This is a guest post by Kelly Bilz, Librarian-in-Residence in the Geography and Map Division.

From Jules Verne’s novel (the title of which I borrowed for this blog) to the 1956 movie The Mole People, many have wondered what happens under the surface of the Earth. And many people, from scientists to storytellers, have come up with imaginative subterranean worlds. The Rare Book Division contains three maps from 1668 that show an impressive interpretation of the planet’s inner workings.

In the 17th century, Athanasius Kircher, a scholar, scientist, and Jesuit priest, created this series of maps as part of his book, Mundus subterraneus (Subterranean World), based on his theories about the world beneath his feet. In particular, Kircher thought that volcanic activity and the movements of the tides could be explained by the subterranean world.

The first map, Systema Ideale Pyrophylaciorum, shows a complex system by which fire travels from the Earth’s core to its surface, breaking through via the eruptions of volcanoes (or montes Vulcanii, mountains of Vulcan, the Roman god of metalworking and fire). The map shows a large central fire (ignis centralis) labelled A, with canals labelled C, and smaller lakes (aestuaria) of fire, labelled B. Much like on the Earth’s surface, there are lakes and rivers—albeit these canals are made of fire. You can see the paths that lead from the central flame to volcanic eruptions around the world. The smoke emerging from the volcanoes almost matches the swirling clouds surrounding the globe, perhaps conjuring images of the smoke and ash that accompany volcanic eruptions.

Athanasius Kircher. Systema ideale pyrophylaciorum. 1668. Rare Book Division.

Kircher admits that there are gaps in his theory, asking in his explanatory notes at the bottom, Quis enim haec observavit? (For who has observed these things?) Though current science tells us that the Earth’s core is solid and surrounded by other layers, the notion of a fiery core is not entirely incorrect: the U.S. Energy Information Administration reports that the temperature of the inner core is as hot as the surface of the sun.

However, according to Kircher, fire or pyrophylacia, (fire-houses) was not the only thing traveling through the underground. There were also hydrophylacia, or “water-houses,” that interacted with the ignis centralis and also moved via canals and lakes.

Athanasius Kircher. System ideale qvo exprimitur, aquarum. 1668. Rare Book Division.

Athanasius Kircher. Detail from System ideale qvo exprimitur, aquarum, showing two whirlpools on the ocean’s surface and the “mouths” at the base of two mountains. 1668. Rare Book Division.

This interaction of water and fire under the surface, Kircher proposed, caused the tides. Water was pushed up through the surface at the base of mountains, the mouths of which can be seen on the map. Kircher’s conception of the Earth’s interior is one of movement, and as with volcanoes, the movement of water under the earth could be destructive, too, causing whirlpools.

Kircher presented a lively view of the subterranean, to be sure. He also made a map showing the effects of these underground systems of water and fire on the surface, with volcanoes (montes vulcanios) and whirlpools (abyssos) labelled, seen below.

This map includes common features of other early maps of territories that had newly been discovered by European colonial powers: California appears as a peninsula, and Australia is connected to Antarctica. Volcanoes appear on every continent, except for Australia/Antarctica, which is labelled as “incognita,” or unknown. Whirlpools can be found in narrow passages and around the capes of continents, underscoring the many dangers of exploration.

Athanasius Kircher. Tabula geographico-hydrographica motus oceani,currents, abyssos, montes ignivomos. 1668. Rare Book Division.

Kircher was not only known for his geological theories. His other accomplishments include mapping the mythic island of Atlantis and pioneering studies in Egyptology. Although his view of the underground does not hold up today, these maps are striking examples of how maps can be used for scientific purposes, both under the Earth and beyond it.

Learn more:

Explore other geological maps in G&M’s digital collections.

Learn about the earth’s magnetism in the blog post, “The Earth Itself Is A Great Magnet”.

Read more about the cartographer, Athansius Kircher, 1602-1680!