or the
presence of the deadly smoke-gas. Lighting one of these, Tom tossed it
into the big excavation.

It fell to the stone floor--to the stone street to be more exact--and,
flaring up brightly, further revealed the rows of houses as they stood,
silent and uninhabited.

"It's all right," Tom announced. "There's no danger so long as the
torch burns. You can go on, Professor."

And Professor Bumper rushed forward, scrambling over the pile of
blasted rock, followed by Tom and the others. Some of the debris from
the explosion had fallen into the cave, and was scattered for some
distance along the main street of what had been Pelone. But beyond that
the way was clear.

"Yes, it is Pelone," cried Professor Bumper. "See!"

He pointed to inscriptions in queer characters over the doorway of some
of the houses, but he alone could read them.

"I have found Pelone!" he kept repeating over and over again.

And that is just what had happened. That last great blast Tom Swift had
set off had broken down the rock wall that hid the lost city from view.
There it was, buried deep down under the mountain, where it had been
covered from sight ages ago by some mighty earthquake or landslide;
perhaps both. And the earth and rocks had fallen over the main portion
of the city of Pelone in such a way--in such an arch formation--that
the greater part of it was preserved from the pressure of the mountain
above it.

The outlying portions were crushed into dust by the awful pressure of
the mountain--millions of tons of stone--but where the natural arch had
formed the weight was kept off the buildings, most of which were as
perfect as they had been before the cataclysm came.

The buildings were of stone block construction, mostly only one story
in height, though some were two. They were simply made, somewhat after
the fashion of the Aztecs. A look into some of them by the light of
portable electric lamps showed that the houses were furnished with some
degree of taste and luxury. There were traces of an ancient
civilization.

But of the inhabitants, there was not a trace: either they had fled
before the earthquake or the volcanic eruption had engulfed the city,
or the countless centuries had turned their very bones to dust.

"Oh, what a find! What a find!" murmured Professor Bumper. "I shall be
famous! And so will you, Tom Swift. For it was your blast that revealed
the lost city of Pelone. Your name will be honored by every
archeologic