our northern progress, both in our sensations of cold, and in the actual state of the weather; for there were only three days of this week free from rain, and even these were raw and hazy. Thermometer on the two first days was 77o; on the third, 76°; and, then, falling regularly two degrees daily; on the 6th it stood at 68°. Admitted 18: 6 bruises; 6 phlegmon; 2 slight ulcer on the leg; 1 cynanche tonsillaris; 1 diarrhoea; 1 pain of bowels; 1 rheumatism. Discharged this week 16, remain 30. After the 5th of this month no lemonade was served out to the ship's company. This week also, the men were ordered to lay aside their light clothing, and to wear their winter dress.

Eighth Week-from 6th to 14th March.

On the 11th we arrived off the mouth of the bay of Chesapeake (about lat. 36°, long. 76°), when we continued to cruise for some time. State of the weather during this week was as follows: first day hazy; next hazy, with frequent showers of rain; two last fair, with a good breeze, and remarkably cold. Thermometer this week exhibited considerable and sudden changes. On the 7th it stood at 65°, on 11th that 61; during the intervening days it was always as high as 64°, and sometimes higher; but on the morning of the 12th it was as low as 51°, being a change of 10° in the course of 16 hours. It continued as low all this day, and only rose one degree on the next. Added to the list this week 21: 12 diarrhoea; I catarrh; 3 rheu matism; 2 phlegmon; 2 bruises; 1 old case of hepatitis. Discharged 22; in the list 29.

Ninth Week-from the 13th to the 21st of March.

The whole of this week we cruized off the mouth of the Chesapeake; during which time no rain fell, though it was generally hazy, and the wind was remarkably cold. Average height of the thermometer 58°, though, to our sensations, the cold was much greater than in the English Channel, when the mercury stood at the same point. Added to the list 20: 9 diarrhoea; 1 cynanche tonsillaris; 1 phthisis; 9 bruises. Two of the diarrhoeas were relapses. Number discharged this week 13; remain on the list 36. On the 17th, the ship's company were put on two-thirds allowance of provisions, and one-half of their allowance of liquor was served in grog. On 20th we left the Chesapeake.

Tenth Week-from 20th to 28th March.

During this week the weather was bad, it having rained for the greater part of four days, with several showers of hail. Average height of the thermometer 64o. Admitted 16 cases: 3 of diarrhea;

dirrhoea; 2 catarrh; 3 phlegmon; 1 hæmorrhois; 1 rheumatism, (re-admitted ;) 3 bruises; 1 fractured rib; 1 ulcer leg; 1 feverish complaint. Discharged 16; remain on the list 36. On 28th we were in lat. 39o, long. 46°.

Eleventh Week-from 27th March to 4th April.

State of the weather this week variable. On the 28th it was very cold, the thermometer being as low as 57°. The three first days of April were rainy, the intervening days very agreeable weather; and the average height of the thermometer for the whole week was 67°. On the 2d of April we were saluted by the battery of Flores, the most westerly of the Western Islands. Admissions this week 11: 5 cases of diarrhoea; 3 catarrh; 1 phlegmon; 1 bruise; 1 ophthalmia. Discharged 19; remain on the list 28.

Twelfth Week-from 3d to 11th April.

During this week, standing to the northward and eastward, we enjoyed good weather; there was no rain, and the temperature did not feel very cold, although the thermometer was falling daily. On the 11th, it stood at 60°. Ten cases added to the list this week-4 diarrhoea, (1 re-admitted ;) 1 catarrh ; 2 phlegmon; 1 feverish; I bruise; 1 rheumatism. Number discharged 12; remain on the list 26.

Thirteenth Week-from 10th to 18th April.

This week occupies the time from our arrival off Cape Clear, in Ireland, till we anchored in Cawsand Bay. There was no rain this week, the sky being generally clear, and a very cold (contrary) wind blowing. Thermometer was now as low as 54°. Admitted 20: 13 cases of diarrhoea, (2 re-admitted;) 1 rheumatism, (readmitted; 2 phlegmon; 3 bruises; 1 catarrh. Discharged 10; remain on the list 36.

Postscript, 10th May 1808.

On the 18th of April we anchored in Cawsand Bay. The ship's company were then put on fresh provisions, and had small beer in lieu of grog and wine: For a week after we came in here, the weather was extremely disagreeable, owing to the almost continued fall of snow and rain; and, indeed, the winter seemed to continue till the first of May, when the sudden change to fine weather exhibited a most striking specimen of the inconstancy of our climate. The weather is now very good. During the whole month of April, the diarrhoeal complaints continued, but gradually decreased in frequency as the month declined. The number

of

of diarrhoeas admitted since the 18th of April has been about 30. Almost the whole of these were admitted before the 28th; two only appeared on the first days of May. In short, the diarrhoea seems now completely gone. I shall only make three remarks upon this diarrhoea: 1. That the greater number of men in the ship were attacked by it, but (except in those that are mentioned) in so slight a degree, as not to interfere with the performance of their duty. 2. That in no case did unequivocal symptoms of dysentery appear; and, 3. That it was not confined to our ship alone, but extended (though I cannot say to what degree) to the other ships of the squadron.

VI.

Observations on the Yellow Fever. By D. J. H. DICKSON, M. D.

THE HE following observations on the non-contagious nature of the yellow fever may not be unacceptable, as the subject has given rise to much discussion, and still continues, I perceive, to excite considerable interest. On my arrival in this country, three years ago, from what I had heard and read of the frequency and mortality of this disease, I was at a loss to account for its ravages, without having recourse to the agency of contagion. Others, I believe, have very generally entertained a similar idea at first; and it is no inconsiderable proof of its fallacy, that it has been so uniformly rejected, after farther investigation and experience. I was not then aware, nor is it sufficiently known, that the danger of the climate, at first, consists in a tendency to induce a peculiar state of the system, or predisposition, so favourable to this fever, that agents, otherwise inefficient, become equal to its production: thus, though the disease most frequently proceeds from the concurrence of strong muscular action, under a vertical sun, with intemperance, yet, where the predisposition is already strongly established, it is excited by causes less powerful, dissimilar, and even obscure. Hence, under these circumstances, when a body of men, as a regiment, or ship's company, are indiscriminatsly exposed to the influence of such powers, the effect will also be general, and so many men will frequently be seized with the same complaint, as to give it an epidemic appearance.

After

After much active service, sickness is unavoidable; but I feel no small satisfaction in being able to prove, that where exposure beyond a certain degree can be escaped, health may be preserved in the West Indies, and mortality obviated to an extent heretofore unknown. I cannot at present enter into a description of the malady in question; but I am inclined to think, that its phenomena may be explained upon principles more satisfactory than that of contagion, and that a contrary opinion must either have arisen from an incomplete view of its nature, in situations where typhoid, or other contagion, actually existed, or from other adventitious and unusual causes, tending to blend and modify diseases different in type and in origin. That many cases which have been detailed as such, were not the legitimate yellow fever of the West Indies, I am warranted to infer, because I am confident, that this disease, when formed, cannot be cured by those means which have been described as having been employed with so much success; and because I have occasionally seen cases so altered, by fortuitous circumstances, as to render the diagnosis extremely dificult.

In this organic fever (if I may use the expression, where orga nic affection of the stomach and viscera forms the great characteristic), the apparent is by no means proportionate to the real danger; it is by experience alone, that the practitioner can be convinced of the fatality which he has to cope with. In forming a diagnosis also, he can only be guided by a combination of symptoms, and not by any one taken individually. Thus, although what has been termed the black vomit, is justly considered the most fatal and infallible criterion of yellow fever; yet a matter supposed to be similar may have been ejected, proceeding from other causes than disorganization of the stomach; as from a mixture of black bilious sordes, from other diseased secretions, from certain ingesta, and especially from a portion of grumous blood effused in consequence of injuries done to the stomach, with or without fever; and, lastly, morbid anatomy has often discovered a darkcoloured fluid in the viscera, in situations where this disease could not be suspected. I may therefore repeat, that its presence can only be ascertained from a conjunction of appearances, and that it sometimes may have been supposed to have been cured where it did not exist. I only mean to show, that misconstructions upon this subject are not improbable.

I cannot help thinking, that the difficulty of elucidating the nature of fever in general, is increased by confounding cause and effect; by not distinguishing between symptoms as the consequence of morbid actions, and those actions themselves; and again, by not attempting, with unwearied assiduity, to rise from

the

the latter to the proximate cause or essence of the disease. Increase of the circulation, and of heat, I take to be examples of symptoms having undue influence upon the mind in judging of fever. Instead of these being considered the result of febrile changes, they are too often taken for the disease itself. No man will deny their utility to a certain extent, as indications in prognosis and in practice; but every man of expe rience must have found, that fever is a great deal more than heat, and a quick pulse; that, allowing he could regulate these aberrations, yet he could not thereby cure this disease; and that, in the slightest cases, he has observed their presence, while, in the worst cases, he has occasionally found them absent.

Aware of the obscurity and difficulty of such discussions, it is now foreign to my purpose to pursue the subject further; but I have long been of opinion, that the operations of the animal conomy, both in health and disease, and particularly in that most complicated disease called fever, cannot be explained by any system which builds upon simplicity as its basis.

I differ, with regret, from some respectable authorities that have attempted to draw a parallel between the plague and yellow fever. I am probably not acquainted with all the arguments adduced; but after having been twelve months in the Levant, with unusual sources of information, I cannot trace any satisfactory analogy in support of this opinion. It is true there are symp toms referable to a change of sensation and of action in the early, and others connected with a loss of vital power in the advanced stages of fever; but these are common to fevers in general, and not peculiar to those in question. As far as I have had an opportunity of observing, the plague (though modified by variations of the attendant fever), is an unknown contagion, obeying its own laws, regular in its habits, and equally inimical to the native and to the stranger. The yellow fever, on the contrary, is generally produced by evident causes, yet requiring predisposition to give them effect. This predisposition, peculiar to the stranger, accumulates for a time, then decreases, and ultimately wears off, leav ing the assimilated constitution like that of the native, free from danger, unless the most powerful causes are applied; and, after a certain time, it is to be doubted if even these can excite the dis

ease.

Finally, neither in the course of my own observations, nor in the numerous communications that have been made to me, as physician and inspector of the naval medical department on this station, have I been able to trace the agency of contagion:-and I am, therefore, led to conclude, that while the quarantine laws

are