These waves are the reverse of sea waves, the form remaining in practically one place while the water flies through.

In many rapids there is an eddy on each side of this tail in which a current runs up-river with great force.

If a boat is caught in this eddy it may be carried a second time through a part of the rapid.

We soon arrived at another rapid in which this very thing happened to our boat.

We were caught by the eddy and carried up-stream to be launched directly into the path of the _Nell_, which had started down.