Sometimes he was under, sometimes on top.

At all times he was in violent motion, now being turned over or around, and again, being smashed against a rock.

And with every rock he struck, he yelped.
His progress was a series of yelps, from which might have been adduced the number of rocks he encountered.
Below the rapid was a second pool, and here, captured by the eddy, he was gently borne to the bank, and as gently deposited on a bed of gravel.

He crawled frantically clear of the water and lay down.

He had learned some more about the world.