A New Perspective on the Natural Philosophy of Steams and Its Relation to the Steam Engine

Historians' understanding of the steam engine's evolution suffers from back-projections of nineteenth-century physical science, notably thermodynamics, onto the eighteenth century. The idea of steam as a "working substance" to merely transfer heat is anachronistic in the eighteenth-century context. It has led to serious misconceptions. To correct this misreading, this article uncovers three major areas discussing steam in the eighteenth century: producing a vacuum for fire engines and fire pumps; examining experimentally the bulk properties of steam; and the "chemistry of steams" that included studying effluvia and miasmas and that considered steam responsible for earthquakes, winds, storms, and other natural phenomena. In the eighteenth century, more natural philosophizing about steam (and other matters) was done in and across practical settings in the large than historians have realized. Subsequent understandings and later divisions of knowledge and practice have obscured much.