John Cleves Symmes Jr. was an officer in the U.S. Army. In 1818 he sent a circular to scholars and politicians claiming that “the Earth is hollow, habitable within, and open at the poles,” and called for an expedition to find the hole at the North Pole.
The supposed entrances to the underworld at the poles came to be called “Symmes holes,” and his lectures made the hollow Earth theory widely known in America. The movement is also said to have been one impetus for later American Antarctic exploration.
