“You need only put your hand over your eyes to hide the sky,” his uncle explained. “A cloud much farther off, but also much larger, produces the same effect: it veils what is surrounding us and makes it all cloudy. But that is only in appearance; beyond the region covered by the cloud the sky may be serene and the weather magnificent. Under the cumulus where the thunder is growling now, it rains, you may be sure, and the sky looks black. To the people in that region the surroundings present only a rainy appearance, because they are wrapped in clouds; if they were to go elsewhere, beyond the clouds, they would find the sky as serene as we have it here.” “With a fast horse they could, then,” suggested Emile, “get from under the clouds, leave the rain, and come into fine weather; as also they could leave the sunshine and get into the rain under the clouds.” “Sometimes that would be possible, but more often not, because clouds can cover large areas. Besides, they travel, they go from one country to another, with such speed that the best horseman could not follow them in their course. You have all seen the shadow of the clouds run over the ground when the wind blows. Hills, valleys, plains, water-courses, all are crossed in less than no time. The shadow of a cloud passes over you at the moment you reach the top of a hill. Before you have taken three steps to descend into the valley, the shadow, with giant strides, is mounting the opposite slopes. Who could flatter himself that he could follow the cloud and keep under its cover? “If rain sometimes falls over great stretches of country, it is never general, absolutely. If it should rain at one time over a whole province, what is that compared with the earth? A clod compared with a large field. Chased by the wind, clouds run hither and thither in the vast spaces of the atmosphere. They travel, and on their way throw a shadow or precipitate rain. Where they pass there is rain; everywhere else, no. In the same place there can even be both rain and fine weather, according as one is below or above the clouds. You know that on a mountain-top the clouds are sometimes beneath one. The plain under the clouds may receive a hard shower, while on the summit the sun shines without a single drop of rain.” “All that is easily understood,” said Jules. “It is my turn now, Uncle, to ask you a question. From the storm-cloud that we see from here, there first came a flash of lightning; then, after waiting some time, the sound of the thunder was heard. Why do not the sound and the lightning come together?”