CHAPTER LXXV

RUNNING WATERS

“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?”

“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 dewdrop, 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.”

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The Story-book of Science · 第 75 / 80 章