he 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!"

In a few minutes a hissing told that the gas was being let out of the
silk bag. Soon the ship began to sink gently toward the earth, through
the clouds of snow.

"Let us go outside," suggested Jack. "The wind doesn't blow now, and the
snow will not hurt us. We will be warm enough in our furs."

Mark voted the suggestion a good one, and the two boys went out on the
deck. Washington was busy in the engine room, and the professor was in
the conning tower, so they did not go, but Tom and Bill said they would
like to get a little fresh air, even if the temperature was far below
zero, and they joined the lads.

The four stood and gazed in wonder at the strange scene. At first the
terrible cold cut them as if it was a keen knife. But they soon grew
used to it, and enjoyed what little of it reached them th