"I've been thinking," began the Doctor thoughtfully as he glanced up at the hills. "There's one theory of Rogers's that was a fallacy. You remember he was quite positive that this change of stature became steadily more rapid, until it reached its maximum rate and then remained constant. If that were so we should probably be diminishing in size more rapidly now than when we first climbed on to the ring. If we had so much trouble getting to the ring then"--he smiled at the remembrance of their difficulty--"I don't see how we could ever get to those hills now." "Gee, that's so," said the Very Young Man. "We'd never be able to get anywhere, would we?" "How do you figure it works?" asked the Big Business Man. The Doctor folded up the paper and replaced it in his belt. "I don't know," he answered. "I think probably it proceeds in cycles, like the normal rate of growth--times of rapid progress succeeded by periods of comparative inactivity." "I never knew people grew that way," observed the Very Young Man. "They do," said the Doctor. "And if these drugs produce the same effect we----" He got no further, for suddenly the earth seemed to rise swiftly under them, and they were thrown violently to the ground. The Very Young Man, as he lay prone, looked upward, and saw the sunlike light above fall swiftly down across the sky and disappear below the horizon, plunging the world about them into the gloom of a semi-twilight. A wind, fiercer than before, swept over them with a roar. "The end of the world," murmured the Very Young Man to himself. And he wondered why he was not frightened. Then came the feeling of an extraordinary lightness of body, as though the ground were dropping away from under him. The wind abruptly ceased blowing. He saw the ball of light rise swiftly from the horizon and mount upward in a great, gleaming arc to the zenith, where again it hung motionless. The three men lay quiet, their heads reeling. Then the Very Young Man sat up dizzily and began feeling himself all over. "There's nothing wrong with me," he said lugubriously, meeting the eyes of his friends who apparently were also more surprised than hurt. "But--oh, my gosh, the whole universe went nutty!" he added to himself in awe. "What did that?" asked the Big Business Man. He climbed unsteadily to his feet and sat upon a rock, holding his head in his hands. The Doctor was up in a moment beside him. "We're not hurt," he said, looking at his companions. "Don't let's waste any more time--let's get into that valley." The Very Young Man could see by his manner that he knew or guessed what had happened. "But say; what----" began the Very Young Man. "Come on," interrupted the Doctor, and started walking ahead swiftly.