"Perhaps we shall upset in the rips," said some of the boys.
"No matter if we do," said Marco; "it is not deep in the rips, and of
course there is no danger."
"That is in our favor certainly," said Forester. "Whenever the current
sets strong, there it is sure to be shallow, so that if we upset
we should not be drowned; and where it is deep, so as to make it
dangerous for us to get in, it is always still, and thus there is no
danger of upsetting."
"What is the reason of that?" said one of the boys.
"The reason is given in this way," said Forester, "in the college
mathematics. The velocity of a stream is inversely as the area of the
section."
The boys did not understand such mathematical phraseology as this, and
so Forester clothed his explanation in different language. He said
that where the stream was shallow or narrow, the current must be more
rapid, in order to get all the water through in so small a space, but
where it is deep, it may move slowly.
Forester landed his crew upon the rocky point, where they had a very
pleasant view up and down the river. He proposed to them to have their
luncheon there, and to this they agreed. So they went back to the edge
of the rocks, where there was a little grove of trees, and they sat
down upon a log which had been worn smooth by the action of the water
in floods, and bleached by the sun.
