is stepped in, and with his curiosity aroused, Ned followed, just as
Bourne's voice came from below, with the question--

"What are you boys doing? Mind how you climb above that hole. You had
better get a little to the right."

"No, we hadn't," said Chris, who was half up the shaft. "Don't speak
yet, Ned. Come on; it's quite easy."

Ned followed, and came in for plenty of dry dust and chips as Chris
climbed on, to find himself directly after in a cell-like chamber,
evidently cut out of the solid rock.

"Ahoy! Where are you, boys?" cried the doctor, in an anxious tone of
voice.

"You look out of the window-opening," said Chris; "I'm going to look
down out of this," and passing as he spoke through a low opening, he
stood in the middle of another cell-like place.

They were saluted with a shout.

"No snakes, then?" said Griggs.

"I don't think so. None here," cried Chris. "Are you all coming up?"

There was no need to answer, for Griggs was already leading the way, and
as soon as they were all up an investigation of the place began, during
which it was found that they had evidently hit upon one of the openings,
or probably enough the principal one into the rock city, where upon the
level where they stood some dozens of roughly carved-out, cell-like
habitations communicated one with another.

There was a great deal of dust and other accumulation, for in damp spots
where there was a chance for plants to exist they seemed to have grown,
died, and turned to earth. Here and there, too, as the party made their
way from cell to cell there were proofs that various animals had taken
possession of the rough shelters and brought the prey they had captured,
stores of well-gnawed bones lying scattered about; but saving the traces
left of construction, cutting out of the rock and building in, they
found nothing to show what kind of people they were who had lived there,
nothing to prove how far back it was in the world's history that the
rock city had been occupied by a teeming population.

"How long is it since people lived here, father?" was asked by Chris,
after they had been wandering about from cell to cell but not finding
any way of getting higher without a dangerous climb from the terrace
outward.

"Ah, you are asking what has been puzzling me," replied the doctor, "and
I seem to be faced by a blank wall built-up between now and the past.
If we could find anything in the shape of weapons or household
impleme