fevers sometimes appear upon the summits of hills, while their
declivities, and the vallies below, are exempted from them. The miasmata,
in all these cases, are arrested by those heights, and are always to be
traced to putrefaction and exhalation in their neighbourhood. Nor is it
any objection to the indissoluble connection between putrid exhalations
and the yellow fever, which has been mentioned, that the disease
sometimes appears in places remote from the source of miasmata in _time_
and _place_. The bilious pleurisies, which occur in the winter and
spring, after a sickly autumn, prove that they are retained in the body
for many months, and although they are sometimes limited in their extent
to a single house, and often to a village, a city, and the banks of a
creek or river, yet they are now and then carried to a much greater
distance. Mr. Lempriere, in his valuable Observations upon the Diseases
of the British Army in Jamaica, informs us, that Kingston is sometimes
rendered sickly by exhalations from a lagoon, which lies _nine_ miles to
the eastward of that town[34]. The greater or less distance, to which
miasmata are carried from the place where they are generated, appears to
depend upon their quantity, upon the force and duration of currents of
wind which act upon them, and upon their being more or less opposed by
rivers, woods, water, houses, wells, or mountains.
[34] Vol. i. p. 84.
3. It is destroyed, like its fraternal diseases, the common bilious and
intermitting fevers, by means of _long-continued_ and _heavy_ rains[35].
When rains are heavy, but of short duration, they suspend it only in warm
weather; but when they are succeeded by cold weather, they destroy all
the forms of bilious fever. The malignant tertians, described by Dr.
Cleghorn, always ceased about the autumnal equinox; for at that time,
says the doctor, "Rain falls in such torrents as to tear up trees by the
roots, carry away cattle, break down fences, and do considerable mischief
to the gardens and vineyards; but, after a long and scorching summer,
they are very acceptable and beneficial, for they mitigate the excessive
heat of the air, and give a check to epidemical diseases[36]." There are
facts, however, which would seem to contradict the assertion that
miasmata are suspended or destroyed by heavy rains. Dr. Lind, in his
Treatise upon the Diseases of Hot Climates, mentions instances in which
they suddenly created fevers. It is probable, in these cases the rains
may have had that effect, by disturbing the pellicle which time often
throws over the surface of stagnating pools of water, and putrid matters
on dry land. I was led to entertain this opinion by a fact mentioned in a
letter I received from Dr. Davidson, dated November 4th, 1794. "Being
ordered (says the doctor) up to Barbadoes, last November, upon service, I
found that the troops had suffered considerably by that formidable
scourge, the yellow fever. The season had been remarkably dry. It was
observed, a rainy season contributed to make the season healthier,
excepting at Constitution-Hill, where the sixth regiment was stationed,
and where a heavy shower of rain seldom failed to bring back the fever,
after it had ceased for some time. I found the barrack, where this
regiment was, surrounded by a pond of brackish water, which, being but
imperfectly drained by the continuance of the drought, the surface was
covered with a green scum, which prevented the exhalation of marshy
putrefaction. After a heavy shower of rain, this scum was broken, and the
miasmata evolved, and acted with double force, according to the time of
their secretion."
[35] Clarke on the Diseases of Long Voyages to Hot Climates, p. 116.
[36] Diseases of Minorca, p. 8.
4. It is completely destroyed by frost. As neither rains nor frosts act
in sick rooms, nor affect the bodies of sick people, they must annihilate
the disease by acting exclusively upon the atmosphere. Very different in
their nature are the small-pox and measles, which are propagated by
specific contagion. They do not wait for the suns of July or August, nor
do they require an impure atmosphere, or an exciting cause, to give them
activity. They spread in the winter and spring, as well as in the summer
and autumnal months: wet and dry weather do not arrest their progress,
and frost (so fatal to the yellow fever), by rendering it necessary to
exclude cold air from sick rooms, increases the force of their contagion,
and thereby propagates them more certainly through a country.
5. It is likewise destroyed, by intense heat, and high winds. The latter,
we are sure, like heavy rains and frost, do not produce that salutary
effect by acting upon the bodies, or in the rooms of sick people.
It is worthy of notice, that while the activity of miasmata is destroyed
by cold, when it descends to frost; by heat, when it is so intense as to
dry up all the sources of putrid exhalation; by heavy rains, when they
are succeeded by cool weather; and by high winds, when they are not
succeeded by warm weather; they are rendered more active by cool, warm,
and damp weather, and by light winds. The influence of damp weather, in
retaining and propagating miasmata, will be readily admitted, by
recollecting how much more easily hounds track their prey, and how much
more extensively odours of all kinds pervade the atmosphere, when it is
charged with moisture, than in dry weather.
It has been asked, if putrid matters produce malignant bilious fevers in
our cities, why do they not produce them in Lisbon, and in several other
of the filthiest cities in the south of Europe? To this I answer, that
filth and dirt are two distinct things. The streets of a city may be very
_dirty_, that is, covered with mud composed of inoffensive clay, sand, or
lime, and, at the same time, be perfectly free from those _filthy_
vegetable and animal matters which, by putrefaction, contaminate the air.
But, admitting the streets of those cities to abound with the filthy
matters that produce pestilential diseases in other countries, it is
possible the exhalations from them may be so _constant_, and so
_powerful_, in their impressions upon the bodies of the inhabitants, as
to produce, from habit, no morbid effects, or but feeble diseases, as was
remarked formerly, is the case in the natives and old settlers in the
East and West-Indies. But if this explanation be not satisfactory, it may
be resolved into a partial absence of an inflammatory constitution of the
air, which, I shall say presently, must concur in producing pestilential
diseases. Such deviations from uniformity in the works of Nature are
universal. In the present instances, they no more invalidate the general
proposition of malignant fevers being every where of domestic origin,
than the exemption of Ireland from venomous reptiles, proves they are not
generated in other countries, or that the pleurisy and rheumatism are not
the effects of the alternate action of cold and heat upon the body,
because hundreds, who have been exposed to them under equal
circumstances, have not been affected by those diseases. There may be
other parts of the world in which putrid matters do not produce bilious
malignant diseases from the causes that have been mentioned, or from some
unknown cause, but I am safe in repeating, there never was a bilious
epidemic yellow fever that could not be traced to putrid exhalation.
It has been asked, if the yellow fever be not imported, why does it make
its first appearance among sailors, and near the docks and wharves of our
cities? I answer, this is far from being true. The disease has as often
appeared first at a distance from the shores of our cities as near them,
but, from its connection with a ship not being discovered, it has been
called by another name. But where the first cases of it occur in sailors,
I believe the seeds of it are always previously received by them from our
filthy docks and wharves, or from the foul air which is discharged with
the cargoes of the ships in which they have arrived, which seeds are
readily excited in them by hard labour, or intemperance, so as to produce
the disease. That this is the case, is further evident from its appearing
in them, only in those months in which the bilious fever prevails in our
cities.
It has been asked further, why were not these bilious malignant fevers
more common before the years 1791, 1792, and 1793? To this I answer, by
repeating what was mentioned in another place[37], that our climate has
been gradually undergoing a change. The summers are more alternated by
hot and cool, and wet and dry weather, than in former years. The winters
are likewise less uniformly cold. Grass is two or three weeks later in
the spring in affording pasture to cattle than it was within the memory
of many thousand people. Above all, the summer has encroached upon the
autumn, and hence the frequent accounts we read in our newspapers of
trees blossoming, of full grown strawberries and raspberries being
gathered, and of cherries and apples, of a considerable size, being seen,
in the months of October and November, in all the middle states. By means
of this protraction of the heat of summer, more time is given for the
generation of putrid exhalations, and possibly for their greater
concentration and activity in producing malignant bilious diseases.
[37] Account of the Climate of Pennsylvania, vol i.
It has been asked again, why do not the putrid matters which produce the
yellow fever in some years produce it _every_ year? This question might
be answered by asking two others. 1st. Why, if the yellow fever be
derived from the We st-Indies, was it not imported every year before 1791,
and before the existence, or during the feeble and partial operation of
quarantine laws? It is no answer to this question to say, that a war is
necessary to generate the disease in the islands, for it exists in some
of them at all times, and the seasons of its prevalence in our cities
have, in many instances, had no connection with war, nor with the
presence of European armies in those and in other sickly parts of the
globe. During the seven years revolutionary war it was unknown as an
epidemic in the United States, and yet sailors arrived in all our cities
daily from sickly islands, in small and crowded vessels, and sometimes
covered with the rags they had worn in the yellow fever, in British
hospitals and jails. I ask, 2dly, why does the dysentery (which is
certainly a domestic disease) rise up in our country, and spread sickness
and death through whole families and villages, and disappear from the
same places for fifteen or twenty years afterwards?
The want of uniformity in the exhalations of our country in producing
those diseases depends upon their being combined with more or less heat
or moisture; upon the surface of the earth being completely dry, or
completely covered with water[38]; upon different currents of winds, or
the total absence of wind; upon the disproportion of the temperature of
the air in the day and night; upon the quantity of dew; upon the early or
late appearance of warm or cold weather; and upon the predisposition of
the body to disease, derived from the quality of the aliments of the
season. A similar want of uniformity in the annual operations of our
climate appears in the size and quality of grain, fruits, and vegetables
of all kinds.
[38] In the Account of the Yellow Fever of 1793, the different and
opposite effects of a dry and rainy season in producing bilious
fevers are mentioned from Dr. Dazilles. In the autumn of 1804, I
have elsewhere remarked, after a summer in which there had fallen
an unusual quantity of rain, the bilious fevers appeared chiefly
on the high grounds in Pennsylvania, which were in a state of
moisture, while scarcely a case of them appeared in the
neighbourhood of marshes, or low grounds, owing to their being so
completely covered with water, as to be incapable of generating,
by putrefaction, the miasmata which produce those forms of
disease.
But the greater violence and mortality of our bilious fevers, than in
former years, must be sought for chiefly in an inflammatory or malignant
constitution of the atmosphere, the effects of which have been no less
obvious upon the small-pox, measles, and the intercurrent fevers of Dr.
Sydenham, than they are upon the summer and autumnal disease that has
been mentioned.
This malignant state of the air has been noticed, under different names,
by all the writers upon epidemics, from Hippocrates down to the present
day. It was ascribed, by the venerable father of physic, to a "divine
something" in the atmosphere. Dr. Sydenham, whose works abound with
references to it, supposes it to be derived from a mineral exhalation
from the bowels of the earth. From numerous other testimonies of a belief
in the influence of the insensible qualities of the air, altering the
character of epidemics, I shall select the following:
"It is certain (says Dr. Mosely) that diseases undergo changes and
revolutions. Some continue for a succession of years, and vanish when
they have exhausted the temporary, but secret cause which produced them.
Others have appeared and disappeared suddenly; and others have their
periodical returns."
The doctor ascribes a malignant fever among the dogs in Jamaica
(improperly called, from one of its symptoms, hydrophobia), to a change
in the atmosphere, in the year 1783. It was said to have been imported,
but experience, he says, proved the fact to be otherwise[39].
[39] Treatise upon Tropical Diseases, p. 43, 44.
"This latent malignity in the atmosphere (says Baron Vansweiten) is known
only by its effects, and cannot easily be reduced to any known species
of acrimony." In another place he says, "It seems certain that this
unknown matter disposes all the humours to a sudden and bad
putrefaction[40]."
[40] Commentaries on Boerhaave's Aphorisms, vol. v. p. 226, 230.
Dr. John Stedman has related many facts, in his Essay upon Insalutary
Constitutions of the Air, which prove, that diseases are influenced by a
quality in it, which, he says, "is productive of corruption," but which
has hitherto eluded the researches of physicians[41].
[41] Page 135.
Mr. Lempriere, after mentioning the unusual mortality occasioned by the
yellow fever, within the last five or six years, in the island of
Jamaica, ascribes it wholly "to that particular constitution of
atmosphere upon which the existence of epidemics, at one period rather
than another, depend[42]."
[42] Vol. ii. p. 31.
Not only diseases bear testimony to a change in the atmosphere, but the
whole vegetable and animal creation concur in it, proofs of which were
mentioned in another place. Three things are remarkable with respect to
this inflammatory constitution of the air.
1. It is sometimes of a local nature, and influences the diseases of a
city, or country, while adjoining cities and countries are exempted from
it.
2. It much oftener pervades a great extent of country. This was evident
in the years 1793 and 1794, in the United States. During the same years,
the yellow fever prevailed in most of the West-India islands. Many of the
epidemics mentioned by Dr. Sims, in the first volume of the Medical
Memoirs, affected, in the same years, the most remote parts of the
continent of Europe. Even the ocean partakes of a morbid constitution of
its atmosphere, and diseases at sea sympathise in violence with those of
the land, at an immense distance from each other. This appears in a
letter from a surgeon, on board a British ship of war, to Mr. Gooch,
published in the third volume of his Medical and Surgical Observations.
3. The predisposing state of the atmosphere to induce malignant diseases
continues for several years, under all the circumstances of wet and dry,
and of hot and cold weather. This will appear, from attending to the
accounts which have been given of the weather, in all the years in which
the yellow fever has prevailed in Philadelphia since 1792[43]. The remark
is confirmed by all the records of malignant epidemics.
[43] Vol. iii. and iv.
It is to no purpose to say, the presence of the peculiar matter which
constitutes an inflammatory or malignant state of the air has not been
detected by any chemical agents. The same thing has been justly said of
the exhalations which produce the bilious intermitting, remitting, and
yellow fever. No experiment that has yet been made, has discovered their
presence in the air. The eudiometer has been used in vain for this
purpose. In one experiment made by Dr. Gattani, the air from a marsh at
the mouth of the river Vateline was found to be apparently purer by two
degrees than the air on a neighbouring mountain, which was 2880 feet
higher than the sea. The inhabitants of the mountain were notwithstanding
healthy, while those who lived in the neighbourhood of the marsh were
annually afflicted with bilious and intermitting fevers[44]. The
contagions of the small-pox and measles consist of matter, and yet who
has ever discovered this matter in the air? We infer the existence of
those remote causes of diseases in the atmosphere only from their
effects. Of the existence of putrid exhalations in it, there are other
evidences besides bilious and yellow fevers. They are sometimes the
objects of the sense of smelling. We see them in the pale or sallow
complexions of the inhabitants of the countries which generate them, and
we observe them occasionally in the diseases of several domestic animals.
The most frequent of these diseases are inflammation, tubercles, and
ulcers in the liver. Dr. Cleghorn describes a diseased state of that
viscus in cattle, in an unhealthy part of the island of Minorca. Dr.
Grainger takes notice of several morbid appearances in the livers of
domestic animals in Holland, in the year 1743. But the United States have
furnished facts to illustrate the truth of this remark. Mr. James
Wardrobe, near Richmond, in Virginia, informed me, that in August, 1794,
at a time when bilious fevers were prevalent in his neighbourhood, his
cattle were seized with a disease, which, I said formerly, is known by
the name of the yellow water, and which appears to be a true yellow
fever. They were attacked with a staggering. Their eyes were muddy, or
ferocious. A costiveness attended in all cases. It killed in two days.
Fifty-two of his cattle perished by it. Upon opening the bodies of
several of them, he found the liver swelled and ulcerated. The blood was
dissolved in the veins. In the bladder of one of them, he found thirteen
pints of blood and water. Similar appearances were observed in the livers
of sheep in the neighbourhood of Cadiz, in the year 1799, during the
prevalence of the yellow fever in that city. They were considered as such
unequivocal marks of an unwholesome atmosphere among the ancients, that
they examined the livers of domestic animals, in order to determine on
the healthy or unhealthy situation of the spot on which they wished to
live.
[44] Alibert's Dissertation sur les Fievres Pernicieuses et Attaxiques
Intermittentes, p. 185.
The advocates for the yellow fever being a specific disease, and
propagated only by contagion, will gain nothing by denying an
inflammatory constitution of the atmosphere (the cause of which is
unknown to us) to be necessary to raise common remittents to that grade
in which they become malignant yellow fevers; for they are obliged to
have recourse to an unknown quality in the air, every time they are
called upon to account for the disease prevailing chiefly in our cities,
and not spreading when it is carried from them into the country. The same
reference to an occult quality in the air is had by all the writers upon
the plague, in accounting for its immediate and total extinction, when it
is carried into a foreign port.
In speaking of the influence of an inflammatory constitution of the
atmosphere in raising common bilious, to malignant yellow fevers, I wish
not to have it supposed, that its concurrence is necessary to produce
sporadic cases of that, or any other malignant disease. Strong exciting
causes, combined with highly volatilized and active miasmata, I believe,
will produce a yellow fever at any time. I have seen one or more such
cases almost every year since I settled in Philadelphia, and particularly
when my business was confined chiefly to that class of people who live
near the wharves, and in the suburbs, and who are still the first, and
frequently the only victims of the yellow fever.
It has been said, exultingly, that the opinion of the importation of the
yellow fever is of great antiquity in our country, and that it has lately
been admitted by the most respectable physicians in Britain and France,
and sanctioned by the laws of several of the governments in Europe. Had
antiquity, numbers, rank, and power been just arguments in favour of
existing opinions, a thousand truths would have perished in their birth,
which have diffused light and happiness over every part of our globe. In
favour of the ancient and general belief of the importation of the yellow
fever, there are several obvious reasons. The idea is produced by a
single act of the mind. It requires neither comparison nor reasoning to
adopt it, and therefore accords with the natural indolence of man. It,
moreover, flatters his avarice and pride, by throwing the origin of a
mortal disease from his property and country. The principle of thus
referring the origin of the evils of life from ourselves to others is
universal. It began in paradise, and has ever since been an essential
feature in the character of our species. It has constantly led
individuals and nations to consider loathsome and dangerous diseases as
of foreign extraction. The venereal disease and the leprosy have no
native country, if we believe all the authors who have written upon them.
Prosper Alpinus derives the plagues of Cairo from Syria, and the
physicians of Alexandria import them from Smyrna or Constantinople. The
yellow fever is said to have been first brought from Siam (where there
are proofs it never existed) to the West-Indies, whence it is believed to
be imported into the cities of the United States. From them, Frenchmen
and Spaniards say it has been re-shipped, directly or indirectly, to St.
Domingo, Havanna, Malaga, Cadiz, and other parts of the world. Weak and
absurd credulity! the causes of the ferocious and mortal disease which we
thus thrust from our respective ports, like the sin of Cain, "lie
exclusively at our own doors."
Lastly, it has been asserted, if we admit the yellow fever to be an
indigenous disease of our cities, we shall destroy their commerce, and
the value of property in them, by disseminating a belief, that the cause
of our disease is fixed in our climate, and that it is out of the power
of human means to remove it. The reverse of this supposition is true. If
it be an imported disease, our case is without a remedy; for if, with all
the advantages of quarantine laws enforced by severe penalties, and
executed in the most despotic manner, the disease has existed annually,
in most of our cities, as an epidemic, or in sporadic cases, ever since
the year 1791, it will be in vain to expect, from similar measures, a
future exemption from it. Nothing but a belief in its domestic origin,
and the adoption of means founded upon that belief, can restore the
character of our climate, and save our commercial cities from
destruction. Those means are cheap, practicable, and certain. They have
succeeded, as I shall say presently, in other countries.
From the account that has been given of the different ways in which this
disease is communicated from one person to another, and from the facts
which establish its propagation exclusively through the medium of the
atmosphere, when it becomes epidemic, we may explain several things which
belong to its history, that are inexplicable upon the principle of its
specific contagion.