“Oh, if only we can sleep without being awakened by an earthquake!” exclaimed Mrs. Nestor, as she prepared to go into the shack with Mrs. Anderson.  “But I am almost afraid to close my eyes!”

“If it would do any good to stay up and watch, to tell you when one was coming, I’d do so,” spoke Tom, with a laugh, “but they come without warning.”

However, the night did pass peacefully, and there was not the least tremor of the island.  In the morning the castaways took courage and, after breakfast, began discussing their situation more calmly.

“It seems to me that the only solution is to build some sort of a raft, or other craft and leave the island,” said Mr. Fenwick.

“Bless my hair brush!” cried Mr. Damon.  “Why can’t we hoist a signal of distress, and wait for some steamer to see it and call for us?  It seems to me that would be more simple than going to sea on a raft.  I don’t like the idea.”

“A signal would be all right, if this island was in the path of the steamers,” said Captain Mentor.  “But it isn’t.  Our flag might fly for a year, and never be seen.”

His words seemed to strike coldness to every heart.  Tom, who was looking at the wreck of the airship, suddenly uttered an exclamation.  He sprang to his reet

“What is it?” demanded Mr. Fenwick.  “Does your sore leg hurt you?”

“No, but I have just thought of a plan!” fairly shouted the young inventor.  “I have it!  Wait and see if I can work it!”

“Work what?” cried Mr. Damon.

Tom did not get a chance to answer, for, at that moment, there sounded, at the far end of the island, whence the yacht castaways had come, a terrific crash.  It was accompanied, rather than followed, by a shaking, trembling and swaying of the ground.

“Another earthquake!” screamed Mrs. Nestor, rushing toward her husband.  The castaways gazed at each other affrighted.

Suddenly, before their eyes, they saw the extreme end of that part of the island on which they were camping, slip off, and beneath the foaming waves of the sea, while the echoes of the mighty crash came to their ears!

CHAPTER XVIII

MR. JENKS HAS DIAMONDS

Stunned, and well-nigh paralyzed by the suddenness of the awful crash, and the recurrence of the earthquake, the castaways gazed spell-bound at one another.

Succeeding the disappearance of the end of the island there arose a great wave in the ocean, caused by the immersion of such a quantity of rock and dirt.

“Look out!” yelled Tom, “there may be a flood here!”

They realized his meaning, and hastened up the beach, out of reach of the water if it should come.  And it did.  At first the ocean retreated, as though the tide was going out, then, with a rush and roar, the waves came leaping back, and, had the castaways remained where they had been standing they would have been swept cut to sea.