
You might not want to live inside this book.
Hollow Earth
If you not only read sf but read about sf, take a look at Standish's Hollow Earth. Though not intentionally focused on science fiction, he spends most of his time talking about it.
This book is a short history of hollow earth ideas from the time of Sir Edmond Halley to the present. To explain abnormalities in the Earth's magnetic field, Halley proposed that the Earth is hollow, and things haven't been the same since.
Standish describes the misbegotten notions of John Cleves Symmes, who believed and taught, for no good reason, that the Earth is hollow and has openings at the poles. He discusses Jules Verne's Journey to the Center of the Earth
Probably his most interesting chapter is on Cyrus Teed and the religion he founded, Koreshanity, which teaches not only that the Earth is hollow but that we're living on its inner, concave surface. His description of the religion is lucid, apparently well researched, and generally free of Standish's sarcastic comments, which grow old after a few chapters. The basic purpose of Teed's religion, apparently, is to replace a fathomless universe with one finite, comforting, and womblike.
From that point forward, the most interesting parts of the book are over. Genuine hollow earth theories are replaced by a parade of science fiction stories, which Standish summarizes. He spends extra time on the Pellucidar stories of Edgar Rice Burroughs, beginning with At the Earth's Core
Hollow Earth eventually peters out with a few New Agey things off the Internet, specifically dealing with the underground New Age paradise of Agartha. Unfortunately, Standish doesn't spend much time giving the details or history of this myth.
The book would be more enjoyable if Standish didn't have such a wiseguy attitude. In particular, an absence of sarcasm would have made his errors more bearable. He mistakenly characterizes The Lord of the Rings
For those who like to know the history of sf ideas, this book is worth reading in spite of its drawbacks. To Standish's credit, his summaries of sf novels never quite grow entirely wearisome.