A tremor passed through the vessel; her propellers churned and thrashed; she bumped, rolled, then slid gently off the beach.

“Hurrah!” shouted Wilson, and flung up his cap. The Seal was afloat once more. Over the rolling waves she flew at full speed, the engineer’s one thought being to regain the beach from which the attack of the great ichthyosaurus had driven him.

Two hours later, after a long search, Wilson found himself back at the old mooring-place. Securely fastening the vessel, he stepped ashore to stretch his limbs.

As he paced backward and forward across the beach, he wondered whether his friends had returned from their expedition during his absence.

Suddenly, as he turned to go on board again, he noticed something gleaming in the sand, almost at his feet.

Stooping, he picked the shining object up. It was the baronet’s revolver! The truth burst upon him in a flash.

“So they came back,” he muttered, “while I was away, for I know Seymour took this with him when he went off the second time.”

Gloomy and depressed beyond measure by the discovery, he stepped across the gangway. Then an idea struck him. Perhaps his friends were still within hearing!

On the impulse of the moment he snatched down a rifle from the rack and fired it into the air.

But no answering report came back to him. Again and again he fired, but with no better result, and at length he gave up in despair.