"I'll adjust these gravity plates now," continued Twiffle, "so the plane won't fall when it passes the boundary." After he had pressed some buttons, he and the Shaggy Man and Twink and Tom climbed out of the Airmobile. The air seemed as solid under their feet as the earth. Nevertheless, this walking on thin air was a most curious experience, and in spite of themselves they found they were treading gingerly, as though they were walking on eggs.
The Lord High Mayor and the crowd of Hightowners that had gathered watched curiously as the Shaggy Man and Tom slowly pushed the Airmobile toward the boundary of Hightown. It was no task at all, since the Airmobile had no weight. They knew the sign that had greeted them as they entered Hightown marked the spot where gravity again exerted its pull, so they pushed the Airmobile slowly over this invisible line.
Zoom! Like an arrow shot from a bow the Airmobile darted upward. Far above their heads it continued its mad climb into the sky. So fast did it move that within a few seconds it was visible only as a tiny speck far above them.
"What in the sky has happened?" gasped the Shaggy Man.
"It is all my fault," said Twiffle despondently. "I must have exposed the gravity plates too much when I adjusted them. I was so afraid the plane would fall. When the Airmobile passed into the area of gravity it shot upward. Now it is lost to us forever." Twiffle looked as if he were about to weep.
"Cheer up, Twiffle," said the Shaggy Man. "Maybe we can get the Airmobile back." Shaggy turned to the Lord High Mayor and asked: "Since we can walk on air as well as you, couldn't we just walk up there and climb into the Airmobile?"
"You could, if you wanted to stop breathing," said the Lord High Mayor cheerfully.