Sectional view of the "subterranean" earth, showing internal magma and volcanic action at the surface, from Athanasius Kircher 's Mundus Suberraeneus.
Kircher was a Jesuit priest and contemporary of Galileo. His Mundus Subterraneus, an encyclopedic survey of the subterranean or "hidden" world was the first serious effort to describe the physical makeup of the earth, proposing theories (sometimes fantastic) in the areas of physics, geography, geology, and chemistry. It was, in part, based on Kircher's observations of the eruption of Vesuvius in 1637 and the two weeks of earthquakes that shook Calabria in 1638. He suggests the existence of a vast network of underground springs and reservoirs, as well as the theory that subterranean temperatures increase directly in proportion to depth.
The image shows a cross-section of the earth' s interior with its magma core and underground water sources. The surface of the earth is shown with erupting volcanoes and ships sailing in the oceans. The sphere issurrounded by clouds and six wind-heads. Two decorative title cartouches complete the fanciful composition.