“Undermined by the sea?” repeated Tom.

“Yes.  It is being slowly washed away.”

“Bless my soul!  Washed away!” gasped Mr. Damon.

“And, in the course of a comparatively short time, it will sink,” went on the scientist, as cheerfully as though he was a professor propounding some problem to his class.

“Sink!” ejaculated Mrs. Nestor.  “The whole island undermined!  Oh, what an alarming theory!”

“I wish I could hold to a different one, madam,” was Mr. Parker’s answer, “but I cannot.  I think the island will sink after a few more shocks.”

“Then what good will my—­” began Barcoe Jenks, but he stopped in confusion, and again his hand went to his belt with a queer gesture.

CHAPTER XVII

A MIGHTY SHOCK

Tom Swift turned to gaze at Mr. Barcoe Jenks.  That individual certainly had a strange manner.  Perhaps it might be caused by the terror of the earthquakes, but the man seemed to be trying to hold back some secret.  He was constrained and ill at ease.  He saw the young inventor looking at him, and his hands, which had gone to his belt, with a spasmodic motion, dropped to his side.

“You don’t really mean to say, Parker, that you think the whole island is undermined, do you?” asked the owner of the resolute.

“That’s my theory.  It may be a wrong one, but it is borne out by the facts already presented to us.  I greatly fear for our lives!”

“But what can we do?” cried Mrs. Nestor.

“Nothing,” answered the scientist, with a shrug of his shoulders.  “Absolutely nothing, save to wait for it to happen.”

“Don’t say that!” begged Mrs. Andersen.

“Can’t you gentlemen do something—­build a boat and take us away.  Why, the boat we came here in—­”

“Struck a rock, and stove a hole in the bottom as big as a barrel, madam,” interrupted Captain Mentor.  “It would never do to put to sea in that.”

“But can’t something else be done?” demanded Mrs. Nestor.  “Oh, it is awful to think of perishing on this terrible earthquake island.  Oh, Amos!  Think of it, and Mary home alone!  Have you seen her lately, Mr. Swift?”

Tom told of his visit to the Nestors’ home.  Our hero was almost in despair, not so much for himself, as for the unfortunate women of the party—­and one of them was Mary’s mother!  Yet what could he do?  What chance was there of escaping from the earthquake?

“Bless my gizzard!” exclaimed Mr. Damon.  “Don’t let’s stand here worrying!  If you folks are hungry come up to our camp.  We have plenty.  Afterward we can discuss means of saving ourselves.”

“I want to be saved!” exclaimed Mr. Jenks.  “I must be saved!  I have a great secret—­a secret—­”

Once more he paused in confusion, and once more his hands nervously sought his belt.

“I would give a big reward to be saved,” he murmured.