Henderson, as he, with all of the ship's company except Mrs. Johnson and Nellie went on deck. "I thought we were lost, sure."

"Lucky our engine didn't go disproportionatin' herself at de mostess criticless moment," put in Washington. "Golly, but she suttinly did hum!"

"And you deserve credit for making her do the humming," went on the professor with a smile.

"Well, we didn't catch the ghost," remarked Jack, "though I certainly saw him, it or her, whatever the thing is. I felt it too."

"It's rather strange," spoke the professor. "Every time, or nearly every time the ghost, as I suppose we must call it for the present, makes its appearance, something terrible happens to the ship. I hope it doesn't show up too often."

It was three o'clock in the morning, and they had battled with the whirlpool over two hours. They talked of little else, and each one told how he or she felt.

"It was just like twisting yourself up tight in the swing, and then letting the rope unwind," said Nellie, and they all agreed that she had described the sensation perfectly. They laughed, also, a thing they had felt little like doing a short time previous.

The engine had run so hard, and some of the bearings had become so warm, that for the rest of the night the professor decided to let the machinery remain stationary. This would give it time to cool down he said, and they could make up the time lost the next day.

Tired out with the night's worry and labors they all slept late the next morning, and it was nearly ten o'clock before breakfast was over. The ship was started on her course once more, and Jack, who was steering, made the engine hum as the submarine scudded along, submerged about fifty feet.

"When you have time I would like to talk to you," said Mrs. Johnson to Captain Henderson.

"I'm at your service now," replied the inventor.

"What are you going to do with Nellie and me?" the lady went on.

"Take you to the south pole with us," was the answer, with a smile.

"It's very kind of you, and I don't want to put you to any trouble,"

went on Mrs. Johnson. "But I would like to go back north."

"I'd like to oblige you," returned the inventor, "but I hate to turn back now. We are well on our voyage, and I may never get another chance to locate the pole. Don't you want to accompany us? Think of the glorious achievement!"

"I'd rather go back north," persisted the lady. "But I wouldn't ask you to turn the ship around. What I was going to suggest was to sail along on the surface for a few days and see if you cannot sight a homeward bound steamer or sailing vessel. Then you could put me and Nellie aboard her."

"Of course!" exclaimed Mr. Henderson. "I never thought of that. Though we will be sorry to lose your company, and that of your little girl, I will do anything to oblige you. We will at once go to the surface."

He called the necessary order to Jack through a speaking tube which led to the conning tower. In a few minutes the ship shot upward, and emerged from the ocean in a little shower of foam and spray.

She lay undulating on the surface, and was just beginning to move forward again, under the influence of the screw, when a dull boom echoed off to the left.

Jack looked from the observation windows in the conning tower and saw, about a mile away a big steamer. From her side a white cloud of smoke floated, and then the water splashed about fifty feet from the blunt nose of the submarine.

Once more came the boom, the white cloud of smoke and this time the water splashed only twenty-five feet away from the bow of the _Porpoise_. A third time came the sound, and the splash was even nearer.

"They're firing on us!" yelled Jack.

At his cry the professor ran on deck. He was just in time to see the fourth shot made, and this time the sh.e.l.l dropped into the water just astern of the _Porpoise_ and so close that when it exploded it sent a shower of spray all over the deck.

"Here! Stop that!" yelled Mr. Henderson, shaking his fist in the direction of the steamer. "You nearly hit us that time. Do your practicing in some other direction!"

"I don't think they can hear you," said Jack. "And besides, I don't believe they are practicing."

"Then what in the world are they doing?"

"Shooting at us I guess."

"Why do they want to shoot at us? We haven't done them any damage."

"Perhaps they think we are a torpedo boat," suggested Jack. "Maybe that vessel's nation is at war with some other one and wants to sink us if it can."

"I believe you're right!" exclaimed Mr. Henderson. "But this will never do. They must stop!"

Once more the big gun on the ship was fired and the sh.e.l.l came dangerously close. At the same time several other reports, less in volume were heard, and the water all about the submarine began to bubble as the missiles from the machine guns cut the waves.

"Maybe it's an English vessel sent to capture Mark and me because of that anarchist trouble at the hotel," Jack went on.

"Nonsense!" exclaimed the captain. "But whatever it is, we must stop it, or they will sink my ship. Wave your handkerchief, Jack."

The boy sprang to the top of the conning tower, in order to permit those on the vessel to see him more plainly, and vigorously shook the white rag. That it was observed was evident when some one on the steamer wig-wagged back a reply. In a few minutes a boat was seen to put off from the ship, and soon a little launch, in command of a lieutenant in uniform, drew up alongside the _Porpoise_.

"Who is captain of this craft?" asked the lieutenant as he came aboard.

"I am," replied Mr. Henderson. "What do you mean by firing on me?"

"I am Lieutenant Muchmore," said the other, saluting. "Captain Wackford, of the _Sylph_, in His Britannic Majesty's service, presents his compliments, and asks you to pardon the occurrence. You see we took you for a derelict and were trying to sink you."

"I thought perhaps war had broken out between some country and the United States since we left port," went on Mr. Henderson, "and that you were trying to make a capture."

"No, it was only that we thought you a waterlogged craft, and a danger to navigation," repeated the lieutenant. "But what sort of a ship have you?"

"Come below and I'll show you the finest submarine that ever was built,"

answered the inventor with pardonable pride. "If you don't mind, give your launch orders to go back to the ship, and I'll show something that will make you open your eyes."

Anxious to see what the strange little craft could do Lieutenant Muchmore sent his launch back, and went below with Captain Henderson. He was astonished at what he saw, and unlike most Englishmen was willing to say so.

Mr. Henderson then went to the conning tower. He directed the man-hole cover to be clamped on, and then filled the tanks. The ship sank fifty feet below the surface and then shot forward.

Seated in the cabin the lieutenant was observing with wonder showing on his face at the accomplishment of sailing along under water. Suddenly the lights were shut off, and the shutters moved back from the bull's-eye windows. The sea, glowing in the beams of the search light, was alive with fish, large and small, beautiful and hideous.

"Wonderful!" exclaimed the Englishman.

The bull's-eyes were closed, the lights switched on, and then, speeding the engine almost to the top notch the captain steered the submarine straight for the war-ship.

He had carefully noted her direction before starting his own craft, and he resolved to do a little manoeuvering that would still further astonish the visitor. By careful reading of the different gages Mr.

Henderson was able to come to the surface right in front of the _Sylph_, to the no small astonishment of the men on the deck of the vessel.

Then, just to show what the _Porpoise_ could do, the inventor darted around the war-ship in a circle. He sunk below the surface, went under the keel of the _Sylph_ and came up on the other side. Then he went the whole length of her, under water, starting at the stern and ending at the bow, where he brought the submarine to a rest in a smother of foam.

"Great! Wonderful! Surprising!" were some of the adjectives Lieutenant Muchmore used as he stepped from the conning tower, with Captain Henderson, onto the deck.

At the appearance of the officer and the inventor a group of those on the _Sylph_ gave three cheers for the little vessel.