"Then we have come past the pole," was Amos Henderson's opinion. "There is only a small spot that is exactly north, and we have passed over it during the storm. We must return. I want to descend exactly there and make some experiments. Tell Washington to start the engines. We will turn the ship around and go back!"
"We may run into the whirlwind again," objected Jack.
"That is so, I did not think of that. However, tell Washington to get everything in readiness."
It was no small task to get the engine room into shape after the upsetting it had been subjected to, but with the help of the boys and the two men Washington succeeded. In about an hour the Monarch was ready to be sent up or down, forward or back. Since she had ceased falling she had remain at a stationary height, about half a mile above the earth.
Meanwhile Professor Henderson was trying to make up his mind what to do. He wanted very much to get to the exact north pole, or the spot where the imaginary pole was supposed to be. But he hesitated about taking the airship back over the course, and run the chance of again encountering the whirlwind.
"The more I think of it," he said to Jack and Mark, who had joined him, "the more I think that the whirlwind is always there. It did not come to us, we ran into it. It may be caused by the magnetic currents at the pole eternally revolving. I am afraid to go back within their influence, for it might mean death."
"I have a plan," said Jack modestly.
"Let us hear it," came from the professor. "I am at a loss what to do."
"Supposing we let the ship down now," Jack continued, "and walk back until we come to the north pole, since it must be near here. We can take along the deflecting needle to tell when we reach it, and the whirlwind will not do much harm if we are on the ground and afoot."
"Good idea!" exclaimed the professor. "We'll do it. Washington, let the gas out and we'll descend!"