Chapter XXIII. The Government Test

For a moment Jackson thought Tom had discovered a clew to, or evidences of, some crime. He had an unpleasant suspicion, for an instant, that there was blood on the files, and that it might prove to be the blood of Mr. Nestor.

But the satisfaction that showed on Tom's face did not seem to indicate such dire possibilities as these.

"What is it?" asked Jackson, unable to guess at what Tom was looking through the powerful glass. "What do you see?"

"Metal filings on the grooves of these files," said the young inventor. "And, unless I'm greatly mistaken, the particles of filings are from the case of my aircraft silencer!"

"What!" cried the machinist. "Do you mean those are the files used in weakening the outer case of your new machine, so that it burst a little while ago?"

"That what I think," answered Tom. "I know it sounds pretty far-fetched," he went on. "But take a look for yourself. If those particles on, the files aren't exactly of the same color and texture as the material of which the silencer case is made, I'll never build another machine."

Jackson peered through the powerful glass moving out a little farther from the shack, so as to get the best light possible on the subject of his examination. It was fast getting dark, but there was enough glow in the western sky for his purpose.

"Am I right?" asked Tom.

"You're right!" declared his helper. "This is exactly the same metal as that of which your silencer case is made. It's a peculiar mixture of aluminum and vanadium steel. I never knew it used in any shop but yours, and these filings are certainly of that metal. It would seem, Tom, that these were the files used to cut a crease in the case of your silencer to weaken it so it would burst."

"My idea exactly!" cried Tom. "The spy, who got into my shop in some undiscovered manner, did his work and then fled here to hide. He left his files behind. Mr. Nestor must have been here, either before or after. No, I'll not say that, either. Finding his wallet here doesn't prove that he was here. It might have been brought here by one of the spies and dropped. But I'm sure we're on the track of the men who damaged my airship, as well as those who know something of the mystery of Mr. Nestor."

"I agree with you," said Jackson. "Of course there's a possibility that the same peculiar metal you used in your silencer case may have been used in some other machine shop, and these files may have come from there, and have been employed in perfectly regular work. But the chances are--"

"There's only one way to make sure," said Tom. "Let's take the files with us and see if they fit in the grooves where the break came. We'll take these back to where we left the Air Scout,"