“That was a light one,” spoke Tom, with an air of relief.  He was becoming used to the shocks now, and, when he saw that his precious machinery was not damaged he could view the earth tremors calmly.

“Slight!” exclaimed Mr. Jenks.  “Well, I don’t call it so.  But I see Captain Mentor and Mr. Hosbrook coming.  Please don’t say anything to them about the diamonds.  I’ll see you again,” and with that, the queer Mr. Jenks walked away.

“We came to see if you were hurt,” called the captain, as he neared the young inventor.

“No, I’m all right.  How about the others?”

“Only frightened,” replied the yacht owner.  “This is getting awful.  I hoped we were free from the shocks, but they still continue.”

“And I guess they will,” added Tom.  “We certainly are on Earthquake Island!”

“Mr. Parker, the scientist, says this last shock bears out his theory,” went on the millionaire.  “He says it will be only a question of a few days when the whole island will disappear.”

“Comforting, to say the least,” commented Tom.

“I should say so.  But what are you doing, Mr. Swift?”

“Trying an experiment,” answered the young inventor, in some confusion.  He was not yet ready to talk about his plans.

“We must begin to think seriously of building some sort of a boat or raft, and getting away from the island,” went on the millionaire.  “It will be perilous to go to sea with anything we can construct, but it is risking our lives to stay here.  I don’t know what to do.”

“Perhaps Captain Mentor has some plan,” suggested Tom, hoping to change the subject.

“No,” answered the commander, “I confess I am at a loss to know what to do.  There is nothing with which to do anything, that is the trouble!  But I did think of hoisting another signal, on this end of the island, where it might be seen if our first one wasn’t.  I believe I’ll do that,” and he moved away, to carry out his intention.

“Well, I think I’ll get back, Tom, and tell the others that you are all right,” spoke Mr. Hosbrook.  “I left the camp, after the shock, because Mrs. Nestor was worried about you.”  The place to which the airship machinery had been removed was some distance from the camp, and out of sight of the shacks.

“Oh, yes.  I’m all right,” said Tom.  Then, with a sudden impulse, he asked: 

“Do you know much about this Mr. Barcoe Jenks, Mr. Hosbrook?”

“Not a great deal,” was the reply.  “In fact, I may say I do not know him at all.  Why do you ask?”

“Because I thought he acted rather strangely.”

“Just what the rest of us think,” declared the yacht owner.  “He is no friend of mine, though he was my guest on the resolute.  It came about in this way.  I had invited a Mr. Frank Jackson to make the trip with me, and he asked if he could bring with him a Mr. Jenks, a friend of his.  I assented, and Mr. Jackson came aboard with Mr. Jenks.  Just as we were about to sail Mr. Jackson received a message requiring his presence in Canada, and he could not make the trip.”