"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.