From this spring, the water escapes in a tiny stream, called a rivulet or creek, and flows along until it enters a river. Many springs make many rivulets; many rivulets make large rivers.
Rivers sometimes receive such great quantities of water that they overflow their banks, and destroy much valuable property. This is called a freshet or a flood.
Many people who live near some of our rivers have lost their houses, furniture, and cattle, which were all swept away by these floods.
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.