also build an artificial changing sun to light their world. Two balloonists, an American and an Englishman, discover this world. Etidorhpa (1895) by John Uri Lloyd is set within a hollow Earth. In the sociologist Gabriel Tarde's only literary work, Underground Man (1896) (original French title Fragments d'Histoire Future), Humanity escapes a second apocalyptic ice age by delving under the earth and reforming society with Art as its central value. Charles Willing Beale's 1899 novel, The Secret of the Earth tells of the adventure of 2 brothers who build an anti-gravity airship and travel to the hollow earth. There they find several lost races, and learn that mankind originated in the hollow earth, but the unruly types were exiled from the hollow earth. They then exit via the South Pole opening and crash on an island in the South Pacific, from which they send off a log of their adventures which forms the novel. The concept was mentioned in Wardon Allan Curtis's 1899 short story "The Monster of Lake LaMetrie". In NEQUA or The Problem of the Ages a visit in a sailing ship is made to Altruria, a society inside the earth. This feminist utopian science fiction novel was published in 1900 in Topeka Kansas. Jack Adams listed as the author, was a pseudonym for A. O. Grigsby and Mary P. Lowe, both newspaper publishers. An underground Nome Kingdom is featured in several of the Oz books by L. Frank Baum, notably Ozma of Oz (1907), Dorothy and the Wizard in Oz (1908) and Tik-Tok of Oz (1914). Willis George Emerson's science-fiction novel The Smoky God (1908) recounts the adventures of one Olaf Jansen who traveled into the interior and found an advanced civilization. Edgar Rice Burroughs wrote adventure stories (beginning with At the Earth's Core in 1914) set in the inner world of Pellucidar, including at one point a visit from his character Tarzan. Burroughs's Pellucidar has oceans on the outer surface corresponding to continents on the inner surface and vice versa. Pellucidar is lit by a miniature sun suspended at the center of the hollow sphere, so it is perpetually overhead wherever one is in Pellucidar. The sole exception is the region directly under a tiny geostationary moon of the internal sun; that region as a result is under a perpetual eclipse and is known as the Land of Awful Shadow. This moon has its own plant