1. Heat and cold. While the former has excited the yellow fever in thousands, the latter has excited it in tens of thousands. It is not in middle latitudes only that cold awakens this disease in the body. Dr. Mosely says it is a more frequent exciting cause of that, and of other diseases, in the island of Jamaica, than in any of the most temperate climates of the globe. It is this which renders cases of yellow fever, when epidemic in our cities, more numerous in the cool months of September and October, than in July and August. For the purpose of avoiding this pernicious and universal influence of cold, the clothing and bed-covers should be rather warmer in those months, in middle and northern latitudes, than is agreeable, and fires should be made every morning and evening in common sitting rooms, and during the whole day, when the weather is damp or cool. They serve, not only to prevent the reduction of the excitement of the blood-vessels, by the gradual and imperceptible abstraction of the heat of the body, but to convey up a chimney all the unwholesome air that accumulates in those rooms during a sickly season. By these precautions, I have known whole families preserved in health, while all their neighbours who neglected them, have been confined by a prevailing autumnal fever. 3. The early morning and evening air, even in warm weather. 4. Fatigue from amusements, such as fishing, gunning, and dancing, and from _unusual_ labour or exercise. The effects of fatigue from this cause have been already noticed[17], in the maids of large families being the only persons who die of the fever, in consequence of their having performed great and _unusual_ services to those branches of the family who survive them, while nurses, who only exercise their ordinary habits in attending sick people, are seldom carried off by it. [17] Account of the Yellow Fever in 1793, vol. iii. 5. Intemperance in eating and drinking. 6. Partaking of _new_ aliments and drinks. The stomach, during the prevalence of malignant fevers, is always in an irritable state, and constantly disposed to be affected by impressions that are not habitual to it. 7. Violent emotions or passions of the mind. 8. The entire cessation of moderate labour. This, by permitting the mind to ramble upon subjects of terror and distress, and by exposing the body to idleness and company, favours an attack of fever. A predisposition to it, is likewise created by alternating labour and idleness with each other.