red the
oars _apeak_, and put the crew at ease. When the oars are apeak,
they are drawn _in_ a little way, so that the handle of each oar
may be passed under a sort of cleat or ledge, which runs along on the
inside of the boat near the upper edge of it. This keeps the oar firm
in its place without the necessity of holding it, the handle being
under this cleat, while the middle of the oar rests in the row-lock.
Thus the oarsmen are relieved from the necessity of holding their
oars, and yet the oars are all ready to be seized again in a moment,
whenever it becomes desirable to commence rowing.

Meantime the boat slowly drifted down the stream. The water was here
deep and comparatively still, and the boys amused themselves with
looking over the sides into the depths of the water. They glided
noiselessly along over various objects,--now a great flat rock, now
a sunken tree, and now a bed of yellow sand. Every now and then,
Forester would order the oars out, and make the oarsmen give way for
a few strokes, so as to give the boat what they called steerage way,
that is, way through the water, so that holding the paddle in one
position or the other would steer it. 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