At the Earth's Core is a 1914 fantasy novel by Edgar Rice Burroughs, the first in his series about the fictional "hollow earth" land of Pellucidar. It first appeared as a four-part serial in All-Story Weekly from April 4–25, 1914. It was first published in book form in hardcover by A. C. McClurg in July, 1922. Short summary:

The author relates how, traveling in the Sahara desert, he has encountered a remarkable vehicle and its pilot, David Innes, a man with a remarkable story to tell. David Innes is a mining heir who finances the experimental "iron mole," an excavating vehicle designed by his elderly inventor friend Abner Perry. In a test run, they discover the vehicle cannot be turned, and it burrows 500 miles into the Earth's crust, emerging into the unknown interior world of Pellucidar. In Burroughs' concept, the Earth is a hollow shell with Pellucidar as the internal surface of that shell.

Chapter I

Toward the Eternal Fires

I WAS BORN IN CONNECTICUT ABOUT THIRTY YEARS ago. My name is David Innes. My father was a wealthy mine owner. When I was nineteen he died. All his property was to be mine when I had attained my majority—provided that I had devoted the two years intervening in close application to the great business I was to inherit.

I did my best to fulfil the last wishes of my parent—not because of the inheritance, but because I loved and honored my father. For six months I toiled in the mines and in the counting-rooms, for I wished to know every minute detail of the business.

Then Perry interested me in his invention. He was an old fellow who had devoted the better part of a long life to the perfection of a mechanical subterranean prospector. As relaxation he studied paleontology. I looked over his plans, listened to his arguments, inspected his working model—and then, convinced, I advanced the funds necessary to construct a full-sized, practical prospector.

I shall not go into the details of its construction—it lies out there in the desert now—about two miles from here. Tomorrow you may care to ride out and see it. Roughly, it is a steel cylinder a hundred feet long, and jointed so that it may turn and twist through solid rock if need be. At one end is a mighty revolving drill operated by an engine which Perry said generated more power to the cubic inch than any other engine did to the cubic foot. I remember that he used to claim that that invention alone would make us fabulously wealthy—we were going to make the whole thing public after the successful issue of our first secret trial—but Perry never returned from that trial trip, and I only after ten years.