Inner Space

http://books.google.com/books?id=zkNRAAAAYAAJ

In 1914 Edgar Rice Burroughs published At the Earth’s Core, a fantastic tale in which an elderly inventor and his young friend discover that the earth is hollow and contains a concave world lit by a tiny sun. This land, known as Pellucidar, is peopled by intelligent races and inhabited by monstrous prehistoric creatures.

Strikingly, a year earlier Marshall Blutcher Gardner had proposed nearly the same idea in earnest. In A Journey to the Earth’s Interior he had described a hidden land lining the interior of our hollow planet:

Here, indeed, we may expect to find a new world — a world the surface of which is probably subdivided, like ours, into continents, oceans, seas, lakes, and rivers. Here, through the heat of the interior sun, plant life may exceed in size and luxuriance any vegetation that ever grew upon the outside surface of the earth. Here may be found strange animals of every description; some of them even larger, perhaps, than the prehistoric mammoth or mastodon, on account of the abundant supply of vegetation, and others of species unrecorded by zoologists. Here, also, may tread the feet of a race of people whose existence is entirely unknown or hitherto unsuspected by us.

Gardner had even patented a hinged globe to help explain his theory. He concluded his book with a call for an expedition to explore this new world, declaring that “the whole truth apparently has not yet been revealed.” In a strange sense, Burroughs’ characters discovered that world the following year.