On and on rushed the Porpoise. The engines were kept at full speed, and after two hours of this fast run another attempt was made to reach the surface. Once more the thick ice intervened.
"Guess we'll have to blast our way out," observed Andy. "We seem to have lots of trouble on this trip."
"Why not try to ram your way through," suggested Jack.
"How do you mean?" asked Mr. Henderson.
"I mean to sink the boat say two hundred feet. Then start her up obliquely and perhaps the sharp prow will cut a hole through the ice."
"Hardly through ice fifteen feet or more thick," said the captain despondently.
"But it may be thinner now," persisted Jack.
"At any rate it will do no harm to try," the inventor admitted. "We can not last much longer down here."
Again the tanks were filled, and by the aid of the deflecting rudder the Porpoise went down into the depths. Then the ballast tanks were quickly emptied, and the rudder turned so as to force the craft upward on a slant. The engine was set going at top speed.
"Hold fast everybody!" called the professor. "It is kill or cure this trip!"