RULE I.Fresh and cool air is to be respired.
The least attention to the phenomena of this disorder will convince us, that its process tends to assimilate part of our liquids to the primary variolous atom applied to any part of the body, either by inoculation or natural contagion. The result of this process is an eruption, the matter of which is exactly like that of the first applied atom. The reproduction therefore, and the multiplication of this atom, or the assimilation of our humors with the variolous matter, constitute the essence of this disorder.
Now, as the whole danger is known to consist in this assimilation, or in the quantity of pustules; the object of the treatment ought to be the reducing of it. The free admission of cool air fully answers this purpose; for as heat is the most powerful and universal agent in nature in propagation, vegetation, fermentation, and in general in every process where one substance is to be converted into another; so cold must check and retard the assimilation of our humors with the variolous matter, as it checks the growth of a plant, or the fermentation of a body.
Other reasons might be alledged to explain the salutary effects of cool air in this
