“What in the world do you suppose those ancients made such a terrible contrivance for?” Ned wanted to know.

“Well, if we could read the warning on the statue we might know,” replied Mr. Damon.  “That probably says that whoever disturbs the status will close up the golden city forever.”

“Maybe there’s another way out—­or in,” suggested Tom hopefully.  “We didn’t look for that.  It must be our next move.  We must not let a single chance go by.  We’ll look for some way of getting out, at the far end of this underground city.”

Filled with gloomy and foreboding thoughts, they walked away from the stone barrier.  To search for another means of egress would take some time, and the same fear came to all of them—­could they live that long?

“It was a queer thing, to make that statue hollow,” mused Ned as he walked between Mr. Damon and Tom.  “I wonder why it was done, when all the others are solid gold?”

“Maybe they found they couldn’t melt up, and cast in a mould, enough gold to make a solid statue that size,” suggested Mr. Damon.  “Then, too, there 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.