at the watch charm. "What can he be doing in this neighborhood? Hiding, too, as if he wanted to overhear something. That's the way he did when we were building our submarine, and now he's up to the same trick when I'm constructing my electric car. I'm sure this charm is his. It is such a peculiar design that I'm positive I can't be mistaken. I thought, when I was chasing after him, that it would turn out to be Andy Foger, or some of the boys, but it was too big for them. Addison Berg, eh? What can he be doing around here? I must not tell dad, or he'd worry himself sick. But I must be on my guard."
Tom examined the charm closely. It was a compass, but made in an odd form, and was much ornamented.
The young inventor had noticed it on several occasions when he had been in conversation with Mr. Berg previous to the attempt on the part of the owners of the rival submarine to wreck Tom's boat. He felt that he could not be mistaken in identifying the charm.
"Berg was afraid I'd catch him, and ask for an explanation that would have been awkward to make," thought the lad, as he turned the charm over in his hand. "That's why he tripped me up. But I'll get at the bottom of this yet.
