Chapter XI. A Day Off

Tom Swift pondered long and intently over what his father had said to him. He sat for several minutes in his private office, after the aged inventor had passed out, reviewing in his mind the talk just finished.

"I wonder," said Tom slowly, "if any of the new men could have obtained work here for the purpose of furthering that plot the lieutenant suspects? I wonder if that could be true?"

And the more Tom thought of it, the more he was convinced that such a thing was at least possible.

"I must make a close inspection, and weed out any suspicious characters," he decided, "though I need every man I have working now, to get the Mars finished in time. Yes, I must look into this."

Tom had reached a point in his work where he could leave much to his helpers. He had several good foremen, and, with his father to take general supervision over more important details, the young inventor had more time to himself. Of course he did not lay too many burdens on his father's shoulders since Mr. Swift's health was not of the best.

But Tom's latest idea, the aerial warship, was so well on toward completion that his presence was not needed in that shop more than two or three times a day.

"When I'm not there I'll go about in the other shops, and sort of size up the situation," he decided. "I may be able to get a line on some of those plotters, if there are any here."

Lieutenant Marbury had departed for a time, to look after some personal matters, but he was to return inside of a week, when it was hoped to give the aerial warship its first real test in flight, and under some of the conditions that it would meet with in actual warfare.

As Tom was about to leave his office, to put into effect his new resolution to make a casual inspection of the other shops, he met Koku, the giant, coming in. Koku's hands and face were black with oil and machine filings.

"Well, what have you been doing?" Tom wanted to know. "Did you have an accident?" For Koku had no knowledge of machinery, and could not even be trusted to tighten up a simple nut by himself. But if some one stood near him, and directed him how to apply his enormous strength, Koku could do more than several machines.

"No accident, Master," he replied. "I help man lift that hammer-hammer thing that pounds so. It get stuck!"

"What, the hammer of the drop forger?" cried Tom. "Was that out of order again?"

"Him stuck," explained Koku simply.

There was an automatic trip-hammer in one of the shops, used for pounding out drop forgings, and this hammer seemed to take especial delight in getting out of order. Very often it jammed, or "stuck," as Koku described it, and if the hammer could not be forced back on the channel or upright guide-plates, it