“It’s an earthquake!” exclaimed the professor, as soon as he was awakened.
As he spoke the whole structure of the Discoverer was shaken as if by a giant hand beneath her.
At the same instant the voice of old Matco was heard calling out as if in prayer.
“Get her loose, for heaven’s sake!” cried Mr. Tubbs, “or we’ll be destroyed!”
“It is the vengeance! The vengeance!” cried old Matco in Spanish, bursting into the cabin.
“Switch on the lights,” ordered the professor.
Joe sprang into the pilot house and threw the switch. A blaze of light illumined the aircraft. It showed a strange scene in her cabin. Half-dressed, and wholly bewildered, the adventurers were being thrown about like so many ninepins. The substructure of the Discoverer shook like an ague-stricken human being, as the earth beneath her rocked and rumbled.
Nat and Joe, the most self-possessed of any on board, sprang out upon the decks. The ropes had been tied, it not having been anticipated that they would want to leave in a hurry.
“Cut them!” shouted Nat above the hubbub about them.
The sky was being ripped and seared by livid lightning, while the flashes of light showed the lake to be a mass of white foam. The air was filled with a strange, roaring sound.