The cold weather in October checked the fever, but it did not banish it from the city. It appeared in November, and in all the succeeding winter and spring months. The weather, during these months, being uncommonly moderate, will account for its not being destroyed at the time in which the disease usually disappeared in former years.
The causes which predisposed to this fever were the same as in the year 1793. Persons of full habits, strangers, and negroes, were most subject to it. It may seem strange to those persons who have read that the negroes are seldom affected with this fever in the West-Indies, that they were so much affected by it in Philadelphia. There were two reasons for it. Their manner of living was as plentiful as that of white people in the West-Indies, and they generally resided in alleys and on the skirts of the city, where they were more exposed to noxious exhalation, than in its more open and central parts.
The summer fruits, from being eaten before they were ripe, or in too large a quantity, became frequently exciting causes of this fever. It was awakened in one of my patients by a supper of peaches and milk. Cucumbers, in several instances, gave vigour to the miasmata which had been previously received into the system. Terror excited it in two of my patients. In one of them, a young woman, this terror was produced by hearing, while she sat at dinner, that a hearse had passed by her door with a person on it who had died of the yellow fever. Vexation excited it in a foreign master of a vessel, in consequence of a young woman suddenly breaking an engagement to marry him. The disease terminated fatally in this instance.
It was sometimes unfortunate for patients when the disease was excited by an article of diet, or by any other cause which acted suddenly upon the system; for it led both them, and in some instances their physicians, to confound those exciting causes with its remote cause, and to view the disease without the least relation to the prevailing epidemic. It was from this mistake that many persons were said to die of intemperance, of eating ice creams, and of trifling colds, who certainly died of the yellow fever. The rum, the ice creams, and the changes in the air, in all these cases, acted like sparks of fire which set in motion the quiescent particles of tinder or gunpowder.
I shall now proceed to describe the symptoms which this fever assumed during the periods which have been mentioned. This detail will be interesting to physicians who wish to see how little nature regards the nosological arrangement of authors, in the formation of the symptoms of diseases, and how much the seasons influence epidemics. A physician, who had practised medicine near sixty years in the city of Philadelphia, declared that he had never seen the dysentery assume the same symptoms in any two successive years. The same may be said probably of nearly all epidemic diseases.
In the arrangement of the symptoms of this fever, I shall follow the order I adopted in my Account of the Yellow Fever of 1793, and describe them as they appeared in the sanguiferous system, the liver, lungs, and brain, the alimentary canal, the secretions and excretions, the nervous system, the senses and appetites, upon the skin, and in the blood.
Two premonitory symptoms struck me this year, which I did not observe in 1793. One of them was a frequent discharge of pale urine for a day or two before the commencement of the fever; the other was sleep unusually sound, the night before the attack of the fever. The former symptom was a precursor of the plague of Bassora, in the year 1773.
I. I observed but few symptoms in the sanguiferous system different from what I have mentioned in the fever of the preceding year. The slow and intermitting pulse occurred in many, and a pulse nearly imperceptible, in three instances. It was seldom very frequent. In John Madge, an English farmer, who had just arrived in our city, it beat only 64 strokes in a minute, for several days, while he was so ill as to require three bleedings a day, and at no time of his fever did his pulse exceed 96 strokes in a minute. In Miss Sally Eyre, the pulse at one time was at 176, and at another time it was at 140; but this frequency of pulse was very rare. In a majority of the cases which came under my notice, where the danger was great, it seldom exceeded 80 strokes in a minute. I have been thus particular in describing the frequency of the pulse, because custom has created an expectation of that part of the history of fevers; but my attention was directed chiefly to the different degrees of force in the pulse, as manifested by its tension, fulness, intermissions, and inequality of action. The hobbling pulse was common. In John Geraud, I perceived a quick stroke to succeed every two strokes of an ordinary healthy pulse. The intermitting, chorded, and depressed pulse occurred in many cases. I called it the year before a sulky pulse. One of my pupils, Mr. Alexander, called it more properly a locked pulse. I think I observed this state of the pulse to occur chiefly in persons in whom the fever came on without a chilly fit.
Hæmorrhages occurred in all the grades of this fever, but less frequently in my practice this year than in the year before. It occurred, after a ninth bleeding, in Miss Sally Eyre, from the nose and bowels. It occurred from the nose, after a sixth bleeding, in Mrs. Gardiner, who was at that time in the sixth month of her pregnancy. This symptom, which was accompanied by a tense and quick pulse, induced me to repeat the bleeding a seventh time. The blood was very sizy. I mention this fact to establish the opinion that hæmorrhages depend upon too much action in the blood-vessels, and that they are not occasioned by a dissolved state of the blood.
There was a disposition at this time to hæmorrhage in persons who were in apparent good health. A private, in a company of volunteers commanded by Major M'Pherson, informed me that three of his messmates were affected by a bleeding at the nose, for several days after they left the city, on their way to quell the insurrection in the western counties of Pennsylvania.