"I HAVE been told," said Emile, "that the Rhone empties its waters into the sea."
"The Rhone does run into the sea," returned his uncle. "It pours into it every second five million liters of water."
"Receiving so much water continually, does not the sea end by overflowing, like a basin, when it is too full?"
"You are out in your reckoning, my dear child. The Rhone is not the only river that goes to the sea. In France alone there are the Garonne, Loire, Seine, and many less important ones. And that is only a very small part of the streams that flow into the sea. All the rivers in the world join it, absolutely all. The Amazon, in South America, is 1400 leagues long, and ten leagues wide at its mouth. What an immense quantity of water it must furnish!
"Imagine that all the streams in the world, small as well as large, the tiniest brooks no less than the enormous rivers, flow unceasingly into the sea. You know the little brook with the crabs. In certain places Emile can jump across it; scarcely anywhere is the water over his knees. Well, the brook goes to the sea exactly as the Amazon does; every second it casts its few liters of water into it; that is all it can do. But it does not dare, tiny little stream, to make the voyage alone and go and find the sea, the immense sea, all by itself. It meets company on the way, joins its thread of clear water to stronger streams which become rivers by joining their forces; the sea-going-river receives tributary streams, and the sea, in receiving the river, drinks the tiny brook."
"All running waters," said Jules, "brooks, torrents, streams, rivers, run into the sea without a break, and that takes place all over the world, so that every second the sea receives incalculable volumes of water. So I come back to Emile's question: How is it that, continually receiving so much water, the sea does not overflow?"
"If, when full, a reservoir receives from a spring just as much as it lets out through some opening, can this reservoir overflow, even when water is always coming in?"
"Certainly not: losing as much as it receives, it must always keep the same level."
"It is the same with the sea. It loses just as much as it gains, and therefore its level always remains the same. Brooks, torrents, streams, rivers, all run into the sea; but brooks, torrents, streams, and rivers also come from the sea. They carry back to the immense reservoir what they took from it, and not a drop more."
"If the crab brook comes from the sea," interposed Emile, "as you say, its water ought to be salt; but I know very well it is not, in the least."
"Certainly it is not salt: but the brook does not come out of the sea as the water of a ditch comes from a reservoir. In coming from the sea, before becoming what it is, the brook has first passed through the air as clouds."
"As clouds, my little friend. Let us recall something I told you a while ago.
"The heat of the sun causes water to evaporate; it reduces it to something invisible, to vapor that is dissipated in the air. Seas present a surface three times that of the dry land. Over these immensities there is constantly taking place an enormous evaporation, raising into the air a part of the waters of the sea. The vapor thus formed becomes clouds; the clouds are borne in all directions, letting down snow and rain; this rain and melted snow penetrate the ground, filter down and give birth to springs, which gradually, by their union, become brooks, streams, and rivers."
"I see why the water of brooks is not salt," said Jules, "although it comes from the sea. When you put salt water in a plate in the sun, only the water goes away; the salt remains. The vapor that rises from the sea is not salt, because the salt does not go with it when it forms. So streams fed by snow and rain that fall from the clouds cannot be salt."
"What you have just told us is very remarkable, Uncle," observed Claire. "All water-courses, rivers, streams, torrents, brooks, come from and return to the sea."
"They come from the sea, an inexhaustible reservoir that covers with its waters a surface three times larger than that of all the continents joined together; from the sea, whose abysses go down at some places to the depth of 14 kilometers, and receive unceasingly the tribute of all the water-courses of the world, without ever being taxed beyond their capacity. The enormous surface of the sea furnishes the air with vapor which turns into clouds; later these clouds dissolve in rain and, chased by the wind, travel like immense watering-pots over the ground, rendering it fertile. In their turn, rain and snow, precipitated by the clouds, give birth to the rivers that carry their waters to the sea. In that way a continual current is effected which, starting from the sea, returns to the sea, after having traveled through the atmosphere in the form of clouds, watered the earth as rain, and crossed continents as rivers.
"The sea is the common reservoir of the waters. Rivers, springs, fountains, every little brooklet, all come from and all return to it. The water of a dew-drop, the water that circulates in the sap of plants, the water that forms beads of perspiration on our foreheads, all come from the sea and are on their way back to it. However small the little drop, do not fear that it will lose its way. If the arid sand drinks it up, the sun will know how to draw it out again and send it to rejoin the vapor in the atmosphere and, sooner or later, to reënter the ocean-basin. Nothing is lost, nothing escapes the eye of God, who has measured the oceans in the hollow of His hand, and knows the number of their drops of water."