"Is it you, Stump?" said Mont, recognizing the voice of his faithful friend.

"At your service, Master Mont. I have been swimming about everywhere looking for you ever since that submarine beast swamped us. Ugh! What a terrible brute it is! It laughs at bullets, and cares no more for sinking a ship than I should for kicking over a stool."

"Is no one saved?"

"I can't tell any more than you; all I thought of was to swim after you."

The situation was as terrible a one as can well be imagined.

Those on board the vessel were in too much trouble, if they were yet living, to think of the perils of the others who had courted destruction by going in the boat to attack the monster.

Nor would Captain Savage feel very friendly disposed toward them, because it was Dr. Woddle's shot that caused the slumbering creature to rush madly upon the vessel.

Mont began to calculate the chances of safety. If the ship had not foundered the crew might lower another boat in the morning to search for them. The sun would not rise for about eight hours. Could they exist so long in the water without fainting or becoming cramped by the sluggish circulation of the blood?

In vain he tried to pierce the dense darkness which surrounded them, for now the moon had disappeared, and bad weather seemed imminent again.

About two o'clock in the morning our hero was seized with extreme fatigue; his limbs were a prey to an agonizing cramp.

Stump put his arm around him, but he drew his breath with difficulty, and evidently required all his strength for himself.

"Let me go, boy," said Mont; "save yourself."

"Certainly not," said Stump quickly. "We're not going down just yet."

At that moment the moon appeared again from under the edge of a thick cloud which had concealed it for a time, and the surface of the sea sparkled under its rays.

This fortunate light put new strength into the boys, and Mont searched the horizon with eager, careful gaze.

He saw the ship, or what appeared to be her, about two miles off, looking like a somber, inert ma.s.s, but there was no sign of a boat.

At first he was inclined to cry for help, but of what use would it have been at that distance?

"Here, this way! Hi! help, help!" shouted Stump.

Was it one of those delusive sounds which the anxious mind sometimes conjures up, or did an answer really come to the lad's cry for help?

"Did you hear anything?" asked Mont.

"Yes, I thought so," said Stump, and he began to cry out again.

"Help, help!"

This time there was no mistake. A human voice clearly responded through the darkness.

Stump lifted himself as high out of the water as he could, and taking a look, fell back exhausted, clinging desperately to the oar.

"Did you see anything?" asked Mont anxiously.

"Yes; don't talk, sir; we want all our strength."

There was a hopeful ring in his voice which inspired Mont, who, however, fancied he heard the boy sigh almost directly afterward.

He thought of the monster. Was it still near them? But, if so, whence came the voice?

They began to swim with all the strength they had left, and after some minutes of continued exertion, for moving was a painful task in their state, Stump spoke again.

"Are you far off?" he said.

"Not far--push on," replied the voice, which Mont fancied he knew.

Suddenly an outstretched hand seized him; he was pulled violently out of the water, just as his senses were going, and, after someone had rubbed his hands vigorously, he opened his eyes and murmured:

"Stump."

"Here, sir," replied the lad.

By the rays of the moon our hero saw a figure which was not that of Stump, but which he recognized easily.

"Dr. Woddle?" he said.

"Right, my lad," answered the man of science.

"Where is Carl?"

"Here," answered our hero's chum. "The doctor and I stuck together, and our only concern has been for you."

"Where are we?" asked Mont puzzled; "this thing I am sitting on seems firm enough."

"It's a floating island," answered Woddle.

A horrible thought crossed Mont's mind to which he could not give expression.

"To put you out of your misery at once," continued Dr. Woddle, "we are on the back of the gigantic creature at whom I shot, and I know now why I did not kill him."

"Why?"

"Because he is ironclad, or something very like it. I can make no impression upon the scaly monster with my knife."

These words produced a strange feeling in Mont's mind. He found that he was really with his friends on the back of the monster, which continued to float on the surface, after causing the partial destruction of the ship.

He got up and stamped his foot. It was certainly a hard, impenetrable body, and not the soft substance of which all the marine inhabitants that he had heard of were made, such as whales, sharks, walruses, and the like. If anything, it more resembled a tortoise or an alligator. A hollow sound was emitted when it was struck, and it appeared to be made of cast-iron plates secured together.

"What is your opinion of the creature, sir?" asked Mont.

"You want my candid opinion as a man of science?" said the doctor.

"Certainly, sir."