This is a delightful read! The tale reminds me of those old-time chase movies because the action goes and goes and goes. The characters (many) explore, get lost, are captured, escape, and the sequence repeats. Meet David Innes and Abner Perry who drill into earth's interior to discover a world within a world, Pellucidar. Inhabited by cave men and beasts of the time, they find themselves stranded. David falls in love with Dian the Beautiful and Perry invents and invents. The adventures of Innes and Perry combine with those of several other characters. It's great fun to read!
The last Pellucidar novel that Edgar Rice Burroughs wrote.
1963 book published by Ace.
From back cover: Two explorers from the Earth's surface had carved themselves an empire at the Earth's core - Pellucidar. The dangers were many. Untamed tribes and vicious beasts were a constant peril, and there were times when the lives of the surface-men were at stake. But, just when things seemed hopeless, they came up with a trump card - a new weapon. What they didn't realize was that it was a weapon that could bring its makers to the brink of disaster.