boys' craft, too. She evidently proposed to retain her overhead
position, and as she shot in closer, Jack was constrained to descend
again to escape collision with her.

"Keep away!" he shouted through the transmitter, and at his cry, and
the bustle about him, the professor was awakened.

But no reply came from the strange aeroplane, although they could see
several figures moving upon her. It swooped down upon them, and Jack
had to deflect his planes again and slant downward toward the
storm-cloud.

And then he saw the other peril. He was between two great dangers. If
the reckless aviator tried to ram him from above, his only escape was
by plunging through the tempest which raged just below them.

Down came the stranger upon the _Snowbird_ again. She surely meant
them ill--she was bent on their destruction. And meanwhile the thunder
roared below and the crackling of the lightning was almost incessant.

Jack Darrow had to decide quickly--and he must determine which of the
two risks to take.




CHAPTER VI

ON THE WINGS OF THE WIND