PA-speaker overhead: "In sixty seconds, the bombs will be
detonated ... thirty seconds ... fifteen seconds ... ten seconds ...
five seconds, four seconds, three seconds, two seconds, one
second...."

Out on the rolling skyline, fifty miles away, a lancelike ray of
blue-white light shot up into the gathering dusk--a clump of five
rays, really, from five deep shafts in an irregular pentagon half a
mile across, blended into one by the distance. An instant later, there
was a blinding flash, like sheet-lightning, and a huge ball of
varicolored fire belched upward, leaving a series of smoke-rings to
float more slowly after it. That fireball flattened, then spread to
form the mushroom-head of a column of incandescent gas that mounted to
overtake it, engorging the smoke-rings as it rose, twisting, writhing,
changing shape, turning to dark smoke in one moment and belching flame
and crackling with lightning the next. The armor-tender began to pitch
and roll; it was all the engineer and one of the assistants could do,
together, to keep it level.

"In about half an hour," the large young man told the girl, "the real
fireworks should be starting. What's coming up now is just small
debris from the nuclear blast. When the shockwaves get down far enough
to crack things open, the gas'll come up, and then steam and ash, and
then the magma. This one ought to be twice as good as the one we shot
three months ago; it ought to be every bit as good as Krakatoa, on
Terra, in 59 Pre-Atomic."

"Well, even this much was worth staying over for," the girl said,
watching the screen.

"You going on to Uller on the _City of Canberra_?" Lourenco Gomes
asked. "I wish I were; I have to stay over and make another shot, in a
month or so, and I've had about all of Niflheim I can take, now. The
sooner I get onto a planet where they don't ration the air, the better
I'll like it."

"Well, what do you know!" the large young man with the hairy legs
mock-marveled. "He doesn't like our nice planet!"

"Nice planet!" Gomes muttered something. "They call Terra God's
Footstool; well, I'll give you one guess who uses this thing to prop
his cloven hoofs on."

"When are you going to Terra?" the girl asked him.

"Terra? I don't know, a year, two years. But I'm going to Uller on the
next ship--the _City of Pretoria_--if we get the next blast off in
time. They want me to design some improvements on a couple of
power-reactors, so I'll probably see you when I get th