Dissolving Illusions
A Continuation of Facts and Observations Relative to the Variolæ Vaccinæ, or Cow-Pox. (1800)

A CONTINUATION OF FACTS AND OBSERVATIONS RELATIVE TO THE VARIOLÆ VACCINÆ, OR
COW POX.
BY EDWARD JENNER, M.D. F.R.S. &c. 1800
SINCE my former publications on the vaccine inoculation I have had the satisfaction of seeing it extend very
widely. Not only in this country is the subject pursued with ardour, but from my correspondence with many
respectable medical gentlemen on the Continent (among whom are Dr. De Carro, of Vienna, and Dr. Ballhorn, ofHanover) I find it is as warmly adopted abroad, where it has afforded the greatest satisfaction. I have the pleasure,
too, of seeing that the feeble efforts of a few individuals to depreciate the new practice are sinking fast into contemptbeneath the immense mass of evidence which has arisen up in support of it.
Upwards of six thousand persons have now been inoculated with the virus of cow-pox, and the far greater part ofthem have since been inoculated with that of smallpox, and exposed to its infection in every rational way that could
be devised, without effect.
It was very improbable that the investigation of a disease so analogous to the smallpox should go forward without
engaging the attention of the physician of the Smallpox Hospital in London.
Accordingly, Dr. Woodville, who fills that department with so much respectability, took an early opportunity of
instituting an inquiry into the nature of the cow-pox. This inquiry was begun in the early part of the present year, andin May, Dr. Woodville published the result, which differs essentially from mine in a point of much importance. It
appears that three-fifths of the patients inoculated were affected with eruptions, for the most part so perfectly
resembling the smallpox as not to be distinguished from them. On this subject it is necessary that I should makesome comments.
When I consider that out of the great number of cases of casual inoculation immediately from cows which from time
to time presented themselves to my observation, and the many similar instances which have been communicated tome by medical gentlemen in this neighbourhood; when I consider, too, that the matter with which my inoculations
were conducted in the years 1797, 1798, and 1799, was taken from some different cows, and that in no instanceanything like a variolous pustule appeared, I cannot feel disposed to imagine that eruptions, similar to thosedescribed by Dr. Woodville, have ever been produced by the pure uncontaminated cow-pox virus; on the contrary, I
do suppose that those which the doctor speaks of originated in the action of variolous matter which crept into theconstitution with the vaccine. And this I presume happened from the inoculation of a great number of the patientswith variolous matter (some on the third, others on the fifth, day) after the vaccine had been applied; and it should beobserved that the matter thus propagated became the source of future inoculations in the hands of many medical
gentlemen who appeared to have been previously unacquainted with the nature of the cow-pox.
Another circumstance strongly, in my opinion, supporting this supposition is the following: The cow-pox has been
known among our dairies time immemorial. If pustules, then, like the variolous, were to follow the communicationof it from the cow to the milker, would not such a fact have been known and recorded at our farms? Yet neither our
farmers nor the medical people of the neighbourhood have noticed such an occurrence.
A few scattered pimples I have sometimes, though very rarely, seen, the greater part of which have generally
disappeared quickly, but some have remained long enough to suppurate at their apex. That local cuticularinflammation, whether springing up spontaneously or arising from the application of acrid substances, such for
instance, as cantharides, pix Burgundica, antimonium tartarizatum, etc., will often produce cutaneous affections, notonly near the seat of the inflammation, but on some parts of the skin far beyond its boundary, is a well-known fact. It
is, doubtless, on this principle that the inoculated cow-pox pustule and its concomitant efflorescence may, in very
irritable constitutions, produce this affection. The eruption I allude to has commonly appeared sometime in the third
week after inoculation. But this appearance is too trivial to excite the least regard.
The change which took place in the general appearance during the progress of the vaccine inoculation at the
Smallpox Hospital should likewise be considered.

1Dissolving Illusions
A Continuation of Facts and Observations Relative to the Variolæ Vaccinæ, or Cow-Pox. (1800)

Although at first it took on so much of the variolous character as to produce pustules in three cases out of five, yet in
Dr. Woodville’s last report, published in June, he says: “Since the publication of my reports of inoculations for the
cow-pox, upwards of three hundred cases have been under my care; and out of this number only thirty-nine hadpustules that suppurated; viz., out of the first hundred, nineteen had pustules; out of the second, thirteen; and out of
the last hundred and ten, only seven had pustules. Thus it appears that the disease has become considerably milder;which I am inclined to attribute to a greater caution used in the choice of the matter, with which the infection wascommunicated; for, lately, that which has been employed for this purpose has been taken only from those patients inwhom the cow-pox proved very mild and well characterized.”1
The inference I am induced to draw from these premises is very different. The decline, and, finally, the total
extinction nearly, of these pustules, in my opinion, are more fairly attributable to the cowpox virus, assimilating thevariolous,2 the former probably being the original, the latter the same disease under a peculiar, and at present an
inexplicable, modification.
One experiment tending to elucidate the point under discussion I had myself an opportunity of instituting. On the
supposition of its being possible that the cow which ranges over the fertile meadows in the vale of Gloucester might
generate a virus differing in some respects in its qualities from that produced by the animal artificially pampered forthe production of milk for the metropolis, I procured, during my residence there in the spring, some cow-pox virus
from a cow at one of the London milk-farms.3 It was immediately conveyed into Gloucestershire to Dr. Marshall,
who was then extensively engaged in the inoculation of the cow-pox, the general result of which, and of the
inoculation in particular with this matter, I shall lay before my reader in the following communication from thedoctor:“DEAR SIR:
“My neighbour, Mr. Hicks, having mentioned your wish to be informed of the progress of the inoculation here forthe cow-pox, and he also having taken the trouble to transmit to you my minutes of the cases which have fallen
under my care, I hope you will pardon the further trouble I now give you in stating the observations I have madeupon the subject. When first informed of it, having two children who had not had the smallpox, I determined toinoculate them for the cow-pox whenever I should be so fortunate as to procure matter proper for the purpose. I was,therefore, particularly happy when I was informed that I could procure matter from some of those whom you had
inoculated. In the first instance I had no intention of extending the disease further than my own family, but the very
extensive influence which the conviction of its efficacy in resisting the smallpox has had upon the minds of thepeople in general has rendered that intention nugatory, as you will perceive, by the continuation of my cases
enclosed in this letter,4 by which it will appear that since the 22d of March I have inoculated an hundred and sevenpersons; which, considering the retired situation I resided in, is a very great number. There are also otherconsiderations which, besides that of its influence in resisting the smallpox, appear to have had their weight; thepeculiar mildness of the disease, the known safety of it, and its not having in any instance prevented the patient fromfollowing his ordinary business. In all the cases under my care there have only occurred two or three which required
any application, owing to erysipelatous inflammation on the arm, and they immediately yielded to it. In theremainder the constitutional illness has been slight but sufficiently marked, and considerably less than I everobserved in the same number inoculated with the smallpox. In only one or two of the cases have any other eruptions
appeared than those around the spot where the matter was inserted, and those near the infected part. Neither does
there appear in the cow-pox to be the least exciting cause to any other disease, which in the smallpox has been1

In a few weeks after the cow-pox inoculation was introduced at the Smallpox Hospital I was favoured with some virus from thisstock. In the first instance it produced a few pustules, which did not maturate; but in the subsequent cases none appeared.—E. J.
2

In my first publication on this subject I expressed an opinion that the smallpox and the cow-pox were the same diseases under
different modifications. In this opinion Dr. Woodville has concurred. The axiom of the immortal Hunter, that two diseased
actions cannot take place at the same time in one and the same part, will not be injured by the admission of this theory.
3

It was taken by Mr. Tanner, then a student at the Veterinary College, from a cow at Mr. Clark’s farm at Kentish Town.

4

Doctor Marshall has detailed these cases with great accuracy, but their publication would now be deemed superfluous.—E. J.

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Dissolving Illusions
A Continuation of Facts and Observations Relative to the Variolæ Vaccinæ, or Cow-Pox. (1800)

frequently observed, the constitution remaining in as full health and vigour after the termination of the disease as
before the infection. Another important consideration appears to be the impossibility of the disease being
communicated except by the actual contact of the matter of the pustule, and consequently the perfect safety of theremaining part of the family, supposing only one or two should wish to be inoculated at the same time.
“Upon the whole, it appears evident to me that the cow-pox is a pleasanter, shorter, and infinitely more safe disease
than the inoculated smallpox when conducted in the most careful and approved manner; neither is the local affectionof the inoculated part, or the constitutional illness, near so violent. I speak with confidence on the subject, having
had an opportunity of observing its effects upon a variety of constitutions, from three months old to sixty years; andto which I have paid particular attention. In the cases alluded to here you will observe that the removal from theoriginal source of the matter had made no alteration or change in the nature or appearance of the disease, and that it
may be continued, ad infinitum (I imagine), from one person to another (if care be observed in taking the matter at aproper period) without any necessity of recurring to the original matter of the cow.
“I should be happy if any endeavours of mine could tend further to elucidate the subject, and shall be much gratified
in sending you any further observations I may be enabled to make.
“I have the pleasure to subscribe myself,“Dear sir, etc.,“JOSEPH H. MARSHALL.
“EASTINGTON, GLOUCESTERSHIRE, April 26, 1799.”
The gentleman who favoured me with the above account has continued to prosecute his inquiries with unremitting
industry, and has communicated the result in another letter, which at his request I lay before the public withoutabbreviation.
Dr. Marshall’s second letter:“DEAR SIR:
“Since the date of my former letter I have continued to inoculate with the cow-pox virus. Including the cases before
enumerated, the number now amounts to four hundred and twenty-three. It would be tedious and useless to detail the
progress of the disease in each individual—it is sufficient to observe that I noticed no deviation in any respect fromthe cases I formerly adduced. The general appearances of the arm exactly corresponded with the account given inyour first publication. When they were disposed to become troublesome by erysipelatous inflammation, an
application of equal parts of vinegar and water always answered the desired intention. I must not omit to inform youthat when the disease had duly acted upon the constitution I have frequently used the vitriolic acid. A portion of adrop applied with the head of a probe or any convenient utensil upon the pustule, suffered to remain about forty
seconds, and afterwards washed off with sponge and water, never failed to stop its progress and expedite theformation of a scab.
“I have already subjected two hundred and eleven of my patients to the action of variolous matter, but everyone
resisted it.
“The result of my experiments (which were made with every requisite caution) has fully convinced me that the true
cow-pox is a safe and infallible preventive from the smallpox; that in no case which has fallen under my observation
has it been in any considerable degree troublesome, much less have I seen anything like danger; for in no instancewere the patients prevented from following their ordinary employments.
“In Dr. Woodville’s publication on the cow-pox I notice an extraordinary fact. He says that the generality of hispatients had pustules. It certainly appears extremely extraordinary that in all my cases there never was but one
pustule, which appeared on a patient’s elbow on the inoculated arm, and maturated. It appeared exactly like that on
the incised part.

3

Dissolving Illusions
A Continuation of Facts and Observations Relative to the Variolæ Vaccinæ, or Cow-Pox. (1800)“The whole of my observations, founded as it appears on an extensive experience, leads me to these obvious
conclusions; that those cases which have been or may be adduced against the preventive powers of the cow-pox
could not have been those of the true kind, since it must appear to be absolutely impossible that I should havesucceeded in such a number of cases without a single exception if such a preventive power did not exist. I cannot
entertain a doubt that the inoculated cow-pox must quickly supersede that of the smallpox. If the many important
advantages which must result from the new practice are duly considered, we may reasonably infer that publicbenefit, the sure test of the real merit of discoveries, will render it generally extensive.
“To you, Sir, as the discoverer of this highly beneficial practice, mankind are under the highest obligations. As a
private individual I participate in the general feeling; more particularly as you have afforded me an opportunity ofnoticing the effects of a singular disease, and of viewing the progress of the most curious experiment that ever wasrecorded in the history of physiology.
“I remain, dear sir, etc.,“JOSEPH H. ARSHALL.”“P.S. I should have observed that, of the patients I inoculated and enumerated in my letter, one hundred and twentyseven were infected with the matter you sent me from the London cow. I discovered no dissimilarity of symptoms inthese cases from those which I inoculated from matter procured in this country. No pustules have occurred, except in
one or two cases, where a single one appeared on the inoculated arm. No difference was apparent in the local
inflammation. There was no suspension of ordinary employment among the labouring people, nor was any medicine
required.
“I have frequently inoculated one or two in a family, and the remaining part of it some weeks afterwards. The
uninfected have slept with the infected during the whole course of the disease without being affected; so that I am
fully convinced that the disease cannot be taken but by actual contact with the matter.
“A curious fact has lately fallen under my observation, on which I leave you to comment.
“I visited a patient with the confluent smallpox and charged a lancet with some of the matter. Two days afterwards I
was desired to inoculate a woman and four children with the cow-pox, and I inadvertently took the vaccine matteron the same lancet which was before charged with that of smallpox. In three days I discovered the mistake, and fully
expected that my five patients would be infected with smallpox; but I was agreeably surprised to find the disease tobe genuine cow-pox, which proceeded without deviating in any particular from my former cases. I afterwards
inoculated these patients with variolous matter, but all of them resisted its action.
“I omitted mentioning another great advantage that now occurs to me in the inoculated cow-pox; I mean the safetywith which pregnant women may have the disease communicated to them. I have inoculated a great number offemales in that situation, and never observed their cases to differ in any respect from those of my other patients.
Indeed, the disease is so mild that it seems as if it might at all times be communicated with the most perfect safety.”
I shall here take the opportunity of thanking Dr. Marshall and those other gentlemen who have obligingly presented
me with the result of their inoculations; but, as they all agree in the same point as that given in the above
communication, namely, the security of the patient from the effects of the smallpox after the cow-pox, their perusal,
I presume, would afford us no satisfaction that has not been amply given already. Particular occurrences I shall, ofcourse, detail. Some of my correspondents have mentioned the appearance of smallpox-like eruptions at thecommencement of their inoculations; but in these cases the matter was derived from the original stock at the
Smallpox Hospital.
I have myself inoculated a very considerable number from the matter produced by Dr. Marshall’s patients,
originating in the London cow, without observing pustules of any kind, and have dispersed it among others who
have used it with a similar effect. From this source Mr. H. Jenner informs me he has inoculated above an hundred
patients without observing eruptions. Whether the nature of the virus will undergo any change from being farther
removed from its original source in passing successively from one person to another time alone can determine. That
which I am now employing has been in use near eight months, and not the least change is perceptible in its mode of4

Dissolving Illusions
A Continuation of Facts and Observations Relative to the Variolæ Vaccinæ, or Cow-Pox. (1800)

action either locally or constitutionally. There is, therefore, every reason to expect that its effects will remain
unaltered and that we shall not be under the necessity of seeking fresh supplies from the cow.
The following observations were obligingly sent me by Mr. Tierny, Assistant Surgeon to the South Gloucester
Regiment of Militia, to whom I am indebted for a former report on this subject:“I inoculated with the cow-pox matter from the eleventh to the latter part of April, twenty-five persons, including
women and children. Some on the eleventh were inoculated with the matter Mr.Shrapnell (surgeon to the regiment)
had from you, the others with matter taken from these. The progress of the puncture was accurately observed, and its
appearance seemed to differ from the smallpox in having less inflammation around its basis on the first days—that
is, from the third to the seventh; but after this the inflammation increased, extending on the tenth or eleventh day to acircle of an inch and a half from its centre, and threatening very sore arms; but this I am happy to say was not thecase; for, by applying mercurial ointment to the inflamed part, which was repeated daily until the inflammation wentoff, the arm got well without any further application or trouble. The constitutional symptoms which appeared on theeighth or ninth day after inoculation scarcely deserved the name of disease, as they were so slight as to be scarcely
perceptible, except that I could connect a slight headache and languor, with a stiffness and rather painful sensation in
the axilla. This latter symptom was the most striking—it remained from twelve to forty-eight hours. In no case did I
observe the smallest pustule, or even discolouration of the skin, like an incipient pustule, except about the part wherethe virus has been applied.
“After all these symptoms had subsided and the arms were well, I inoculated four of this number with variolous
matter, taken from a patient in another regiment. In each of these it was inserted several times under the cuticle,
producing slight inflammation on the second or third day, and always disappearing before the fifth or sixth, except
in one who had the cow-pox in Gloucestershire before he joined us, and who also received it at this time byinoculation. In this man the puncture inflamed and his arm was much sorer than from the insertion of the cow-pox
virus; but there was no pain in the axilla, nor could any constitutional affection be observed.
“I have only to add that I am now fully satisfied of the efficacy of the cow-pox in preventing the appearance of thesmallpox, and that it is a most happy and salutary substitute for it.
I remain, etc.,“M. J. TIERNY.”
Although the susceptibility of the virus of the cow-pox is, for the most part, lost in those who have had the smallpox,
yet in some constitutions it is only partially destroyed, and in others it does not appear to be in the least diminished.
By far the greater number on whom trials were made resisted it entirely; yet I found some on whose arm the pustulefrom inoculation was formed completely, but without producing the common efflorescent blush around it, or any
constitutional illness, while others have had the disease in the most perfect manner. A case of the latter kind having
been presented to me by Mr. Fewster, Surgeon, of Thornbury, I shall insert it:“Three children were inoculated with the vaccine matter you obligingly sent me. On calling to look at their arms
three days after I was told that John Hodges, one of the three, had been inoculated with the smallpox when a year
old, and that he had a full burthen, of which his face produced plentiful marks, a circumstance I was not before madeacquainted with. On the sixth day the arm of the boy appeared as if inoculated with variolous matter, but the pustule
was rather more elevated. On the ninth day he complained of violent pain in his head and back, accompanied withvomiting and much fever. The next day he was very well and went to work as usual. The punctured part began tospread, and there was the areola around the inoculated part to a considerable extent.
“As this is contrary to an assertion made in the Medical and Physical Journal, No. 8, I thought it right to give you
this information, and remain,“Dear sir, etc.,“J. FEWSTER.”

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Dissolving Illusions
A Continuation of Facts and Observations Relative to the Variolæ Vaccinæ, or Cow-Pox. (1800)

It appears, then, that the animal economy with regard to the action of this virus is under the same laws as it is withrespect to the variolous virus, after previously feeling its influence, as far as comparisons can be made between thetwo diseases.
Some striking instances of the power of the cow-pox in suspending the progress of the smallpox after the patients
had been several days casually exposed to the infection have been laid before me by Mr. Lyford, Surgeon, of
Winchester, and my nephew, the Rev. G. C. Jenner. Mr. Lyford, after giving an account of his extensive andsuccessful practice in the vaccine inoculation in Hampshire, writes as follows:“The following case occurred to me a short time since, and may probably be worth your notice. I was sent for to apatient with the smallpox, and on inquiry found that five days previous to my seeing him the eruption began toappear. During the whole of this time two children who had not had the smallpox, were constantly in the room with
their father, and frequently on the bed with him. The mother consulted me on the propriety of inoculating them, but
objected to my taking the matter from their father, as he was subject to erysipelas. I advised her by all means to havethem inoculated at that time, as I could not procure any variolous matter elsewhere. However, they were inoculatedwith vaccine matter, but I cannot say I flattered myself with its proving successful, as they had previously been solong and still continued to be exposed to the variolous infection. Notwithstanding this I was agreeably surprised tofind the vaccine disease advance and go through its regular course; and, if I may be allowed the expression, to thetotal extinction of the smallpox.”
Mr. Jenner’s cases were not less satisfactory. He writes as follows:“A son of Thomas Stinchcomb, of Woodford, near Berkeley, was infected with the natural smallpox at Bristol, andcame home to his father’s cottage. Four days after the eruptions had appeared upon the boy, the family (none ofwhich had ever had the smallpox), consisting of the father, mother, and five children, was inoculated with vaccine
virus. On the arm of the mother it failed to produce the least effect, and she, of course, had the smallpox, 5 but therest of the family had the cow-pox in the usual way, and were not affected with the smallpox, although they were in
the same room, and the children slept in the same bed with their brother who was confined to it with the natural
smallpox; and subsequently with their mother.
“I attended this family with my brother, Mr. H. Jenner.”
The following cases are of too singular a nature to remain unnoticed.
Miss R——, a young lady about five years old, was seized on the evening of the eighth day after inoculation withvaccine virus, with such symptoms as commonly denote the accession of violent fever. Her throat was also a little
sore, and there were some uneasy sensations about the muscles of the neck. The day following a rash wasperceptible on her face and neck, so much resembling the efflorescence of the scarlatina anginosa that I was induced
to ask whether Miss R——had been exposed to the contagion of that disease. An answer in the affirmative, and therapid spreading of the redness over the skin, at once relieved me from much anxiety respecting the nature of themalady, which went through its course in the ordinary way, but not without symptoms which were alarming both tomyself and Mr. Lyford, who attended with me. There was no apparent deviation in the ordinary progress of thepustule to a state of maturity from what we see in general; yet there was a total suspension of the areola or florid
discolouration around it, until the scarlatina had retired from the constitution. As soon as the patient was freed fromthis disease this appearance advanced in the usual way.6
The case of Miss H—— R—— is not less interesting than that of her sister, above related. She was exposed to thecontagion of the scarlatina at the same time, and sickened almost at the same hour. The symptoms continued severe
about twelve hours, when the scarlatina-rash shewed itself faintly upon her face, and partly upon her neck. After
5

Under similar circumstances I think it would be advisable to insert the matter into each arm, which would be more likely toinsure the success of the operation.—E. J.
6

I witnessed a similar fact in a case of measles. The pustule from the cow-pox virus advanced to maturity, while the measles
existed in the constitution, but no efflorescence appeared around it until the measles had ceased to exert its influence.

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Dissolving Illusions
A Continuation of Facts and Observations Relative to the Variolæ Vaccinæ, or Cow-Pox. (1800)

remaining two or three hours it suddenly disappeared, and she became perfectly free from every complaint. My
surprise at this sudden transition from extreme sickness to health in great measure ceased when I observed that theinoculated pustule had occasioned, in this case, the common efflorescent appearance around it, and that as it
approached the centre it was nearly in an erysipelatous state. But the most remarkable part of this history is that, on
the fourth day afterwards, so soon as the efflorescence began to die away upon the arm and the pustule to dry up, thescarlatina again appeared, her throat became sore, the rash spread all over her. She went fairly through the disease
with its common symptoms.
That these were actually cases of scarlatina was rendered certain by two servants in the family falling ill at the sametime with the distemper, who had been exposed to the infection with the young ladies.
Some there are who suppose the security from the smallpox obtained through the cow-pox will be of a temporary
nature only. This supposition is refuted not only by analogy with respect to the habits of diseases of a similar nature,but by incontrovertible facts, which appear in great numbers against it. To those already adduced in the former partof my first treatise7 many more might be adduced were it deemed necessary; but among the cases I refer to, one will
be found of a person who had the cow-pox fifty-three years before the effect of the smallpox was tried upon him. As
he completely resisted it, the intervening period I conceive must necessarily satisfy any reasonable mind. Should
further evidence be thought necessary, I shall observe that, among the cases presented to me by Mr. Fry, Mr. Darke,
Mr. Tierny, Mr. H. Jenner, and others, there were many whom they inoculated ineffectually with variolous matter,
who had gone through the cow-pox many years before this trial was made.
It has been imagined that the cow-pox is capable of being communicated from one person to another by effluvia
without the intervention of inoculation. My experiments, made with the design of ascertaining this important point,
all tend to establish my original position, that it is not infectious except by contact. I have never hesitated to suffer
those on whose arms there were pustules exhaling the effluvia from associating or even sleeping with others who
never had experienced either the cow-pox or the smallpox. And, further, I have repeatedly, among children, caused
the uninfected to breathe over the inoculated vaccine pustules during their whole progress, yet these experiments
were tried without the least effect. However, to submit a matter so important to a still further scrutiny, I desired Mr.
H. Jenner to make any further experiments which might strike him as most likely to establish or refute what had
been advanced on this subject. He has since informed me that he inoculated children at the breast, whose mothers
had not gone through either the smallpox or the cow-pox; that he had inoculated mothers whose sucking infants
have never undergone either of these diseases; that the effluvia from the inoculated pustules, in either case, had been
inhaled from day to day during the whole progress of their maturation, and that there was not the least perceptible
effect from these exposures. One woman he inoculated about a week previous to her accouchement, that her infant
might be the more fully and conveniently exposed to the pustule; but, as in the former instances, no infection wasgiven, although the child frequently slept on the arm of its mother with its nostrils and mouth exposed to the pustulein the fullest state of maturity. In a word, is it not impossible for the cow-pox, whose only manifestation appears toconsist in the pustules created by contact, to produce itself by effluvia?
In the course of a late inoculation I observed an appearance which it may be proper here to relate. The punctured
part on a boy’s arm (who was inoculated with fresh limpid virus) on the sixth day, instead of shewing a beginning
vesicle, which is usual in the cow-pox at that period, was encrusted over with a rugged, amber-coloured scab. The
scab continued to spread and increase in thickness for some days, when, at its edges, a vesicated ring appeared, andthe disease went through its ordinary course, the boy having had soreness in the axilla and some slight indisposition.
With the fluid matter taken from his arm five persons were inoculated. In one it took no effect. In another it
produced a perfect pustule without any deviation from the common appearance; but in the other three the progress of
the inflammation was exactly similar to the instance which afforded the virus for their inoculation; there was acreeping scab of a loose texture, and subsequently the formation of limpid fluid at its edges. As these people were all
employed in laborious exercises, it is possible that these anomalous appearances might owe their origin to thefriction of the clothes on the newly inflamed part of the arm. I have not yet had an opportunity of exposing them tothe smallpox.
7

See pages 206, 207, 208, 209, 210, etc.

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A Continuation of Facts and Observations Relative to the Variolæ Vaccinæ, or Cow-Pox. (1800)

In the early part of this inquiry I felt far more anxious respecting the inflammation of the inoculated arm than atpresent; yet that this affection will go on to a greater extent than could be wished is a circumstance sometimes to be
expected. As this can be checked, or even entirely subdued, by very simple means, I see no reason why the patient
should feel an uneasy hour because an application may not be absolutely necessary. About the tenth or eleventh day,
if the pustule has proceeded regularly, the appearance of the arm will almost to a certainty indicate whether this is to
be expected or not. Should it happen, nothing more need be done than to apply a single drop of the aqua lythargyri
acetati8 upon the pustule, and, having suffered it to remain two or three minutes, to cover the efflorescencesurrounding the pustule with a piece of linen dipped in the aqua lythargyri compos. 9 The former may be repeated
twice or thrice during the day, the latter as often as it may feel agreeable to the patient.
When the scab is prematurely rubbed off (a circumstance not unfrequent among children and working people), theapplication of a little aqua lythargyri acet. to the part immediately coagulates the surface, which supplies its place,and prevents a sore.
In my former treatises on this subject I have remarked that the human constitution frequently retains its
susceptibility to the smallpox contagion (both from effluvia and contact) after previously feeling its influence. In
further corroboration of this declaration many facts have been communicated to me by various correspondents. I
shall select one of them.
“DEAR SIR:
“Society at large must, I think, feel much indebted to you for your Inquiries and Observations on the Nature andEffects of the Variolæ Vaccinæ, etc., etc. As I conceive what I am now about to communicate to be of some
importance, I imagine it cannot be uninteresting to you, especially as it will serve to corroborate your assertion of
the susceptibility of the human system of the variolous contagion, although it has previously been made sensible ofits action. In November, 1793, I was desired to inoculate a person with the smallpox. I took the variolous matterfrom a child under the disease in the natural way, who had a large burthen of distinct pustules. The mother of thechild being desirous of seeing my method of communicating the disease by inoculation, after having opened apustule, I introduced the point of my lancet in the usual way on the back part of my own hand, and thought no moreof it until I felt a sensation in the part which reminded me of the transaction. This happened upon the third day; on
the fourth there were all the appearances common to inoculation, at which I was not at all surprised, nor did I feelmyself uneasy upon perceiving the inflammation continue to increase to the sixth and seventh day, accompaniedwith a very small quantity of fluid, repeated experiments having taught me it might happen so with persons who had
undergone the disease, and yet would escape any constitutional affection; but I was not so fortunate; for on theeighth day I was seized with all the symptoms of the eruptive fever, but in a much more violent degree than when I
was before inoculated, which was about eighteen years previous to this, when I had a considerable number ofpustules. I must confess I was now greatly alarmed, although I had been much engaged in the smallpox, having atdifferent times inoculated not less than two thousand persons. I was convinced my present indisposition proceededfrom the insertion of the variolous matter, and, therefore, anxiously looked for an eruption. On the tenth day I felt avery unpleasant sensation of stillness and heat on each side of my face near my ear, and the fever began to decline.
The affection in my face soon terminated in three or four pustules attended with inflammation, but which did not
maturate, and I was presently well.
“I remain, dard sir, etc.,“THOMAS ILES.”This inquiry is not now so much in its infancy as to restrain me from speaking more positively than formerly on theimportant point of scrophula as connected with the smallpox.

8Extract of Saturn.

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Goulard water. For further information on this subject see the first Treatise on the Var. Vac., Dr. Marshall’s letters, etc.

8Dissolving Illusions
A Continuation of Facts and Observations Relative to the Variolæ Vaccinæ, or Cow-Pox. (1800)

Every practitioner in medicine who has extensively inoculated with the smallpox, or has attended many of those
who have had the distemper in the natural way, must acknowledge that he has frequently seen scrophulous
affections, in some form or another, sometimes rather quickly shewing themselves after the recovery of the patients.
Conceiving this fact to be admitted, as I presume it must be by all who have carefully attended to the subject, may I
not ask whether it does not appear probable that the general introduction of the smallpox into Europe has not beenamong the most conductive means in exciting that formidable foe to health? Having attentively watched the effectsof the cow-pox in this respect, I am happy in being able to declare that the disease does not appear to have the least
tendency to produce this destructive malady.
The scepticism that appeared, even among the most enlightened of medical men when my sentiments on theimportant subject of the cow-pox were first promulgated, was highly laudable. To have admitted the truth of adoctrine, at once so novel and so unlike any thing that ever had appeared in the annals of medicine, without the testof the most rigid scrutiny, would have bordered upon temerity; but now, when that scrutiny has taken place, not only
among ourselves, but in the first professional circles in Europe, and when it has been uniformly found in suchabundant instances that the human frame, when once it has felt the influence of the genuine cow-pox in the way thathas been described, is never afterwards at any period of its existence assailable by the smallpox, may I not withperfect confidence congratulate my country and society at large on their beholding, in the mild form of the cow-pox,
an antidote that is capable of extirpating from the earth a disease which is every hour devouring its victims; a disease
that has ever been considered as the severest scourge of the human race!

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