“Going to give those Arabs some gob-tabs.” “How are you going to get them to take the gobs?” asked the little green sprite, grinning broadly. “You just watch me and see,” Bob replied complacently; “and do whatever I tell you to do.” [Illustration] “All right. But you’ve got some giant-tabs there, too. What are you going to do with those?” “You’ll see. Hist! Here come the Arabs. Now, don’t you hesitate to do what I tell you, Fitz.” “I won’t, Bob.” The Arabs, some on horses and others on camels, came galloping to the spot, raising a great cloud of sand. They formed in a circle round the two diminutive aëronauts and their balloon; and dismounted and stood silently, sullenly scowling. At last the sheik of the tribe advanced and said: “You two are devils. You’ve poisoned the spring where we drink and refresh ourselves and our beasts. You must die; we’re going to kill you.” Bob replied composedly: “Great sheik, we are magicians, not devils. We worked enchantment upon the spring, but did not poison it. As soon as the sun shines a few hours, the waters of the spring will again be pure and sweet—purer and sweeter than ever before. To convince you that we’re magicians, we’re ready to perform before you. See! I will make a giant of my green comrade.” The boy gave a giant-tab to the goblin and motioned him to swallow it. Unhesitatingly Fitz obeyed; and almost immediately he grew and swelled to gigantic size. With gestures and cries of amazement the Arabs drew back. Several of them touched their foreheads and muttered strange words; others prostrated themselves and hid their faces upon their extended arms. But the fierce old sheik gave no sign of wonder or fear. Instead, he said firmly, boldly: “Devils can work magic upon devils; but devils cannot work magic upon Allah’s elect. I’ll put you to the test; and if you fail,—as you will!—you die. Give me and my children of your magic medicine.” At a word from their sheik, the Arabs formed a line. Then the fierce old warrior of the desert said: “My children, these devils cannot injure you with their magic medicine. If they succeed in making giants of us, we shall then be able to overcome all our enemies; if they fail, we shall be as we are—and the devils shall die.” Then to Bob: “Give us of your devil drugs.” The boy stepped forward and dropped a gob-tab into the outstretched palm of each warrior. The sheik gave a signal; and twenty red mouths flew open and twenty gob-tabs disappeared. At the same moment Bob took a giant-tab. And a few minutes later two giants stood triumphantly grinning down upon twenty bearded and turbaned pygmies!