the system in the usual manner; but being under some apprehensions from the preceding Cases that a troublesome erysipelas might arise, I determined on making an experiment with the view of cutting off its source. Accordingly after the patients had felt an indisposition of about twelve hours, I applied in two of these Cases out of the three, on the vesicle formed by the virus, a little mild caustic, composed of equal parts of quick-lime and soap, and suffered it to remain on the part six hours[1]. It seemed to give the children but little uneasiness, and effectually answered my intention in preventing the appearance of erysipelas. Indeed it seemed to do more, for in half an hour after its application, the indisposition of the children ceased[2]. These precautions were perhaps unnecessary as the arm of the third child, Mary Pead, which was suffered to take its common course, scabbed quickly, without any erysipelas. [Footnote 1: Perhaps a few touches with the lapis septicus would have proved equally efficacious.] [Footnote 2: What effect would a similar treatment produce in inoculation for the Small-pox?] _CASE XXIII._ From this child's arm matter was taken and transferred to that of J. Barge, a boy of seven years old. He sickened on the 8th day, went through the disease with the usual slight symptoms, and without any inflammation on the arm beyond the common efflorescence surrounding the pustule, an appearance so often seen in inoculated Small-pox. After the many fruitless attempts to give the Small-pox to those who had had the Cow-pox, it did not appear necessary, nor was it convenient to me, to inoculate the whole of those who had been the subjects of these late trials; yet I thought it right to see the effects of variolous matter on some of them, particularly William Summers, the first of these patients who had been infected with matter taken from the cow. He was therefore inoculated with variolous matter from a fresh pustule; but, as in the preceding Cases, the system did not feel the effects of it in the smallest degree. I had an opportunity also of having this boy and William Pead inoculated by my Nephew, Mr. Henry Jenner, whose report to me is as follows: "I have inoculated Pead and Barge, two of the boys whom you lately infected with the Cow-pox. On the 2d day the incisions were inflamed and there was a pale inflammatory stain around them. On the 3d day these appearances were still increasing and their arms itched considerably. On the 4th day, the inflammation was evidently subsiding, and on the 6th it was scarcely perceptible. No symptom of indisposition followed. To convince myself that the variolous matter made use of was in a perfect state, I at the same time inoculated a patient with some of it who never had gone through the Cow-pox, and it produced the Small-pox in the usual regular manner." These experiments afforded me much satisfaction, they proved that the matter in passing from one human subject to another, through five gradations, lost none of its original properties, J. Barge being the fifth who received the infection successively from William Summers, the boy to whom it was communicated from the cow. * * * * * I shall now conclude this Inquiry with some general observations on the subject and on some others which are interwoven with it. Although I presume it may be unnecessary to produce further testimony in support of my assertion "that the Cow-pox protects the human constitution from the infection of the Small-pox," yet it affords me considerable satisfaction to say, that Lord Somerville, the President of the Board of Agriculture, to whom this paper was shewn by Sir Joseph Banks, has found upon inquiry that the statements were confirmed by the concuring testimony of Mr. Dolland, a surgeon, who resides in a dairy country remote from this, in which these observations were made. With respect to the opinion adduced "that the source of the infection is a peculiar morbid matter arising in the horse," although I have not been able to prove it from actual experiments conducted immediately under my own eye, yet the evidence I have adduced appears sufficient to establish it. They who are not in the habit of conducting experiments may not be aware of the coincidence of circumstances necessary for their being managed so as to prove perfectly decisive; nor how often men engaged in professional pursuits are liable to interruptions which disappoint them almost at the instant of their being accomplished: however, I feel no room for hesitation respecting the common origin of the disease, being well convinced that it never appears among the cows (except it can be traced to a cow introduced among the general herd which has been previously infected, or to an infected servant), unless they have been milked by some one who, at the same time, has the care of a horse affected with diseased heels. The spring of the year 1797, which I intended particularly to have devoted to the completion of this investigation, proved, from its dryness, remarkably adverse to my wishes; for it frequently happens, while the farmers' horses are exposed to the cold rains which fall at that season that their heels become diseased, and no Cow-pox then appeared in the neighbourhood. The active quality of the virus from the horses' heels is greatly increased after it has acted on the nipples of the cow, as it rarely happens that the horse affects his dresser with sores, and as rarely that a milk-maid escapes the infection when she milks infected cows. It is most active at the commencement of the disease, even before it has acquired a pus-like appearance; indeed I am not confident whether this property in the matter does not entirely cease as soon as it is secreted in the form of pus. I am induced to think it does cease[1], and that it is the thin darkish-looking fluid only, oozing from the newly-formed cracks in the heels, similar to what sometimes appears from erysipelatous blisters, which gives the disease. Nor am I certain that the nipples of the cows are at all times in a state to receive the infection. The appearance of the disease in the spring and the early part of the summer, when they are disposed to be affected with spontaneous eruptions so much more frequently than at other seasons, induces me to think, that the virus from the horse must be received upon them when they are in this state, in order to produce effects: experiments, however, must determine these points. But it is clear that when the Cow-pox virus is once generated, that the cows cannot resist the contagion, in whatever state their nipples may chance to be, if they are milked with an infected hand. Whether the matter, either from the cow or the horse will affect the sound skin of the human body, I cannot positively determine; probably it will not, unless on those parts where the cuticle is extremely thin, as on the lips for example. I have known an instance of a poor girl who produced an ulceration on her lip by frequently holding her finger to her mouth to cool the raging of a Cow-pox sore by blowing upon it. The hands of the farmers' servants here, from the nature of their employments, are constantly exposed to those injuries which occasion abrasions of the cuticle, to punctures from thorns and such like accidents; so that they are always in a state to feel the consequences of exposure to infectious matter. It is singular to observe that the Cow-pox virus, although it renders the constitution unsusceptible of the variolous, should, nevertheless, leave it unchanged with respect to its own action. I have already produced an instance[2] to point out this, and shall now corroborate it with another. Elizabeth Wynne, who had the Cow-pox in the year 1759, was inoculated with variolous matter, without effect, in the year 1797, and again caught the Cow-pox in the year 1798. When I saw her, which was on the 8th day after she received the infection, I found her affected with general lassitude, shiverings, alternating with heat, coldness of the extremities, and a quick and irregular pulse. These symptoms were preceded by a pain in the axilla. On her hand was one large pustulous sore, which resembled that delinated in Plate No. 1. It is curious also to observe, that the virus, which with respect to its effects is undetermined and uncertain previously to its passing from the horse through the medium of the cow, should then not only become more active, but should invariably and completely possess those specific properties which induce in the human constitution symptoms similar to those of the variolous fever, and effect in it that peculiar change which for ever renders it unsusceptible of the variolous contagion. May it not, then, be reasonably conjectured, that the source of the Small-pox is morbid matter of a peculiar kind, generated by a disease in the horse, and that accidental circumstances may have again and again arisen, still working new changes upon it, until it has acquired the contagious and malignant form under which we now commonly see it making its devastations amongst us? And, from a consideration of the change which the infectious matter undergoes from producing a disease on the cow, may we not conceive that many contagious diseases, now prevalent among us, may owe their present appearance not to a simple, but to a compound origin? For example, is it difficult to imagine that the measles, the scarlet fever, and the ulcerous sore throat with a spotted skin, have all sprung from the same source, assuming some variety in their forms according to the nature of their new combinations? The same question will apply respecting the origin of many other contagious diseases, which bear a strong analogy to each other. There are certainly more forms than one, without considering the common variation between the confluent and distinct, in which the Small-pox appears in what is called the natural way.--About seven years ago a species of Small-pox spread through many of the towns and villages of this part of Gloucestershire: it was of so mild a nature, that a fatal instance was scarcely ever heard of, and consequently so little dreaded by the lower orders of the community, that they scrupled not to hold the same intercourse with each other as if no infectious disease had been present among them. I never saw nor heard of an instance of its being confluent. The most accurate manner, perhaps, in which I can convey an idea of it is, by saying, that had fifty individuals been taken promiscuously and infected by exposure to this contagion, they would have had as mild and light a disease as if they had been inoculated with variolous matter in the usual way. The harmless manner in which it shewed itself could not arise from any peculiarity either in the season or the weather, for I watched its progress upwards of a year without perceiving any variation in its general appearance. I consider it then as a _variety_ of the Small-pox[3]. In some of the preceding cases I have noticed the attention that was paid to the state of the variolous matter previous to the experiment of inserting it into the arms of those who had gone through the Cow-pox. This I conceived to be of great importance in conducting these experiments, and were it always properly attended to by those who inoculate for the Small-pox, it might prevent much subsequent mischief and confusion. With the view of enforcing so necessary a precaution, I shall take the liberty of digressing so far as to point out some unpleasant facts, relative to mismanagement in this particular, which have fallen under my own observation. A Medical Gentleman (now no more), who for many years inoculated in this neighbourhood, frequently preserved the variolous matter intended for his use, on a piece of lint or cotton, which, in its fluid state was put into a vial, corked, and conveyed into a warm pocket; a situation certainly favourable for speedily producing putrefaction in it. In this state (not unfrequently after it had been taken several days from the pustules) it was inserted into the arms of his patients, and brought on inflammation of the incised parts, swellings of the axillary glands, fever, and sometimes eruptions. But what was this disease? Certainly not the Small-pox; for the matter having from putrefaction lost, or suffered a derangement in its specific properties, was no longer capable of producing that malady, those who had been inoculated in this manner being as much subject to the contagion of the Small-pox, as if they had never been under the influence of this artificial disease; and many, unfortunately, fell victims to it, who thought themselves in perfect security. The same unfortunate circumstance of giving a disease, supposed to be the Small-pox, with inefficaceous variolous matter, having occurred under the direction of some other practitioners within my knowledge, and probably from the same incautious method of securing the variolous matter, I avail myself of this opportunity of mentioning what I conceive to be of great importance; and, as a further cautionary hint, I shall again digress so far as to add another observation on the subject of Inoculation. Whether it be yet ascertained by experiment, that the quantity of variolous matter inserted into the skin makes any difference with respect to the subsequent mildness or violence of the disease, I know not; but I have the strongest reason for supposing that is either the punctures or incisions be made so deep as to go _through_ it, and wound the adipose membrane, that the risk of bringing on a violent disease is greatly increased. I have known an inoculator, whose practice was "to cut deep enough (to use his own expression) to see a bit of fat," and there to lodge the matter. The great number of bad Cases, independent of inflammations and abscesses on the arms, and the fatality which attended this practice was almost inconceivable; and I cannot account for it on any other principle than that of the matter being placed in this situation instead of the skin. It was the practice of another, whom I well remember, to pinch up a small portion of the skin on the arms of his patients and to pass through it a needle, with a thread attached to it previously dipped in variolous matter. The thread was lodged in the perforated part, and consequently left in contact with the cellular membrane. This practice was attended with the same ill success as the former. Although it is very improbable that any one would now inoculate in this rude way by design, yet these observations may tend to place a double guard over the lancet, when infants, whose skins are comparatively so very thin, fall under the care of the inoculator. A very respectable friend of mine, Dr. Hardwicke, of Sodbury in this county, inoculated great numbers of patients previous to the introduction of the more modern method by Sutton, and with such success, that a fatal instance occurred as rarely as since that method has been adopted. It was the doctor's practice to make as slight an incision as possible _upon_ the skin, and there to lodge a thread saturated with the variolous matter. When his patients became indisposed, agreeably to the custom then prevailing, they were directed to go to bed and were kept moderately warm. Is it not probable then, that the success of the modern practice may depend more upon the method of invariably depositing the virus in or upon the skin, than on the subsequent treatment of the disease? I do not mean to insinuate that exposure to cool air, and suffering the patient to drink cold water when hot and thirsty, may not moderate the eruptive symptoms and lessen the number of pustules; yet, to repeat my former observation, I cannot account for the uninterrupted success, or nearly so, of one practitioner, and the wretched state of the patients under the care of another, where, in both instances, the general treatment did not differ essentially, without conceiving it to arise from the different modes of inserting the matter for the purpose of producing the disease. As it is not the identical matter inserted which is absorbed into the constitution, but that which is, by some peculiar process in the animal economy, generated by it, is it not probable that different parts of the human body may prepare or modify the virus differently? Although the skin, for example, adipose membrane, or mucous membranes are all capable of producing the variolous virus by the stimulus given by the particles originally deposited upon them, yet I am induced to conceive that each of these parts is capable of producing some variation in the qualities of the matter previous to its affecting the constitution. What else can constitute the difference between the Small-pox when communicated casually or in what has been termed the natural way, or when brought on artificially through the medium of the skin? After all, are the variolous particles, possessing their true specific and contagious principles, ever taken up and conveyed by the lymphatics unchanged into the blood vessels? I imagine not. Were this the case, should we not find the blood sufficiently loaded with them in some stages of the Small-pox to communicate the disease by inserting it under the cuticle, or by spreading it on the surface of an ulcer? Yet experiments have determined the impracticability of its being given in this way; although it has been proved that variolous matter when much diluted with water, and applied to the skin in the usual manner, will produce the disease. But it would be digressing beyond a proper boundary, to go minutely into this subject here. At what period the Cow-pox was first noticed here is not upon record. Our oldest farmers were not unacquainted with it in their earliest days, when it appeared among their farms without any deviation from the phænomena which it now exhibits. Its connection with the Small-pox seems to have been unknown to them. Probably the general introduction of inoculation first occasioned the discovery. Its rise in this country may not have been of very remote date, as the practice of milking cows might formerly have been in the hands of women only; which I believe is the case now in some other dairy countries, and, consequently that the cows might not in former times have been exposed to the contagious matter brought by the men servants from the heels of horses[4]. Indeed a knowledge of the source of the infection is new in the minds of most of the farmers in this neighbourhood, but it has at length produced good consequences; and it seems probable from the precautions they are now disposed to adopt, that the appearance of the Cow-pox here may either be entirely extinguished or become extremely rare. Should it be asked whether this investigation is a matter of mere curiosity, or whether it tends to any beneficial purpose? I should answer, that notwithstanding the happy effects of Inoculation, with all the improvements which the practice has received since its first introduction into this country, it not very unfrequently produces deformity of the skin, and sometimes, under the best management, proves fatal. These circumstances must naturally create in every instance some degree of painful solicitude for its consequences. But as I have never known fatal effects arise from the Cow-pox, even when impressed in the most unfavourable manner, producing extensive inflammations and suppurations on the hands; and as it clearly appears that this disease leaves the constitution in a state of perfect security from the infection of the Small-pox, may we not infer that a mode of Inoculation may be introduced preferable to that at present adopted, especially among those families, which, from previous circumstances we may judge to be predisposed to have the disease unfavourably? It is an excess in the number of pustules which we chiefly dread in the Small-pox; but, in the Cow-pox, no pustules appear, nor does it seem possible for the contagious matter to produce the disease from effluvia, or by any other means than contact, and that probably not simply between the virus and the cuticle; so that a single individual in a family might at any time receive it without the risk of infecting the rest, or of spreading a distemper that fills a country with terror. Several instances have come under my observation which justify the assertion that the disease cannot be propagated by effluvia. The first boy whom I inoculated with the matter of Cow-pox, slept in a bed, while the experiment was going forward, with two children who never had gone through either that disease or the Small-pox, without infecting either of them. A young woman who had the Cow-pox to a great extent, several sores which maturated having appeared on the hands and wrists, slept in the same bed with a fellow-dairy maid who never had been infected with either the Cow-pox or the Small-pox, but no indisposition followed. Another instance has occurred of a young woman on whose hands were several large suppurations from the Cow-pox, who was at the same time a daily nurse to an infant, but the complaint was not communicated to the child. In some other points of view, the inoculation of this disease appears preferable to the variolous inoculation. In constitutions predisposed to scrophula, how frequently we see the inoculated Small-pox, rouse into activity that distressful malady. This circumstance does not seem to depend on the manner in which the distemper has shewn itself, for it has as frequently happened among those who have had it mildly, as when it has appeared in the contrary way. There are many, who from some peculiarity in the habit resist the common effects of variolous matter inserted into the skin, and who are in consequence haunted through life with the distressing idea of being insecure from subsequent infection. A ready mode of dissipating anxiety originating from such a cause must now appear obvious. And, as we have seen that the constitution may at any time be made to feel the febrile attack of Cow-pox, might it not, in many chronic diseases be introduced into the system, with the probability of affording relief, upon well-known physiological principles? Although I say the system may at any time be made to feel the febrile attack of Cow-pox, yet I have a single instance before me where the virus acted locally only, but it is not in the least probable that the same person would resist the action both of the Cow-pox virus and the variolous. Elizabeth Sarsenet lived as a dairy maid at Newpark farm, in this parish. All the cows and the servants employed in milking had the Cow-pox; but this woman, though she had several sores upon her fingers, felt no tumors in the axillæ, nor any general indisposition. On being afterwards casually exposed to variolous infection, she had the Small-pox in a mild way.--Hannah Pick, another of the dairy maids who was a fellow-servant with Elizabeth Sarsenet when the distemper broke out at the farm was, at the same time infected; but this young woman had not only sores upon her hands, but felt herself also much indisposed for a day or two. After this, I made several attempts to give her the Small-pox by inoculation, but they all proved fruitless. From the former Case then we see that the animal economy is subject to the same laws in one disease as the other. The following Case which has very lately occurred renders it highly probable that not only the heels of the horse, but other parts of the body of that animal, are capable of generating the virus which produces the Cow-pox. An extensive inflammation of the erysipelatous kind, appeared without any apparent cause upon the upper part of the thigh of a sucking colt, the property of Mr. Millet, a farmer at Rockhampton, a village near Berkeley. The inflammation continued several weeks, and at length terminated in the formation of three or four small abscesses. The inflamed parts were fomented, and dressings were applied by some of the same persons who were employed in milking the cows. The number of cows milked was twenty-four, and the whole of them had the Cow-pox. The milkers, consisting of the farmer's wife, a man and a maid servant, were infected by the cows. The man servant had previously gone through the Small-pox, and felt but little of the Cow-pox. The servant maid had some years before been infected with the Cow-pox, and she also felt it now in a slight degree: But the farmer's wife who never had gone through either of these diseases, felt its effects very severely. That the disease produced upon the cows by the colt and from thence conveyed to those who milked them was the _true_ and not the _spurious_ Cow-pox[5], there can be scarcely any room for suspicion; yet it would have been more completely satisfactory, had the effects of variolous matter been ascertained on the farmer's wife, but there was a peculiarity in her situation which prevented my making the experiment. Thus far have I proceeded in an inquiry, founded, as it must appear, on the basis of experiment; in which, however, conjecture has been occasionally admitted in order to present to persons well situated for such discussions, objects for a more minute investigation. In the mean time I shall myself continue to prosecute this inquiry, encouraged by the hope of its becoming essentially beneficial to mankind. FINIS. [Footnote 1: It is very easy to procure pus from old sores on the heels of horses. This I have often inserted into scratches made with a lancet, on the sound nipples of cows, and have seen no other effects from it than simple inflammation.] [Footnote 2: See Case IX.] [Footnote 3: My friend Dr. Hicks, of Bristol, who during the prevalence of this distemper was resident at Gloucester, and Physician to the Hospital there, (where it was seen soon after its first appearance in this country) had opportunities of making numerous observations upon it, which it is his intention to communicate to the Public.] [Footnote 4: I have been informed from respectable authority that in Ireland, although dairies abound in many parts of the Island, the disease is entirely unknown. The reason seems obvious. The business of the dairy is conducted by women only. Were the meanest vassal among the men, employed there as a milker at a dairy, he would feel his situation unpleasant beyond all endurance.] [Footnote 5: See Note in Page 7.] _ERRATA._ Page 5, Line 4, after the word _shiverings_ insert _succeeded by heat_. Line 16, for _needlessly_ read _heedlessly_. ---- 24, Last line but one, for _sore_ read _tumour_. ---- 40, Line 12, for _Macklove_ read _Marklove_. ---- 41, Note--for _scepticus_ read _septicus_. ---- 60, Last line, for _moderate_ read _modern_. * * * * * Transcriber's note For this e-text, all the errors in the original book's "Errata" section have been corrected, as well as the following: Introductory letter: "C. H PARRY" corrected to "C. H. PARRY". Introduction: Inserted "to" after "But this disease is not". Case XX: "begining" corrected to "beginning". Conclusions: Added full-stop after "on the subject of Inoculation". The following archaic spellings of words were used in the original book and have been retained: head-ach; concuring; delinated. 
49319	----	[Decoration] AN ESSAY ON _Contagious Diseases_. [Decoration] AN ESSAY ON _Contagious Diseases_: More particularly On the _Small-Pox_, _Measles_, Putrid, Malignant, and Pestilential Fevers. By _Clifton Wintringham_. YORK: Printed by _Charles Bourne_ for _Francis Hildyard_, and are to be Sold by _W. Taylor_, at the Sign of the _Ship_ in _Pater-noster-Row_ LONDON, 1721. [Decoration] THE PREFACE. _The Design of this small Treatise being to deduce the Causes, and explain the_ Phoenomena _of some of the most Fatal Diseases which afflict Mankind, can stand in Need of no Excuse, whatever the_ _Performance it self may; and especially at a Time, when not only several of them Rage amongst us with uncommon Violence, but we are Daily threatned with the dreadful Calamity of a Raging Pestilence. I have endeavour'd to reduce these Diseases to the same Simplicity with Others, to speak Intelligibly of them, and show the real Changes in the Animal Oeconomy, from the Principles of the Modern Philosophy._ _The Learned Authors who have already wrote on this Subject, have rejected this Part of it, as being so easie and obvious as to need no Explanation. I doubt not indeed but this is their Case: But how easie soever it may be to explain these_ Phoenomena, _'tis not every one, conversant in the Practice of Physick, that will give himself the trouble to deduce them; and 'tis for such chiefly that this small Tract is designed; to_ _whom if it prove any way serviceable, I shall gain the End I proposed by it._ York, _June 1st_. 1721. [Illustration] ERRATA. Page 8. Line 20. before Contagion insert _a Pestilential_. Page 52. Line 17. read _Buboes_. [Illustration] OF _Contagious Diseases_. [Decoration] CHAP. I. _Contagious Diseases_ are generally defin'd by Physicians to be such, as are capable of being communicated to us by the Air, or the Effluvia of Morbid Bodies. When the Cause producing these Diseases is general, and not occasioned by the peculiar Qualities of particular Places, but brought from Abroad, they are stiled _Epidemic_. The Causes therefore of these Diseases must either be generated in the Air, or produced from the Effluvia of Animal, Vegetable, or Mineral Substances floating in it. And consequently the Effects of the Contagious Particles must be extreamly various, according to the Qualities of the Bodies from which they are produced. When any of these Causes is of so deleterious a Nature, as not only to be Infectious, but to destroy all or most of those that are affected by it, That Disease is called a Pestilence. But before I proceed to examine the particular Properties and Effects of the Contagious Particles, it will be Necessary to Demonstrate the following Propositions. PROP. I. The Magnitude of the Particles of the Blood being increased, Obstructions will be formed in the Ramifications of the smaller Vessels, which will happen sooner or later, in Proportion to the increased Magnitude of the Particles, and the smallness of the Vessels. _Demonstration._ [Illustration] Let the Canal A be an Artery of a middle Size, sending out the Branches C, D, E, F, G, H; Let the Dotts represent the increased _Moleculæ_ of the Blood, it is evident that these must be stopt some where or other in the Ramifications of the Vessels C, D, E, F, G, H, whenever the Diameters of the _Moleculæ_ exceed those of the containing Vessels. PROP. II. The Magnitude of the Particles of the Blood being increased, those Capillary Vessels nearest the Heart will be soonest obstructed, and _vice versa_; The rest in Proportion to the Velocity of the Blood, Diameters of the Canals, and their Distance from the Heart. _Demonstration._ This is sufficiently evident from the foregoing; For the sooner those _Moleculæ_ arrive at the Capillary Vessels, the sooner those Vessels will be obstructed, and _vice versa_, and consequently _cæteris paribus_ the Capillaries of the Branches C, H, in the preceeding Figure, which are nearest the Heart, will be sooner obstructed than those of E, F. PROP. III. The Magnitude of the Particles of the Blood must be increased either by the Union of a greater Number of them than in a Natural State; Or by the Alteration of their Figure, by which their Surfaces become larger than before. _Demonstration._ This is evident from the Observations of _Lewenhoeck_ and _Malpighius_ on the perspirable and other ultimate Vessels, which are visible by the Microscope, and consequently larger than the Orifices of the Lacteals, which the best Glasses will not discover. Whence it will follow, that no Particle can pass this way into the Blood, which single can obstruct the Vessels, and consequently this Effect can only be produced by the Action of the Particles upon each other, _viz._ either by the Union of a greater Number, or some Alteration in their Figures, whereby their Surfaces become larger than before. Thus the Globules of the Blood as appears by the Microscope, are nearly of a Spherical Figure, which being the most capacious, as well as most apt to constitute a Fluid Body, by touching in the fewest Points The farther any Particles deviate from this Figure, the more likely they will be to obstruct the Vessels, and _vice versa_. PROP. IV. The Contagious Particles being admitted into the Blood, do there coagulate its Parts, and form _Moleculæ_ of a larger Size than ordinary. _Demonstration_ The Force of the Heart and Cavities of the Canals being the same, when the Infection is first taken, as before, the Blood would pass with the same Facility thro' the Vessels as at other Times, and Obstructions could not be formed, were not the _Moleculæ_ thus increased; as our Senses show they are by the Eruption of Pustules in the Small-Pox, by the great Inflammations, Mortifications, Buboes, and Carbuncles in Malignant and Pestilential Fevers; and consequently the Contagious Particles do increase the Bulk of several of the constituent Parts of the Blood, by altering the Figures of its Particles, and forming _Moleculæ_ of a larger Size than in a Natural State. [Decoration] CHAP. II. It has been the constant Observation of Physicians, as well ancient as modern, and confirm'd by numerous Instances, that a hot and moist Constitution of the Air, joyn'd with southerly Winds, was generally a Fore-runner of malignant and Pestilential Fevers. Thus _Hippocrates_ observes, that the Constitution of the Air preceeding that malignant Fever describ'd in the 3d Book of his Epidemics, 'was calm, moist, and southerly, and succeeded a hot, and dry Season; the Winter, calm, cloudy, rainy, warm, southerly; some Showers, and Northerly Winds about the Equinox; the Spring, calm and southerly, with great Rains; the Summer very hot, with little Wind, and much Rain about the Dog-days[a]. Some Authors led by the Title of this Book of his Epidemics, _viz._ [Greek: Katastasis Loimôdês], or the Pestilential Constitution, have imagin'd the Diseases here spoken of, to be the same with that terrible Plague describ'd by _Thucydides_, which taking its Rise in _Æthiopia_, and passing thence thro' _Lybia_ and _Ægypt_, miserably harass'd all _Persia_, _Phoenicia_, _Judea_, _Greece_, and _Coele Syria_, and was one of the most dreadful Calamities of this kind that ever appeared in the World. But whosoever will give himself the Trouble to compare the Symptoms of the Fevers here described by _Hippocrates_, with those related by that accurate Historian[b], who both had it himself, and visited many others in it, will find that there is not the least Similitude between them. The one being highly infectious, and not the least Appearance of Contagion in the other: _Galen_ also the best Interpreter of _Hippocrates_, in his Comment on this Book of his Epidemic's suspects, this Title to be spurious, tho' both he and others observe much the same Constitution of the Air to be the Fore-runner of these Diseases. [a] _Hippoc._ Epidem. lib. 3. sect. 3. _Galeni_ Com. in hunc Loc. _Titi Lucret_, lib. 6. [b] _Thucydides_ lib. 2. [Sidenote: _What Places most Subject._] Pestilential and Malignant Fevers, are likewise observ'd to be the most frequent in those Places where the Climate is hot and scorching, and especially when Rains fall in such Seasons of the Year. Thus in _Ægypt_ and some other Parts of _Africa_, if Rains fall during the Months of _July_ and _August_, the Plague usually breaks out the _September_ following[c]. [c] _Joan. Leon._ Hist. _Afric._ lib. 1. cap. 10. _Purchas_ Pilgrim. lib. 6. cap. 17. _Athan._ _Kircheri Scrutin. Pestis_, pag. 179. This is still more remarkable in such Places, as not only are Situated in the forementioned Climate, but are likewise deprived of a constant Succession of pure and clear Air. An Instance of this we have in _Grand Caire_, which besides being subject to the common Disadvantages of the Country, (as are a Climate hot and scorching, a Situation low and flat, exposed chiefly to the warm Winds, their Water fetid and stagnating, being reserv'd in Vaults and Canals, which are Annually fill'd by the Overflowing of the River, the Air abounding with putrid Steams and Exhalations, arising from the Parts of Animals, Vegetables, and other Substances brought down and there deposited by the River), lies close under the Hill of the Castle, by which all Wind and Air is intercepted, which causes such a stifling Heat there, as ingenders many Diseases.[d] [d] _Therenot_'s Travels, Part. 1. pag. 128. That these may justly be esteem'd the Causes of the greater Frequency of these Diseases in this Place, than others in the same Climate, appears from their being so rarely known in those Places, which tho' equally hot, enjoy an Air free from Vapours.[e] Thus in _Numidia_ and some other Parts of _Africa_, the Plague is scarce to be found once in a hundred Years, and hardly at all in the Land of _Negroe_.[f] [e] _Piso_ Hist. _Ind._ & _Brasil_. [f] _Purchas_ Pilgrim. lib. 6. cap. 13. [Sidenote: _Several Causes of the Plague._] The other Observations of the Causes of these Fevers, may be reduced to such as arise from the Stinks of stagnating Waters in hot and close Weather, to some putrid Exhalations of the Earth, to the Parts of Animals and Vegetables putrifying in the open Air, or the taking of corrupt & unwholsome Nourishment. Of the first kind was that at _Selinis_, occasioned by the stinking Exhalations of the stagnating Waters adjacent, which the discerning _Empedocles_ removed by scouring its Ditches from their Filth, by a fresh Current of Water drawn from two Rivers in the neighbouring Country[g]. [g] _Plutarchi_ Lib. [Greek: peri polypragmosynês]. To the second Class may be reduced that Pestilential Fever, which the same great Philosopher check'd at _Agrigentum_, by stopping the Mouths of some neighbouring Mountains, whose pernicious Fumes had infected the adjacent Country[h]; As also that mentioned by _Ammianus_ _Marcellinus_, which broke out in _Seleucia_, and over-ran a great Part of _Greece_, _Italy_, and _Parthia_, and took its Rise from the opening of an old Vault in the Temple of _Apollo_. [h] _Diog. Laert._ in Vit. Emped. To the Third belong, such as are occasioned by the Parts of Vegetables and Animals, especially those of Men, putrifying in the open Air. As was that mention'd by _Livy_, which over-ran a great Part of _Italy_, and owed its Rise to the dead Bodies of the _Romans_ and _Fidenates_ left unburied in the Field of Battle[i]. Analogous to this was that which from the same Cause appeared in _Germany_, _Anno 1630_; And likewise that mentioned by _Ambrose Parree_ from the same Cause; as also that mentioned by _Diodorus Siculus_, occasioned by great Quantities of Locusts driven by Winds into the Sea, and thence cast up in Heaps on the Shore. To this likewise must be reduced those Malignant and Pestilential Fevers, which so frequently attend Camps and Seiges, especially in the hot Eastern Countries, whose numerous Armies frequently feel the dismal Effects of these stinking Fumes: As do likewise the vast Caravans of the _Mahometans_ in their Annual Pilgrimages to _Mecca_. [i] _Tit. Livii_ Hist. _Roman._ To the last belong those Pestilential Fevers, which take their Rise from a preceeding Famine, as was that in _Judea_ in the time of _Herod_[k], in which the Product of the Ground being consumed by the great Heat, and long Drought of the preceeding Summer, the poorest sort of People were obliged, thro' the Scarcity of Provisions, to make use of such Food as afforded unwholesome and putrifying Juices. [k] _Joseph_. Antiq. _Judæor_. lib. 15. cap. 12. [Decoration] CHAP. III. The Changes wrought in the Animal Oeconomy from the above-mention'd Causes, may be reduced to such as depend either on the Increased Heat of the Air join'd with its Humidity; Or to such as are produced from the particular Qualities of the putrid and Contagious Particles floating in it; Or to the united and complicated Effects of all together. [Sidenote: _Effects of a hot and moist Air._] The Alterations produced in the Body from a greater Heat continually surrounding it, provided it be not Excessive, are a Rarefaction of the Juices, and Relaxation of the _Fibres_ on the Surface of the Body, and greater Derivation of the Fluids that way. Whence proceeds a large Evacuation of the perspirable Matter. This being continued in a greater Proportion than in a Natural State, will gradually deprive the Blood of its Aqueous and Spirituous Parts, and leave the remaining serous Part more stock'd with acrid and pungent Salts, and the Gross, Terrestrious, Oleaginous, and Viscous Particles more firmly united by their nearer Approach, and stronger Cohesion to each other. This greater Heat or Quantity of Fiery Particles, continually surrounding the Body, will necessarily insinuate it self into, and unite with the Saline, Sulphureous, and other Particles, in the same manner as we see it does with other Substances, both Solid and Liquid[l]; And likewise by increasing the Velocity of the Circulation and Attrition of the Particles against each other, render them on these Accounts also more Volatile, Pungent and Stimulating, and consequently the Blood will consist of Particles more gross and inspissated or coagulated, and likewise of those of a more acrid and pungent Disposition than in a natural State. [l] _Boyl_'s Experm. Nov. de Pond, Ignis & Flam. _Newtoni_ Optic. Quæst. 21 & 22. The Blood being in this depraved Condition, the rest of the Animal Juices must degenerate in Proportion thereto, and the Nervous Fluid, as it consists of the most volatil and subtil Parts, be extreamly acrid and pungent, as well as unequal in its Texture and Fluidity, from the more viscous Parts contain'd in it. [Sidenote: _Putrid Fevers how produced._] This then being the State of the Blood and other juices of the Body, it is easy to perceive how from very Slight, and otherwise trivial Occasions, a Fever of a very Malignant Nature may be produced. Thus the perspirable Matter from a slight Cold taken being retained, or the Vessels any otherwise filled by Irregularities in Diet, or others of the Non-naturals, the Weight of the moving Fluid will be increased, and the Circulation be more languid and slow. Whence the intestine Motion of the Particles of the Blood being diminished, the viscous Parts will cohere more strongly and in greater Quantities than before, and obstruct the Capillary Arteries, especially in the Extremities, and a Coldness, Stretching, Yawning, Torpor, _&c._ necessarily succeed, the constant Attendants of a beginning Fever; All which will bear a Proportion to the Quantity retain'd, and the Viscosity of the moving Fluid. These Disorders will necessarily be increased on account of the Air's Spring being weakned by its Heat, the Vessels of the Lungs being less inflated, and the Globules of the Blood less broken and divided, and the more especially in a humid Air, Heat and Moisture necessarily relaxing the Tone of the Fibres and Vessels, and rendring them less Springy and Elastic. Hence then the Quantity of Spirits being diminish'd, and their Motion more slow, the Contraction of the Heart and other Muscles will be more weak and languid, and being stimulated by the Acrimony of the Circulating Liquors, must contract more frequently than in a Natural State; The Consequence of which is Weakness, Faintness, Thirst, and Dejection of Spirits. These and the preceeding Symptoms will necessarily continue, 'til such time as the gross and viscous Matter, being shook and loosen'd by the Action of the Capillary Vessels, is washed away into the Veins by the force of the Circulating Fluids, and there continues its Course with the rest, 'til it be either attenuated and secreted, or lodged again in the Capillaries to excite new Disorders. [Sidenote: _Malignant Fevers._] Now if to this evil Disposition of the Air be added a number of pungent stimulating Particles, whether bred in the Body or floating in the Air, and thereby communicated to the Blood, which are apt to coagulate the Animal Juices, so as to form _Moleculæ_ of such Shapes and Sizes as more firmly obstruct the Capillary Vessels, and at the same time stimulate and corrode the nervous Parts; It will necessarily happen, that the preceeding Symptoms must be highly exasperated, and a Fever of a much worse Nature produc'd. Hence then must follow a violent Hurry and Colluctation of the Fluids, the Viscid and coagulated Parts of the Blood in some Parts obstructing the Circulation of the Juices, and the Acrid, Volatil, and Fiery Parts, rarefying and dissolving others of the more Liquid, to the greatest degree of Pungency and Volatility imaginable. Hence it is easy to perceive how the Motion of the Blood must necessarily be in some Parts more languid, by the Cohesion of the more Viscous parts, in others quicker, join'd with a pungent and stimulating heat, from the increased Velocity and Acrimony of the moving Fluid, and the various Actions of the Particles upon each other, and their Impulses on the containing Vessels; As also how these are capable of almost infinite Variations, in Proportion to the different Quantities and Qualities of the constituent Particles. Hence then appears the Reason of that wandering and uncertain Heat and Coldness, in different Parts of the Body at the same time. Hence appears the Reason of that great Inquietude and Anxiety, of those uncertain and partial Sweats, Watchings, Tremors, stretching Pains of the head, and the like, as will be more fully shown hereafter. But before I proceed to explain the Nature of a Fever truly Pestilential, it will be necessary to observe, that notwithstanding the foremention'd putrid Disposition be generally a Prelude to a Pestilential Constitution of the Air, yet it has never that I know of been observ'd, that these Causes alone at their first Onset, produced a real Plague or Pestilential Contagion, without the Concurrence of some preceeding Infection, either brought from abroad, or gradually augmented from the increased Putrifaction of the Air, and Poisonous Steams of Morbid Bodies. Thus the putrid Air of Camps in hot Countries is frequently found to produce Pestilential Fevers, but this never happens at their first Onset; The Diseases first appearing being Fluxes, Putrid, and afterwards Malignant Fevers; which being exasperated and propagated by the Virulent Effluvia of Diseased Bodies, and the increased Putrifaction of the Air, grow up gradually to those of a Pestilential, and exceedingly infectious Disposition. [Sidenote: _Of Putrifaction & Fermentation._] Now Putrifaction being only a kind of Fermentation, wherein the Particles of a putrifying Body are put into an intestine Motion, and by their Action and Attrition broken and divided, and since all fermenting Substances do emit vast Quantities of small separable Parts, it will necessarily follow, that the most subtil and active Particles of the Purifying Body will be elevated into the Air, and float in it. [Sidenote: _Effluvia from putrified Bodies what._] These Effluvia consist of the finest and most volatil saline and oleaginous Particles, highly attenuated and set at Liberty from the gross Oil and Terrestrious Part, as appears from the Distillation of such Substances, all which afford great Quantities of a pungent and volatil Salt. It is likewise observable, that the subtil Oleaginous Particles being specifically lighter, as well as more easily attenuated and divided than those of a Saline Nature, will be thrown off in greater Proportion in the beginning of the Fermentation or Putrifaction than the heavier Salts will be, which must either be more attenuated and volatilised, or require a greater force to raise them into, and sustain them in the Air than the former, and consequently the greatest Emission of these saline Particles will be after the Fermentation has been for some time continued; As we find it happens in all fermenting Liquors, as Wine, Beer, Cyder, and the like. All which emit, during the Fermentation, greater Quantities of Particles of an active attenuated Oil or Spirit for some time, than of a Saline Nature, which requiring a longer time in order to attenuate them, are not raised till the former are in a manner quite exhaled, as appears from collecting the Steams of fermenting Liquors, and of those which are turn'd sower by Distillation, and consequently the Exhalations arising from putrifying Bodies will after some time consist mostly of Saline Particles highly attenuated and volatilised, and those not wrapt up and sheathed in the Oily ones, and thereby render'd innocuous, and often useful to the Body, but naked and exceedingly acrid and poignant. How unfit an Air stock'd with these kind of Particles is for Respiration, appears from several of Mr. _Boyl_'s Experiments on Animals, shut up with putrified Air in the Receiver, most of which with incredible Inquietude die sooner than in _Vacuo_, as also from the pernicious Effects of the Steams of Vaults, Mines, the _Grotto de Cane_, and such like. But besides this Inaptitude of such Air to expand the Pulmonary Vessels, these minute and pungent Particles may be considered as so many _Stimuli_ or Lancets, acting upon and penetrating the Coats of the Stomach, Lungs, and other Vessels. On which Account they are not only capable of creating great Disordes, as Inflamation, Pain, Sickness, Anxiety, Vomiting, _&c._ in the Stomach and Nervous Parts; But likewise being carried immediately into the Blood, will there stimulate the ultimate Vessels, ferment, dissolve, or coagulate the circulating Juices according to the particular Qualities and Quantity of the Contagious Particles. Nor is it unlikely, that from the various Action of the Particles upon each other, and their different Combinations in a stagnating Air, Particles may be formed of Qualities vastly differing from, and in their Force almost infinitely exceeding those of their Primogenial Salts and first Principles, as in Sublimate, some Preparations of Antimony, _&c._ Instances of which those versed in Chymistry are no Strangers to. [Sidenote: _Infectious Particles how produced._] Now supposing the Blood Saturated with these kind of Particles, and a Malignant Fever produced by their means, we all know that the Blood in this State throws off vast Quantities of subtil and active Particles thro' the Perspirable, Salival, and other Excretory Ducts of the Body, which not only must load the adjoining Air with great Quantities of them, and render it capable of producing more dismal Effects than the preceeding, but also the Particles thus thrown off must be endued with a more acrid and pungent Disposition than the former, inasmuch as they are more subtily divided and attenuated by the Force of the Fever, than those in the preceeding Disposition of the Air, where so powerful an Agent was wanting, And consequently produce a Fever of a most infectious and deleterious Nature; And especially when the Infection is taken toward the latter end of the Disease, at which time the Saline Particles will be more exalted and volatilised, as well as thrown off in greater Quantities, and thereby made more capable of producing an infectious Contagion. For the Blood in these Circumstances may not unaptly be compared, as was before hinted, to a fermenting Liquor, whose Parts being constantly in Motion, are continually throwing off great Quantities of subtil and active Spirits, capable of exciting the same Fermentation, and producing the same Qualities in those of the like Species, as appears from our manner of fermenting Ale, Beer, _&c._ with Yeast, which is a Spirituous Ferment, and also from the Sower Ferments used in making Vinegar, _&c._ Analogous to this we may observe, that the Blood in different Diseases, as well as different Animals, throws off great Quantities of active Particles, which when mixed with the Blood of a Healthful Person, are capable of exciting the same Fermentation and Disorder in the Animal Juices, with those of the Morbid Animal from which they exhale, as we find in the _Small-Pox_, _Measles_, _Saliva_ of a _Mad-dog_, and the like. This then being the Disposition of the Blood and other Juices, in those Fevers which we call Pestilential, it is evident, that whatever the particular Substance of the Contagious Particles may be, they must be endued with such Qualities as will Coagulate the Animal Juices, Stimulate the _Fibres_ to frequent Vibrations, cause Obstructions in the Capillary Vessels, and render the Blood and other Juices of the Body exceedingly Acrid and Pungent, as appears from hence and the foregoing Propositions; The Symptoms and Consequences (_cæteris paribus_) being the same, whether the Disease has gradually grown up to this Height, or took its Rise only from Contagious Particles brought from abroad. [Sidenote: _How propagated._] This is the Method by which I suppose these Contagious and Pestilential Particles to be first generated and produced, in those places which are most subject to them, and thence propagated first into the Neighbourhood, and afterwards to greater Distances by way of Intercourse and Commerce. The Pestilential _Effluvia_ being pack'd up and conveyed in Goods of a soft and loose Texture, as Silk, Wool, Cotton, and the like; And so much the more easily, as the Air into which these infested Materials are brought, is predisposed to act in full Concert with them; as happens in all Places at some times more than others; At which time if these infectious Particles be communicated, they exert their Rage with the utmost Violence, but frequently are either dissipated and lost, or produce Diseases of less fatal Consequence, in an opposite Disposition of the Air. [Sidenote: _Why the Plague ceases._] Thus hard Frost, strong cold and Northerly Winds, are found frequently to put an End to, or at least bridle the Fury of Contagious Diseases, and render them more mild and curable, as was observable in the Beginning of the last great Plague in _London_[m], and frequently taken Notice of in other places by the Writers on this Subject. Consonant to this we find in _Ægypt_, that the Rising of the _Nile_ by giving a fresh Motion to, and altering the Disposition of their stagnating and putrid Air, by the mild Vapours and Nitrous Exhalations[n] issuing from it, immediately checks the Raging of the Plague, and reduces it to a Fever of a more mild and curable Nature; insomuch that as _Purchas_ and others inform us, if there die in _Grand Caire_ 500 Persons of the Plague the Day before, yet upon the Increase of the River it ceases to be Pestilential, and none die of it[o]. And indeed it can hardly be imagin'd, how the Plague when it has once got establish'd in any Place, shou'd cease but with the Destruction of all or most of the Inhabitants, was it not checked by some Alteration in the Disposition of the Air, and gradually reduced to a Fever of a more mild and curable Disposition. [m] _Hodges_ de Peste. [n] _Boyle_'s determ. Nat. Effluv. cap. 4. _Plot_'s Nar. Hist. of _Staffordsh._ cap. 2. pag. 42. [o] _Purchas_ Pilgrim, lib. 6, cap. 7. _Sandy_'s Travels, lib. 2. cap. 97. It will I think be needless to show, that the Distempers here treated on are propagated by Contagion; But it may not be altogether unnecessary to explain by what Methods these Alterations in the Animal Oeconomy are brought about, and especially as the Means by which they are chiefly communicated, have not that I know of been fully examin'd. [Decoration] CHAP. IV. [Sidenote: _Of a Pestilence by Contagion._] The Contagious Particles whether they be generated in the Air, or produced by the _Effluvia_ of Morbid Bodies, being sustain'd in it, are thereby applied to the Surface of our Bodies, with a Force equal to the Pressure of the Incumbent Atmosphere. This Pressure upon the External Superficies of a human Body of a middle Size, has been demonstrated to be equal to 39900 Pounds Troy-weight, and consequently supposing the Body in every Part encompassed with these Particles, the whole Force with which all these Particles are on this Account propell'd into the Body, will amount to the aforesaid Sum. But every single Particle is only applied with the Force of a Column of Air of the Height of the Atmosphere, and whose Base is equal to the Surface of that Side of the intruding Particle, opposite to the cutting Angle. Now the Contagious Particles from their extream Smallness and pungent Angles, may not only be consider'd as Bodies applied to us with the preceeding Force, but likewise as so many small Knives or Lancets, acting upon and penetrating the Coats of the Lungs and Surface of our Bodies, with a Force proportional to the Smallness of their cutting Angles. This appears not only from several Propositions in Mechanics, but even to our Senses, by the strong Contraction of a Cord or Fiddle-string in moist Weather. The Particles of Water from their exceeding Smallness, being protruded into the Cord, with a Force capable of Raising the greatest Weights. Now if to these be likewise added the strong attractive force of these small Volatil Particles, occasioned from their Exiguity, it will be no difficult matter to conceive, that they are capable of penetrating the Vessels of our Bodies. Thus the Attractive Force of the Magnet is greater in Proportion to its Bulk, in Small ones, than in those of a larger Size, from the greater Proximity of all its Particles to each other. And 'tis on this Account that Sir _Isaac Newton_ computes the Attractive Force of the Particles of Light, to be to that of other Bodies, as 1000000000000000 to 1, in Proportion to the Quantity of Matter contained in them[p]. [p] Optic, in sine Quest. 22. This I think is sufficient to shew, that these Acrid and Pungent Particles are able to penetrate the Surface of our Bodies, and get into the Blood that way; And indeed Experience it self confirms it in all other Pungent and Acrid Substances, as _Garlic_, _Cantharides_, _Arsenic_, and all _Pungent_ and _Corroding_ Bodies. [Sidenote: _The Pressure of the Air on the Internal Surface of the Lungs in Breathing determined._] But tho' the whole Superficies of our Bodies are Penetrable by these Poisonous Particles, yet the principal Mischief is communicated to the Blood in its Passage thro' the Lungs. For considering the prodigious Number of the Pulmonary Vesicles, into all which the Air enters in Respiration, and likewise the vast Increase of their Surfaces on that Account, and also the greater Force by which these Particles are applied to the Internal Surfaces of the Vesicles in Expiration, in Proportion to that whereby they are applied to other Parts of the Body of equal Superficies; it will evidently appear, that the Contagion is chiefly communicated by these Vessels to the Blood. For it appears by the Barometer, that every Inch Square upon the Surface of our Bodies is pressed upon by a Weight nearly equal to 1800 Drams, when the Mercury stands highest in the Barometer. Now supposing with Dr. _Kiel_[q] that both the Lobes of our Lungs contain 226 solid Inches, of which only 1/3 or 75 Inches are Vesicles. Supposing also the Diameter of a Vesicle to be 1/50 Part of an Inch, the Surface of the Vesicle will be .001256 and the Solidity .0000043, by which if we divide 75 the Space fill'd by the Vesicles, the Quotient, _viz._ 17441860 X .001256 the Surface of a Vesicle, gives the Sum of the Surfaces of all the Vesicles, = 21906.976 square Inches. Which Sum being multiplied by 1800, the Number of Drams which every square Inch of the Surface of our Bodies sustains, gives the Weight which the whole Internal Surface of the Lungs sustains by the sole Pressure of the Atmosphere, when the Mercury stands highest in the Barometer, equal to 39442556.800 Drams, equal to 410859.966 + 64/96 lib. _Troy_ weight, as appears from the known Laws of _Hydrostaticks_[r]. [q] Animal Secret. [r] _Marriote_'s Hydrostaticks. 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. [s] _Kiel_'s Animal Secretion, _Edit. ult._ 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]. [s] _Ph. Col._ No. II. p. 17. 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. [t] _Boyl_'s Hist. Humani Sang. _Friend_'s Emonalogia in Fine. 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. [Decoration] 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_. [Sidenote: _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. [Sidenote: _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. [Sidenote: _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. [Sidenote: _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. [u] _Sydenham_ de Peste. [Sidenote: _Diarrhoea._] A _Diarrhoea_ 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. [Sidenote: _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. [Sidenote: _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_. [Sidenote: _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. [Sidenote: _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. [Sidenote: _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. [Sidenote: _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. [Sidenote: _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_. [Sidenote: _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. [Sidenote: _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. [Sidenote: _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. [Decoration] 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. [Illustration] THE APPENDIX. [Illustration] 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. [Illustration] 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._ 2_s._ 6_d._ 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_, 2_s._ 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_, 4_s._ 6_d._ Antiquities of _York-City_, and the Civil Government thereof, _&c._ to the Year 1720, 2_s._ 6_d._ 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_, 8_vo_. 1_s_. 6_d_. The Praise of _Yorkshire_ Ale, _&c._ to which is added a _Yorkshire_ Dialogue in its pure Natural Dialect. 1_s._ Transcriber Notes: Passages in italics were indicated by _underscores_. Small caps were replaced with ALL CAPS. Throughout the document, the oe ligature was replaced with "OE". Errors in punctuation, spelling, and hyphenation were not corrected unless otherwise noted. Many of the spellings look strange by modern standards, but then the rules for spelling changed since 1721. Footnotes were moved to after the paragraph they were referenced in. The footnote identifiers are the same as in the book, with the identifier "s" being used twice, On page 38, "Convnlsions" was replaced with "Convulsions".