In the winter of 1883, the Ohio River received so much water from the thousands of rivulets flowing into it, that it overflowed its banks.
The result of this overflow was one of the greatest floods ever known, and many, no doubt, who read this, were there to see its terrible effects.
But where does all this water come from? you may ask.
Let me see if I can explain it to you. The water in all these rivers, lakes, and oceans is constantly rising into the air in what is called moisture or vapor. We can not see this moisture, neither can we see the air.
If the air is cold, moisture does not rise rapidly; but, as the air becomes heated, it takes up more moisture, so that the more heat there is in the air, the more moisture rises.
Heated air is light, and rises higher and higher from the ground, taking the moisture with it, until it reaches a point where it begins to cool.
Then as the air cools, the moisture forms into clouds, and these clouds are, in a certain sense, floating water.
Floating water! How can water float! do you ask?
Well, I will tell you. Cold air is heavier than heated air, and until the clouds become so full of moisture as to return some of it to the earth, in the shape of rain, they float because they are lighter than the air underneath them.
The winds, by the flapping of their mighty wings, drive the clouds over the land to the hills and the mountains and the thirsty fields; and there they pour their blessings on the farms, pastures, orchards, and the dusty roads and way-side grass, bringing greenness and gladness every-where.
Without water nothing would grow; every thing would dry up and wither.
All animals drink water, for it forms a part of their blood and thus helps to keep them alive. All trees and plants drink it by drawing it through their roots or leaves, for it helps to form their sap.
Sometimes on a summer morning you will see drops of clear sparkling water on flowers and grass.
To look at them you would think it had rained during the night; but, noticing that the ground is dry, you know that no rain has fallen.
What then are these glittering drops of water? Where do they come from?
I will tell you. These drops are called dew. As night comes on, the grass and the leaves of flowers and plants become cool.
When the warm air touches them, it becomes chilled, and as the air can not then carry so much moisture as before, it leaves some of its moisture on the flowers and grass.
A moisture like dew sometimes collects in the house. Did you ever observe it in drops on the outside of a pitcher of cold water? Some people suppose that the water comes through the pitcher, but it does not.
The water being cold makes the pitcher cold, and as the warm air of the room strikes it, a moisture like dew is left on the pitcher, in the same manner as dew is left on grass, leaves, and flowers.