"Dat's de impression I done endeavored to prognostigate to yo', but seems laik I ain't understood," replied Washington with an injured air. "Oh, I understand you, all right," said Jack, "but I thought you meant some one was gettin in the machine shop." "No, dere ain't been no one dere, but I was skeered dat somebody was after mah chickens, but I guess it were only a rat. I'll go back an stay on guard now." "No, you'd better go to bed," decided Jack. "Mark and I will finish out the night." "All right," agreed Washington, who, to tell the truth, was getting sleepy. There were no further disturbances, and Mark and Jack found their tour of duty rather lonesome. "Well, I suppose we'll start in a day or so," marked Jack, as they paced about the big shed which housed the great projectile. "Yes. The motor seems to be in good working order again. But say, I've just thought of something." "What?" "Suppose something should happen to Mr. Roumann or to the motor while we were half way to Mars? I mean, suppose he should die, why, we wouldn't know how to stop the motor, and we might keep on going forever." "Oh, I guess he'll tell the professor enough about it so that in case anything happened we could start it or stop it. It's only the secret of the power that he wants to keep." "I wonder what he wants to go to Mars for, anyhow?" "Well, you know what he said. That he wants to get possession of some wonderful substance. I guess it is the same stuff that makes the planet seem red to us." "What's he going to do with it?" "I don't know." "Wonder what it is?" "I don't know that, either. Maybe it's some sort of a mineral, like radium." "Radium would be valuable, if he could get that. Maybe that's what he's going after." "No, I think not. If it was, he wouldn't be particular about not telling us. We'll just have to wait and see." The following two days were busy ones, as many little adjustments had to be made to the machine. But at last Mr. Roumann announced that all was completed. "We will start day after to-morrow," he said. "All the stores are in the projectile, I have every thing arranged, and we will begin our trip Mars." "Are we going to go up like a balloon, through the roof of the shed?" asked Jack. "If we we'll have to take the roof off." "No, we'll start out through the great doors," said the German. "My plan is to elevate the nose or bow, of the projectile, point it toward the sky, at a slight angle, by means of propping it up on blocks. Then we will get in, seal all the openings, and I will turn on the power, and off we go. We can shoot right through the big doors at the end of the shed, and no one will know anything about it, for we will leave the earth so fast that before any one is aware of our plans we will be out of sight." "That is a good idea," commented Mr. Henderson. "Have you boys put everything in the projectile that you'll need?"