e may have been no means of getting it on the pedestal if
they made it too heavy."

They discussed these and other matters as they hurried on to seek
for some way of escape. In fact to talk seemed to make them less
gloomy and sad, and they tried to keep up their spirits.

For several hours they searched eagerly for some means of getting
out of the underground city. They went to the farthest limits of it,
and found it to be several miles in diameter, but eventually they
came to solid walls of stone which reached from roof to ceiling, and
there was no way out.

They found that the underground city was exactly like an overturned
bowl, or an Esquimo ice hut, hollow within, and with a tunnel
leading to it--but all below the surface of the earth. The city had
been hollowed out of solid rock, and there was but one way in or
out, and that was closed by the seamless stone.

"There's no use hunting any longer," declared Tom, when, weary and
footsore, they had completed a circuit of the outer circumference of
the city, "the rock passage is our only hope."

"And that's no hope at all!" declared Ned.

"Yes, we must try to raise that stone slab, or--break it!" cried Tom
desperately. "Come on."

"Wait a bit," advised Mr. Damon. "Bless my dinner plate! but I'm
hungry. We brought some food along, and my advice to you is to eat
and keep up our strength. We'll need it."

"By golly gracious, that's so!" declared Eradicate. "I'll git de
eatin's."

Fortunately there was a goodly supply, and, going in one the houses
they ate off a table of solid gold, and off dishes of the precious,
yellow metal. Yet they would have given it all--yes, even the gold
in their dirigible balloon--for a chance for freedom.

"I wonder what became of the chaps who used to live here?" mused Ned
as he finished the rather frugal meal.

"Oh, they probably died--from a plague maybe, or there may have been
a war, or the people may have risen in revolt and killed them off,"
suggested Tom grimly.

"But then there ought to be some remains--some mummies or skeletons
or something."

"I guess every one left this underground city--every soul."
suggested Mr. Damon, "and then they turned on the river and left it.
I shouldn't be surprised but what we are the first persons to set
foot here in thousands of years."

"And WE may stay here for a thousand years," predicted Tom.

"Oh, good land a' massy; doan't say dat!" cried Eradicate. "Why
we'll all be dead ob star