He stepped to a shelf and returned with a large volume, which he opened at a beautifully executed map of Amtor. It showed three concentric circles. Between the two inner circles lay a circular belt designated as Trabol, which means warm country. Here the boundaries of seas, continents, and islands were traced to the edges of the two circles that bounded it, in some places crossing these boundaries as though marking the spots at which venturesome explorers had dared the perils of an unknown and inhospitable land. “This is Trabol,” explained Danus, placing a finger upon that portion of the map I have briefly described. “It entirely surrounds Strabol, which lies in the center of Amtor. Strabol is extremely hot, its land is covered with enormous forests and dense undergrowth, and is peopled by huge land animals, reptiles, and birds, its warm seas swarm with monsters of the deep. No man has ventured far into Strabol and lived to return. “Beyond Trabol,” he continued, placing his finger on the outer band designated as Karbol (Cold Country), “lies Karbol. Here it is as cold as Strabol is hot. There are strange animals there too, and adventurers have returned with tales of fierce human beings clothed in fur. But it is an inhospitable land into which there is no occasion to venture and which few dare penetrate far for fear of being precipitated over the rim into the molten sea.” “Over what rim?” I asked. He looked at me in astonishment. “I can well believe that you come from another world when you ask me such questions as you do,” he remarked. “Do you mean to tell me that you know nothing of the physical structure of Amtor?” “I know nothing of your theory concerning it,” I replied. “It is not a theory; it is a fact,” he corrected me gently. “In no other way may the various phenomena of nature be explained. Amtor is a huge disc with an upturned rim, like a great saucer; it floats upon a sea of molten metal and rock, a fact that is incontrovertably proved by the gushing forth of this liquid mass occasionally from the summits of mountains, when a hole has been burned in the bottom of Amtor. Karbol, the cold country, is a wise provision of nature that tempers the terrific heat that must constantly surge about the outer rim of Amtor. “Above Amtor, and entirely surrounding her above the molten sea, is a chaos of fire and flame. From this our clouds protect us. Occasionally there have occurred rifts in the clouds, and at such times the heat from the fires above, when the rifts occurred in the daytime, has been so intense as to wither vegetation and destroy life, while the light that shone through was of blinding intensity. When these rifts occurred at night there was no heat, but we saw the sparks from the fire shining above us.”