In this way Forester guided the boat in the right direction, keeping it pretty near the middle of the stream.
This mill-stream, as has already been stated, emptied into the river, and the boat was now rapidly approaching the place of junction.

In a few minutes more the river came into view.

The boys could see it at some distance before them, running with great rapidity by a rocky point of land which formed one side of the mouth of the brook.
"Now, boys," said Forester, "is it safe for us to go out into that current ?" "Yes," said Marco, "by all means,--let us go." "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.