of moving rapidly through the air in a machine as skillfully
guided as was the one piloted by Tom Swift was delightful. Up and
up they went, and then suddenly Mary felt a lurch, and the plane,
which was now about a thousand feet high, seemed to slip to one
side.

Mary screamed, and began reaching for the buckle of the safety
belt that fastened her to her seat. She saw that something
unusual had occurred, for Tom was working frantically at the
mechanism in front of him.

But, in spite of this, he seemed aware that Mary was in danger,
not so much, perhaps, from what might happen to the machine, as
what she might do in her terror.

"Oh! Oh!" cried the girl, and Tom heard her above the terrific
noise of the motor, for she was speaking with her lips close to
the tube that served as a sort of inter-communicating telephone
for the craft. "Oh, we are falling! I'm going to jump!"

"Sit still! Sit still for your life!" cried Tom Swift. "I'll
save you all right! Only sit still! Don't jump!"

Mary, her red cheeks white, sank back, and the young inventor
redoubled his efforts at the controls and other mechanisms.

And that Tom was perfectly qualified to make a safe landing,
even with engine trouble, Mary Nestor well knew. Those of you who
have read the previous books of this series know it also, but,
for the benefit of my new readers, I shall state that this was by