Yes, he thought to himself, animals. Somebody put some animals in the space just below me. Sounds like monkeys' chattering. Must be where the air is coming from. He had a headache. Bad air in here, he thought, and realized that had it not been for the animals being placed below him, he might have suffocated in that space. It was then that he fully realized what had happened--that he'd fallen asleep. The animals hadn't been there when he had first climbed in. So he must have slept for several hours at least. He squirmed around, reflecting on it, still not quite gathering his drugged wits together. That meant that the men must have arrived and started work on this rocket again. He thought this over, and a great uneasiness came over him. He strove to remember something urgent, something he knew he had to bring back to mind. Something about five o'clock and six o'clock. Loading time, launching time. Yes! They were firing this rocket at six! But what time was it now? How long had he slept? He looked at the luminous dial of his watch but was chagrined to find it had run down and he'd forgotten to wind it. He glanced rapidly around his little space, wondering how he could find out whether it was already day. Several glimpses of light hit his eyes. He saw that in three or four places there were tiny glass openings no larger than would admit a thick wire. He tried to look through one, but all he could see was blue sky. It was morning then. He strained his ears for outside noises, truck engines, men talking. But there was not a sound from outside. Only the faint squeakings of the animals below him. He twisted around again to face the little round door. It was padded on the inside, it had no handle there, nothing to get a grip on. He scrabbled in the padding with his fingers, reached the rim, and tried to push. There was no give. It was airtight, automatically sealed. He pushed against it, wondered what to do. He squirmed around against the padding, lay back with his head against the cushioning on the opposite side, his back resting on the floor padding, and put his feet against the side of the little door. Thus braced he was all set to shove the strength of his legs against the door in an effort to push it outward. He was about to do so when the rocket went off. _4. Riding the Atoms_ Suddenly it felt as if a giant had placed his huge palm squarely on Robin's chest and was pushing him down. As he tried to exert pressure against the door, the counter pressure of the invisible hand increased. For an instant Robin was thunderstruck. Had he suddenly become weak? What was this? His first emotion, that of amazement, changed in a split second to one of terror at his newly discovered weakness, and again from that to a feeling of stunned shock. There was no invisible hand! It was the rocket itself moving!