“It’s run by jets going out from the back,” he went on. “If you held a large balloon before you and it exploded, it would push you over. That plane works something like that. The Italians tried it. Their jet went straight back out of the fuselage. It ran the plane, but took too much fuel. This one takes air from the sky into a large compressor. When it is under high pressure it is mixed in a chamber with explosive gas from kerosene. This mixture is ignited under terrific pressure, then carried round a right-angle bend and blown through fans that somehow give it a lot more power.” The girl was silent. Did she understand? He wondered. But now the man in the cockpit was ready for one more move. Once again he set the motor howling. This time however he released the brakes, dropped his lantern into the cockpit, touched the accelerator, and went gliding away into the night. Jack had watched his every move. “That,” he whispered, “is about the easiest flying plane in the world. I could fly it right now.” “So could—” The girl stopped, then added, “Yes, yes, I am sure you could.” “I will, too,” Jack told himself, but did not say it aloud. No use telling too much. They listened to the plane until its strange wail faded into nothing. “He’s gone,” the girl said, half rising. “I think he will be back,” Jack said, remaining in his place. “I want to find out all I can,” he added. The girl settled back in her place. “That’s the fastest plane in the world,” Jack whispered. “I have seen it take off in daylight. In the air close to earth, it takes lots of fuel, but in the stratosphere, where other planes can’t travel because there’s no air for the propeller to bite into, this jet plane goes like the wind on just about no fuel at all.” “O-o-o!” the girl murmured excitedly. “They left a scrapbook telling all about it down there on the rocks,” he explained. “I got a look at it. Wish I’d taken it with me, but you see, I thought those first two men might be our friends. You don’t take books from friends.” “No, you don’t,” she agreed. “Say!” he exclaimed in a hoarse whisper. “Who are you? Where did you come from? Those natives are not your people.” “They are not my people,” she agreed. “My home is far away. When you need to know more you shall be told. Is that fair?” “Fair enough,” said the boy. The jet plane came screaming back. Jack watched intently while the pilot put the ship to bed for the night. Then he said: “We’d better go.” When they reached the well-beaten trail he said, “Thanks a lot. I’ll be seeing you.” “I’ll be seeing you,” she repeated. He went one way, she the other, into the night. As he approached his own camp Jack saw no sign of life there. The fire had burned out. Nothing moved. All was silence and darkness. “It’s like returning to an empty house at midnight,” he told himself.