I have told you how water is in motion whenever it can be. It runs whenever it can get a chance to do it; but it is in motion in another way, which I will now tell you about.
From what water goes up into the air.
You hang out a wet cloth to dry. When it is dry, what has become of the water that was in it? It has gone somewhere. Where has it gone? It has flown, like the birds, into the air; but it has gone so quietly that nobody has seen it go. The little fine particles of the water that I have told you about have mixed up with the air, and are blown about with it every where. And so, when you write, as the ink dries on the paper, the water in it flies off into the air, leaving the dark part of the ink behind.
There is a great deal of water that is going up into the air in this way all the time. It goes up from every thing that is wet. After a shower, the ground, the stones, the houses, the trees, and plants are all very wet, but in a little time they are dry again. Most of the water on them has gone up in the air, and is mingled up with it. It has mingled with it in such a way that you can not see it. The air is generally as clear with all this water in it as it is when it is perfectly dry. Even in a bright, clear day, there is a great deal of water mixed up with the air.
But water goes up into the air not merely from things that appear wet. You remember that, in Part First, I told you that wateris all the time going out from the pores of the leaves. A great deal of water is furnished to the air in this way.
Experiment with the arm and a glass jar.
Then there is water going up from the skins of animals. Much water goes from your skin into the air constantly, even when you can not see that you are perspiring. You can prove this by putting your arm into a glass jar, and holding it there some time. The inside of the jar will become covered with the water that comes from the pores of the skin on your arm. This is like the experiment with leaves noticed on page 77 of Part First.
Water in the breath.
There is water, too, coming out from the lungs of animals and mixing with the air. It comes from their lungs just as it does from the leaves, which you know are the lungs of plants. You can see this if you breathe upon a cold window. The moisture or water that is breathed out with the air from the lungs gathers upon the glass. In the morning you often see the panes of the windows in your chamber very wet. All this water has come from your lungs as you have slept. In a very cold day the water in your breath freezes upon whatever is about your mouth. You see the water of the breath of a horse frozen on the hairs about his mouth.
So you see water is going up into the air all the time from the ground, the leaves, the animals, and indeed from every thing that is at all moist. It goes up also in great quantities from seas, rivers, lakes, etc. Water, then, is always moving. It runs and it flies. It flies up into the air, and comes down again in the rain to run in the streams. It is ever going its rounds, going up and coming down, and none of it ever stays long in one place. The only way in which it can be made to keep still is to shut it up.Let it be free, and it will soon be gone, either by running or flying.
Water in the air seen in fog.
Commonly the water in the air is not seen, as I have before told you; but sometimes you can see it. You see it in the breath in a very cold day. The cold air makes it look like smoke coming out of the mouth. You see it, too, in the fog. When there is a fog there is a great deal of water in the air. The reason that you can see it is that the particles of water are not as finely divided up as when the air is clear. They are in little companies, as we may say, but there are not enough of them together to make drops. If they were in companies large enough to make drops, they would fall to the ground—that is, we should have a rain.
A beautiful scene.
Sometimes the fog is every where; sometimes it hangs only just over the water. If you are on a very high hill, where you can look off and see a river in the distance, you can sometimes see in the morning a line of fog stretching along where the river is, while it is nowhere else. I once saw a very singular and beautiful scene made by the fog. I had been out on horseback in the night to visit a sick person. As I returned, just before sunrise, I saw from a very high hill a thick fog over all the river below. From the river arose high hills, irregular in their shape, and on the sides of these hills were houses at different heights. The lower houses were all so covered by this dense fog that I could not see them, while those that stood high up on the hills I could see as plainly as ever. It looked as if a sea had come in while I was gone on my visit, and had filled up the valley where the river ran, for the fog rose to the same height on the sides of allthe hills. Many of the houses stood upon the very edge of this sea. The scene was so beautiful that I waited to see the sun rise upon it. As it rose, it shone over the tops of the hills, and lighted up this sea of fog, which it in a little time scattered by its heat.
Dense fogs often hanging over large cities.
Very thick fogs often hang over large cities, while all around in the country the air may be perfectly clear. London is often covered with such a fog. Sometimes it has been so dense that people could not see to do any business. It is related that the fog over the city of Paris was once so thick that persons who went about with torches often ran against each other, because even lights could not be seen unless they were very near. And in Amsterdam, in a fog in the year 1790, there were over two hundred persons drowned by falling in the darkness into the canals which run through every part of that singular city.
Questions.—What becomes of the water when a cloth is dried? Tell about the drying of ink on the paper. Tell about water’s going up in the air after a shower. Can you commonly see the water that is in the air? Does water go into the air from things that do not appear wet? What is said about its going from the skins of animals? Tell about the experiment with the glass jar. What is said about water’s being breathed out from the lungs? In what ways do you see this shown? What is said about water’s being in constant motion? When there is a fog, why is it that you see the water that is in the air? Tell what is said about fogs. Tell about the fogs that hang over large cities.
Questions.—What becomes of the water when a cloth is dried? Tell about the drying of ink on the paper. Tell about water’s going up in the air after a shower. Can you commonly see the water that is in the air? Does water go into the air from things that do not appear wet? What is said about its going from the skins of animals? Tell about the experiment with the glass jar. What is said about water’s being breathed out from the lungs? In what ways do you see this shown? What is said about water’s being in constant motion? When there is a fog, why is it that you see the water that is in the air? Tell what is said about fogs. Tell about the fogs that hang over large cities.