a change.
Koku seems to like this hammer, and knows how to get it in order once
it gets off the guides. You say you have had experience in airship
construction?"

"Yes, sir. I've worked on the engines, and on the planes."

"Know anything about dirigible balloons?"

"Yes, I've worked on them, too, but the engineering part is my
specialty. I'm a little out of my element on a trip-hammer."

"I see. Well, perhaps I'll give you a trial. Meanwhile you might break
Koku in on operating this machine. If I transfer you I'll put him on
this hammer."

"Thank you, Mr. Swift! I'll show him all I know about it. Oh, there
goes the hammer again!" he exclaimed, for, as he started it up, as Tom
turned away, the big piece of steel once more jammed on the
channel-plates.

"Me fix!" exclaimed the giant eagerly, anxious for a chance to exhibit
his great strength.

"Wait a minute!" exclaimed Tom. "I want to get a look at that machine."

He inspected it carefully before he signaled for Koku to force the
hammer back into place. But, if Tom saw anything suspicious, he said
nothing. There was, however, a queer look on his face as he turned
aside, and he murmured to himself, as he walked away:

"So you want to be transferred to the airship department, do you? Well,
we'll see about that We'll see."

Tom had more problems to solve than those of making an aerial warship
that would be acceptable to the United States Government.

Ned Newton called on his chum that evening. The two talked of many
things, gradually veering around to the subject uppermost in Tom's
mind--his new aircraft.

"You're thinking too much of that." Ned warned him. "You're as bad as
the time you went for your first flight."

"I suppose I am," admitted Tom. "But the success of the Mars means a
whole lot to me. And that's something I nearly forgot. I've got to go
out to the shop now. Want to come along, Ned?"

"Sure, though I tell you that you're working too hard--burning the
electric light at both ends."

"This is just something simple," Tom said. "It won't take long."

He went out, followed by his chum.

"But this isn't the way to the airship shed," objected the young bank
clerk, as he noted in which direction Tom was leading him.

"I know it isn't," Tom replied. "But I want to look at one of the
trip-hammers in the forge shop when none of the men is around. I've
been having a little trouble there."

"Trouble!" exclaimed his chum. "Has that plot Lieutenant