"I feel pretty sure that no business rival had anything to do with the theft," observed the young aviator confidently. "Well, you work this affair out in your own way. Remember, as I told you, expense is no point whatever. When shall we see you again?" "To-morrow evening, or the next morning at the latest." Something in Dave's manner seemed to convince the shrewd manager of the Interstate Aeroplane Company that their young employee was started on the right track. He shook hands cordially with Dave when the latter left the office. Dave went at once to the railroad depot. He learned that a train left in two hours. "That will bring me to Columbus before dark," he reflected. "I wonder what Mr. King will say?" The young aviator had a good deal on his mind, enough to make the average lad impatient. He had, however, learned a hard lesson of discipline with his tyrannical guardian, old Silas Warner. Then, too, since coming under the helpful influence of Mr. King, he had acquired a certain self reliance that now stood him in good stead. Running an airship took nerve, steadiness of purpose, a definite, concrete way of looking at things. Dave knew in his own mind that the Drifter was each hour speeding farther and farther away from the haunts of men. He recalled the old adage, however, which says "the more haste the less speed," and he determined to stick to the plan he had mentally outlined at the start. "I'm going to work on this affair slow but sure," he told himself. "I think I can guess where the Drifter is headed for. If I am right, I know that I shall find it." Dave reached Columbus about dark. He went straight from the depot to the aero grounds. The plan he had formed in his mind took in a talk with Mr. King right away. The Baby Racer hangar, however, was on his way to the Aegis quarters. As he neared it he saw a light in the shed where the little biplane was housed. Dave went to the half open door of the place to find Hiram Dobbs with a lantern puttering about the machine. "What have you been up to, Hiram?" challenged Dave. "Why, hello! Got back? Good!" cried Hiram, rushing forward to warmly welcome his best friend. "Yes, just arrived," answered Dave. "I've been cleaning up the machine," explained Hiram. "It's old Grimshaw's fault." "What is?" "Taking the Baby Racer out." "Oh, the machine has been out, then, has it?" remarked Dave. "Yes, and up. Say, Dave, I made the five hundred feet level. I hope you're not put out. It was a chance to make fifty dollars." "Fifty dollars?" "Uh-huh," bobbed Hiram in a broad grin. "How was that?" "Why, Grimshaw was piloting a party over the grounds. Rich man and his family-wife, son and two daughters. The youngest one was a daring little miss. She wanted to fly, and would fly. Grimshaw got to bragging about what you had done with the Baby Racer. Well, nothing would do but I must roll the little beauty out."