The Hollow Earth (Rudy Rucker, 1990)

''In 1836, Mason Algiers Reynolds leaves his family’s Virginia farm with his father’s slave, a dog named Arf, and a mule named Dammit. Branded a murderer, he finds sanctuary with his hero, frustrated genius Edgar Allan Poe, and together they embark on an extraordinary expedition to the South Pole, and the entrance to the Hollow Earth. It is there, at the center of the world, where strange physics, strange people, and stranger creatures abound, that their bizarre adventures truly begin.''


https://archive.org/details/TheHollowEarth