A
SEMI-ANNUAL
ORATION,
ON THE
ORIGIN OF PESTILENTIAL DISEASES,
DELIVERED BEFORE
THE ACADEMY OF MEDICINE OF PHILADELPHIA,
On the 17th day of December, 1798.
By CHARLES CALDWELL, A. M. M. D.
Senior Vice-President of the Academy.
PHILADELPHIA : 
Printed by THOMAS and SAMUEL F. BRADFORD, No. 8.
South Front Street.
1799.

 
 

EXTRACT FROM THE MINUTES OF 
THE ACADEMY OF MEDICINE.
December 17th, 1798.
" RESOLVED, that the thanks of the Academy be
" presented to DR. CHARLES CALDWELL, for his learned, ele-
" gant, and ingenious discourse, upon the origin of pestilen-
" tial diseases, delivered before the Academy this day."
" RESOLVED, that DR. CALDWELL be requested
" to furnish a copy of it for immediate publication."
JOHN C. OTTO, Sec'ry.

 
 

To THE PRESIDENT AND MEMBERS OF THE 
ACADEMY OF MEDICINE OF PHILADELPHIA.
GENTLEMEN,
PURSUANT to your special appointment, was the following
oration prepared and delivered, and in compliance with your
express order, is it now introduced to the notice of the pub-
lic. In this state of things, it presents, on your attention
and patronage, that claim, which, I am confident, none of
you will be reluctant to allow. Accept it, as an humble,
but well meant offering, from your friend, and
Fellow-member,
THE AUTHOR.
Philadelphia, January 27th, 1799. 

 
 

INTRODUCTION.
THAT the following oration may lead to no miscon-
ception of the opinion I entertain, respecting the actual
origin of our late epidemics, I beg leave to introduce it to
the notice of my fellow-citizens, by a few preliminary re-
marks.
I. I do not believe that, either, in the years ninety three,
ninety seven, or ninety eight, the American pestilence was
exclusively of domestic origin. I am persuaded that, on
each of those occasions, a very powerful cause of this dis-
ease, was introduced into Philadelphia, through the channel
of commerce. I do not, however, with some physicians,
conceive, that this cause was introduced in the form of
human contagion, generated in the diseased bodies of men,
but in that of foul air, resulting from the putrid ballast, or
damaged cargoes of vessels. Nor have I, on enquiry, found
reason to believe, that there exists, on record, a single well
authenticated instance, of the disease in question, having,
ever, in the former method, been introduced into any part 

viii INTRODUCTION.
of the United States. As often as commerce has borne a
part in giving birth to this disease, in any of our seaports,
it does not appear to have been through the instrumentality
of human contagion, imported from the East or West Indies,
from the Levant, or the shores of Africa ; but, as lately
in this place, through that of pestiferous air, generated by
the putrefactive dissolution of the cargoes or ballast of ves-
sels at sea. Nor is it a matter of the smallest import, from
what quarter of the globe these cargoes come. Provided,
they be of a putrefiable nature, and arrive in our ports,
during the intensity of our summer heats, (but, particularly,
between the middle of July and last of September,) it is
wholly immaterial whether they be the native productions
of Europe, of Asia, of Africa, or of the West India Islands.
And it is equally immaterial, from which of those places
they are immediately imported. The suspension, therefore,
of commercial intercourse, during certain months in the
year, with the West India Islands alone, would be a mea-
sure wholly inadequate to the prevention of this disease.
Were such suspension adopted by the Government of the
Union, it should, unquestionably, extend to all parts of the
globe, from which putrefiable cargoes may be imported.
But such an impolitic measure, suggests at once sufficient
cause for its immediate rejection, as it is evidently pregnant
with nothing less than absolute ruin to the commerce of
our country.
II. I have not found sufficient cause to believe, that,
without the co-operation of foul air, from the vessels at our
wharves, the American pestilence would have become

INTRODUCTION. ix
epidemic, in our city, in either of the years, to which I have
alluded. I have even gone so far as to flatter myself, with
a belief, that, in the present state of our city, such co-ope-
ration is absolutely necessary to its epidemic prevalence.
In this belief, however, I am, by no means, confirmed.
Perhaps, even now, the filth of our city and suburbs has
accumulated to a sufficient height, to give to pestilence an
epidemic rage. In ninety three, I had not completed my
medical studies, and can, therefore, say nothing respecting
the immediate source of particular cases, that might have
occurred in the city during that year. But I hesitate not
to say, with as much confidence, as I ought to use, in
speaking on any speculative subject in physics, that, in
ninety seven and ninety eight, I saw, myself, several cases
of the disease in question, which must have necessarily re-
sulted from the operation of domestic causes. I am further
confident, that many cases of a similar nature, were attend-
ed by some of my medical friends. If, then, from the pre-
sent sources of our city, solitary, or (to speak in medical
language) sporadic cases of pestilence may now occur, how
melancholy is our prospect, should the filth in our city and
suburbs, be suffered to accumulate with the progress of
time! Of such an accumulation must not an epidemic be
finally the offspring?
But let us, even, for a moment, admit, that not a single
case of the epidemics of ninety three, ninety seven, or nine-
ty eight, originated from the exclusive operation of domes-
tic causes. Still, it is a position, which no one will venture
A 

x INTRODUCTION.
to deny, that their rapid and extensive propagation, was ef-
fected by some peculiarity in the atmosphere of our city.
This inference we draw from the very few instances, in
which, the pestilence, under consideration, was propagated
by contagion when taken from the city to the unadulter-
ated atmosphere of the country.
Were the atmosphere of Philadelphia preserved in purity,
by a due degree of attention to domestic cleanliness, and
by preventing vessels, charged with foul air, from entering
our port, pestilence, as an epidemic, would never again
occur, to swell the catalogue of our future misfortunes.—
In such a state of things, sporadic cases of the disease
might, possibly, originate with ourselves, and might, un-
questionably, be introduced from distant places ; but the
evil would terminate with the death or recovery of those
first attacked, and would never spread, to the distress of our
citizens, and the depopulation of our city. The baleful
plant, though fairly ingrafted on our systems, would lan-
gnish, wither, and die for want of nourishment!
III. Thus, whatever principles, I may advocate, with
respect to the practicability of pestilence originating and
existing, as an epidemic, in our city, under certain circum-
stances, from the exclusive operation of domestic causes, I
believe this to be an event, which has never yet occurred.
Commerce appears to have been, at all times, justly charge-
able with part of the calamity, that has never failed, to
accompany this worst of evils. The epidemic train would 
seem to have been, always, laid in our atmosphere, by the ac-

INTRODUCTION. xi
tion of the summer-fun on the filth of our city and suburbs,
while immense volumes of foul air, discharged from the
holds of vessels at our wharves, served as the spark to rouse
it into flame. Had not the train existed, the spark would
have expired without effect, and had not the spark been
applied, the train would have lain dormant, and, perhaps
never burst into actual explosion—If, then, by the destruc-
tion of either of these, we might acquire an exemption
from the inevitable effects of their co-operation, by the re-
moval of the one, and the prevention of the other, we be-
come doubly secure against the calamities, to which they
give origin.
I hope I will be indulged in attempting, by another ana-
logy, a farther illustration of the above intricate and inter-
esting subject. With this view, I would compare the sum-
mer atmosphere of our city, deeply contaminated by putrid ex-
halations from domestic sources, to a mass of paste or dough,
duly kneaded, and prepared to undergo the process of fermen-
tation. In this state of things, the yeast, or leven, calculated
and intended to give actual birth to this process, not unfit-
ly represents the foul air issuing from the holds of vessels
at our wharves, and mixing, in abundance, with our viti-
ated atmosphere. As the operation of the ferment is well
known to be, that of assimilating to itself, the mass into
which it is introduced, such would seem to be the effect of
the deleterious air discharged along our wharves. It com-
municates to the atmosphere of our city, perhaps, by a
peculiar species of fermentation, its own pestilential and

xii INTRODUCTION.
destructive properties. Or, like the matter of the small-
pox, introduced into a system predisposed to its reception,
it inoculates our atmosphere with effect, and thus, possibly,
by an indescribable species of sympathetic action, approxi-
mates to its own nature, the air that surrounds us.
If we pay due attention to all the branches of domestic
cleanliness, and keep soul vessels at a distance from our
wharves, war may rage in the West-Indies,* till the passions
of man begin to languish, and the ambition of nations be-
come exhausted, and the yellow-fever may there spread de-
solation from island to island, yet, still, amid this deplora-
ble wreck and confusion, will our city remain exempt from
an epidemic pestilence! Whereas, on the other hand, if
these requisites be not attended to,—if our city and sub-
urbs be suffered to continue immersed in their present filth,
and vessels be allowed to disembogue their pestilential va-
pours along our wharves, though the West Indies should be
converted into an Eden of peace, fragrance, and healthful-
ness, and though the seeds of pestilence, should be, for ever,
blasted along the shores of Asia, and Africa, yet still, will
Philadelphia—hapless Philadelphia, remain subject to a rei-
teration of the melancholy scenes of ninety three, ninety
seven, and ninety eight!
* Of all the explications, which have been hitherto given for the existence
of our late epidemics, none has appeared to me, so completely the child of
fancy, as that, which attributes it to the prevalence of war in the West
Indies. For my own part, I must confess, I am not able to discover
any more necessary physical connection between war in the West Indies, 
and pestilence in America, than between coach-making in Philadelphia,
and button-making in London! 

A
SEMI-ANNUAL
ORATION, &c.
MR. PRESIDENT AND GENTLEMEN,
IN rising to address you on the present occasion,
my feelings impel me to a two-fold acknowledgment— An
acknowledgment for the unexpected honour, with which I
have been distinguished, in your appointing me to prepare
and deliver the first of the semiannual addresses enjoined by
our constitution ; and a most cordial acknowledgment for
the liberal indulgence, which I experienced from you, on a
former occasion, when indisposition interfered, and, by frus-
trating my attempt to comply with my engagement, dis-
appointed, for the time, the expectations of the Academy.
Would that I could suffer my exordium to terminate here!
But circumstances forbid that this should be the case. The
pleasure of acknowledgment I must now exchange for the 
task of apology.
A 

14
In behalf of the following performance, I would address my-
self, not to that rigid, unaccommodating justice in criticism,
which I have reason to believe most of you have at com-
mand, but to that forbearance and clemency, of which, I,
am well assured, you are all possessed. I must solicit you
to extend to the subsequent oration, some share of that par-
tiality, with which, on various occasions, you have honour-
ed the Orator. Let me not be disappointed in shattering
myself, that the usual benevolence of your natures will
throw, at least, some shadow of palliation over such faults
as the clearness of your understandings will inevitably dis-
cover, and the justness of your sentiments oblige you to
condemn.
Suffer it to operate in mitigation of your impending sen-
tence, when I assure you, that the following address was
prepared amid numerous avocations, of a nature more than
usually unfavourable to success in composition. But satis-
fied that I have more—much more, to expect from the in-
genuous liberality of your minds, than from the humble me-
rit of my own defence, I will no longer address you in the
language of apology. Part of the imperfections of the ora-
tion I am about to deliver, arise no less from want of abilities,
than from want of leisure. A portion of the censure must,
therefore, in justice,rest on yourselves, for not having bees
more circumspect in your choice of an orator.
It was my intention to have paid in this place, a passing tri-
bute to the memory of our two deceased friends and fellow-
members, Dr. Sayre and Dr. Cooper. I had even prepared 

15
myself for the discharge of this mournful duty. Impressed
by respect for the talents and learning, and by sentiments
of esteem and friendship for the numerous virtues of those
two medical philosophers, I was unwilling to neglect so
fair an opportunity of expressing my sense of their distin-
guished worth. Being superceded however, in this duty, by
a very judicious and respectful appointment of the Academy,
for the express purpose of doing justice to their memories,
I shall pass in silence over the melancholy subject. But
when the name of Cooper, in particular, is mentioned, to
suffer oblivious silence to usurp the place of descriptive and
just eulogium, is, with me, no inconsiderable effort of self-
restraint. On such an occasion my feelings would prompt
me to a far different conduct. As I have ever ranked the
acquisition of the friendship of this gentleman among the
most fortunate occurrences of my life, it will not be
thought strange, that I should feel an inclination to contri-
bute my mite to the immense treasure of respect, which his
numerous acquaintance will pay to his memory. But an
indulgence of my feelings on this occasion, would lead to
an unwarrantable digression from what I propose as the im-
mediate subject of my address.
Instead of attempting, therefore, to cherish in your
breasts a kind, but unavailing sorrow for the dead, allow
me to solicit your attention to a few general observations
relative to the origin of pestilential diseases. I shall after-
wards confine my remarks and speculations more immedi-
ately to the origin of that disease, whose ravages and con- 

16
comitant terrors, have thrice, of late, reduced the gay and
crouded streets of our city to a dismal scene of desolation
and solitude.
As my subject is, evidently, very extensive and copious,
should I even engross a little more of your time than you
at present anticipate, I hope you will bear, with a patient
indulgence, the unintentional but unavoidable trespass.
It is, in this place, worthy of remark, that Pestilence
has been, at all times, treated by the world, as an illigiti-
mate child, without an acknowledged parent—in other words,
as a plant perfectly exotic as to every inhabited soil and
climate — or as a physical evil, existing in almost every region,
yet (strange inconsistency!) originating in none!
It is a fact not more singular than true, that, there is
not to be found in the whole range of the globe, a single
country, which is acknowledged by its own inhabitants, to
be the immediate birth-place of pestilence. When this
dreadful scourge makes its appearance in any place, howe-
ver favourable, from climate and local causes, to its domes-
tic generation, its existence never fails to be attributed ei-
to introduction by land, or importation by sea, from some
foreign country. As it, for the most part, appears first
in large commercial cities, the latter of these is most com-
monly considered as the channel of its conveyance. Hence
the evils of pestilence have been generally charged to the
account of commerce. Thus, when the plague prevails in 

17
any part of Europe, it is uniformly asserted to have been
imported in merchandize from Asia. When it breaks
out in the latter place, where it not unfrequently depopu-
lates towns and villages, and, occasionally, lays even whole
countries waste, it is always traced, or what, with the in-
dolent and unthinking natives, amounts to the same thing,
is supposed to be traced to some communication with the
continent of Africa. But the hardy sons of this burning
climate, spurn, with indignation, what they consider not on-
ly as an insult to the healthfulness, but also as an injury
to the prosperity of their country, and contend, that the
plague is never generated with them, but is always intro-
duced from some distant quarter. Nor is this obstinate spirit
of reluctance in the human race to admit pestilence to be
a native of the fame soil and climate with themselves,
confined to the continent of the old world. But five years
ago, the same thing might have been said with respect to
most of the inhabitants of the United States. Few of
them could then be induced to believe, that the western
shores of the Atlantic could possibly give birth to a pesti-
lential disease. They seemed to suppose, that a physical
evil of such a magnitude, must necessarily be the growth
of a foregn climate, not so highly favoured by heaven as
their own.
To you, Gentlemen, it is scarcely necessary for me to
observe, that this unwillingness in mankind to acknowledge
pestilence to be a native of the same country with them-
selves, Should be viewed as an inveterate prejudice, sup- 

18
ported, like all other prejudices, by the two gothic pillars
of ignorance and error. It requires no uncommon depth
of logic to prove, that pestilential diseases, having an exis-
tence, must have also a place of origin ; and, that this place,
must be in some of the inhabited parts of the earth. But
so extraordinary and absurd is the prejudice, of which I
have spoken, that it literally denies these diseases to have
originated in any place. Taking the sentiments of man-
kind, on this subject, for our guide, we would find a search
after the real birth-place of pestilence equally abortive with
the poet's search after the North, which he so energetically
represents in the following lines.
" But where th' extreme of vice was ne'er agreed ;
" Ask, Where's the North ? at York 'tis on the Tweed;
" In Scotland, at the Orcades, and there,
" At Greenland, Zembla, or the Lord knows where!"
So it is with respect to the birth-place of pestilence. In
America it is in the West-Indies ; in the West-Indies, it is,
at one time, at Siam in the East-Indies ; and again at Boulam
in Africa ; while, at these places, it is still farther to the
east as if the rising was capable of exalting the poison of
putrefaction to higher malignity than even the mid-day fun.
Were not the subject too serious to be treated as a jest, I
would farther say, that this singular absurdity, in most men,
with respect to the birth-place of pestilence, brings to my
recollection the humourous story of Goldsmith's pauper,
who, in quest of the real or acknowledged place of his birth. 

19
(the place where, by the municipal regulations of his coun-
try, he was entitled to a subsistance for life,) was carted
about from parish to parish, till, use the poor fellow's
own words, he "thought in his soul, they would not al
low that he had been born in any parish at all."
Let us, for a moment, trace this prejudice through all
its windings to its fountain head. It springs from the
bosom of self-love. This real though secret principle of all
our sentiments, opinions, and actions, will not suffer us to
admit, that we ourselves can be the source of any thing 
evil, or of any thing disastrous. From ourselves we are
inclined to extend this favourable opinion to our friends,
acquaintance, and countrymen ; and from them, to the air
which we breathe, the soil which gave us birth, and even
to the waters which variegate the landscapes that surround
us. The same selfish principles — the same contracted spi-
rit, which led the reprobate Jews of old to exclaim, "Can
any thing good come out of Galilee" induces the more fa-
voured, but, in some respects, not much more enlightened,
moderns to ask, can any thing evil originate in our beloved
country?
This prejudice, respecting the origin of pestilential dis-
eases, derives no inconsiderable support from the operation
of a narrow but powerful principle of self-interest. We
are apprehensive, that should our country be characterized
as the birth-place of pestilence, such an opinion would 

20
prove injurious to its population and prosperity, and that, 
consequently our interests as individuals must suffer. This
however, is a mistaken fear. General truth and general
utility are sworn friends, and inseparable companions. Nor
are they more so, in any instance, than in that which claims
our present attention. The same enlightened views in sci-
ence which declare, that pestilence may originate among
ourselves, afford us, at the same time, the most firm and
consolatory assurance, that we have in our own hands the
means of prevention and safety. Nor is this our only con-
solation. Were physical truth, on this subject, fully evolv-
ed, it would set most, if not all countries and climates,
nearly on a level with respect to the origin of pestilential
diseases. For I am persuaded that there exists not a spot
on the surface of the globe, which may not, under certain,
circumstances, become capable of giving birth to these
wasteful epidemics.
I beg it may not, from the foregoing observations, be
understood, that I mean, on the subject of the origin of
pestilential diseases, to accuse the whole human race of ig-
norance and error. Far from it—There have, at all times,
existed many distinguished instances of exemption from such
a charge. There have, in all ages, and in all countries,
existed men, who, in opposition to an overbearing torrent
of popular prejudice and indignation, have boldly main-
tained the diseases in question to have been the offspring
of the places where they have spread desolation. 

21
This is well known to have been formerly the case, in
London and Marseilles, during the unparalelled calamities
inflicted by pestilence on those two ancient and populous
cities. Nor was it of late, less remarkably the case in dif-
ferent parts of the United States, but more particularly in
the city of Philadelphia. When the Yellow Fever (which
might with more propriety have been denominated the A-
merican pestilence) made its appearance in this city in the
antumn of ninety three, to have said that it was a disease of
domestic origin, was considered as an unfounded slander on
our climate, and the man, who dared to advocate such an
opinion, was viewed in the light of ah enemy to his coun-
try. Almost every mind was then big with the idea of
importation, and almost every eye fixed on a tropical region,
as the only place capable of giving birth to such an irre-
sistable malady. To this blindfold state of the public mind,
there fortunately existed some degree of exception. Amid
the general gloom of ignorance and error, by which we
were overshadowed, there appeared, even then, a few twink-
ling stars, the joyous harbingers of a brighter day. The
dawn of that day has already reached us, and we have eve-
ry reason to believe, that we will very shortly be wrapt in
its full meridian.
The opinion, that our late epidemic must be necessarily
imported to us from a tropical climate, will soon become as
unpopular as it was once extensive. Already is it greatly
circumscribed in its limits—Already is it confined almost
entirely to those, who were originally active and clamorous
C

22
in its support. By such characters we are not to expect
that it will be immediately abandoned. They have already
pledged themselves to the world for its support, and consi-
der, therefore, its fate as in some measure interwoven with
the fate of their own characters, as philosophers in medi-
cine. Like a parent, with all his tenderness awakened by
the approaching dissolution of a beloved child, they will
cling to it with the greater fondness, the more nearly they
see it about to expire. But expire it will, nor can all the
partial and studied efforts of its supporters prolong its fleet-
ing existence. Like the old system of chemistry tottering
before the new, it must finally sink beneath the doctrine of
domestic generation, nor will it find, among all its advocates,
a Priestly to appear great and unshaken in the midst of its
ruins!
We have already observed, that in all parts of the world,
and in all periods of society, mankind, in general, have en-
tertained and exhibited a most profound hostility against the
opinion of their own country being, under any circumstan-
ces, the birth-place of pestilence. Nor has the matter end-
ed here. They have been solicitous and active to defend,
not only their own immediate country, but even our whole
globe, from the charge of giving origin to an evil of such
magnitude. Whenever this disease has appeared, they have,
like many physicians and citizens of the United States, been
extremely anxious and industrious to trace it to some par-
ticular species of importation. It may not be altogether
useless nor uninteresting, to trace the many singular and ab- 

23
surd modifications, through which this opinion, of the fo-
reign importation of pestilential diseases, has successively
passed.
In the earliest ages of the world, when ignorance and
superstition led men to attribute all extraordinary pheno-
mena to the direct agency of supernatural beings, pestilence
was supposed to be imported immediately from Heaven.
This is the opinion which appears to have prevailed among
the ancient Hebrews, and may be ranked at the head of
the catalogue of absurdities on this subject. The domini-
on of prejudice over the minds of that ignorant and obsti-
nate people, appears in this instance particularly striking.
Such was the depth of their blind bigotry in favour of the
healthfulness of the globe they inhabited, that they would
seem to have considered it as even superior to that of the
celestial regions. Hence, unwilling, to believe that their
favourite earth could give origin to an evil so dreadful as
pestilence, they imported the seeds of this calamity from
the more unhealthful climate of heaven!!
Another species of importation no less extraordinary than
the former, is that which derived pestilential diseases from
the sun. An opinion of this kind appears to have been en-
tertained, respecting the origin of that pestilence, which de-
solated the Grecian camp before the walls of Troy.
Another description of importation from distant worlds
remains yet to be mentioned. During that period of error, 

24
in which the science of medicine, in common with most
other branches of science, was deeply perverted by astrolo-
gical notions, not one of the planets (our own perhaps ex-
cepted!) escaped the charge of giving origin to pestilential
diseases. Thus Saturn, Jupiter, Mars, Venus, and Mer-
cury, may all be found arraigned in the dark catalogue.
Nor did the moon herself escape. Even the celebrated,
but fanciful Paracelsus, boldly accused this fair luminary,
as being the parent of deadly pestilence.—Had nature, pre-
viously to this period of intellectual perversion, by a happy
effort, raised up a Herschel, to soar, an astronomical Colum-
bus, through the immensity of space, there is little doubt, but
that the orb, which now bears his name, would, even from
its distant bourne, have been called to the narrow bar of
human prejudice, to answer to the charge of having been
the birth-place and nursery of the same disease!
In support of the foregoing opinions, however irrational
and absurd in the view of a more enlightened age, our re-
mote ancestors appear to have acted in concert. Such was
their blind partiality in favour of the world they inhabited,
that they could not, for a moment, admit the belief of its
ever giving rise to true pestilence. At length, however, were
they forced to abandon the ground they had originally
taken — At length was this extraordinary metastisis of error
obliged to relinquish entirely the heavenly bodies, and fix
on earth as its final retreat. At this period men became
divided in their opinion, respecting the origin of the evil
in question. Obliged to acknowledge it as a native of our 

25
own globe, they commenced a zealous search for the parti-
cular soil and climate from which it sprang. Here it was
that their opinions became hostile. Each one desirous of
preserving, in purity, the character of his own country,
charged the birth of pestilence to the country of an other.
Nor has the controversy as yet subsided. We have seen
very evident traces of it in the researches of men after the
origin of that malignant pestilence, by which we have,
lately, been three times visited. Thus, in America, the
West India Islands were, at first, considered as its birth-
place. Some physicians, in the West Indies, on the other
hand, attribute its prevalence there to importation from the
coast of Africa. While, no doubt, the hardy African will
retort the charge, and say, that they are indebted, for this
disease, to the lawless intrusion of white men on their peace-
ful shores. Thus we see that the same illiberal spirit of
prejudice which, in the earlier ages of the world, induced
our forefathers to attribute the origin of pestilence to hea-
ven, to the sun, the moon, and the various planetary bodies,
still continues, though under a different form, among their
more highly favoured posterity. They went to distant
worlds in quest of the origin of this disease, whereas we
rest satisfied with shorter excursions, and travel only to
distant countries!
I have called that prejudice, which leads to remote parts
of the globe, in quest of the origin of pestilential diseases, an
illiberal one; nor am I at all inclined to retract the epithet.
I think it narrow and illiberal, because it frequently urges 

26
men on to defend the character of their own climate and
country, at the expence of that of other places, which na-
ture has favoured with equal advantages. As formerly
observed, the very same principle of illiberality which leads
us to deny, to other portions of the globe, the possession of
advantages and excellencies which they undoubtedly hold,
induces us also to load them with the imputation of evils,
from which they are wholly exempt. This is a principle
which the enlightened Americans should indignantly re-
nounce. From its undue operation, in the minds of Euro-
peans, they themselves have already suffered much. There
was a time when America was considered, by most Euro-
peans, as capable of giving birth to but little that was va-
luable. And shall we, now, actuated by the same narrow
principle, and governed by the same circumscribed views,
contend, that it can give origin to nothing embraced in
the catalogue of evils ? I flatter myself with a confidence
that we never will. For though proud and happy in the
belief, that the wisdom and spirit of Americans will be at
all times competent and prompt to defend our country and
its character from every description of insult and injustice,
I should yet be sorry and humiliated at the appear-
ance of a selfish national spirit, inclining us to the defama-
tion of other countries, for the illiberal purpose of adding a
superior lustre to our own!
From arguments to be laid before you in a subsequent
part of this address, it will I trust appear, that America is,

27
equally with other parts of the world, capable of giving
birth to the worst of diseases.
With respect to the opinion, that our late pestilence is
necessarily imported from the West Indies, it is with pleasure
I observe, that its relinquishment has already very evident-
ly commenced. Even some of its most strenuous advocates
have found it necessary, in attempting its defence, to aban-
don entirely their original ground. They, at first, con-
tended that the seeds of this disease were imported to us in
the form of human contagion only, adhering to the clothes
or bodies of seamen or passengers, or to the timbers, appa-
rel, or contents of vessels. This however, constitutes no longer
an article in their medical creed. They are now willing to al-
low, that the seeds of the disease may be brought, not only
under the form of human contagion, but also under that of
foul air, produced by a high state of putrefaction in the ves-
sel's ballast or cargo. This must be granted by all, to be a
very materia1, and you will indulge me in adding, a very
auspicious change of opinion. But the change will not
stop here. Having so far relinquished their original ground
as to allow, that the American Pestilence can originate
from putrefaction in the hold of a vessel at sea, they will
next accede to the proposition, that it may, under certain
circumstances, result from a similar process on shore. Hence
the warmer regions of North America will, in all proba-
bility, be next suspected of giving birth to the formidable
disease in question. But at this point opinion will not re-
main stationary. The change will still continue to progress, 

28
till, at length, when the shades of error and prejudice
shall have been entirely dissipated, each citizen of Phila-
delphia will see the principal cause of the pestilence that
afflicts him, not in the immediate hand of a benevolent
Deity—not in the malign aspect of the sun, the moon, or the
planetary bodies — not on the burning shores of Africa or
the West Indies, but in the very centre of his own city!
Indulge me, for a few moments, in a detail of the lead-
ing arguments, which induce me to consider our pestilenti-
al diseases as the genuine offspring of our own country.
Pestilence can become epidemic only, when aided by a
concurrent constitution of Atmosphere. This position is
founded on the collective experience of ages. Where such
a constitution does not prevail, sporadic cases of pestilence
may indeed occur, but they will again disappear, and leave
surrounding individuals unhurt. The nature of that pecu-
liar state of atmosphere, favourable to the propagation of
pestilential diseases, has hitherto eluded the researches of
philosphers. The reality of its existence, however, is suf-
ficiently established from the obvious effects to which it
gives rise. Though ridiculed, of late, by some physicians,
under the denomination of an occult quality, reason and
observation still declare it to be a quality resting, for the
certainty of its existence, on evidence as substantial, as that
which supports the great Newtonian principle, the gravi-
tation of all terrestrial bodies. 

29
A pestilential constitution of atmosphere may be either
general or local. The general is that which extends over
whole countries, sometimes even over entire continents,
and, for the most part, prolongs its duration for several suc-
cessive years. The local is confined to particular spots,
most commonly to large commercial cities, and terminates
with the disappearance of certain topical causes, which ge-
nerally possess but a short lived existence.
Various opinions have been entertained, by philosophers,
respecting the cause of this general pestilential constitution.
By some, it has been attributed to a general and permanent
exhalation, perhaps of a mineral nature, resulting from the
action of subterraneous fires ; by others, to an immense
volume of poisonous gas, forcibly discharged from the bow-
els of the earth, during the dreadful convulsions of an earth-
quake ; and by others again, to torrents of pestiferous air eject-
ed into the atmosphere from the craters of Volcanos. In sup-
port of these two latter opinions, some degree of evidence
is derived from the circumstance of the prevalence of pesti-
lence, being very often either preceded or accompanied by
the occurrence of earth-quakes, or by repeated and dread-
ful volcanic eruptions. Of the frequent and striking coin-
cidence, both in point of time and place, between the exist-
ence of pestilence and the occurrence of earth-quakes and
eruptions from volcanos, the records of medicine afford am-
ple proof. An unanswerable argument in favour of the
reality of this general constitution of atmosphere, is derived
from the frequent (I had almost said uniform) cotemporary
D 

30
prevalence of pestilential diseases, in different and distant
parts of the globe.
That such a general constitution of atmosphere may exist
in America, as well as in other places, is a position, which,
abstractly considered, we have no reason to doubt. And
that it even does actually prevail, at this time, is an opinion
entertained by many respectable characters, and supported
by various physical phenomena. On a full and minute
statement of these phenomena, time will not suffer me, at
present, to enter. I flatter myself, however, that the fol-
lowing facts, relative to this curious and interesting sub-
ject, will not be deemed unworthy the attention of the
Academy.
For some years past, several species of insects, whose ex-
istence is known no be intimately connected with the state
of the atmosphere, have been more than usually abundant
in our country. Of the truth of this, our farmers are able
to furnish us with but too many unequivocal and, to them,
expensive testimonies. It will require many years to obli-
terate from the memory of this useful and respectable class
of our fellow-citizens, the injuries they have sustained from
the invasion and ravages of the Hessian Fly.
The origin of this destructive insect has, like that of our late
epidemic, constituted a subject of speculation and doubt, among
the literary characters of the United States. While some have
traced it to foreign importation, others have contended
that it is a native of our own country. Were I to lay 

31
before you the result of my own enquiries and reflection on
this point of natural history, I should be inclined to advo-
cate the latter opinion. I am rather disposed to believe,
that what is vulgarly denominated the Hessian Fly origi-
nates entirely with ourselves. There is reason to suspect,
that our fields and forests contain, perhaps, at all times, this
insect in certain numbers, and that it superabounds, and,
depredates on the labours of the husbandman in those sea-
sons only, during which there prevails a state or constitu-
tion of atmosphere, more peculiarly favourable to its propa-
gation and existence. For it is a fact well known to natu-
ralists, that no less in the œconomy of insects than in that
of plants, certain seasons are favourable, and others unfa-
vourable to their generation and growth.
Again, it is a fact, with which men of observation, can-
not be unacquainted, that for several years past, but more
particularly during the last and preceding autumns, muski-
tos were more than usually abundant in those situations
which they generally infest — Nor is this all — These insects,
not willing to be confined, during the two last seasons, to
their former limits, made their way into many places, which,
before, had been almost wholly exempt from their invasion.
But from the well known circumstance, that muskitos uni-
formly abound at the same time, and in the same places,
with epidemic bilious fevers, we are very fairly authorized
to conclude, that these noxious insects depend, for their ex-
istence, on an insalubrious state and constitution of atmos-
phere. Nor must I here omit to observe, that the immen- 

32
sity of grass-hoppers, which infested our country, during last
summer, bespoke a condition of atmosphere different from
what usually prevails at that season.
If then our country has, of late, been characterized by
an unusual prevalence of insects and of disease in different
places, and if these insects and disease have, in most instan-
ces, prevailed, not only at the same time, but also in the
same situations, (both of which facts are unquestionably true)
have we not, at least, a very ostensible ground of belief, that
these unusual and cotemporary phenomena proceed from the
same cause, and that this cause is no other than a state and
constitution of our atmosphere, different from those that
usually characterize the atmosphere of our country?
In corroboration of the preceding inference, namely,
that the same constitution of atmosphere, which favours the
prevalence of pestilential diseases, is, in like manner, fa-
vourable to the existence of insects, I beg leave to give a
brief statement and explanation of an interesting fact, which,
we learn from the history of former ages. For more than
fifty years, during the reign of the emperor Justinian, the
plague raged in Europe, Asia and Africa, with such unpa-
ralelled violence and malignity, as sometimes to threaten,
in appearance, even the depopulation of the whole earth.
Throughout this period of devastation and calamity, such
was the immensity of locusts which infested the countries
where the pestilence prevailed, that many were disposed to
attribute the existence of this disease to the death and pu- 

33
trefaction of these destructive insects. This latter opinion,
however, we conceive to be founded, in a great measure,
in error. For although the pestilential constitution of at-
mosphere was, no doubt, strengthened by the deleterious
gas, arising from the putrefactive dissolution of such an im-
mense volume of animal matter, it is by no means likely
that it resulted from this as its primary cause. There ex-
ists certain facts which render it much more probable, that
the same constitution of atmosphere, resulting originally
from some more powerful source, proved favourable, at once,
to the generation of locusts, and to the birth and propaga-
tion of the pestilence of the age.
Might not a like physical explanation be given of the
cause of several of the plagues, which sacred writ declares
to have visited, in ancient times, the incorrigible Egypti-
ans; and which were then supposed, to have been inflicted
by the immediate hand of the Deity? I allude particularly
to the destructive swarms of locusts, and flies, and to the
pestilence among men, and the murrain among cattle, two
diseases, which appear to be intimately connected. Is it
not, I say, at least, an admissible conjecture, that there
prevailed, at that time, a certain pestilential constitution of
atmosphere, which operated as the leading physical cause
of all these evils? The profound darkness which, shortly
afterwards, overshadowed, for a time, the dominions of the
impious and tyrannical Pharaoh, was probably nothing 
more than a natural concomitant of the same constitution. 

34
That there was something peculiar and uncommon, in
the general state and condition of the air, during our epide-
mics of ninety three, ninety seven, and ninety eight, we
would deduce from the vast number of fiery meteors, (com-
monly denominated falling or shooting stars) which appear-
ed in our atmosphere during those periods. I think it
highly probable, that these blazing meteors, always abound
during the existence of a pestilential constitution of atmos-
phere, and that on their uniform appearance, superstition
has erected a belief, that certain strange and supernatural
phenomena in the heavens, never fail to give premonition
of the approach of pestilence.
As a farther evidence in favour of the existence of a pe-
culiar constitution of atmosphere, particularly during the
years ninety three and ninety eight, it deserves to be men-
tioned, that, in those years, the fruits of our country, in
general, ripened and rotted with much more than their
usual rapidity. And that, on many of our fruit trees, se-
cond crops of blossoms appeared early in the autumn of the
same years, and, on some of them, even second crops of
fruit made considerable advances toward maturity. Nor
could the occurrence of these phenomena be fairly deduced
from the existence of any peculiarity in the sensible quali-
ties of the atmosphere. Seasons as warm and dry as those,
to which I have referred, are not uniformly productive of
similar effects. To the agency, therefore, of some imper-
ceptible cause in our atmosphere, must we attribute the
several phenomena in question. 

35
Another unanswerable argument in favour of the occa-
sional existence of a general morbid constitution of atmos-
phere in our country, is derived from the extensive preva-
lence of the catarrhal fever (commonly denominated in-
fluenza) in the years eighty eight and eighty nine. This
disease, which I believe is acknowledged by all to have re-
fulted from a certain deleterious constitution or state of the
air we inspired, was so general, as to pervade every part of
the United States. But the constitution, from which it
originated, must have been, in like manner, general, being
necessarily co-extensive with the disease itself. During
part of the continuance of this catarrhal constitution, a
deep duskiness, or want of due transparency in the atmos-
phere, considerably obscured the sun, in many, if not most,
parts of our country, thus constituting an approach toward
Egyptian darkness, which, as formerly observed, was, pro-
bably, nothing more than a natural effect or concomitant
of the then existing pestilential constitution.
The causes, which give rise to that local constitution of
atmosphere, favourable to the generation and propagation of
pestilence, are by far more obvious in their nature, operate
on a much less entensive scale, and possess an existence by no
means so durable. They are principally confined to large
cities, camps, and garrisons, where multitudes of people are
crowded together, and where personal and other descripti-
ons of cleanliness do not receive the attention they merit.
They may be said, in general, to be, all such causes as tend,
in the above descriptions of places, to generate foul air, and 

36
thus produce a vitiated state of atmosphere. The principal
of these shall hereafter become subjects of particular speci-
fication. This local constitution of atmosphere extends,
frequently, beyond the immediate confines of cities, camps
and garrisons, and, sometimes, even pervades considerable
tracts of country, particularly such as are low and marshy.
It is an evil, which may be said to owe its origin, in gene-
ral, to that indolence and inattention, which unfortunately,
constitute such predominant traits in the character of the
human race. This peculiar constitution, of which we have
spoken, is nothing else than a predisposition or capability
in the atmosphere to generate and propagate pestilential dis-
eases. It would seem to consist, either in the actual admix-
ture of pestilential effluvia with the air which we breathe,
or in the presence of some aeriform substance, which favours
the existence and conveyance of such effluvia, and prevents
their action from being destroyed by the influence of the at-
mosphere.
Your attention, for a few moments, is next solicited to
the remote cause of pestilential diseases. It need scarcely
be observed, that this subject is very nearly allied to that of
which we have last treated. So intimate, indeed, is their
connection, that they might, without any impropriety, have
been both spoken of under the same head. This remote cause
may be defined, a gas of a highly poisonous nature, which,
when brought into contact with the human body, renders it
liable, if exposed at the same time to the action of exciting
causes, to an attack of the disease denominated pestilence. 

37
A knowledge of the peculiar physical properties of this gas
has hitherto remained, and, I fear, will very long continue
to remain, an important desideratum in the science of me-
dicine. Even the reality of its existence is, as yet, esta-
blished, only, by its unparalelled ravages on the system of
man, and on the systems of a few species of inferior animals.
So extremely subtle and evanescent is its nature, that we
have not been able to separate it from surrounding matter,
to embody it together, and thus subject it to the test of
observation and experiment.
A knowledge of the actual source of this pestilential va-
pour is equally interesting to physical science, and impor-
tant to the welfare of the human race. Though it be pos-
sible that it may occasionally arise, in the form of exhala-
tion, in consequence of the action of subterraneous fires ;
and though it be probable that it has, in some instances, been
thrown from the bowels of the earth, during the convulsions
of an earthquake, or the eruption of a volcano, yet these
are by no means its most frequent sources. It appears to
be now reduced to a certainty, as decisive as any existing in
physical science, that organized bodies, in a high and long
continued state of putrefaction, constitute the legitimate
parent of pestilential effluvia.*
* I have not thought proper to attempt a minute detail of all the evi-
dence that might be collected in favour of the above position. It is, by far,
too extensive to be embodied within the nececssary limits of my address. It
may be found most copiously diffused through the works of all philosophical
E 

38
That this is the case, we justly infer, from the circum-
stance of pestilence never raging, to an alarming extent, un-
less in situations where putrefaction goes forward on an ex-
physicians, who have written expressly on the subject of pestilence. A con—
densed statement of it here, would be nothing more than a needless repeti-
tion of what must be familiar to the mind of every one, who has attended
to the cultivation of the science of medicine. Ever since pestilence was first
acknowledged to be a native of our globe, it has been uniformly derived, by
physicians of observation, from the poisonous gas resulting from the putre-
factive dissolution of organized bodies. This would lead me to a few ob—
servations on the subject of poisons.
This destructive class of substances has been, generally, divided into the ani-
mal, the vegetable and the mineral, to which should be added, that much
more formidable description of poison, derived originally from the process
of putrefaction. Under these four denominations, are embraced all the
species and varieties of poisons, that have hitherto attracted the notice of
philosophers. That pestilential and infectious diseases are the result of poi-
sonous effluvia, operating on the system of man, is a truth, to which medical
characters have long given their assent. An interesting question would
seem to arise here,namely, to what denomination of poisons, do these effluvia
appear to belong ? It cannot be supposed to be to the animal, the vegetable,
or the mineral poisons, because these deleterious substances have never been
known, nor even suspected, to be capable of propagating themselves. Thus, 
a person under the painful operation of an over-proportion of arsenic, or
of opium, or agonized by the bite of the rattle-snake, is incapable of com-
municating his disease to any of his attendants. The same thing may be
said respecting the morbid affections, resulting from any species of either of
the three foregoing genera of poisons. I believe it to be a truth, that
they have never been known to be, in any instance, communicable. The
poison, therefore, giving birth to pestilential and infectious diseases, be-
longs to that genus, which derives its origin from the putrefactive process. 

39
tensive scale. In turning over the annals of medicine,
even from their earliest period, down to the present day, we
will not find a single record of pestilence having prevailed
Putrefaction I would consider as a generic term, embracing several
specific or a least various modes, in which organized bodies undergo
dissolution, and recombination into gaseous results, some of them of a delete-
rious or poisonous nature. These poisonous results would seem to differ
from each other, according to the varieties of the process by which they
were produced. Thus for example, from one particular description or mo-
dification of the putrefactive process, or, if the reader be more pleased with
the hypothesis, from the putrefaction of a particular description or matter,
originated the poisonous effluvia or seeds of pestilence ; from another, those
of small-pox, from another, those of measles, from another, those of lues
venerea, &c. From the foregoing principles it would appear, that all
infectious diseases, as the small-pox and lues venerea, instead of being, as
they have been generally supposed, the specific and exclusive growth of the
East, the West, or of any particular climate or situation, may, under cer-
tain circumstances, originate in my inhabited portion of our globe. Nor
do I consider our own country as by any means exempt from this general
charge. I believe, that the small pox may originate in America or Europe,
as well as in Asia, and that the venereal disease may originate in Asia or
Europe, as well as in America. I am persuaded that the great and irre-
versible principles, by which, the decomposition and recomposition of matter
are governed, operate uniformly in all places, and that no spot on the globe
is privileged with a special exemption from their influence.
I am aware, that, by some physicians, this note will be considered as
nothing else than the mere child of fancy, or as the airy effusion if a specu-
lative mind—Be it so-I will, however, most sincerely thank such solid
and sagacious characters, to point out to me a more probable source of pes-
tilential and infectious diseases, than the putrefactive dissolution of organized
bodies!

40
and spread in places, where cleanliness has been attended to
in all its branches. Whereas, on the other hand, most
large cities, and even considerable tract of country, where pu-
trefying filth has been suffered to abound, have repeatedly
experienced this scourge in all its malignity. Thus the
plague of Egypt, unquestionably derives its birth from the
filth spread around by the waters of the Nile. The im-
mensity of putrefying animal and vegetable substances, with
which the streets and suburbs of Constantinople abound,
afford origin to the pestilence, which so frequently visits
that unfortunate city. And the Yellow Fever or plague of
the West Indies, appears to be indebted, for its birth and
existence, entirely to the extensive putrefactive dissolution
of organized bodies, produced by the fervors of a topical Sun.
From a similar source, namely, the filth of a crouded
garrison city, must we deduce the celebrated plague of A-
thens, which, to the eye of fancy, seems still to live and
rage with consummate malignity, in the descriptive elo-
quence of Thucidides: And to causes precisely similar,
must we attribute that dreadful pestilence, which before the
walls of Syracuse, made greater havoc among the Roman
legions, than even the stupendous engines of Archimedes—
To what causes, I would beg leave to ask, are we to ascribe
the more frequent and general prevalence of pestilential
diseases in camps, garrisons, and other places of military
establishment? Is it not to a want of cleanliness?— To
the immensity of putrefying filth, with which such places,
for the most part, abound? A want of cleanliness, and a 

41
greater exposure of men to actual hardship and fatigue, are
the two only circumstances, relative to health and disease,
in which military situations differ materially from others.
To these circumstances, therefore, are we bound to attri-
bute the more frequent visitations of pestilence, to which
such places are unfortunately subjected. The former of
these, namely, a want of cleanliness, gives rise to the remote,
and the other, viz. exposure to hardships, acts as the ex-
citing cause of the malady. Let me me not, on the pre-
sent occasion, fail to observe, that when pestilence breaks
out in any place, it never fails to make its appearance about
that period, when, from the usual co-operation of physical
causes, the process of general putrefaction, has arrived to
its summit. — Thus may pestilential effluvia be generated in
every spot on the surface of the globe, where the soil gives
birth to organized bodies, and the climate affords a suffici-
ency of heat and moisture, to give rise to a high putrefac-
tive process. There exist numerous proofs, sacred, I had
almost said, as those of holy writ, of pestilence having been
the native growth of many places on the continent of Eu-
rope. Even beneath the frozen sky of Russia, has this De
mon of putrefaction burst into existence, from domestic
causes, and called up death and desolation, as the concomi-
tants of his career. ! 
If the foregoing propositions and assertions be true,—
and confident I am, they are such, as rest on a basis, no
less secure than the experience and observation of ages,
cemented by the fairest deductions of reason — If it be true, 

42
I say, that pestilence can originate from the putrefaction of
organized bodies in Europe, Asia and Africa, what shadow
of reason have we to suppose America privileged with an
exemption from a similar misfortune? Can we have the
vanity—I might have said the presumption, to allege, that
the God of a general providence has condescended to enact a
law of special dispensation in favour of us, because we inha-
bit the western shore of the Atlantic? Has he, for us alone,
laid aside his robes of Deity? has he, for us alone, stooped
from the unaccommodating majesty of his character? has
he forfeited his title, as the impartial ruler of the universe,
and belittled himself by becoming a partizan on behalf of
the continent of America? — Highly as I think of my na-
tive country, and proud as I am of my birth-right as an
American, my patriotic fervor has not yet so far obscured
my understanding, as to bear me out in a belief so irrati-
onal, and presumptuous! But to relinquish, for a moment,
our views in theology, and address you in language more
strictly philosophical.—Are the atmosphere, the waters and
the organized productions of the new world, exempt from
the government of the great physical principles, to the in-
fluence of which, those of the old are uniformly and neces-
sarily subjected? Have we not, within ourselves, an im-
mensity of the requisites necessary for carrying putrefaction
to the highest stage? When advanced to such stage, will
not this process produce, with us, the very same deleterious
effluvia to which it gives birth in other quarters of the
globe? And, when once evolved, will not this effluvia ge-

43
nerate and propagate pestilence here, with as much readiness,
and with as much malignity, as in countries situated be-
yond the Atlantic? To answer those propositions in the
negative, would be to deny, that the same physical causes,
when uncontrouled in their operation, will always be pro-
ductive of the same effects. As well may we say, that the
same animals which propagate their likeness in Europe, can-
not in America; or that the same sun which wakes to life
the sleeping blossom there, cannot rouse it from its wintry
slumbers here!
Let not chemists, in the pride of their knowledge, deny,
that pestilential effluvia can be the offspring of putrefaction,
because they are unable to produce it in their laboratories.
Let them remember, that they are not yet able to operate,
in all respects, as nature does, nor are they possessed of any
chemical tests to ascertain, with decision, where these efflu-
via do and where they do not prevail. Their effects on
the human body constitute the only indubitable testimony
of their existence ; and these, as mentioned before, never
occur to any extent, except in places abounding with sub-
stances in a state of putrefaction.
It may not be improper, on the present occasion, to ob-
serve, that of all animal substances, the matter of human
perspiration is by no means the least liable to putrefaction.
After its discharge from the pores of the body, it would
seem to run, with much rapidity, into this offensive state.
Nor is it the most innocent, in its nature, when under the 

44
actual influence of this process. There is reason to believe,
that, from the putrefaction of the perspirable gas, in places
where numbers have been unduly crouded in small, unven-
tilated apartments, diseases of a pestilential nature have re-
sulted. But, unless when vitiated by means of putrefaction
or actual disease, I believe the matter of perspiration to be
perfectly unnoxious.
The relationship between the American pestilence, the
yellow fever, or pestilence of the West Indies, and the plague
of Asia, shall now constitute the subject of a few remarks.
From all the information I have been able to collect
from observation, books, or conversation, respecting those
three diseases, I have not been able to perceive that there
exists between them any radical or essential difference. They
seem evidently to originate from the same source, they are
alike influenced by the usual vicisitudes of the seasons, they
invade the human system in the same manner, and are charac-
terized, in their course, by the same train of general symptoms.
They appear, in fact, to be the very same disease, modified,
to a certain degree, by various causes, of which the most
powerful is that of climate. This is, indeed, a cause, the
operation of which but few things are able to resist. It
is well known that climate possesses a power of changing
the aspect of plants, the appearance of inferior animals,
and even the figure, complexion, and countenance of the
human race. Thus, how different, in all these respects, is the
appearance of an Asiatic from that of a native of Africa, 

45
of Europe or America? May we not then, very rational-
ly conclude, that the same cause, which possesses such an
immense influence over plants and animals, is, in like man-
ner, fully competent to the modification of disease? I will
venture to affirm, that there exists a much greater differ-
ence between the general appearance of an Asiatic, and
that of an American, than between the symptoms and pro-
gress of the American, and those of the Asiatic pestilence.
But the men of Asia and America are held to be nothing
more than varieties in the human race, resulting from a
difference of climate and of the state of society. When
any inconsiderable difference, then, is discovered in the ge-
neral appearances of the pestilential diseases, by which the
two countries are occasionally invaded, it may doubtless be
attributed to the same causes.
With regard to the pestilence of the West Indies, it
might, at first sight, appear to be, in one respect, very ma-
terially different from the other two. Thus, we learn from
physicians, on whose report we may, most confidently, rely,
that the former disease is never, in any instance, known to
be contagious, whereas there is, perhaps, reason to believe,
that the case is different with respect to the two latter.
That they are occasionally propagated by contagion, is a poi-
tion, to the truth of which physicians of the highest emi-
nence have, at all times, afforded the testimony of their as-
sent. On farther reflection, however, it will be immedi-
ately perceived, that this trait in the character of the West
F 

46
India pestilence results entirely from the influence of a tro-
pical climate. For it is a fact, well known to physicians
of experience and information, that a high and uniform
temperature of atmosphere, is decidedly hostile to the com-
munication of pestilential diseases. Such a temperature,
continued for some time, arrests the progress of even the
desolating pestilence of Asia. It is a truth, which must be
alike familiar to you all, that, at Constantinople, the sum-
mer no less than the winter Solftice bestows on the inhabi-
tants a temporary respite from the ravages of that dread-
ful calamity.— As, then, the men of Europe, Asia, Africa
and America, are held, by our most eminent philosophers,
to belong to the same species, and to owe the diversities in
their appearance, principally, to the influence of climate and
manner of life, would not a similar observation appear to
be admissible, with respect to the pestilential epidemics of
those four divisions of the globe? May not these diseases
be, very rationally, viewed as the same in their nature, va-
riously modified by climate, and by the habits and man-
ners of the human race?
From subjects of speculation, let us now turn our atten-
tion to an object, which claim, from its situation, the soli-
citude of us all. Let us look around on Philadelphia,
which has so lately exhausted the cup of calamity, and
whose agonies, from the bitter draught, no friendly opiate
has yet entirely lulled to rest.— Let us, I say, survey this
opulent mart, this once fair and flourishing metropolis, and
say, can it, or can it not, from causes within itself, give 

47
birth to a genuine pestilential disease? To you, gentle-
men, who have considered the matter with so much delibe-
ration, I need hardly observe, that on the just decision of
this question, and the subsequent measures established there-
on, depends little less than the future existence of our city.
It merits, therefore, the most profound attention of every
American, who is a friend to his country, or who wishes
well to the interest of the human race.
The subject of the origin of our late and preceding epi-
demics, has been already so amply discussed, that those who
take it up, at this period, can be considered as little else
than gleaners in the field of controversy. I cannot, how-
ever, close my address, without laying before you the fol-
lowing remarks. To strike, by their novelty, is not my
intention, because I am sure they are already familiar to
you all. To gain your assent to their truth and justice,
constitutes, at present, the height of my ambition.
I. Considerably remote from the breezes of the ocean, and
standing on a scite of but a moderate elevation, Philadelphia
is by no means favourably situated for free ventilation.
These disadvantages, co-operating with those of numerous,
lofty, and crouded buildings, produce a stagnation in the
air of most parts of the city, unknown in places exempt
from such obstructions. This stagnation is very sensibly,
and even oppressively, experienced, by our citizens, during
the warmth of the summer months. It is unnecessary to
observe, that an atmosphere, such as this, is in a fit state 

48
for the reception and retention of noxious effluvia. Nor does
it, under this evident want of motion, appear, by any means,
well calculated to dilute or weaken such effluvia, and thus
obviate their pernicious influence on the human system.
II. Philadelphia, though situated in the latitude of forty,
is, notwithstanding, annually subjected to all the fervors of a
tropical climate, for the successive space of, at least, eighty or
ninety days. Suffering, during this lengthy period, a heat
superior, by three or four degrees, to that of the surround-
ing country, it may be considered as a perfect hot-house,
with regard to generating and fostering the seeds of pesti-
lential disease. Granting, therefore, that pestilence is the
more native offspring of a tropical sky, and that it is even
incapable of springing spontaneously beneath the natural
temperature of a milder climate, yet still, may it rise and
flourish luxuriantly in the hot-bed of a city as large and po-
pulous as that of Philadelphia. Thus, the plants of the
tropics are reared in hot-houses by the curious, beneath the
highest and most rigorous latitudes inhabited by man. In
like manner may pestilence, (though possible the more na-
tural product of a tropical climate,) be reared to perfection
in the hot-bed of Philadelphia.
III. The two evils, which I have just specified, are, in
some measure, necessarily attendant on our unfortunate ci-
ty. Though, by wisdom and industry, they may be dimi-
nished, to remove them, entirely, is beyond the limited pow-
ers of man. Their foundation is laid in the works of na-

49
ture, and art is, therefore, incompetent to their removal.
Its utmost extent is to obviate the mischiefs which they
tend to produce. We cannot countermand the excessive
heats of our climate, we are unable to elevate the ground
on which Philadelphia stands ; nor can we invoke, with ef-
fect, the breezes of the Atlantic, to shed refreshment
through our oppressive streets!*
Another evil remains yet to be mentioned, very differ-
ent, in its nature, from the preceding two. It is altogether
of artificial birth, and art and industry are, therefore, com-
petent to its extinction. I allude to the immensity of filth,
with which the different parts of our city and suburbs a-
bound. Nor is this an evil of inferior magnitude. It may
be considered as the hydra, whose malignant breath, gave
birth to the calamities we have three times suffered. The
severities of the season have paralised it, for the present,
and reduced it to its customary state of hybernation. But
unless prevented, by an adoption of the most wise and ener-
getic measures, there is but too much reason to apprehend,
that it will be again awakened to life and action, by the re-
turning warmth of the summer sun! Before the arrival of
that eventful period, may some favoured champion — some
* Notwithstanding the above observations, I am persuaded, that, by a
due attention to domestic cleanliness, co-operating with such port regula-
tions, as will prevent vessels containing foul air from entering our har-
bour, the city of Philadelphia may be rendered as perfectly exempt from
pestilential epidemics, as any commercial city in the world. 

50
enterprising Hercules arise, and strike from existence this
infatiate monster!
In taking a survey of many parts of our city and suburbs,
our senses are struck by the offensive and dangerous spec-
tacle, of an accumulation of the filth of nearly a cen-
tury. In passing, in several directions, to a considerable
distance from the pavements of our streets, we are not even
suffered to tread on the soil of nature. We travel over
artificial ground, made up of a fermenting assemblage of
the most noxious materials. Here, to the depth of several
inches beneath the surface, is promiscuously blended toge-
ther, animal and vegetable matter, in a state of high putre-
faction, while the same substances in a similar state, are
most plenteously strewn over the surface itself. Nor is
moisture wanting to give vigour to the process.— During
the excessive heats of our summer solstice, what, I would
ask, must be the effect of the poisonous exhalation, arising
from so extensive a source, added to that proceeding
from numerous other domestic causes? Must it not be, (to
use the language of the poet,) the conversion of the whole
atmosphere of our city into a "foul and pestilent con-
gregation of vapours?" During this portentous feed-time
of pestilence, we are not privileged to breathe the untaint-
ed air, prepared for our systems by the operations of nature,
but are obliged to inhale a mixture of deleterious exhala-
tions, proceeding from the indolence, ignorance, and in-
attention—I had almost said, from the criminality of man.-
Nor is the experience of time devising measures for the re-

51
moval of this enormous evil, nor erecting any barriers to
check its growth. Even the melancholy reverse of this is true.
Notwithstanding the numerous declarations we hear, in favour
of the cleanliness of our streets, at present, compared to what
existed some years ago, it is an unquestionable truth, that,
in the existing state of things, as year succeeds to year, the
aggregate mass of filth in our city and suburbs encreases.*
Should our civic police, (as far as it respects the prevention
of disease,) continue supine and feeble, as it is, at present,
what a dark and gloomy prospect is opened to our view!
With the future progress of time, danger would seem to
accumulate on danger, and distress to blacken over distress,
till imagination becomes bewildered, in attempting to cal-
culate the melancholy result.
Owing to such a state of domestic filth, as now prevails
in and around the city of Philadelphia, was the plague, in
former times, the scourge of London, and other populous ci-
ties of Europe ; and, owing to a similar state, does it still
* The filth taken up from our streets, not excepting even that which
is removed from our necessaries themselves, is, at present, conveyed to such
an inconsiderable distance from the city, that it might almost as well, be
suffered to remain in its original situation. Instead of employing such ma-
terials for filling up ponds, and levelling the ground, in the south-western
part of the city, would it not be much more wise and economical, to con-
vert them to the purpose of fertilizing the ground, under cultivation in
the neighbourhood, where, instead of proving destructive to the life of
man, the effluvia which they emit, might contribute, to rear up vegeta-
bles for his sustenance and comfort? 

52
continue, occasionally, to rage in Constantinople, and in ma
ny other devoted places in the East.
However painful the prospect, and however unpopular
the idea, may, at present, be with many, it is, in my ap-
prehension of things, a truth which ought not to be forgot-
ten, that unless the misfortune be averted, by the most vi-
gilant and energetic measures of domestic cleanliness, the
the large commercial cities of America will, in, perhaps,
less than a century, become as remarkable for giving birth
to pestilence, as any ever have been in Europe, or as any
are now on the continent of Asia.
To enumerate all the sources of our domestic filth, is not
my present object. This has already been ably done, in
several memorials from the Academy of medicine. There
exist, however, two sources in particular, to which, I will be
pardoned for thinking, that the public attention has not
been directed, in a manner sufficiently forcible. These are 
the vast quantity of putrid and putrefying timber, which en-
ters into the formation of our docks and wharves, and the
immensity of animal and vegetable substances, strewn, in a
putrefactive state, along the commons, in a south-western
direction from the city.
From the former of these sources, an incalculable volume
of deleterious air must be discharged, to the great annoy-
ance of the crews of vessels in our harbour, and of all whose
business demands their attendance along shore. For this
evil the remedy is easy and obvious. The timbers ought to 

53
be removed, as much as possible, from the docks and wharves;
and their place supplied by brick or stone.
From the latter source, namely, the abundance of putri-
fying substances, dispersed over the commons, in a south wes-
tern direction, the air of the city must be deeply contami-
nated. To have a due sense of the propriety and weight
of this observation, it is necessary to recollect, that, parti-
cularly, during the months of July, August, and September, 
our prevailing winds are from that quarter. Whatever
noxious effluvia, therefore, may be evolved from those sub-
stances, by the process of putrefaction, is wasted, immedi-
ately, into the heart of our city, and mingled with the air
of the streets which we breathe. There is certainly reason
to believe, that, to these effluvia, we were indebted, in no
inconsiderable degree, for that local constitution of atmos-
phere, so highly favourable to the propagation of our late
epidemic.
It is scarcely necessary to observe, that the remedy for
this evil is the immediate and entire removal of the offen-
sive substances. If the places, which those matters now
occupy, were planted with trees or shrubbery, or, even, put
under a crop of inferior vegetation, the effect, on the city,
would be both pleasant and salutary. Vegetables are
known to emit, during their wakeful and active state, large
quantities of pure respirable air. Were the above regu-
lation, therefore, adopted, instead of the offensive and per-
nicious vapour of putrefaction, this fluid of life, would,
G 

54
in consequence of the south-western winds of summer and
autumn, glide through our streets, and diffuse both health
and vigour from its wings.
To the two preceding sources of the vitiation of our at-
mosphere, let me not omit to subjoin that which is consti-
tuted by our public burying grounds. To a mind eying,
with deep solicitude, the apparently dubious balance of fate,
with respect to the future prosperity of our city, these ex-
tensive reservoirs, fraught with the mouldering relicts of
the dead, present themselves, as objects of painful apprehen-
sion. They appear equally melancholy and dangerous, and,
in neither respect, is the degree inconsiderable. Situated,
as some of them are, in the very centre of our city, these
spacious inclosures, a great part of the soil of which, is com-
posed of human exuviæ, cannot do otherwise than aid in
contaminating the air of our streets, and the water of our
pumps. That the water of our city is injured, by the
immensity of dead bodies, deposited in our grave-yards, we
would infer, from the very considerable distance, to which
the putrid effluvia, from the contents of a grave, have been
known to make their way, through the bowels of the earth.
And, that the same cause, has a tendency to vitiate our at-
mosphere, we would conclude, in particular, from certain
physical phenomena, for which ancient grave-yards have
been always remarkable. The phenonema, to which I al-
lude are, a kind of burning meteors, that sweep along the
surface of the ground, and which are known, under the
vulgar denomination of Will-with-the-wisp, or Jack-with- 

55
the-lanthern. These would seem to owe their existence,
principally, to an inflammable gas, discharged, through the
pores of the earth, from the putrefying contents of the
graves, and have, probably, aided much, in giving origin to
the superstitious legends of the ignorant, respecting church-
yards being haunted, by goblins and ghosts.
For this evil, I need hardly observe, that the only reme-
dy is, the removal of our burying grounds, to a distance
from the city. Nor let an attachment and veneration,
however natural and amiable, for the relicts of our friends,
prevent the adoption of such a salutary measure! If we
painfully feel and deplore the loss of our friends deceased,
why dispose of their bodies, in such a way, as to sow the
seeds of pestilence and death, among those that survive, and
thus, voluntarily, subject ourselves to additional sorrow?
To a feeling and reflecting mind, it is, doubtless, a much
more eligible alternative, to have a portion of our relatives
and friends still living, and those that are dead, buried in
a distant situation, and, even, in what some might consider
as unhallowed ground, than to have them all swept off,
though buried in the immediate vicinity of our dwellings,
and in ground duly consecrated for the purpose of interment.
On taking the preceding general view of the situation
and circumstances of Philadelphia—On considering it as a
large and populous city, deprived of the advantage of free
ventilation, subjected, during the summer months, to a
heat equal, at least, to that of the tropics, and enveloped, 

56
during that period, in a cloud of poisonous exhalation, from
the putrefactive dissolution of organized bodies.—On ma-
turely weighing, I say, the foregoing considerations, and,
at the same time, recollecting, that, under similar circum-
stanees, pestilential diseases have, unquestionably, arisen in
other places, what shadow of reason have we to doubt the
practicability of pestilence originating in our city, from do-
mestic causes alone? As well may we assert, that the same
fun, which promotes vegetation, in the eastern, has no such
influence in the western hemisphere, as deny to causes, which
are known and acknowledged to give birth to pestilence, in the
cities of Asia, the power of producing the same disease,
when operating, with equal force, in the cities of America.
Could I be persuaded, that, under similar circumstances, the
same causes, do not, uniformly and necessarily, produce the
same effects in Asia and America, I would, immediately,
subscribe to the Pagan belief of Polytheism. In such a
state of things, I would be constrained to believe, that the
God of the old world, was not, in like manner, the God of
the new, but that the two hemispheres of our globe, were
governed by distinct Deities, through the medium of differ-
ent physical laws!
I have, hitherto, treated my subject in a manner rather
abstract and general, and have indulged myself, occasion-
ally, in discussive speculation. I have endeavoured to de-
monstrate, on principles long since known and established
the practicability of pestilential diseases originating on the
western shores of the Atlantic. From general reasoning, 

57
I might now descend to particular specification, and ex-
change principles in science, for plain and undeniable mat-
ters of fact. Thus, might I advert to the history of a far
distant period, and shew, from authentic records, that, pre-
viously to the establishment of any commercial intercourse,
between America and the West Indies, even the depth of
our forests were unable to shelter the aborigines of our
own country, from the invasion of pestilence. I might
point to our extensive north western lakes, and the country
adjacent, where pestilential epidemics not unfrequently pre-
vail with high malignity, and where, at the same time, fo-
reign intercourse is altogether unknown. But leaving
former times, and remote places, I might proceed to shew,
that, within a few years past, and, in places not far
distant, numerous instances of the American pestilence have
appeared, which could not possibly be traced to any com-
munication with a foreign climate or infected source, and
which must have, therefore, originated in the very places
where they occured. But I am precluded, from a more ex-
tensive view of my subject, by an unwillingness to intrude
any farther on your time, and, thus, be guilty of an undue
trespass on your politeness and indulgence.
Before concluding my address, allow me, Gentlemen, to
congratulate you on the success, I had almost said, the triumph
of the principles, which the Academy advocates, respecting
the origin of the late epidemics of America. To say, that
these diseases are of domestic growth, is no longer denounced
as medical heresy, nor as a species of blasphemy against our 

58
country. On this subject, the Shades of prejudice and error
are rapidly retreating, before the radiance of liberality and
truth. As far as relates to the necessary importation of
pestilential diseases from foreign countries, the time-worn
fabric of superstition in medicine, has received a revoluti-
onary blow, from which it is tottering to the depth of its
foundation! Nor is the time far distant, when this humi-
liating monument of the bigotry of ages, shall tumble to
irreparable ruins around the hoary* heads of its supporters.
Persevere, then, my fellow-members, to the completion of
the work you have so laudably undertaken. Wage for
yourselves, both jointly and individually, nothing less than
a war of utter extermination, against those prejudices and
errors, which threaten the depopulation of the cities of
* Of those physicians, who advocate the opinion, that the disease, in
question, is necessarily of foreign origin, there are but very few, who are not 
considerably advanced in years. This, on first view, might appear to be
an evidence, of some degree of respectability, in favour of the authenticity
and truth of the opinion. The force of this evidence, however, will be
muck diminished, when we recollect, that almost the only medical charac-
ters, in Great Britain, who opposed the truth of Harvey's discovery of
the circulation of the blood, and blindly adhered to the antiquated and ab-
surd error of its flux: and reflux through the same channels, were such at
had, at the time of the discovery, passed the fortieth year of their age.
On the death of those characters, all opposition to the Harveaen doctrine
ceased. Such will be the fate of the doctrine which embraces the do-
mestic origin of the pestilence of America. Our medical posterity will
unanimously adopt it, nor will they fail to wonder, why it was reject-
by any of their ancestors. 

59
America. While thus engaged, whatever may be the fate
of your reputations, with a few of your narrow minded
cotemporaries, be assured, that, if you continue firm in the
track, where philanthropy leads and science lights the way,
you will not—you cannot fail, to receive the approbation
and applause of a more enlightened and grateful posterity!
END.