don't say anything about what I have told you."
"Why?" asked Ned quickly.
Mr. Petrofsky approached closer to the lads, and in a low voice said:
"I am not sure about it, but of late I think I have been shadowed. I have seen strange men in the village near here and they have eyed me rather suspiciously. Then, too, I have surprised several men around my house. I live here all alone, you know, and do most of my own work, a woman coming in occasionally to clean. But I don't like these suspicious characters hanging about.
"Who do you think they are?" asked Tom.
"I'm almost afraid to think, but from my past experience I think—nay, I fear—they may be spies, or agents of the Russian government."
"Spies!" cried Ned.
"Hush. Not so loud," cautioned Mr. Petrofsky. "They may even now be in hiding, especially since your aeroplane landed so near my house. They may see something suspicious even in that. "
"But why should the Russian government set spies on you?" asked Tom in a low voice.
"For two reasons. I am an escaped exile, and I am not a citizen of the United States. Therefore I may be sent back to the sulphur mines. And another reason is that they may think I know the
