e streams, until it
grows to be much larger.

There is a large word used for a stream that feeds another stream. Do
you know what it is? The word, is _tributary_. Tributaries are often
called _branches_.

Before we leave this part of the river, I wish you to learn another hard
word.

You have seen the water run off the roof of a _shed_. The ridge; or
highest part of the roof, divides the rain that falls on it, so that
part of the rain flows down the one side, and part of it flows down the
other side.

[Illustration: "HILLS SEND OFF STREAMS ON BOTH SIDES."]

Now, hills, like the roof of a house, send off streams on both sides.
When it rains, or the snow melts, some of the water goes down on one
side, some on the other. And that is why the hills which divide or part
the waters of streams are called a _water-parting_ or _water-shed_.

Let us now go further down the stream.

Here we see it rushing rapidly down a steep slope. Its waters foam and
dash between the great rocks that lie in the stream. Such places in the
river are called _rapids_. Can you tell why they are so called?

[Illustration: "SUCH PLACES ARE CALLED RAPIDS."]

The stream flows on. It has now reached a high ledge of rock. Over this
it leaps, making a great foam and noise.

When the water of a river falls over high rocks, it is called a
waterfall or _cataract_.

You may have seen the Falls of Niagara, the greatest waterfall in the
world.

[Illustration: "YOU MAY HAVE SEEN THE FALLS OF NIAGARA."]

The course of our river is now through a lower country. The valley in
which it flows spreads out, and the stream grows wider and wider. The
water moves slower and slower.

Why is the river swift in some places, and in others slow?

At length it flows through an almost level country. It is here widest
and deepest. Its course is more winding.

Do you know why it is crooked and winding?

Because on the steep hillside the water runs very rapidly, and is not
easily turned aside. Where the ground is nearly level, it runs slowly,
and is easily turned from its course.

LESSON XX.

THE BROOK.

From a fountain
In a mountain,
Drops of water ran
Trickling through the grasses;
So our brook began.

Slow it started;
Soon it darted,
Cool and clear and free,
Rippling over pebbles,
Hurrying to the sea.

Children straying
Came a-playing
On its pretty banks;
Glad, our little brookl