nd the others nodded, grimly.

"I imagine she'll have about a hundred and twenty miles to travel in a
straight line--perhaps a little less," said Harry. "She can make that in
about two hours, or less. And she'll travel without lights, and in the
dark. Big as they are, those airships are painted so that they're almost
invisible from below. So if she comes by night, getting here won't be as
hard a job as it seems at first thought."

Then the three of them went over in every detail the plan Harry had formed.
Dick and Harry took their places in the monoplane and rehearsed every
movement they would have to make.

"I can't think of anything else that we can provide for now," said Harry,
at last. "Of course, we can't tell what will come up, and it would be
wonderful if everything came out just as we had planned. But we've provided
for everything we can think of. You know where you are to be, Jack?"

"Yes."

"Then you'd better start pretty soon. Good-bye, Jack!" He held out his
hand. "We could never have worked this out without you. If we succeed
you'll have had a big part in what we've done."

A little later Jack said good-bye in earnest, and then there was nothing to
do but wait. About them the voices of the insects and frogs changed, with
the darkening night. The stars came out, but the night was a dark one.
Harry looked at his watch from time to time and at last he got up.

"Time to start!" he said.

He felt a thrill of nervousness as the monoplane rose in the air. After
all, there was a difference between being the pilot and sitting still in
the car. But he managed very well, after a few anxious moments in the
ascent. And once they were clear of the trees and climbing swiftly, in
great spirals, there was a glorious sensation of freedom. Dick caught his
breath at first, then he got used to the queer motion, and cried aloud in
his delight.

Harry headed straight into the east when he felt that he was high enough.
And suddenly he gave a cry.

"Look!" he shouted in Dick's ear. "We didn't start a moment too soon. See
her--that great big cigar-shaped thing, dropping over there?"

It was the Zeppelin--the battleship of the air. She was dipping down,
descending gracefully, over Bray Park.

"I was right!" cried Harry. "Now we can go to work at once--we won't have
to land and wait!"

He rose still higher, then flew straight for Bray Park. They were high,
but, far below, with lights moving about her, they could see the