He was disappointed when he found out what they meant to do, but he took his disappointment pluckily when he saw that there was no help for it. Harry explained very quietly to both Jack and Dick what he meant to do and they listened, open mouthed, with wonder.
"You'll have your part to play, Jack," said Harry. "Somehow I can't believe that the letter I wrote to Colonel Throckmorton last night won't have some effect. You have got to scout around in case anyone comes and tell them all I've told you. You understand thoroughly, do you?"
"Yes," said Jack, quietly. "When are you going to start?"
"There's no use going up much before eleven o'clock," said Harry. "Before that we'd be seen, and, besides, if a Zeppelin is coming, it wouldn't be until after that. My plan is to scout to the east and try to pick her up and watch her descend. I think I know just about where she'll land–the only place where there's room for her. And then–"
He stopped, and the others nodded, grimly.
"I imagine she'll have about a hundred and twenty miles to travel in a straight line–perhaps a little less," said Harry. "She can make that in about two hours, or less. And she'll travel without lights, and in the dark. Big as they are, those airships are painted so that they're almost invisible from below. So if she comes by night, getting here won't be as hard a job as it seems at first thought."
Then the three of them went over in every detail the plan Harry had formed. Dick and Harry took their places in the monoplane and rehearsed every movement they would have to make.
"I can't think of anything else that we can provide for now," said Harry, at last. "Of course, we can't tell what will come up, and it would be wonderful if everything came out just as we had planned. But we've provided for everything we can think of. You know where you are to be, Jack?"
"Yes."
"Then you'd better start pretty soon. Good-bye, Jack!" He held out his hand. "We could never have worked this out without you. If we succeed you'll have had a big part in what we've done."