"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.