each other after the
sudden startling change from darkness to light.

"They are in the laboratory!" cried one. "Let's cut off their escape!"

The angry sophomores made a rush for the door.

"Hurry girls!" urged David, who had just returned to the laboratory
after manipulating the lights. "They'll catch us before we know it."

But the young fugitives were too late. Just then there was the sound of
many feet running up the stairs from the other door.

"How about one of the gallery doors?" asked Grace.

"They are all locked," answered David. "There only remain the skylight
trap-door and the roof. Do you think you could manage it if I helped
you?"

"Of course; we could manage anything," protested the freshmen girls.

It was an easy matter to climb up the ladder, and clamber through the
trap-door on to the roof.

"We're just in time," whispered David. "They have found the right key to
the gallery door, and they'll be coming in both ways. Crawl carefully
now, girls, for heaven's sake, and don't slip!"

The seven young people began slowly to draw themselves along the
gymnasium roof on their hands and knees. Fortunately, it was not a very
sloping roof, and their only danger lay in their movements being heard
from below. Meanwhile the gymnasium had emptied itself, and parties of
enraged sophomores were engaged in searching the adjoining class rooms
and passages.

"Let's surround the building on the outside," cried one of the class
leaders. "They can't escape, then, by any of the fire escapes, and we
are sure to catch them!"

In a few moments, David peeping over the edge of the roof, saw figures
stationed at every possible exit, waiting patiently.

"Lie low," he whispered, "and crawl on your stomachs, or you're surely
caught."

Soon after the seven had reached the end of the hundred feet of
gymnasium, where their flight was stopped short by a blank wall where
the gymnasium joined the High School building.

"Here's a pretty pass," whispered David. "I forgot about this old school
wall. The only thing to do, now, is to hide behind this chimney and wait
for the row to quiet down."

There they lay, as flat as possible, listening with bated breath to the
sophomores below. Presently there was a sound of footsteps on the
gymnasium roof and they heard Miriam's voice saying:

"They must have escaped through the trap-door in the laboratory and come
along here. Wait a minute, girls, and I'll see."

"O Grace, we're caug