The violence and fatality of this disease have directed very powerfully the attention of physicians to its nature, and particularly of those who have been engaged in the conduct of such epidemics. As it obviously occurred at the period when autumnal remittents were common on the American continent and in the southern parts of Europe, it was highly probable that this was only the usually returning epidemic, from accidental circumstances rendered more violent and fatal. Yet when its nature was more closely examined, this idea was entertained with greater hesitation. It was obviously bilious, but less clearly remittent; its rapid progress did not keep pace with that of the true bilious fever, and symptoms of peculiar debility came on in a very early stage. In short, it was highly probable that it was a typhus, attended with bilious symptoms, rather than a remittent of a peculiarly malignant kind. Some little remission may be observed in the earliest stage, but it is transient, and perhaps not more than by careful attention may generally be observed in typhus.

When the violence and malignity of the disease were ascertained, no country was willing to claim the destructive visitant. It was supposed to be an importation, and probably was so. At Martinique it was the fever from Siam: in America, from Bulam. The discussion would be too long; but, from a careful examination of all the facts, it appears probable that some contagion, uniting with the epidemic tendency of the bilious autumnal remittent of the country, has produced the destructive monster. The observations in Philadelphia seem to trace it to some foreign importation. At Martinico, at Grenada, and Jamaica, there appears always to have been a concurring cause. Iris doubtful, however, whether this is constantly contagion. The putrefaction of vegetable and animal substances, which in any situation may occasion typhus, in concurrence with the autumnal remittent, may produce the yellow fever.

These views will discriminate it from the causus, from the gaol and hospital, as well as from the common bilious fever. In the gaol fever there are little accumulation and discharge of bile: in the others, little of the asthenic and putrefactive state. When we consider fever more generally, we shall distinguish these states, and point out in what cases putrefaction may produce debility, and where debility occasions putrefaction. The yellow fever and the plague are, we think, referable to the latter; and-the distinction is not an object of curiosity and refinement only, for it assists in directing the cure, particularly the exhibition of the Peruvian bark. Much idle - it is an improper word - many highly pernicious disquisitions have been indulged, whether this fever is contagious. The existence of a doubt shows that it may not be highly so. Yet it has in so many instances been communicated from an infected person, that the utmost caution is requisite. It has been even doubted whether the plague is contagious; but those who have suggested and disseminated the doubts, are answerable for the lives of thousands, and in some instances have paid the forfeit with their own.

On dissection, the contents of the brain and thorax were uninjured; but the blood is fluid like that of persons who have been destroyed by electricity. The stomach and duodenum were generally inflamed; sometimes a little extravasation; sometimes pus and a black fluid, black, generally from containing flakes, and evidently a depraved secretion of bile, were observed. On the surface of the other viscera some distended veins were seen, but the liver was generally sound, oes and mulattoes escaped better than the white inhabitants, and those were less frequently and violently affected than strangers. In America, however, the inhabitants and strangers were equally susceptible of the disease.

The American physicians have differed greatly in opinion, whether this fever was an inflammatory or a putrid one. The difference has, we fear, led each party to an injurious plan of treatment: which, as usual, has been pursued with more pertinacity, because it was their own system. We see in this disease, as we have said, an asthenic fever, joined with biliary accumulations; a fever hastening rapidly to a fatal termination, while we do not possess a power of supporting the strength without previously exciting proper discharges; or of producing the necessary evacuations without inducing a fatal debility. The great debility, the anxiety, the sighing, the distended veins, prove the existence of a highly asthenic state. The absence of internal mortification shows, that if the disease becomes pun-id, it is when long protracted.

In the cure, Dr. Rush, adopting the idea of its being inflammatory, bled largely and repeatedly; he adds with success. But were his success so conspicuous, his brethren would not probably have so strenuously urged an opposite plan; nor would the relations of the patients screamed with terror when the bleeding was proposed. This he tells us has often happened. Though we consider Dr. Rush, however, as the slave of prejudice and system, we believe him to speak what he thinks; and we can easily suppose that early bleeding in the manner described may have been useful. We know that Sydenham bled in the plague, and Dover in putrid fevers; we know, too, that other practitioners in the West Indies have bled in the yellow fever with advantage. The bleedings must however be large, and confined to the first twenty-four, or at most thirty-six hours. Dr. Rush at first extended the period in which this remedy might be proper, but in the following epidemics was more cautious. It is not necessary to assign a reason for the utility of bleeding, though we can perceive some foundation for the practice. When in asthenic cases the blood is determined to the larger vessels, if these are not excited to action by the distention, they become still more torpid. Lessening actively the general mass relieves the over distended torpid vessels in a greater degree than the loss of blood weakens the whole system: their action commences, and the salutary discharges are induced.