the rising power that was fouled. He learned this in a moment. He
sought to move it to and fro in its socket and could not do so. He had
overlooked this lever before.

Again the _Snowbird_ dashed herself from a height of five hundred feet
toward the earth.

They still flew over the forest. The tops of the trees intervened, and
Mark managed to counteract the plunge before the prow of the machine
burst through the treetops. She rose again, and using both hands, Mark
jerked the wheel stick into place.

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