An Essay on Contagious Diseases / more particularly on the small-pox, measles, putrid, malignant, and pestilential fevers

The essay offers a practitioner-focused explanation of several infectious maladies, defining contagion as airborne or effluvial and distinguishing epidemic from pestilential outbreaks. It advances physiological propositions that infectious particles cause blood corpuscles to aggregate or change shape, forming larger molecules that obstruct small vessels and produce eruptions, inflammations, buboes, mortifications, and other symptoms. Early microscopic observations are invoked to support these mechanisms. The author also surveys climatic and atmospheric conditions thought to favor malignant fevers, compares classical epidemic accounts, and presents demonstrations linking observable phenomena to contemporary natural-philosophical principles.