<div class="chaptext" id="l19"><SPAN name="less19"></SPAN>
<div class="lesson">LESSON XIX.</div>
<div class="chaphead">MORE ABOUT RIVERS.</div>
<p>Let us have another chat about the river. We may fancy that we are
following it in its course to the sea. We shall then learn for
ourselves many things we do not know about rivers.</p>
<p>We will begin our journey at its source. Here it is a little rill,
formed by water that trickles from a spring, or by the melting of
snow.</p>
<p>As it flows on, it is joined by many other little streams, until it
grows to be much larger.</p>
<p>There is a large word used for a stream that feeds another stream.
Do you know what it is? The word, is <i>tributary</i>. Tributaries
are often called <i>branches</i>.</p>
<p>Before we leave this part of the river, I wish you to learn another
hard word.</p>
<p>You have seen the water run off the roof of a <i>shed</i>. 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.</p>
<table summary="illustration" class="centeredimage" width="100" cellpadding="5"
cellspacing="0" border="0">
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<td><SPAN href="images/030_l.gif" target="_blank" id="ill30"><ANTIMG src=
"images/030.jpg" border="0" alt="HILLS SEND OFF STREAMS ON BOTH SIDES." /></SPAN></td>
</tr>
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<td>
<div class="caption">HILLS SEND OFF STREAMS ON BOTH SIDES.</div>
</td>
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</table>
<p>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
<i>water-parting</i> or <i>water-shed</i>.</p>
<p>Let us now go further down the stream.</p>
<p>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 <i>rapids</i>. Can you tell why they
are so called?</p>
<table summary="illustration" class="centeredimage" width="100" cellpadding="5"
cellspacing="0" border="0">
<tr>
<td><SPAN href="images/031_l.gif" target="_blank" id="ill31"><ANTIMG src=
"images/031.jpg" border="0" alt="SUCH PLACES ARE CALLED RAPIDS." /></SPAN></td>
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<td>
<div class="caption">SUCH PLACES ARE CALLED RAPIDS.</div>
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<p>The stream flows on. It has now reached a high ledge of rock. Over
this it leaps, making a great foam and noise.</p>
<p>When the water of a river falls over high rocks, it is called a
waterfall or <i>cataract</i>.</p>
<p>You may have seen the Falls of Niagara, the greatest waterfall in
the world.</p>
<p><SPAN href="images/032_l.gif" target="_blank" id="ill32"><ANTIMG align=
"left" src="images/032.1.jpg" border="0" alt="YOU MAY HAVE SEEN THE FALLS OF NIAGARA." /><ANTIMG align="left" src=
"images/032.2.jpg" border="0" alt="YOU MAY HAVE SEEN THE FALLS OF NIAGARA." /></SPAN> 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.</p>
<p>Why is the river swift in some places, and in others slow?</p>
<p>At length it flows through an almost level country. It is here
widest and deepest. Its course is more winding.</p>
<p>Do you know why it is crooked and winding?</p>
<p>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.</p>
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