"Hold on—wait a minute!" exclaimed Tom. "We want to know who that man is—and why we're going to chase after him. Koku, I guess it's up to you. Something has been going on here that I don't know anything about. Explain!"

"Well, it's no use to chase after him now," said Ned. "There he goes on his motor-cycle."

As he spoke the man, who, even from a rear view, presented all the characteristics of an army man, so straight was his carriage, leaped upon a motor-cycle that he pulled from the roadside bushes, and soon disappeared in a cloud of dust.

"No, he's gone," spoke Tom, half-regretfully. "But who was he, Koku? You seemed to know him. What was he doing out here, watching my test?"

"Me tell," said the giant, simply. "Little while after Master come back from where him say big gun all go smash, man come to shop when Master out one day. Him very nice man, and him say him know you, and want to help you make big cannon. I say, 'Master no be at home.' Man say him want to give master a little present of powder for use in new cannon. Master be much pleased, man say. Make powder better. I take, and I want Master to be pleased. I put stuff what man gave me in new powder. Man go away—he laugh—he say he be here today see what happen—I tell him you go to make test today. Man say Master be much surprised. That all I know."

Silence followed Koku's statement. To Ned and Mr. Damon it was not exactly clear, but Tom better understood his giant servant's queer talk.

"Is that what you mean, Koku?" asked the young inventor, after a pause. "Did some stranger come here one day when I was out, after I had made my new powder, and did he give you some 'dope' to put in it?"

"What you mean by 'dope'?"

"I mean any sort of stuff."

"Yes, man give me something like sugar, and I sprinkle it on new powder for to surprise Master."