“Oh!”—in open-mouth admiration,—“that’s great! And when you want to go up again you just let the compressed air out, don’t you?” “Sure!” blinked the goblin. “I’ll show you.” He caught hold of the anchor rope, jerked the hook loose from the window-sill, and wound up the slender line. Then he flew to the air apparatus and turned a cock. Immediately there was the hiss of pent air escaping through a hole in the bottom of the tank, and the balloon began to ascend—slowly and gently at first, then more swiftly. When it was a short distance above the housetop Fitz Mee closed the cock, remarking: “There! I guess that’ll balance us about right. We’ll rise a few hundred feet and float there.” His prediction proved true. When the balloon had cleared the hilltops, it stopped rising and floated motionless, like a great bubble with a dripping blob at its pendant point. “Say!” Bob cried, suddenly. “Well?” said the goblin. “That tank looks just like the one papa has in his office.” “It _is_ just like it,” the goblin assured him. “And the car looks just like mamma’s old clothes-basket.” “Yes.” “And the bag looks just like grandma’s old feather-bed.” The goblin nodded and winked and smiled. “Well,” Bob declared triumphantly, “I could take those things and make me a balloon.” “Of course you could,” grinned Fitz Mee, “if you were going to stay at home.” “And couldn’t I have fun showing off before the other boys!” Bob chuckled, gloatingly. “You’ll have lots more fun with me, in Goblinland,” his companion said quickly. “Maybe I will,” the boy murmured reflectively, a little sadly. Then observing that the balloon had stopped rising: “Why, what made us stop going up?” “Don’t you know?” the goblin returned with a half sneer. “No, I don’t,” the lad admitted. “Ho, ho!” Fitz Mee laughed, “You’re wonderfully dumb, you are, Roberty-Boberty.” Bob bristled instantly. “Don’t you call me names,” he cried angrily. “You old—old Epilepsy!” “Epilepsy!” the goblin cackled hoarsely, holding his sides and weaving to and fro. “What does that word mean?” “Fits,” the boy answered tersely. “Ho—ho!” the goblin continued to tackle. “You call me names, but you don’t want me to call you names. Say, Bob?” Bob made no reply. “Bob?” Fitz repeated in as pleasant a voice as he could command. Bob maintained a stubborn silence. “Bob,” his companion went on, “the reason we stopped rising is because the weight of the balloon just balances an equal volume of air at this height. Understand?” “Yes,” the lad muttered rather grumpily. “All right, and if we wished to go higher—” “We’d have to let out more of the compressed air,” Bob interrupted, brightly. “And if we desired to descend—” “We’d have to pump more into the tank.” “Of course,” mumbled the goblin. “You’ll make a great aëronaut one of these days.” [Illustration]