vation in dat time."

"Before then, I guess," muttered Tom. "I wonder if there's any water
in this hole?"

"We'll need it--soon," remarked Ned, looking at the scanty supply
they had brought in with them. "Let's have a hunt for it."

"Let Rad do that, while we work on the stone gate," proposed the
young inventor. "Rad, chase off and see if you can find some water."

While the colored man was gone, Tom, Ned and Mr. Damon went back to
the stone gate. To attack it without tools, or some powerful
blasting powder seemed useless, but their case was desperate and
they knew they must do something.

"We'll try chipping away the stone at the base," suggested Tom. "It
isn't a very hard rock, in fact it's a sort of soft marble, or white
sand stone, and we may be able to cut out a way under the slab door
with our knifes."

Fortunately they had knives with big, strong blades, and as Tom had
said, the stone was comparatively soft. But, after several hours'
work they only had a small depression under the stone door.

"At this rate it will take a month," sighed Ned.

"Say!" cried Tom, "we're foolish. We should try to cut through the
stone slab itself. It can't be so very thick. And another thing. I'm
going to play the flames from the gas torches on the stone. The
fires will make it brittle and it will chip off easier."

This was so, but even with that advantage they had only made a
slight impression on the solid stone door after more than four hours
of work, and Eradicate came back, with a hopeless look on his face,
to report that he had been unable to find water.

"Then we've got to save every drop of what we've got," declared Tom.
"Short rations for everybody."

"And our lights, too," added Mr. Damon. "We must save them."

"All out but one!" cried Tom quickly. "If we're careful we can make
them gas torches last a week, and the electric flashes are good for
several days yet."

Then they laid out a plan of procedure, and divided the food into as
small rations as would support life. It was grim work, but it had to
be done. They found, with care, that they might live for four days
on the food and water and then--

Well--no one liked to think about it.

"We must take turns chipping away at the stone door," decided Tom.
"Some of us will work and some will sleep--two and two, I guess."

This plan was also carried out, and Tom and Eradicate took the first
trick of hacking away at the door.

How they managed to live in the