"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 starvation 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."