Marbury spoke
of developed?"

"Not exactly. This is something else," and Tom told of the trouble with
the big hammer.

"I had an idea," the young inventor said, "that the man at the machine
let it get out of order purposely, so I'd change him. I want to see if
my suspicions are correct."

Tom carefully inspected the hammer by the light of a powerful portable
electric lamp Ned held.

"Ha! There it is!" Tom suddenly exclaimed.

"Something wrong?" Ned inquired.

"Yes. This is what's been throwing the hammer off the guides all the
while," and Tom pulled out a small steel bolt that had been slipped
into an oil hole. A certain amount of vibration, he explained to Ned,
would rattle the bolt out so that it would force the hammer to one
side, throwing it off the channel-plates, and rendering it useless for
the time being.

"A foxy trick," commented Tom. "No wonder the machine got out of kilter
so easily."

"Do you think it was done purposely?"

"Well, I'm not going to say. But I'm going to watch that man. He
wants to be transferred to the airship department. He put this in the
hammer, perhaps, to have an excuse for a change. Well, I'll give it to
him."

"You don't mean that you'd take a fellow like that and put him to work
on your new aerial warship, do you, Tom?"

"Yes, I think I will, Ned. You see, I look at it this way: I haven't
any real proof against him now. He could only laugh at me if I accused
him. But you've heard the proverb about giving a calf rope enough and
he'll hang himself, haven't you?"

"I think I have."

"Well, I'm going to give this fellow a little rope. I'll transfer him,
as he asks, and I'll keep a close watch on him."

"But won't it be risky?"

"Perhaps, but no more so than leaving him in here to work mischief. If
he is hatching a plot, the sooner it's over with the better I shall
like it. I don't like a shot to hang fire. I'm warned now, and I'll be
ready for him. I have a line on whom to suspect. This is the first
clue," and Tom held up the incriminating bolt.

"I think you're taking too big a risk, Tom," his chum said. "Why not
discharge the man?"

"Because that might only smooth things over for a time. If this plot is
being laid the sooner it comes to a head, and breaks, the better. Have
it done, short, sharp and quick, is my motto. Yes, I'll shift him in
the morning. Oh, but I wish it was all over, and the Mars was accepted
by Uncle Sam!" and Tom put his hand to his head