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Previously to the description of his own manner of finding the longitude, the Viscount describes about twenty other methods which have been proved to be ineffectual; this part is the least unamusing of the whole treatise; and M. de Vaux is nowhere so successful as when he points out the defects of the plans which he describes. We suspect that his own method, however, will not obtain reception, even in an age of diminished prejudice. It is by no means, nor in any respect, to be compared with the method of finding the longitude by observation but perhaps it is not fair to compare it with the astronomical mode, since it is intended to be used always, and when the former cannot be adopted on account of obscurations. The Viscount's method rests on a machine which may be called an improved log, but to which he has given the less vulgar name of an Hydroscope. In its essential parts, it consists of a globe, which is to be immersed at the stern of the ship; this globe, through an inclined tube, is connected by means of a cord with a spring, such as would be formed by circumvolving an elastic wire round a cylinder: the spring is furnished with an index; and when the motion of the ship increases, the globe's resistance is also increased, the spring is drawn out, and the quantity of the elongation is shewn by the index; and similarly, in a relaxation of the ship's velocity. On this method, the Viscount relies for a good dead reckoning; and he certainly has obtained and stated the testimony of Dr. Mackay in favour of the superiority of his hydroscope over the common log. The Board of Longitude, we apprehend, rejected his plan: yet he still seems to entertain hopes of converting the members to its adoption, by re-stating a list of queries; the purpose of which, however, may be only to convince the public of the want of discernment and impartiality in the Board. Some of the queries would not give much trouble in decision to commissioners who are philosophical: for instance, can any astronomical observations be made during foggy weather, or when the heavenly bodies are obscured by clouds or otherwise?'-Again, would not the invention of a better instrument than the log, for the purpose of ascertaining a ship's way, be of great benefit to the public?"
At the end of his tract, the author informs us that his plan has been four years before the Admiralty, and two years before the Board of Longitude and the India House. If his hydroscope should he found likely to produce practical benefit, we are persuaded that he will have no reason to complain of the justice and liberality of those societies. M. de Vaux is certainly possessed of ingenuity, though we have not been able to praise his composition; and the application of his
tim to the pursuits of science is so deserving of general
ART. XI. A Letter to John Haygarth, M.D. F.R.S. &c. from
CONSIDERABLE time has now elapsed, since Dr. Chisholm published an account of the fatal fever which prevailed in the year 1793 in the island of Grenada*. He supposed that it was brought there by a vessel called the Hankey, which had been employed in an unsuccessful attempt to establish a colony at Bulama on the west coast of Africa. The crew of that ship had suffered severely from fever in their passage across the Atlantic, and arrived in the West Indies loaded with contagion the disease was first communicated to Grenada, and thence to the other islands; and Dr. Chisholm thinks that it was afterward conveyed to the United States of America, and that it gave rise to the destructive epidemic which has generally been denominated Yellow Fever. This opinion concerning the origin and contagious nature of the fever, which has at different times proved so fatal to the North American cities, is contrary to that which is entertained by a majority of their medical writers; and it was accordingly attacked with that warmth, and we must add rudeness, which are but too characteristic of transatlantic literary productions. In the publication now before us, Dr. Chisholm vindicates his former opinion, and endeavours to bring forwards new arguments in its support; while, at the same time, he spares no pains to point out the insufficiency and unfairness of the attack which has been made on him. His principal antagonist is Dr. Miller, the editor of the New York Medical Repository; and it was in a report drawn up by him respecting the fever which prevailed at New York in the autumn of 1805, that Dr. C.'s doctrines were the most severely criticised, and to which the present volume may be considered as an immediate reply.
Dr. Chisholm undertakes his defence by stating the following propositions, which refer to allegations brought against him by Dr. Miller:
See Rev. Vol. xix. N.S. p. 62,
1st. That my opinions concerning the malignant pestilential fever, as it appeared at Grenada, and the other West India islands in 1793, 4, 5, and 6. are not singular. 2d. That this fever and the yellow remittent are not "precisely the same disease." 3d. That my deduction of the disease from the pestilential state of the ship Hankey is just, correct, and supported by evidence corroborative of that which I received from Mr. Paiba. 4th. That in my letter, published in a mutilated state in the Medical Repository of New York, and quoted by Dr. Miller, I have not relinquished the doctrine and opinions I upheld in my essay.'
As far as Dr. C. is personally concerned, we think that he is very successful in his defence; that he clearly proves the existence of inaccuracy, if not a want of candor, in the representations which have been made respecting his former publication; that conclusions were formed from his writings which could not fairly be inferred from them; and that subsequent investigation has still farther confirmed his original statement of facts. We do not feel ourselves warranted in bringing against Dr. Miller the serious charge of intentional misrepresentation: but, though we may acquit him of this transgression, we must condemn the intemperate zeal which he displays in support of his hypothesis; a zeal which leads him to magnify all that is favourable to it, and to shut his eyes against all that opposes it.
Besides what relates to Dr. Chisholm individually, this volume derives considerable interest from the light which it throws on the question whether the American fever be really contagious, or whether it be produced by existing causes, which act at the same time on a number of individuals. The facts adduced by Dr. C. are strongly in favour of his opinion; and it can scarcely be doubted that the fever which prevailed at Grenada in 1793 was brought thither from Africa, and that it spred from Grenada to the other parts of the West Indies. It must also be admitted that the intercourse, which subsisted between the West Indies and the cities of the United States, was sufficient to carry the malady to the Continent; and that it commenced there in the way in which a disease might be supposed to appear that was propagated by contagion. Yet this hypothesis is not without its difficulties. In the first place, we may observe that, considering the violence and frequency of the disease, it is remarkable that its contagious nature should ever have been a subject of controversy. Were a typhus fever to exist in this country in a degree nearly equal to the epidemic of Philadelphia or New York, the direct effects of contagion would be too evident to admit of any scepticism. Another circumstance, which appears to us not sufficiently explained by those who maintain the doctrine of contagion, is
that, notwithstanding the extreme violence with which the fever raged in the large towns, and the perpetual emigration of the inhabitants into the country, the disease was (generally speaking) confined to the large towns. The third difficulty which presents itself to us is the manner in which it made its appearance, only at particular seasons of the year; coming on after intervals of perfect health: prevailing for a limited time with great violence; and then suddenly ceasing. We are aware that none of these points can be absolutely conclusive on either side of the question: though the disease be propagated by contagion, yet particular states of the atmosphere may be necessary to render that contagion active; and the contagion of different diseases may obey different laws as to the mode of its propagation, the extent of its sphere of infection, and the previous state of the constitution which is necessary for receiving its influence. On some of these points, Dr. Chisholm has offered many ingenious observations; and he has partly anticipated our difficulties, by endeavouring to prove that the American fever is a disease sui generis, which actually possesses distinct properties, both as to its symptoms and as to the mode of its production. His remarks on the relation which it bears to the true plague, such as exists on the shores of the Mediterranean, afford a good example of his powers of discrimination, and probably for the most part must be admitted as forming a correct deduction from acknowleged facts:
I imagine it would be doing injustice to my subject, did I not advert to a very striking peculiarity of the malignant pestilential fever; I mean its affinity to that disease, which, to be distinguished, has been named the true plague. I know however there are some excellent men, and learned and enlightened physicians, who have more than insinuated that, in proving this affinity, too much is proved; or in other words, that he who attempts to establish that the true plague and the malignant pestilential fever are one and the same disease, goes far to overthrow the doctrine of infection and contagion in general. There is nevertheless a manifest distinction; for whilst it is evident even to the common observer that an affinity between the two diseases exists, it is evident to the acute observer that there is a line of demarkation. Thus an affinity is manifest in the remote cause, infection, and in the predisposing habit of body neces sary to give activity to the virus of that infection: thus there is a distinction in the mode of divergence of the effluvia emanating from the diseased to the healthy; and in as much as the same atmospheric temperature promotes in one and checks in the other, the diffusion of contagion. This is the cause why the two diseases have never been found to exist at the same time in the same country; this is the cause why true plague has never been seen within the tropics; it is also the cause why the malignant pestilential fever may exist without as well as within the tropics, when the temperature of the atmo
sphere of the former rises to the degree generally prevalent in the latter.'
Our minds have been very forcibly impressed, during the perusal of this work, and of others that we have read on the subject of the American fever, with the remark that, whatever may be the fact with respect to the existence of contagion, the causes which have been assigned for the production of the disease by the opposite party are futile in the extreme. A large city has been supposed to be half depopulated by a few heaps of putrid vegetable or animal matter, by a cargo of damaged coffee, or even by some putrid fish that was thrown on a lime-kiln! It appears, indeed, that the greatest part of the American physicians have unfortunately set out on the inquiry with their minds firmly persuaded of the truth of a particular hypothesis; and that they have then thought of nothing. but pressing into their service any incident, however trifling, which might seem in the smallest degree to favour their opinion. --Another observation which we shall make on the same subject is that, if this dreadful pestilence be of domestic origin, if it really did proceed from the filthy state of their cities, and if those reservoirs of putrefaction actually exist which are described in such glowing language by Dr. Miller and his disciples, the inhabitants of the United States give a proof of unfeeling inattention to the lives of their fellow-citizens which is in the highest degree culpable and shameful. In all the kingdoms of Europe, as wealth and civilization have advanced, one of the first consequences has been an increased attention to cleanliness, and a proportionate diminution of the diseases which arise from the want of it :-but, according to the hypothesis of Dr. Miller, it has been reserved for America alone to exhibit an example of the contrary progress. Let those who believe in the domestic origin of the complaint extricate themselves from the disgraceful dilemma in which they are placed; and let them be on the watch to obviate every circumstance which, according to their hypothesis, can produce the disease. If it be subdued, the object is gained; if it still recur, let them acknowlege their error, and then co-operate in the means which are known to be most effectual for preventing the introduction of contagion.