Lost Inside the Earth

David Innes and his inventor friend, when they sought to test the practicability of their "subterranean prospector" made an amazing discovery. The two men pierced through the Earth's crust and found, instead of a core in a highly molten and gaseous state, a world, with living, breathing, functioning humans and animals, but a world still in the Stone Age. The hair-breadth escapes of the two men, the weird monsters encountered, the touch of romance and the manner of telling make this one of Burroughs' very best.

This version has been condensed when published in Modern Mechanix and Inventions magazine.