Apparatus for Subterranean Fire (from Mundus Subterraneus)

This engraving depicts a cross-section of a subterranean environment. On the right, a rocky reservoir labeled 'Fons petrolei' (fountain of petroleum) is connected by a winding lead pipe ('Plumbeus Canalis') to a cylindrical lamp on the left. The lamp, set within an arched stone alcove, contains a burning flame. Letters of the alphabet serve as labels for the various components of this mechanical system.

This diagram is from Athanasius Kircher's 1665 'Mundus subterraneus', a seminal work of early modern natural philosophy that attempted to map the earth's interior as a complex, interconnected system of heat, fire, and fluid dynamics.