“Don’t you see it?” the boy asked eagerly. The goblin nodded, still smiling. Bob leveled his glass upon the distant city and continued to observe it. It was a most beautiful sight, that city. It stood upon the bank of a blue lake; and its white walls, its domes and spires, glistened in the rays of the declining sun. But gradually it began to fade away; and little by little it disappeared from view. “Why—why,” the boy cried, “what’s become of it, Fitz? I can’t see it any more. What’s become of it?” “Don’t you know?” the goblin snickered. “No.” “You didn’t see any city, Bob.” “I know I _did_! Think I can’t _see_?” “Yes, you can see; but you didn’t see any city.” “What did I see, then?” “A mirage.” “Oh!” “You know what I mean?” “Yes. Was that all it was?” “That was all.” “Well, it was beautiful, anyway. And there’s another one—a lot of grass and green trees this time.” “That’s an oasis.” “Maybe it’s just another mirage.” “No, it’s an oasis. See! It’s getting closer and clearer all the time. There’s where we’ll stop.” The swift speed of their air-vessel soon brought them to the green oasis. There they descended to the earth, pumped the tank full of air, and firmly secured the balloon to a tree. Then Fitz set about to repair the selector, and Bob began to search for fruit. The boy was successful in his quest and soon returned to his comrade, his cap full of luscious dates. The goblin was sitting upon the ground, his back against the side of the basket, apparently glum and half asleep. “Have some, Fitz,” the boy mumbled, his mouth full of fruit, offering a share to his companion. Fitz drowsily shook his head. “Did you get the selector fixed?” Bob inquired. The goblin nodded, batting his eyes. “I—I _guess_ I’ve got it fixed,” he said. “What was the matter with it?” “I don’t know, Bob. I never had a selector act like this one does; I’m afraid it’s permanently magnetized.” “Why, what would put it in that condition, Fitz?” “Oh! I don’t know, I guess.” “Yes, you do. Out with it.” “I don’t want to scare you, Bob, but—” [Illustration] “Scare me? Pooh! Out with it.” “Well, down here in Africa somewhere—I don’t know just where—there’s a magnetic mountain; and we goblins have had trouble with it. Whenever we get within the zone of its power with our balloons, it magnetizes our selectors so they won’t work right; and if we get too close, it draws us to it—and we have great trouble in getting away. Some of my countrymen have had to abandon their balloons and walk miles and miles, and then send a wireless message home for help.” “Is that _so_?”—mouth agape. “Yes, indeed.” “And you think that’s what ails our selector?” “I’m afraid it is.” “Well, what’re we going to do about it?”