"Young ladies, attention!" called Miss Delafield. "You will observe the large red body at the top, that is—"

"I'd rather have you explain it," whispered Mary Nestor to Tom. "Come on, slip around to the other side. May I bring a few of my friends with me? I can't bear Miss Delafield. She thinks she knows everything. She won't see us if we slip around."

"I shall be delighted," replied Tom, "only I fear I may have to help Mr. Sharp out of this trouble."

"Don't worry about me, Tom," said the balloonist, who overheard him. "Let me do the explaining. I'm an old hand at it. Been in trouble before. Many a time I've had to pay damages for coming down in a farmer's corn field. I'll attend to the lady principal, and you can explain things to the young ones," and, with a wink, the jolly aeronaut stepped over to where Miss Perkman, in spite of her prejudice against the airship, was observing it curiously.

Glad to have the chance to talk to his young lady friend, Tom slipped to the opposite side of the car with her and a few of her intimate friends, to whom she slyly beckoned. There Tom told how the Red Cloud came to be built, and of his first trip in the air, while, on the opposite side, Miss Delafield lectured to the entire school on aeronautics, as she thought she knew them.

Mr. Sharp evidently did know how to "explain" matters to the irate principal, for, in a short while, she was smiling. By this time Tom had about finished his little lecture, and Miss Delafield was at the end of hers. The entire school of girls was grouped about the Red Cloud, curiously examining it, but Mary Nestor and her friends probably learned more than any of the others. Tom was informed that his friend had been attending the school in Rocksmond since the fall term opened.

"I little thought, when I found we were going to smash into that tower, that you were below there, studying," said the lad to the girl.

"I'm afraid I wasn't doing much studying," she confessed. "I had just a glimpse of the airship through the window, and I was wondering who was in it, when the crash came. Miss Perkman, who is nothing if not brave, at once started for the roof, and we girls all followed her. However, are you going to get the ship down?"

"I'm afraid it is going to be quite a job," admitted Tom ruefully. "Something went wrong with the machinery, or this never would have happened. As soon as Mr. Sharp has settled with your principal we'll see what we can do."

"I guess he's settled now," observed Miss Nestor. "Here he comes."