"In the first place," said Mark, as he and his chum turned from the yard, and walked along a quiet country road, "I think our best plan will be to find Dick Johnson, and ask him just where it was he met the man who gave him a quarter to bring the note to me." "What for?" asked Jack. "Why, then, we can tell where to start from. Perhaps Dick can give us a description of the man, or tell from what direction he came. Then we'll know how to begin on the trail." "That's a good idea, I guess. We know where he disappeared to, or, rather, in nearly what direction, so that will help some." "Sure. Well, then, let's find Dick." To the inquiries of the two lads from the projectile, Dick Johnson replied that, as he had asserted once before, that the man was a stranger to him. "He was tall, and had a big black mustache," Dick described, "but he kept his hat pulled down over his eyes, so I couldn't see his face very well. Anyhow, it was dark when I met him." "Where did you meet him?" asked Mark. "Not far from your house. He was standing on the corner, where you turn down to go to the woollen mill, and, as I passed him, he asked me if I wanted to earn a quarter." "Of course you said you did," suggested Jack. "Sure," replied Dick. "Then he gave me the note, and told me where to take it, and I did. That wasn't wrong, was it?" "No; only there seems to be something queer about the man, and we want to find out what it is," replied Mark. "What was the man doing when you saw him?" asked Jack. "Standing, and sort of looking toward your house." "Looking toward our house?" repeated Jack. "Was he anywhere near the big shed where we build the machines?" "Well, I couldn't say. Maybe he might have been." "I guess that's all you can tell us," put in Mark, with a glance at his chum, to warn him not to go too much into details with Dick, for they did not want it known that some enemy had tried to wreck the projectile. "Yes, I can't tell you any more," admitted the small lad. "Well, here's a quarter for what you did tell us," said Jack, "and if you see that man again, and he gives you a note for us, just keep your eye on him, watch where he goes, and tell us. Then you will get a half-dollar." "Gee! I'll be on the watch," promised Dick, his eyes shining at the prospect of so much money. "Come on," suggested Jack to his chum, after the small chap had departed. "Let's go down by the white bridge and make some inquiries of people living in that vicinity. They may have seen a stranger hanging around, and, perhaps we can get on his trail that way." "All right," agreed Mark, and they walked on together. They had gone quite a distance away from the bridge, and had made several inquiries, but had met with no success, and they were about to give up and go back home. "I know one person we haven't inquired of yet," said Mark, as they tramped along. "Who's that?"