believe it, Babs."

There was an odd quivering underfoot. Trees shook. There was no other
peculiarity anywhere. Nothing fell. No rocks rolled. In a valley among
volcanoes, where the smoke from no less than six cones could be seen at
once, temblors would not do damage. What damage mild shakings could do
would have been done centuries since.

Babs said uneasily:

"That feels--queer, doesn't it?"

Cochrane nodded. But just as he and Babs had never been conditioned to
be afraid of animals, they had been conditioned by air-travel at home
and space-travel to here against alarm at movements of their
surroundings. Temblors were evidently frequent at this place. Trees were
anchored against them as against prevailing winds in exposed situations.
Landslides did not remain poised to fall. Really unstable slopes had
been shaken down long ago.

"I wish we had a helicopter," Cochrane repeated. "The look of the
mountains as we came down, with glaciers between the smoking cones--that
was good show-stuff! We could have held interest here until we worked
that naming contest. We could use the extra capital that would bring in!
As it is, we've got to move on with practically nothing accomplished.
The trouble is that I didn't think we would succeed as we have! Heaven
knows I could have gotten helicopters!"

He helped her up a small steep incline, where rock protruded from a
hillside.

The ground trembled again. Not alarmingly, but Babs' hold of his hand
tightened a little. They continued to climb. They came out atop a small
bare prominence which rose above the forest. Here they could see over
the treetops in a truly extensive view. The mountains all about were
clearly visible. Some were ten and some twenty miles away. Some, still
farther, were barely visible in the thin haze of distance. But there was
a thick pall of smoke hovering about one of the farthest. It was
mushroom-shaped. At one time in human history, it would have seemed
typically a volcanic cloud. To Cochrane and Babs, it was typically the
cloud of an atomic explosion.

The ground shook sharply underfoot. Babs staggered.

Flying things rose from the forests in swarms. They hovered and darted
and flapped above the tree-tops. Temblors did not alarm the creatures of
the valley. But ground-shocks like this last were another matter.

A great tree, rearing above its fellows, toppled slowly. With ripping,
tearing noises, it bent sedately toward the smoking, far-away mountain