There were two falls, not one, for even while the black was in the air Barry slipped from his back and struck the water clear of Satan.
They came up again struggling in the last effort toward the shore.

The impetus of their leap had washed them well in toward the bank, but the currents dragged them out again toward the center of the stream where the rocks waited.

Down river they went, and Black Bart alone had a ghost of a chance for success.

His leap had been farther and he skimmed the surface when he struck so that by dint of fierce swimming he hugged close to the shore, and then his claws bedded in the sand-bank.
As for Barry, the waters caught him and sent him spinning over and over, like a log, whipping down stream, while the heavier body of Satan was struggling whole yards above.

There was no chance for the master to reach the sand-bank, and even if he reached it he could not cling; but the wolf-dog knew many things about water.