At once the flying machine responded to the change. She rode straight on, slightly rising as he had pointed her, and Mark dared touch the motor switch again. Instantly the machine speeded ahead.
"Hurrah for Mark!" shrieked Jack. "He's pulled us through."
"He has indeed," agreed the professor, and they settled into their seats and gave attention to the working of the apparatus. Mark now had the Snowbird well under control.
Jack changed places with his chum and managed the Snowbird equally well. At his touch she darted upward at a long slant until the altimeter registered two thousand feet above the sea. And the sea was actually below them, for Jack had guided the flying machine away out from the land.
"Boys," said Professor Henderson, quietly, "you have done well—remarkably well. I am certainly proud of you. Some day the people of the United States will be proud of you. I am sure that the inventor's instinct and the scientist's indefatigable energy are characteristics you both possess."
"That's praise indeed!" exclaimed Jack, smiling at his chum. "When the professor says we've won out, I don't care what anybody else says."
"Do you think the Snowbird is fit for long-distance travel?" asked
Mark of Professor Henderson, now displaying more eagerness than before.
"I do indeed. I think you have a most excellent flying machine. I would not hesitate to start for San Francisco in her."
"Or farther?" asked Jack.
"Certainly."