re is no telling," replied the professor. "But it must have been
several years. I have read of all recent polar expeditions, and within
the last twenty years there has been no one of this name to venture
toward the pole. Besides the copper cap on the cylinder has become
rusted on, and that would indicate the passage of considerable time."

"I wonder if there are people at the pole?" came from Mark.

"We'll go and see!" exclaimed the professor.

"You don't mean to say you are going further north after what that
message says?" asked Andy Sudds.

"Certainly; why not?"

"We may all be killed."

"We'll try not to have that happen," said the professor. "I am glad you
boys found this. It is a valuable relic," and Amos Henderson put the
message, the trinkets and the cylinder carefully away.

"I--I guess I won't go--" began Andy.

At that instant the airship gave a sudden tremble. Then the whole craft
shivered. Next it began to rise in the air.

"Here we go!" cried the professor.

CHAPTER XIII

FORWARD ONCE MORE

The airship rose rapidly. Washington had continued to operate the gas
machine until there was a sufficient quantity of vapor to overcome the
contracting influence of the cold atmosphere.

"Forward once more!" cried the professor, hurrying to the engine room.
"This time we may reach the north pole!"

He and Washington soon started the motors, the dynamos and engines. The
propeller revolved rapidly. The adventurers were under way again.

"Jack and Mark, go into the conning tower and steer!" called Mr.
Henderson from the engine room. "Take her up about half a mile, and send
her straight north by the compass. I have to adjust some of the
machinery."

Delighted at the prospect of running the airship, the two boys hurried
forward. Mark went to the steering wheel, which was similar to the kind
used on automobiles. The _Monarch_ was heading to the west, having no
one to guide her, but Mark soon brought her around until her bow was
poked directly for the north.

Under the guidance of the two boys, the airship rushed forward. They had
become somewhat used to the queer feeling of being high up in the air,
and now it did not seem wonderful to be sailing among the clouds, though
two weeks before they would have laughed at the idea of such a thing.
Andy and the two farmers had, likewise, become a little indifferent to
the strange sensations, and, aside from being careful not to go too near
the rail of th