"Tom, aren't you going to try to get a look at that German?" whispered Ned, as he and his chum came down from the elevated gallery at the conclusion of the cast. "I mean the one who tried to get in!"

"I'd like to, Ned, but I don't want to arouse any suspicion," replied Tom. "I've got to stay here a while yet, and arrange about shrinking on the jackets, after the core is rifled. I don't see how--"

"I'll slip out and see if I can get a peep at him," went on Ned. "If it's like the one Koku described, we'll know that he's still after you."

"All right, Ned. Do as you like, only be cautious."

"I will," promised Tom's chum. So, while the young inventor was busy arranging details with the steel manager, Ned slipped out of a side door of the casting shop, and looked about the yard. He saw a little group of workmen surrounding a man who appeared to be angry.

"I dell you dot is my shop!" one of the men was heard to exclaim--a man whom the others appeared to dragging away with main force.

"And I tell you, Baudermann, that you're mistaken!" insisted one, evidently a foreman. "I told you to work in the brazing department. What do you want to try to force your way into the heavy casting department for? Especially when we're doing one of the biggest jobs that we ever handled--making the new Swift cannon."

"Oh, iss dot vot vas going on in dere?" asked the man addressed as Baudermann. "Shure den, I makes a misdake. I ask your pardon, Herr Blackwell. I to mine own apartment will go. But I dinks my foreman sends me to dot place," and he indicated the casting shop from which he had just been barred.

"All right!" exclaimed the foreman. "Don't make that mistake again, or I'll dock you for lost time."

"Only just a twisted German employee, I guess," thought Ned, as he was about to turn back. "I was mistaken. He probably didn't understand where he was sent."

He passed by the group of men, who, laughing and jeering at the German, were showing him where to go. He seemed to be a new hand in the works.

But as Ned passed he got one look at the man's face. Instead of a stupid countenance, for one instant he had a glimpse of the sharpest, brightest eyes he had ever looked into. And they were hard, cruel eyes, too, with a glint of daring in them. And, as Ned glanced at his figure, he thought he detected a trace of military stiffness--none of the stoop-shouldered slouch that is always the mark of a moulder. The fellow's hands, too, though black and grimy, showed evidences of care under the dirt, and Ned was sure his uncouth language was assumed.

"I'd like to know more about you," murmured Ned, but the man, with one sharp glance at him, passed on, seemingly to his own department of the works.

"Well, what was it?" asked Tom, as his chum rejoined him.

"Nothing very definite, but I'm sure there was something back of it all, Tom. I wouldn't be surprised but what that fellow-- whoever he was--whatever his object was--hoped to get in to see the casting; either to get some idea about your new gun, or to do some desperate deed to spoil it."

"Do you think that, Ned?"

"I sure do. You've got to be on your guard, Tom."

"I will. But I wonder what object anyone could have in spoiling my gun?"

"So as to make his own cannon stand in a better light."

"Still thinking of General Waller, are you?"

"I am, Tom."

There was nothing more to be done at present, and, as it would take several days for the big mass of metal to properly cool, Tom, Ned and Mr. Damon returned to Shopton.

There Tom busied himself over many things. Ned helping him, and Mr. Damon lending an occasional hand. Koku was very useful, for often his great strength did what the combined efforts of Tom and his friends could not accomplish.

As for Eradicate, he "puttered around," doing all he could, which was not much, for he was getting old. Still Tom would not think of discharging him, and it was pitiful to see the old colored man try to do things for the young inventor--tasks that were beyond his strength. But if Koku offered to help, Eradicate would draw himself up, and exclaim:

"Git away fom heah! I guess dish yeah coon ain't forgot how t' wait on Massa Tom. Go 'way, giant. I ain't so big as yo'-all, but I know de English language, which is mo' 'n yo' all does. Go on an' lemme be!"

Koku, good naturedly, gave place, for he, too, felt for Eradicate.

"Well, Ned," remarked Tom one day, after the visit of the postman, "I have a letter from the steel people. They are going to take the gun out of the mould tomorrow, and start to rifle it. We'll take a run down in the airship, and see how it looks. I must take those drawings, too, that show the new plan of shrinking on the jackets. I guess I'll keep them in my room, so I won't forget them."

Tom and Ned occupied adjoining and connecting apartments, for, of late, Ned had taken up his residence with his chum. It was shortly after midnight that Ned was awakened by hearing someone prowling about his room. At first he thought it was Tom, for the shorter way to the bath lay through Ned's apartment, but when the lad caught the flash of a pocket electric torch he knew it could not be Tom.

"Who's there?" cried Ned sharply, sitting up in bed.

Instantly the light went out, and there was silence.

"Who's there?" cried Ned again.

This time he thought he heard a stealthy footstep.

"What is it?" called Tom from his chamber.

"Someone is in here!" exclaimed Ned. "Look out, Tom!"