Page:Maury's New Elements of Geography, 1907.djvu/19

Rh the river basin. On page 87 find three great river systems and the basin which each one drains.

Sheets of water surrounded by land are called lakes. Some lakes are called seas. Many rivers rise in lakes.



The tack in the orange shows our position on the earth: 1, at midnight; 2, at sunrise; 3, at noon.

1. What makes day and what makes night? We shall try to learn in this lesson.

Of course we know that it is day when the sun shines upon as. But why is it not always day? What makes the sun set and the light fade? And then, what makes the sun rise again in the morning?

People used to think that the sun really did come up and go down. They thought that it went under the earth at night, and came out again in the morning. They supposed that the rising and setting of the sun were like taking a lighted lamp and carrying it across a table, and then putting it under the table and bringing it out after a while at the opposite side. But we know that all this was a mistake.

2. What really happens? Let us see. Suppose we put an orange or a ball in the sunlight, or in the light of a lamp. Does the light shine all over it? No. Only one-half of it is in the light. The other half is dark. Like the orange or the ball, the earth is in the sunshine; but only one-half of it can be bright at a time. The other half must be in the dark.

Now let us stick a knitting-needle or a sharp piece of wood right through the orange at the place where the stem used to be. Next let us hold the orange in the sunlight or lamplight, and make it turn round upon the knitting-needle. We shall in this way bring the side that was first dark into the light, and the side that was first light into the dark.

The knitting-needle stuck through the orange may be called the axis of the orange. And the orange, when it turns on the needle, is said to turn on its axis.

3. Now the earth turns round from west to east. It is said to rotate, or turn on its axis. Of course, we must not suppose that it really has a rod of iron or anything else stuck through it for an axis. But it turns as if it had.

One thing more we notice about our turning orange. It soon stops if we do not keep on making it turn. But the earth never stops. First one side is in the sunlight and then the other. ''The bright side has day. The dark side has night.''

Whenever it is daylight with us, it is night with the people who live on the other side of the earth. When we are eating our breakfast or hurrying off to school, the children who live on the other side of the earth are getting their supper or going to bed.

We turn the orange round on its knitting-needle in a few seconds. But it takes the earth twenty-