Abstract Summary
Boyle’s mechanistic interpretations of fire and the ‘spring of air’ are relatively well known. The elusive link between these two branches of his science—in particular his sustained and original work on the nature of fluidity—remains understudied, partly due to Newton’s long shadow in the history of fluid mechanics. This paper explores some early eighteenth-century ramifications of these subjects, epitomized by Roger Cotes’s 1708 comment that “hydrostaticks and pneumaticks have in nature so near a relation to each other, that they ought never to be separated.” Building on Boyle and Newton, the first half of the eighteenth century saw the rise of what I call ‘fluid cosmologies’—broad explanatory frameworks constrained by experimental results—combining themes and methods we associate today with geophysics, meteorology, chemistry, and physiology. Two prominent examples appeared in 1727, in Herman Boerhaave’s New Method of Chemistry, which included a famous treatise on fire (one of his four elements-instruments), and Stephen Hales’s Vegetable Staticks, best known for its new analysis of air. Situated in the context of fluid cosmologies, we see how old elements were still employed while being reimagined as universal agents of change. They straddled and marked new natural boundaries and entities, like activity vs. fixity and solution vs. cohesion; the subterraneous, terrestrial, and atmospheric spheres; and material vs. immaterial bodies and environments. More generally, we gain insights into the relations between natural philosophy and natural history as well as pneumatic matter theory after Newton but before Joseph Black and Antoine Lavoisier.
