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 water in it is not in a liquid state. A cloud is just a great mass of vapor, in which the water is as finely divided as in fog or steam. When the cloud is blown upon by a current of  cold air, the vapor runs together, turning to liquid, or the form in which we know it as water. But it cannot form a mass of water in the air, because it hasn’t time before it gets so heavy that it falls. And vapor always condenses on something solid, as you can see it do on a window—pane or the outside of a pitcher of ice—water. The only solid things in the air are particles of dust. Using a grain of dust as a center of attraction, vapor condenses on it in just as big drops as the air will hold up. As that amount is very small, indeed, the vapor in a cloud falls in millions of little round drops, and each drop has a tiny grain of dust in the very center. No wonder the sky looks as if it had had its face washed after a rain!

HOW TO FIND YOUR WAY BY THE STARS
Away down in the kindergarten the little tots sing a song:


 * "This way's east and this way's west,
 * Soon I'll learn to know the rest."

They do learn, too. They learn that if one stands with the right hand pointing to the morning sun, one faces north, and the back is to the south. But they do not learn, until they are much older, and sometimes not at all, how to find the way at night. And it’s worst of all to be lost at night, too.

Very high in the sky, on clear nights, is always to be seen a certain group of bright stars. There are seven stars in the group, and they make a very big dipper with a handle. Four of the stars form the flaring-bowl, two at the top, two nearer together at the bottom. The other three stars make a handle for the dipper. The last star is lower, giving a bend to the handle. Now, you must find the two stars that form the outer line of the dipper’s bowl, from the top to the bottom. Imagine a straight line connecting those stars. Extend that line upward in the same direction until it runs into another bright star. That is the north, or polar star. Face toward the polar star and you will be looking almost due north. For many hundreds of years sailors guided vessels over wide seas by this polar star. So don’t you think it might be useful to a lost child?