1. It exists independently of the sensible qualities of the air, and in all kinds of weather. Dr. Patrick Russel has proved the plague to be equally independent of the influence of the sensible qualities of the atmosphere, to a certain degree.
2. The influenza passes with the utmost rapidity through a country, and affects the greatest number of people, in a given time, of any disease in the world.
3. It appears from the histories of it which are upon record, that neither climate, nor the different states of society, have produced any material change in the disease. This will appear from comparing the account I have given, with the histories of it which have lately been given by Dr. Grey, Dr. Hamilton, Dr. A. Fothergill, Mr. Chisholm, and other modern physicians. It appears further, that even time itself has not been able materially to change the type of this disease. This is evident, from comparing modern accounts of it with those which have been handed down to us by ancient physicians.
I have hinted in a former essay at the diminutives of certain diseases. There is a state of influenza, which is less violent and more local, than that which has been described. It generally prevails in the winter season. It seems to originate from a morbid matter, generated in crowded and heated churches, and other assemblies of the people. I have seen a cold, or influenza, frequently universal in Philadelphia, which I have distinctly traced to this source. It would seem as if the same species of diseases resembled pictures, and that while some of them partook of the deep and vivid nature of mosaic work, others appeared like the feeble and transient impressions of water colours.
Footnote:
[88] Mr. Howard informs us that the use of tobacco is not a preservative against the plague, as has formerly been supposed; of course that apology for the use of an offensive weed should not be admitted.