Chenobi gazed with pride upon his giant steed. It would mean no slight wrench when the time came for him to part with the magnificent brute; but that had not to be considered yet. Time enough to think of that when they got out of the grip of the tidal wave, which foamed forward relentless as ever.

The shore had long since faded from view. Nought was visible on either hand but a waste of waters, tumbling and foaming in mad confusion. And ever and anon a thunderous explosion would burst out, echoing across the water like the firing of great guns.

Once, close alongside, the mighty body of an ichthyosaurus was flung up, rent and torn in ghastly fashion by some giant natural force.

Suddenly a cry came from Seymour.

“Great Scott! Look there!”

The others turned quickly. To starboard a beetling line of cliffs loomed into view, threatening and terrible. Next moment an exclamation from the American announced the appearance of a similar barrier upon the port side. Through the canyon or gorge thus formed, the waters swept in a maddened torrent, the Seal lurching and rolling in a fashion which bade fair to capsize her. A hundred times—ay, more—she seemed likely to be dashed against one or other of the rocky walls, but by a miracle she escaped destruction in this manner.

So for perhaps an hour she was swept forward; then a terrible fact became apparent to the adventurers. Silas was the first to notice it.

“Say!” he remarked, “I guess these yer cliffs are closing in on us.”

“What do you mean?” asked the scientist; “how closing in?”

“Just cast your eye to the top of this starboard wall,” was the reply; “if the hull outfit ain’t leaning outward, call me a darn nigger.”