John Cleves Symmes Jr. believed the Earth was hollow and habitable inside. He spent his life trying to get the US government to fund an expedition to the North Pole entrance. He failed. But the idea outlived him.

The Victorian Engineer Who Accidentally Invented a New Religion

9 April 2026

In 1818, a retired US Army captain named John Cleves Symmes Jr. mailed a circular to every member of Congress, every university in America, and assorted institutions in Europe. The circular announced his theory that the Earth was hollow, open at the poles, and inhabited by a civilisation inside. He requested funding for an expedition.

He did not receive funding. He did, however, receive something more durable: followers.

This episode traces the strange afterlife of Symmes's idea — through the hollow earth novels of the nineteenth century, through the occult movements of the 1880s and 1890s, and into the twentieth century where versions of the theory appeared in some genuinely dark places.

What we discuss

Symmes's original theory and its sources. The Congressional response. The hollow earth novel as a literary genre. How the idea entered occult and theosophical circles. The twentieth century revival and its political dimensions.