"No, they are real wheels, and they are on the walls," announced Mark. "Then where in the world are we?" went on Jack. "In a machine shop or a railroad wreck?" "Looks like--" began Mark, when he was interrupted by a voice calling: "Hurry up, Perfessor! De boys has awakened from de unconsciousability!" And, to the astonishment of Jack and Mark, the old man and his negro helper hurried from the inner room and stood in front of the bed. CHAPTER IV THE AIRSHIP "Do you feel better?" asked the professor, anxiously, as he came forward and felt of the boys' pulses. "A great deal," answered Jack. "But what has happened? Where are we? What are all these wheels for?" "Slowly, slowly," said the old man with a pleasant laugh. "One question at a time. For the first: what happened was a railroad wreck." "I remember now," said Jack, slowly. "We tried to stop the cars." "And you didn't succeed very well," went on the old man. "However, the sand bank did it for you, and stopped you two at the same time. As for your second question, you are here in my shop. As to the third, those wheels are parts of my great invention. But I will tell you about that after a while. I must give you some medicine now, and something to eat. Here, Washington!" "Comin', Perfessor!" Jack and Mark were more surprised than before when they saw a big colored man, seemingly as strong as an ox, coming toward them with two steaming bowls of beef broth. Washington was grinning with delight. "Dis am de best beef stew dat eber transpositioned itself into yo' vicinity!" he exclaimed, setting the bowls down on a table near the bed. "Now, Washington," cautioned the old man. "No big words, remember." "All right, Perfessor," was the answer. "Do you boys feel like eating?" asked the aged inventor. "I do," replied Jack. "There was a time, though, when I thought I'd never get a chance to eat again. That was just before the crash." "You were both knocked unconscious," the professor went on. "Washington and I happened to be near by and brought you here. Fortunately I am something of a doctor as well as an inventor, and I used a strong medicine I have." "I'm sure we're much obliged to you," answered Mark. "Let me see how much improved you are by eating," suggested the old man. "I can trust Washington to cook good meals, even if he does use big words." Then, while the colored man grinned cheerfully at them, Jack and Mark, sitting up on the bed, for they were still weak and sore, ate the broth. After that both boys said they felt better. "See if you can walk," suggested the inventor. Mark and Jack stepped on the floor. They both uttered cries of pain. They were stiff and lame from the shaking they had received. "A day in bed will do you no harm," said their strange rescuer. "I have some liniment that will soon take the soreness out of every one of your muscles."