Here, in one big pool, lay frozen in the ice a monster white shark. It had battered itself to death against the rocks in trying to escape. Through yonder blow-hole in another pool there suddenly appeared an enormous bewhiskered head, with great tusks like the drooping mustache of a soldier. "A walrus!" exclaimed Jack, recognizing the creature. "And yonder are seals playing in the open pool," said Mark. "These pools, or lakes, are still of salt water," said the professor, thoughtfully. "Ah! what would I not have given to have been on that headland yonder at the moment the ocean went out." "Not me! Not me!" cried Phineas Roebach. "I'd gone completely off my head then, for fair--I know I would!" "Mr. Roebach is not quite sure now that he isn't suffering from some form of insanity," said Jack, chuckling. "Den it suah is too bad dat we nebber kin fin' dat chrisomela bypunktater plant ter cure him wid," declared Washington White, dolefully. "But, by the piper that played before Pharaoh!" ejaculated Phineas Roebach, at last brought to a point where he _had_ to admit that no reasonable explanation would fit the conditions confronting them, "tell me this: What has become of the Arctic Ocean?" "You can search me!" drawled Jack. "I can assure you, Mr. Roebach, that I haven't seen it. Have you got it, Mark?" "The question of what has become of this great sea which once washed the shore we are now leaving," said Professor Henderson, seriously, "is a remarkably interesting one. The ocean may have merely receded for a few miles at the time of the volcanic eruption and earthquake which threw off this new planet." Phineas Roebach shook his head at this, but said nothing. "It may be," pursued Mr. Henderson, "that that part of our old world that was shot into space did not include much of this Arctic sea. We may find beyond here," pointing, as he spoke, ahead, "instead of the receded ocean, no ocean at all. We cannot believe that this island in the air is spherical like our own old earth. It is a ragged form which will show on what we may call the _under_ side the very convolutions and scars made by its breaking away from the old earth. Do you get my meaning?" "Yo' suttenly is a most liquid speaker, Perfesser," declared Washington White. "Yo' was sayin' dat w'en disher new planet broke off de earf, she slopped over de whole Arctic Ocean." "Perhaps that puts it quite as simply," said Professor Henderson, smiling grimly. "The ocean 'slopped over'. It was either left behind to partly fill the cavity left by the departure of this torn-away world we are living on, or it has receded into the valleys and sinks upon the other side of this small planet." Phineas Roebach threw up both hands and groaned. "It's as clear as mud!" he cried. "I don't understand a thing about it." But the old professor went on without heeding him, knowing that his pupils, Jack and Mark, were deeply interested in the mystery of this torn-away world, or island in the air.