"You had better luck than I. I got fifteen."

"I have twenty and Fenn has ten," put in Frank.

"That's enough to break up a dozen dances," spoke Ned. "Come on now, we've got to do a bit of climbing."

The hall, where the dance was being held, was over the drug store. This was in the center of a business block, the drug structure being higher than any of the buildings amid which it stood. The ballroom was on the top floor.

"Have you arranged about getting in?" asked Fenn.

"We can't get in," Ned replied. "They've got every door doubly guarded, for they suspect we're up to something. In fact we don't want to get in.

I have a better way. Come along."

Ned led the way, through back streets until he came to a certain high fence.

"One of us has got to climb over and open the gate," he said. "After that the rest is easy."

Bart, being a good climber, was soon over the obstruction, and admitted his companions to a yard in the rear of a group of buildings.

"Where are we?" asked Fenn.

"We're in back of Williamson's hardware place," replied Ned. "That's right next to the drug store. We're going to the roof of that, and when we get there we can go up a short ladder until we get to the roof of the drug store."

"How did the ladder get there?" asked Frank.

"I bribed a telephone lineman, who was stringing some wires on the buildings yesterday, to leave it there."

"But what are we going to do when we get on the roof of the drug store?"

asked Fenn.

"You watch and you'll see," Ned answered.

By means of an outside stairway, and by climbing up on a rear porch, the boys reached the roof of the hardware building. Thence it was an easy task to get on top of the structure in which the dance was being held.

They could hear the music below them, and the sound of merry feet tripping to the melody of a two-step.

"There's a scuttle near the center," Ned spoke. "Walk quietly now. It's a tin roof, and they may hear us, in spite of the music. Go easy!"

They found the scuttle, and it was unlocked. Ned had seen to that, by giving a judicious hint to the janitor of the place the day before. The boys cautiously removed the covering to a hole that led into a sort of attic or ventilating s.p.a.ce. A few minutes later the four chums were in a dark loft, looking through the grating of a ventilator in the wall right down on the dancing floor.

"My, but they're having a good time!" exclaimed Ned in a whisper. "It seems a pity to spoil it."

"Pity nothing!" exclaimed Bart. "What did they do to us? Besides, there's no harm in this. There'll be a little screaming from the girls, but that's all."

"Have you got 'em in paper bags?" asked Ned, as he began to open the box he carried.

"Sure," replied Bart, and the others answered in the affirmative.

"When I open the grating just toss the bags out, right in the middle of the floor," Ned went on. "Do it quick, as I want to close the ventilator before they see where the things come from."

An instant later Ned had opened the ventilator grating, which he had previously loosened. Then, through the air, went sailing four paper bags.

They struck almost in the middle of the ballroom floor and burst.

Then from the bags there scampered over three score mice, rushing, running, leaping and darting amid the dancers, with frightened squeaks and squeals.

For a moment there was silence, broken only by the noise of the rodents.

Then every girl in the room, and there were forty of them, uttered a frightened scream and rushed for a place of safety.

"A mouse! A mouse! Oh, save me!" was the universal cry, and the music came to a stop in a crash of discord as the dance was most effectually broken up.

CHAPTER VIII

FRANK IS WARNED

All over the room ran the mice, and all about darted the frightened girls. The boys were, at first, too surprised to know what to do, but, at a rallying cry from someone, they started after the mice. However, they had no weapons to kill the rodents with, and had to be content with taking kicks at them as they darted past, seeking means of escape.

"Couldn't have worked better!" exclaimed Bart, as he and his chums watched the scene from where they were hidden.

"I hope none of the girls faint," said Fenn.

"Oh, Stumpy's getting worried about Jennie, I s'pose," remarked Ned.

"No danger of any of 'em fainting," said Bart. "They're too much afraid a mouse would bite 'em."

So it seemed, for the girls contented themselves with screaming and getting up on whatever offered in the way of chairs or benches.

Meanwhile the mice, bewildered by the lights, the noise and the strange place, were running about, squealing as loudly as they could. Every time one of the frightened creatures came near a girl, or a group of them, the cries of the damsels drowned the squeaks of the rodents.

The boys of the Upside Down Club were at their wits' ends, for they could wage no effectual warfare against the mice. One or two of the committee of arrangements scurried around until they secured brooms, but by this time the mice had hidden in corners, whence they scurried out occasionally, to the great fright of the girls.

The dance had come to a sudden end, for the girls, even after comparative quiet was restored, refused to venture on the floor. Even Alice, who was braver than most girls, stayed in a corner.

"Who did it?"

"Where did they come from?"

"How did it happen?"

These and many more questions were heard on every side. The paper bags from which the mice had burst were still in the center of the floor. Some of the first-year boys picked them up. From them dropped slips of paper on which were printed:

_COMPLIMENTS OF THE DAREWELL BASEBALL NINE_.

"I thought so!" exclaimed Walter Powell, the chairman of the arrangement committee of the dance. "The Darewell Chums had a hand in this. We must find 'em, fellows!"

"Come on!" exclaimed Ned to his companions in the ventilator s.p.a.ce. "We'd better skip. They may find us."

They went out as they had come in, and soon were on their way home.