and there may be some danger getting this one off the roof."
"Wouldn't you like to stay and take a ride in it?" Tom asked Miss Nestor.
"Indeed I would," she answered daringly. "It's better than a motor-boat. May I?"
"Some day, when we get more expert in managing it," he replied, as he shook hands with her.
"Now for some hard work," went on the young inventor to Mr. Sharp, when the roof was cleared of the last of the teachers and pupils. But the windows that gave a view of the airship in its odd position on the roof were soon filled with eager faces, while in the streets below was a great crowd, offering all manner of suggestions.
"Oh, it's not going to be such a task," said Mr. Sharp. "First we will repair the rudder and the machinery, and then we'll generate some more gas, rise and fly home."
"But the broken propeller?" objected Tom.
"We can fly with one, as well as we can with two, but not so swiftly. Don't worry. We'll come out all right," and the balloonist assumed a confident air.
It was not so difficult a problem as Tom had imagined to put the machinery in order, a simple break having impaired the working of the rud-
