There is also a biography of Populist politician Ignatius Donnelly focusing on his speculations regarding Atlantis and like matters, and then a speculative chapter regarding future languages, essentially a didactic piece on language change with application to science fictional treatments of time-travel. It leads into a discussion of nonscientific claims about the "fourth dimension" in general. This part of the book also includes reviews of Immanuel Velikovsky's Worlds in Collision and Erich von Däniken's Chariots of the Gods?, both of which de Camp discounts.