John Cleves Symmes

John Cleves Symmes (November 5, 1780 - May 28, 1829) was an American army officer, trader, and later author of the hollow earth theory of "Concentric Spheres and Polar Voids," holding that "earth is hollow and habitable within; containing a number of solid concentric spheres, one within the other, and that it is open at the poles twelve or sixteen degrees."