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. Then, almost as suddenly as the ship had started to fall, it ceased, and rode on an even keel, righting and floating easily in the air. The wind no longer blew with the circular motion, the whirling having come to an end. But the blinding snow continued. Jack staggered from the conning tower, where he had gone to look at the deflecting compass. "What has happened?" he cried. "No one knows," answered Professor Henderson. "We are in dire straits. Did you look at the needle, Jack?" "I did."