On the whole, Dr. Monson concludes, “that the yellow fever is seldom or never generated in this country, and that it is always imported from abroad. An objection to the idea of its being generated in this country is, that it was never known in the interior of this state, or of the United States, so far as I can learn. Had it ever appeared in Connecticut before the year 1743, and June 1794, we should undoubtedly have had some record of the fact. There is no such record, and no person remembers to have heard of such a disease, but at these periods, prevailing in any part of the state. There are numbers of aged persons in New Haven who remember the putrid ulcerous sore throat, small pox, measles, dysentery, &c. raging here with great mortality, but have no recollection of any yellow fever. Hence we may rationally conclude that it never did appear in this state but in the years 1743 and 1794.
“It is evident, from facts before mentioned in this letter, that the yellow fever was propagated in no other way than by contagion, and that this is a specific contagion, and no more diversified, in its operation on the human system, than that of the small pox and measles.
“If the citizens of large commercial cities were attentive in tracing the origin of the yellow fever, on its first appearing among them, they would often find that the disease was imported. In some instances it would be extremely difficult to discover the origin. But the mischief lies in this; that the inhabitants of such cities, whenever a contagious disease makes its appearance among them, endeavour to suppress all rumour of it, from an apprehension of alarming the country, and injuring their commerce; unwilling to believe that there is evil in the city, till the disease spreads in every direction. Then, indeed, when it is too late, they are solicitous in the use of means to arrest its progress. As it extends itself slowly at first, seasonable exertion might both detect its source, and prevent its increase; but when it is diffused through a city, it spreads with rapidity, and it is no longer possible to discover where it began. But as, whenever the yellow fever has appeared in the United States, it has always been in sea-port towns, and originated near wharves, docks, and warehouses, there seems to be high probability that the disease is imported.”
The evidence here seems so strong, that no counter-evidence that can be brought appears likely to invalidate it. The coincidence of the commencement of the fever with the arrival of the ship hath not been denied, as in other cases; and, though it has been attempted to prove that a fever might have arisen from the quantity of putrid or putrescent matters at that time in the town, yet the circumstances of those who were present at the opening of the chest of clothes being taken with the fever, and those who were sick of it in so many cases infecting one another, cannot by any means be overthrown. But the fact is, that even those who contend most violently against importation, do yet allow that it may in some cases be so; but they contend that if proper care be taken it will not spread. Dr. Smith in his letter to Dr. Buel says, “that infection may be brought into any place from abroad; that, under certain circumstances of the place where it is introduced, it becomes very destructive; but that, when these circumstances do not exist, however the person immediately affected, if it be introduced by a sick person, may suffer, it is harmless so far as the general health of that place is concerned. If the subject were viewed in this light, as most assuredly it ought to be, the question of importation or non-importation would sink into its merited insignificance.” But, with due respect to the memory of Dr. Smith, this must surely be accounted a very inconsiderate mode of reasoning. In the instance he speaks of, that of the Zephyr lately mentioned, he allows that Dr. Treat might have caught the disease on board the vessel,[158] “but (says he) as no other person is known to have been infected by that vessel, and as the Doctor communicated it to no person, the advocates for importation would not be greatly benefited by the concession.” Surely we must look upon the life of Dr. Treat himself to have been a matter not entirely insignificant, and if he caught the fever by going on board, a number of others who went in full confidence of the impossibility of importation, might have done the same. As far therefore as the prevention of such accidents can be accounted a matter of importance, it is also of importance to believe the doctrine of imported contagion. It is true, Dr. Smith, in the passage just quoted, adds immediately after, that “no such concession (with regard to Dr. Treat) is necessary;” but, in p. [104], he does make an ample concession, as we have seen, viz. that the contagion may not only be imported, but, under certain circumstances, be very active and destructive. The question therefore rests here: Can we at all times promise that, with the utmost care that can be taken, the circumstances of a place may not be such as to give activity to an imported contagion? In the nature of things it is impossible that the docks, wharves, streets and alleys of a large town can be absolutely clean. It is equally impossible that all men can be advised to be temperate, cleanly, and neat in their lodgings; and we are unable to determine how far people may deviate from the rule of right in those respects without danger. Before any theory of this kind could be supported, it would be absolutely necessary to bring an unequivocal proof that yellow fever had been in one instance at least produced by local causes; but this cannot be done. Among the Hottentots, the dirtiest people in the world, no such disease exists. Among the peasants of Poland, who likewise live in a very dirty manner, their mode of life is said to produce not a fever, but a disease of the hair, called the plica Polonica. In the Medical Repository, vol. i, p. 276, Dr. Mitchill of New York describes a disease called elephantiasis, liktraa, or scurvy, occasioned by loathsome, putrefying diet, such as rotten fish, fish-livers and roe, fat and train of whales and sea-dogs, congealed sour milk, with little or no vegetable provisions, and by exposure to wet and cold. This disease prevails in Iceland, in the Ferro islands, in two districts of Sweden, and in Madeira; yet this disease is not the yellow fever, though it is said to make the person afflicted with it more like “a putrefying corpse than a living man.” The cold seems to be assigned as a reason why the disease does not assume a febrile form; but, however this may hold with Iceland, it cannot with Sweden, where the summer is so hot, that the sun has been said to set forests on fire. This is probably a fable; but we are assured by Pontoppiddan, in his Natural History of Norway, a country to the full as cold as Sweden, that in summer the heat is very great. His expression is, that it is enough to “make a raven gape.” As to Madeira, where the climate is warm, there can be no such objection. But a particularity of this disease is, that it is infectious. Supposing then that by any means it should be exalted into a fever, have we any reason to imagine that in such a case it would lay aside its infectious property? Surely not. If this then is the case with a disease produced by the same causes with the yellow fever, we have the very same reason to suppose that the latter is infectious, as that the former would be so if it could lay aside its present form, and assume that of fever. Another proof that mere dirtiness cannot at all times produce a distemper, or even propagate its infection, may be deduced from the sixth case quoted p. [355] from Dr. Russel, where he says that a poor Jewish family lived in a place such as he had always considered as one of the receptacles of contagion, yet only one in six of those who remained in it was taken with the plague. In all cases of plague, or of violent epidemic disorders, it has indeed been observed that the poor were more subject to an attack than the rich. This was so remarkable in the plague of London in 1665 that Dr. Hodges says it was called the poor’s plague; and Dr. Ferriar tells us from Diemerbroeck, that in some parts of Italy it was customary in the beginning of a pestilence to drive out the poor; and likewise that this cruel expedient was used at Marseilles. The bad success of the experiment at this last place, however, shows that people of any description, and in any circumstances, may be attacked. A very probable cause, entirely distinct from any mode of living, may be assigned in this case, viz. that the poor are more exposed to infection than others, both from their circumstances and their rashness; for it will be evident to those who converse with the most uninformed people of any country, that the Turkish notion of predestination is far from being confined to Mahometans. It is not, however, denied, that dirtiness, as well as other local causes, may do much hurt, and occasion the spreading of a disease which otherwise would not spread; because uncleanness of all kinds seems to be the proper vehicle of infection, in which it appears to delight to take up its abode. In the Medical Extracts, vol. ii, p. 174, we have from Goldsmith the following anecdote concerning the concentration of pestilential infection in the plague of London:
“A pious and learned schoolmaster, who ventured to stay in the city during the plague, and took upon himself the humane office of visiting the sick and dying who had been deserted by better physicians, averred, that, being once called to a poor woman, who had buried her children of the plague, he found the room where she lay so little, that it could scarce hold the bed on which she was stretched. However, in this wretched abode, beside her, in an open coffin, her husband lay, who had some time before died of the distemper, and whom she soon followed. What shewed the peculiar malignity of the air, thus suffering from human miasmata or effluvia, was, that the contagious steams had produced spots on the very wall of their wretched apartment. And Mr. Boyle’s own study, which was contiguous to a pest-house, was also spotted in the same frightful manner.” This shows not how infection may be produced, but how it may be concentrated in such miserable apartments. The appearance on the walls brings to remembrance what is said in the book of Leviticus concerning the appearance of the leprosy in walls and clothes.
But, supposing we should allow that dirtiness may bring on a yellow fever (and it is plain that this cannot be proved) we have, in the case of the Busbridge Indiaman, a demonstration that cleanliness cannot keep it off.[159] This vessel sailed from England for the East Indies, in the year 1792, much about the same time that the Hankey sailed for the coast of Africa. She had on board 264 people in all, viz. 109 belonging to the ship’s company, 130 recruits, and 25 passengers. She had very boisterous weather at first setting out, but crossed the equator on the 26th of May, where the weather was sultry, with heavy showers of rain. The disease now made its appearance first among the recruits, and in a fortnight spread among the ship’s company. It was common for six or seven to be attacked with it daily from the commencement; “and in the space of twelve weeks almost every person in the ship not only had laboured under it, but many had suffered repeated relapses.” For several weeks the weather was hot and sultry; but, when in the vicinity of the Cape of Good Hope, they experienced a reverse, and were driven by a storm as high as S. lat. 42. Here the thermometer indicated a temperature only 13° above frost, but no material change in the disease took place. Afterwards, when returning into the warm latitudes, they experienced the sultry heats of the Atlantic without any change either for the better or the worse, and this for no less a space than three months.
As to the origin of the disease, Mr. Bryce the surgeon, though inclined to ascribe it to contagion, could not trace it to any origin of that kind, as the vessel had been six weeks at sea before it appeared. It “could not be ascribed to want of air or cleanliness, as every possible attention had been used to preserve these: the different apartments were thoroughly cleaned and fumigated with wetted gun-powder; the decks were sprinkled with boiling vinegar; and the windsails were attentively kept in order at each hatchway. Mr. Bryce is inclined to conjecture that a peculiar combination in the circumstances of diet, situation, and state of the atmosphere, may have given rise to this calamity. But the same combination of circumstances so frequently takes place without any fever, that it appears much more probable the disease had its origin either from an imported fomes, or from a fomes generated in some individual in the ship, from whence it was afterwards propagated to others by contagion.” The disease produced on board the ship was not contagious to the people on board another vessel with whom they had communication, nor to the people ashore among whom the convalescents were put, nor to new passengers taken on board the vessel in the East Indies; circumstances certainly not a little surprising.
It doth not therefore appear, that, without the intervention of some other cause, mere dirtiness can produce the yellow fever. Let us next see what can be done by confinement, want of air, or, as it has been lately called, abstraction of oxygen. On this, however, we must observe, that in all cases where people are allowed to breathe, their lungs must be filled with the due quantity of some elastic fluid. If the fluid they breathe contains a smaller quantity of oxygen, it must contain a greater quantity of something else. If a disease therefore is produced, it must be occasioned by the presence of that other fluid, as well as by the absence of oxygen. Now, in confined air, we know that not only the oxygen is diminished, and consequently a larger proportion of azote or septon mixed with it, but in addition to this increased proportion of azote, there is also a positive augmentation of the deleterious part of the atmosphere by the effluvia from the bodies of those who are confined. These effluvia, as we have seen, p. [90], contain a great quantity of fixed air. Others have shown that they contain also azote; and it may be so; but still we are sure that the fixed air predominates. Besides this, from the breath we know that a great quantity of aqueous moisture proceeds. Experiments on the action of these different kinds of fluids are yet in an imperfect state, yet some important facts relating to them are known. 1. Oxygen breathed in great proportion produces an augmentation of heat, and proves an universal stimulant. See p. 118. By itself it quickens the pulse.[160] 2. Pure fixed air breathed by itself destroys life with the circumstances of increased heat, rarefaction of the blood, and rupture of the vessels. See p. [206]. 3. The circumstances attending death by breathing azote are not particularly recorded; but we know that by breathing an atmosphere lowered by it the consumptive fever is not increased, but diminished; and there is an account in the Medical Annals of a person who was perfectly cured of a consumption by the smell of the bilge-water of a ship. 4. It has formerly been shown, from Dr. Black’s experiments, that, when the vapour of water is condensed in the body, a great quantity of heat must be thus communicated to it. In confined air therefore there is a diminution of the oxygen which produces heat; but there is an augmentation of the fixed air and of the aqueous moisture which increases it; so that, on the whole, the balance must be considered as in favour of the augmentation of heat in the human body; not to mention the quantity of sensible heat continually added to the atmosphere by that which evaporates from the body. This position, however, doth not stand upon the uncertain ground of theory; it is confirmed by the following remarkable fact: Commodore Billings, who commanded a Russian expedition fitted out by the late empress, found, in his travels through the northeastern part of Asia, that the cold of the atmosphere exceeded not only what was known in other climates, but even what most people had been able to produce by freezing mixtures. Dr. Guthrie informs us that he was unable to produce a greater degree of cold than 36 below 0 of Reaumur, though assisted by 20 below 0 of natural cold, and the power of all the freezing mixtures he knew. “How much then (says he) was I surprised to hear Mr. Billings assert, that some spirit thermometers which he had with him, graduated according to Reaumur’s scale, were often as low as 40° below the freezing point of water, that is, 8 deg. below the freezing point of mercury. And once or twice he observed them at 42 deg. below the freezing point of quicksilver.[161]
“During this severe cold (probably 42 below 0 of Fahrenheit) the Nomade Tchutski (a wandering nation on the northeastern extremity of the Asiatic continent) who were conducting him along the coast of the Frozen ocean, in sledges drawn by rein-deer, encamped every night on the frozen snow in low tents, which they quickly formed with the skins of rein-deer, spreading some of them on the surface of the snow, on which they all slept; and he assured me, that, so far from suffering from cold during the night, the heat was so excessive in these fur tents, where from ten to fifteen slept together, according to its dimensions, that no one could bear even a shirt; but all lay in a violent perspiration, naked as they were born, till dawn of day, without the aid of fire, excepting a train-oil lamp, which lighted each tent.”
From this account it seems pretty evident, that, by the accumulation of animal effluvia, a heat may be communicated to the atmosphere greater than that of the human body. We cannot suppose the heat of the tent which put the people in a violent perspiration to have been less than 90° of Fahrenheit; and, supposing the temperature of the external atmosphere to have been at a medium 30° below 0, there must have been a generation of 120 degrees of heat; but the heat of the human body does not exceed 97 degrees, and it cannot communicate more heat than it has. But we must suppose the tents to have been capable, had they been filled to the top, of containing twice the number who did sleep in them. They could communicate to the air therefore only one half of 97 degrees, or 48 1/2°; the remaining 71 1/2° therefore must been derived from the breath and perspiration of the body.[162]