Pellucidar, as every schoolboy knows, is a world within a world, lying, as it does, upon the inner surface of the hollow sphere, which is the Earth. It was discovered by David Innes and Abner Perry upon the occasion when they made the trial trip upon the mechanical prospector invented by Perry, wherewith they hoped to locate new beds of anthracite coal. Owing, however, to their inability to deflect the nose of the prospector, after it had started downward into the Earth's crust, they bored straight through for five hundred miles, and upon the third day, when Perry was already unconscious owing to the consumption of their stock of oxygen, and David was fast losing consciousness, the nose of the prospector broke through the crust of the inner world and the cabin was filled with fresh air. In the years that have intervened, weird adventures have befallen these two explorers. Perry has never returned to the outer crust, and Innes but once—upon that occasion when he made the difficult and dangerous return trip in the prospector for the purpose of bringing back to the empire he had founded in the inner world the means to bestow upon his primitive people of the stone age the civilization of the twentieth century. But what with battles with primitive men and still more primitive beasts and reptiles, the advance of the empire of Pellucidar toward civilization has been small; and in so far as the great area of the inner world is concerned, or the countless millions of its teeming life of another age than ours, David Innes and Abner Perry might never have existed. When one considers that these land and water areas upon the surface of Pellucidar are in opposite relationship to the same areas upon the outer crust, some slight conception of the vast extent of this mighty world within a world may be dreamed. The land area of the outer world comprises some fifty-three million square miles, or one-quarter of the total area of the earth's surface; while within Pellucidar three-quarters of the surface is land, so that jungle, mountain, forest and plain stretch interminably over 124,110,000 square miles; nor are the oceans with their area of 41,370,000 square miles of any mean or niggardly extent. Thus, considering the land area only, we have the strange anomaly of a larger world within a smaller one, but then Pellucidar is a world of deviation from what we of the outer crust have come to accept as unalterable laws of nature. In the exact center of the earth hangs Pellucidar's sun, a tiny orb compared with ours, but sufficient to illuminate Pellucidar and flood her teeming jungles with warmth and life-giving rays. Her sun hanging thus perpetually at zenith, there is no night upon Pellucidar, but always an endless eternity of noon. There being no stars and no apparent movement of the sun, Pellucidar has no points of compass; nor has she any horizon since her surface curves always upward in all directions from the observer, so that far above one's line of vision, plain or sea or distant mountain range go onward and upward until lost in the haze of the distance. And again, in a world where there is no sun, no stars and no moon, such as we know, there can be no such thing as time, as we know it. And so, in Pellucidar, we have a timeless world which must necessarily be free from those pests who are constantly calling our attention to "the busy little bee" and to the fact that "time is money." While time may be "the soul of this world" and the "essence of contracts," in the beatific existence of Pellucidar it is nothing and less than nothing. Thrice in the past have we of the outer world received communication from Pellucidar. We know that Perry's first great gift of civilization to the stone age was gunpowder. We know that he followed this with repeating rifles, small ships of war upon which were mounted guns of no great caliber, and finally we know that he perfected a radio. Knowing Perry as something of an empiric, we were not surprised to learn that his radio could not be tuned in upon any known wave or wave length of the outer world, and it remained for young Jason Gridley of Tarzana, experimenting with his newly discovered Gridley Wave, to pick up the first message from Pellucidar. The last word that we received from Perry before his messages faltered and died out was to the effect that David Innes, first Emperor of Pellucidar, was languishing in a dark dungeon in the land of the Korsars, far across continent and ocean from his beloved land of Sari, which lies upon a great plateau not far inland from the Lural ...FROM THE BOOKS.