"Then you are really going to search for the pole?" asked Jack.

"I am, my boy, and, what is more, I am going to find it. Why, it is
simple with the wonderful gas I have discovered. That is the whole
secret of what will be my success. It is easy enough to make an airship
that will move, but the trouble is no one has yet been able to make a
gas strong enough to lift the heavy weight of the ship high into the
air. That is where I have the advantage."

"I wish I could see your ship sail," said Jack.

"You may if you like," exclaimed the old man. "Do you remember what I
asked you when the knock interrupted us? I asked you if you wanted to go
to the north pole. Now I have taken a great liking to both you boys. I
haven't even asked your names yet, but I like you. I need some help in
running the ship, also in making my explorations in the frozen north.
Would you like to go along?"

For a few seconds the boys did not know what to say. It was a strange
and sudden proposition. They had been through so many adventures in the
last few hours that their brains were fairly bewildered. But to both of
them there came a great desire to make this wonderful trip through the
air. Before they could make a reply Professor Henderson spoke again:

"Perhaps you had better think it over a bit," he said. "I realize that
it comes rather suddenly. Supposing you go to bed, and we'll talk more
in the morning. Come, Washington, make up a couple of bunks for the boys
in this room. You can sleep in the balloon shed as usual."

In a few minutes the colored man had made rude but comfortable beds on