"What is it--a way out?" asked Lieutenant Marbury anxiously.

"No, but means to that end," Tom replied. "Look, a file and a saw, left
here by some of my workmen, perhaps," and he brought out the tools. He
had found them behind a barrel in the far end of the compartment.

"Hurray!" cried Ned. "That's the ticket! Now we'll soon show these
fellows what's what!"

"Go easy!" cautioned Tom. "We must work carefully. It won't do to slam
around and try to break down the door with these. I think we had better
select a place on the side wall, break through that, and make an
opening where we can come out unnoticed. Then, when we are ready, we
can take them by surprise. We'll have to do something like that, for
they outnumber us, you know."

"That is so," agreed Captain Warner. "We must use strategy."

"Well, where would be a good place to begin to burrow out?" asked Ned.

"Here," said Tom, indicating a place far back in the room. "We can work
there in turns, sawing a hole through the wall. It will bring us out in
the passage between the aft and amidship cabins, and we can go either
way."

"Then let's begin!" cried Ned enthusiastically, and they set to work.

While the aerial warship pitched and tossed in the storm, over some
part of the Atlantic, Tom and his friends took turns in working their
way to freedom. With the sharp end of the file a small hole was made,
the work being done as slowly as a rat gnaws, so as to make no noise
that would be heard by their captors. In time the hole was large enough
to admit the end of the saw.

But this took many hours, and it was not until the second day of their
captivity that they had the hole nearly large enough for the passage of
one person at a time. They had not been discovered, they thought.

Meanwhile they had been given food and water at intervals, but to all
demands that they be released, or at least told why they were held
prisoners, a deaf ear was turned.

They could only guess at the fate of Koku. Probably the giant was kept
bound, for once he got the chance to use his enormous strength it might
go hard with the foreigners.

The Mars continued to fly through the air. Sometimes, as Tom and his
friends could tell by the motion, she was almost stationary in the
upper regions, and again she seemed to be flying at top speed.
Occasionally there came the sound of firing.

"They're trying my guns," observed Tom grimly.

"Do you suppose they are being attacked?" asked Ned, h