"Had we started with the golden cloud, or rather with the mass of air which that cloud represents, from the southern pole, we should have seen precisely the same effects produced," said the Genius. "You now understand what mortals call the theory of the trade-winds. You read in the sacred word of God, which in his mercy and goodness he gave to men to guide them in their passage through life, that, `The wind goeth toward the south, and turneth about unto the north; it whirleth about continually, and the wind returneth again according to his circuits' (Eccles. i. 6). Now, boy, you have seen how true and beautiful is that account written by the wise king of Israel." The boy listened attentively. "We will fly back to the equatorial calms," said the Genius; "see what effect the direct rays of the sun have on the earth, or that portion of its surface. They affect the air likewise; heat expands it, and then makes it rise; and it also changes its specific gravity. Cold contracts it, and also changes its specific gravity. These two causes are unceasingly at work to produce the currents of air whose courses we have been observing. The heat of the sun at the equator expands the air, and thus it rises and flows north and south; having arrived once more at the tropics, owing to the counter current it meets, it descends, as we saw, and flowing along near the earth, receives from it a rotatory motion, which increases as it approaches the pole, where, contracted by the cold, it masses into a dense body, and ultimately is whirled upwards, forming an ascending column, when it once more commences its never-ceasing journey." As they flew towards the mountain whence they set out, the boy expressed his thanks to the Genius; if he did not comprehend all that she had shown him and told him, he knew more about the matter than he had before done. She saw by the expression of his countenance the gratification he had enjoyed. "'Tis well," she continued; "as a drop of water is to the ocean which lies beneath us, so is the knowledge you may obtain in a lifetime to the wonders nature has to reveal. You desire to know more; gladly will I show you more. Whenever you climb up to this rocky height I will meet you, as I have done to-day, and each time unfold new wonders to your view. Ah, you think that I might descend to you, without making you toil up the mountain; but know that knowledge will not come to you; you must exert yourself, you must labour to attain it. You say that you will willingly climb the height. That is well. That is the spirit which ensures success. Return to your companions. They will not have missed you." Suddenly the boy found himself as he had been before, sitting a little apart from his friends. He was silent and thoughtful as he descended the mountain, resolving to return as soon as possible, to learn from the Genius more of the wondrous mysteries of nature. Story 10--CHAPTER ONE. STORY TEN--A TERRIBLE BLANKET.