as of great guns--the boom of the breaking seas.

The plank was almost twisted from his grasp, but he clung to it
desperately, although its edges tore his arms. When the rollers broke
over him he held his breath, and when he was tossed skywards on their
curves, drew it again in quick, sweet gasps. Now he sat upon the very
brow of one of them as a merman might; now he dived like a dolphin,
and now, just as his senses were leaving him, his feet touched bottom.
Another moment and Robert was being rolled along that bottom with a
weight on him like the weight of mountains. The plank was rent from him,
but his cork jacket brought him up. The backwash drew him with it into
deeper water, where he lay helpless and despairing, for he no longer had
any strength to struggle against his doom.

Then it was that there came a mighty roller, bigger than any that he had
seen--such a one as on that coast the Kaffirs call "a father of waves."
It caught him in the embrace of its vast green curve. It bore him
forward as though he were but a straw, far forward over the stretch of
cruel rocks. It broke in thunder, dashing him again upon the stones
and sand of the little river bar, rolling him along with its resistless
might, till even that might was exhausted, and its foam began to return
seawards, sucking him with it.

Robert's mind was almost gone, but enough of it remained to tell him
that if once more he was dragged into the deep water he must be lost. As
the current haled him along he gripped at the bottom with his hands,
and by the mercy of Heaven they closed on something. It may have been
a tree-stump embedded there, or a rock--he never knew. At least, it was
firm, and to it he hung despairingly. Would that rush never cease? His
lungs were bursting; he must let go! Oh! the foam was thinning; his head