s soon as the professor could leave Andy in charge of Mark, he went to
the engine room. There he found everything in good shape. Next he went
to the conning tower, where Jack was steering.

"How is she heading?" asked the old man.

"Straight for the north!" replied the boy.

"Good! Keep her so. Let me see; we are about a mile high now. I guess
that will do," and he turned off the gas generator. "Moving about
twenty miles an hour," he added. "That is fast enough. I wonder how
cold it is?"

He consulted the dial that was connected to a thermometer outside.

"Whew!" he whistled. "Fifty below! I'm glad we are here!"

Jack was too. The old inventor glanced at the direction compass and then
at the deflecting one that indicated how near the north pole they were.
As he did so he uttered a cry.

"What is it?" cried the boy.

For answer Mr. Henderson pointed to the needle. It was almost straight
up and down.

"Well?" asked Jack, who did not understand much about scientific things.

"That means we are almost at the north pole!" cried the professor. "At
the exact north the needle points straight down, because the pole is a
magnet, and being directly underneath pulls the end of the needle down.
See, it is almost down now. I believe we shall really get to the pole,
and my ambition will be realized."

Aside from the wound Andy had received, none of the party was any the
worse for their adventures as prisoners. Now that they were safe back on
the ship they were inclined to laugh at the fears they had felt.

For several hours the _Monarch_ was held to her course at a fairly good
speed. Then, at the professor's order, the engines were turned on at
full power, since the air was still, and there was no sign of a storm.
Straight to the north the craft shot, every one on board now anxious, as
they became aware that they were near to their destination.

The former life was resumed, and the hours of watch were marked out as
they had been. The sun still shone, never setting, but by this time the
adventurers were used to perpetual day. Dirola kept to herself, not
saying a word to anybody.

"I think I'll drop the ship down a bit and see what sort of a country is
beneath us," announced Mr. Henderson about four o'clock, though whether
it was four o'clock in the morning or the afternoon, no one knew.
However, it did not matter much. "If there is an open sea around the
north pole, as some believe," he went on, "we ought to see some si