ered, these few were saved.
Their cave connected with a long passage, a tunnel that led into the
bowels of the earth. With the outer entrance blocked by the upheaval
they had no alternative save to continue downward."

"They traveled for days and days. Some were overcome by hunger and
fell by the wayside. The most hardy survived to reach Theros, a series
of enormous caverns that extends for hundreds of miles under the
surface of your country. Here they found subterranean lakes of pure
water; forests, game. They had a few tools and weapons and they
established themselves in this underground world. From that small
beginning came this!"

Phaestra's slim fingers worked rapidly at the controls. The scenes
shifted in quick succession. They were once more in the present, and
seemed to be traveling speedily through the underground reaches of
Theros. Now they were racing through a long lighted passage; now over
a great city similar to the one in which they had arrived. Here they
visited a huge workshop or laboratory; there a mine where radium or
cobalt or platinum was being wrested from the vitals of the unwilling
earth. Then they visited a typical Theronian household, saw the
perfect peace and happiness in which the family lived. Again they were
in a large power plant where direct application of the internal heat
of the earth as obtained through deep shafts bored into the interior
was utilized in generating electricity.

They saw vast quantities of supplies, fifty-ton masses of machinery,
moved from place to place as lightly as feathers by use of the gravity
discs, those heavily charged plates whose emanations counteracted the
earth's attraction. In one busy laboratory they saw an immense
television apparatus and heard scientists discussing moot questions
with inhabitants of Venus, whose images were depicted on the screen.
They witnessed a severe electrical storm in the huge cavern arch over
one of the cities, a storm that condensed moisture from the
artificially oxygenated and humidified atmosphere in such blinding
sheets as to easily explain the necessity for well-roofed buildings in
the underground realm. And, in all the speech and activities of the
Theronians, there was evident that all-pervading feeling of absolute
contentment and freedom from care.

"What I can not understand," said Frank, during a quiet interval, "is
why the Theronians have never migrated to the surface. Surely, with
all your command of science and