"They'll never get after me," boasted the man. "This is a good joke. To think that I can pass myself off as you; that I can join them in the projectile, and they never will be the wiser!" "They'll soon discover that you are disguised as me," declared Mark, "and when they do they'll have you arrested." "Yes, but they'll not discover it until we have left the earth, and are on our way to the moon. Then it will be too late to turn back, and my object will have been accomplished. I will be with them in the _Annihilator_, and I'll have my revenge! The projectile is due to sail to-morrow, and I'll be on hand. I'm going to leave you now. I have left orders with a friend of mine that you are to be released to-morrow night. In the meanwhile you will have to be as comfortable as you can. I wish you no harm, but I must keep you here. "I will feed you well before I go, and put some water where you can get it. But I must leave you tied. I'll not gag you, for, no matter how you yell, no one will hear you. I have posted a notice in front of this place that it is under the watch of the police, so no tramps will venture in, and your friends will not come back. "Now, just make yourself comfortable here, and I'll go to the moon in your place. I think I shall enjoy the trip. As I said, you will be released to-morrow night, several hours after the projectile has left the earth." "How do you know it is to start to-morrow morning?" asked Mark. "Oh, I have been spying around, and I overheard the professors talking. I know a thing or two, and I'll be on hand, on time, in your place! Now, I have to leave you. I've left ten dollars to pay for your suit, which I need to disguise myself with." Then the man was gone, and Mark was left with his bitter thoughts to keep him company. The whole daring scheme of the man had been revealed. He did look something like Mark, and, attired in the lad's clothes, and by keeping his face concealed, he might pass himself off as Jack's chum; at least, until after the projectile had started. "And then, as he says, it will be too late to return to earth and get me," thought Mark bitterly. "Oh, why did I ever try to learn this man's secret? Who is he, anyhow? Why didn't I wait for Jack at the barn, as I promised? It's all my fault. I wonder if I can't get loose?" Mark struggled several hours desperately and at last he felt the ropes giving slightly. He redoubled his efforts. Strand by strand the cords parted. He put all his efforts into one last attempt, and to his great joy he felt his hands separate. He was partly free! But scarcely half his task was accomplished. He had yet to discover the secret of the hidden room--a room, as he afterward learned, which had been built during slavery days to conceal the poor black men who were escaping from the South. "But now I have my hands to work with!" exulted Mark.