22. We have still to add, that sometimes, early in the cold stage, a headach comes on; but which, more commonly, is not felt till the hot stage be formed, and then is usually attended with a throbbing of the temples. The headach continues till the sweat breaks out; but as this flows more freely, that gradually goes off. At the same time with the headach, there are commonly pains of the back, and of some of the great joints; and these pains have the same course with the headach.

23. These are nearly the whole, and are at least the chief, of the phenomena which more constantly appear in the paroxysm of an intermittent fever; and we have pointed out their ordinary concourse and succession. With respect to the whole of them, however, it is to be observed, that, in different cases, the several phenomena are in different degrees; that the series of them is more or less complete; and that the several parts or stages, in the time they occupy, are in a different proportion to one another.

24. It is very seldom that a fever consists of a single paroxysm, such as we have now described; and it more generally happens, after a certain length of time has elapsed from the ceasing of the paroxysm, that the same series of phenomena again arises, and observes the same course as be

fore; and these states of FEVER and APYREXIA often continue to alternate with one another for many times. In such cases, the length of time from the end of one paroxysm to the beginning of another, is called an INTERMISSION; and the length of time from the beginning of one paroxysm to the beginning of another next succeeding, is called

an INTERVAL.

25. When the disease consists of a number of paroxysms, it is generally to be observed, that the intervals between them are nearly equal; but these intervals are of different lengths in different cases. The most usual interval is that of forty-eight hours, which is named the TERTIAN period. The next most common is that of seventy-two hours, and is named the QUARTAN period. Some other intervals also are observed, particularly one of twentyfour hours, named therefore the QUOTIDIAN; and the appearance of this is pretty frequent. But all other intervals longer than that of the quartan, are extremely rare, and probably are only irregularities of the tertian or quartan periods.

26. The paroxysms of pure intermittent fevers are always finished in less than twenty-four hours; and though it happens that there are fevers which consist of repeated paroxysms, without any entire intermission between them; yet in such cases it is observed, that though the hot and sweating stages

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of the paroxysm do not entirely cease before the twenty-four hours from their beginning have expired, they suffer, however, before that time, a considerable abatement of REMISSION of their violence; and, at the return of the quotidian period, a paroxysm is in some shape renewed, which runs the same course as before. This constitutes what is called a REMITTENT FEVER.

27. When in these remittents the remission is considerable, and the return of a new paroxysm is distinctly marked by the symptoms of a cold stage at the beginning of it, such fevers retain strictly the appellation of REMITTENTS. But when it happens, as it does in certain cases, that the remission is not considerable, is perhaps without sweat, and that the returning paroxysm is not marked by the most usual symptoms of a cold stage, but chiefly by the aggrevation or EXACERBATION of a hot stage, the disease is called a CONTINUED FEVER.

28. In some cases of continued fever, the remissions and exacerbations are so inconsiderable as not to be easily observed or distinguished; and this has led physicians to imagine, that there is a species of fever subsisting for several days together, and seemingly consisting of one paroxysm only. This they have called a CONTINENT FEVER; but, in a long course of practice, I have not had an opportunity of observing such a fever.

29. It is, however, to be observed here, that the fevers of a continued form are to be distinguished from one another; and that, while some of a very continued form do still belong to the section of intermittents, there are others which, though still consisting of separate and repeated paroxysms, yet, as different by their causes and circumstances from intermittents, are to be distinguished from the whole of these, and are more strictly to be called and considered as cONTINUED, Such are most of those which have been commonly supposed to be CONTINENT; and those which by most writers have been simply named CONTINUED, and which term I have employed as the title of a section, to be distinguished from that of INTER

MITTENT.

I shall here add the marks by which, in practice, these different continued fevers may be distinguished from one another.

Those fevers of a continued form, which, however, still belong to the section of intermittents, may be distinguished by their having passed from an intermittent or remittent form, to that of a continued; by their shewing some tendency to become intermittent, or at least remittent; by their being known to have been occasioned by marsh miasmata; and, for the most part, by their having but one paroxysm, or one exacerbation and remis sion, in the course of twenty-four hours.

On the other hand, continued fevers, to be more strictly so called, may be distinguished by their shewing little tendency to become intermittent or remittent in any part of their course, and especially after the first week of their continuance; by their being occasioned by human contagion, at least by other causes than the marsh miasmata; and by their having pretty constantly an exacerbation and remission twice in the course of every twenty-four hours. In both cases, the knowledge of the nature of the epidemic for the time prevailing, may have a great share in determining the nature of the particular fever.

30. With respect to the form, or TYPE, of fevers, this further may be observed, that the quartan, while it has the longest interval, has, at the same time, the longest and most violent cold stage; but, upon the whole, the shortest paroxysm: That the tertian, having a shorter interval than the quarten, has, at the same time, a shorter and less violent cold stage, but a longer paroxysm: and lastly, that the quotidian, with the shortest interval, has the least of a cold stage, but the longest paroxysm.

31. The type of fevers is sometimes changed in their course. When this happens, it is generally in the following manner: both tertians and quartans change into quotidians, quotidians into remit