speeded up the motor and sent the Arrow on her homeward way.
The boys and Mr. Swift were much interested in the experiences of the balloonist and asked him many questions, which he answered modestly. Several hours passed and late that afternoon the party approached Shopton.
"Here we are!" exclaimed Mr. Swift, relief in his tones. "Now to see of what I have been robbed and to get the police after the scoundrels!"
When the boat was nearing the dock Mr. Sharp, who had been silent for some time, suddenly turned to Tom and asked:
"Ever invent an airship?"
"No," replied the lad, somewhat surprised. "I never did."
"I have," went on the balloonist. "That is, I've invented part of it. I'm stuck over some details. Maybe you and I'll finish it some day. How about it?"
"Maybe," assented Tom, who was occupied just then in making a good landing. "I am interested in airships, but I never thought I could build one."
"Easiest thing in the world," went on Mr. Sharp, as if it was an everyday matter. "You and I will get busy as soon as we clear up this robbery." He talked as though he had been a friend
