“Well, come on then—and no more fooling. I’ll be a good comrade to you; we’ll have lots of fun. I’ll call you Bob and you’ll call me Fitz. Oh, we’ll have a bully time!” “All right!” the lad cried courageously. “I’m ready.” “That’s the stuff!” chuckled the goblin. They leaped upon the window-sill. Fitz Mee caught the anchor rope and shinned up it, and Bob nimbly followed. As the lad clambered into the basket he remarked: “Your balloon’s bigger than I thought it was, Fitz.” “You’re smaller than you were, that’s all,” the goblin grinned in reply. The car was indeed quite roomy and comfortable for such small beings. A box-shaped bench encircled it on the inside, serving as seat and locker, and at one side was a small tank of polished metal, with a pump attachment. “What’s that thing?” the boy inquired, indicating the shining tank. “What thing?” asked Fitz Mee. “That shiny thing.” “Why, that’s my air-tank and pump.” “It looks just like the air machine papa has in his office,” Bob remarked. His father was a physician. “He uses his in treating people’s throats. What do you use yours for?” “Don’t you know?” queried the goblin in surprise. “No,” answered the boy. “Well—well! It’s plain you never had anything to do with feather-bed ballooning. I use it in raising and lowering the balloon.” “In raising and lowering the balloon?” “Yes.” “You do?” “Certainly; that’s what I said.” “But how do you use it?” “I’ll show you in a minute,” Fitz Mee answered complacently. “You know how they raise and lower gas balloons, don’t you?” “Yes, I—I guess so,” the boy replied, a little dubiously. “The gas raises ’em.” “Of course,” snapped the goblin, “that’s the lifting power, and feathers raise feather-bed balloons. But what do they use for ballast in gas balloons, eh?” “Sand bags,” Bob answered. “Yes,” the goblin pursued; “and when they want to go higher they throw out sand, don’t they?” “Yes.” “And when they want to come down what do they do?” “Let the gas out of the bag,” Bob said at a venture. “That’s it,” Fitz Mee nodded. “And then they can’t go up again till they’ve refilled the bag—eh?” “I guess that’s the way of it.” “To be sure it is. Well, we work the thing better with our feather-bed balloons.” “We?” Bob cried. “Do all goblins use feather-bed balloons?” “Of course we do; that’s the way we travel. Didn’t you know that?” “No; I never heard of it.” “My—my!” Fitz Mee laughed. “You have a lot to learn, Bob. But I’ll show you how I can bring my balloon to earth or send it to the skies in a jiffy. When I wish to descend I just pump that tank full of compressed air. See?” “No, I don’t see,” Bob declared. “You don’t?” muttered the goblin, in surprise and irritation. “No, I don’t.” “Why, compressed air’s heavier than ordinary air, isn’t it?” “Yes, of course.” “Well, then, when I get that tank full the balloon’s heavier; and the increased weight overcomes the buoyancy of the feathers, and down I come.”