Then he hurried forward to the conning tower.  As he did so the ship was whirled quickly around several times, and the sudden motion threw the old man down, his head striking on the edge of one of the bunks.  He lay white and still.

“He’s killed!” cried Washington.

“We are in a whirlwind!” yelled Bill at the same instant.  “We’ll be sucked up to the sky!”

The airship was swinging around and around as if in the grasp of some giant.  The craft was really caught in the centre of a whirlwind, which spun it around like a top.  Every one felt sick and dizzy from the queer motion.

“We must see to the professor!” said Jack.  “Washington, get some of the remedy you used before.  I think he has only fainted.”

At this moment the old inventor opened his eyes.

“What happened?” he asked feebly.  “Please give me some water.  I am all right.”

They brought him a drink, and he managed to sip a little of it.  Then he attempted to sit up.  But the effort was too much for him.

“What—­what is the matter?” he asked.  “I feel so strange.  I am dizzy.  Has anything happened?”

“Somebody am a-playin’ ‘Ring around de Rosy’ wid dis airship!” exclaimed Washington, “My head am a-swimmin’ so I can’t stand.”

“I must get to the conning tower!” muttered the old inventor.  “I must get there.”

“Let me go, you can never make it,” said Jack.  “What is it you want to see?”

“Look at the deflecting needle!” was the answer.  “See how the needle points and come back and tell me!  It may be we are at the north pole!”

Jack started forward, crawling on his hands and knees.  Indeed, this was the only way he could advance.  The professor watched him with anxious eyes.  The ship spun around even faster.  Old Andy had awakened and was gazing around with fear-stricken eyes.

Then, just as Jack reached the door of the conning tower, and started inside, the Monarch gave a violent motion.  She seemed to stop for a moment, and then, with a great lurch, turned completely over, throwing the occupants to the ceiling.  Then she plunged straight down to the earth, through the centre of the whirlwind, like an arrow falling!

CHAPTER XX

AT THE NORTH POLE?

For an instant the utmost confusion reigned.  The adventurers fell in a heap on the ceiling that, for the time being, became the floor.  Then, as the ship righted herself, they fell back again to the floor.  The cords that bound Andy to his bunk broke, and he toppled with the rest.

“Repel the enemy!” yelled the old hunter, thinking in his delirium that the ship was again attacked.

“We are lost!” cried the professor, as he felt the Monarch plunging down.

For a hundred feet or more the ship shot earthward bow first, so that the adventurers all slid down to that end.  It was well that everything, including the gasolene tanks, had been lashed fast, or there would have been a great jumble inside the craft.