pushers in all directions. The man with the grizzled beard began talking rapidly into his hand-phone, then hung it up. There was a series of bumps, and the armor-tender, weightless on contragravity, shook as the handling-machine came aboard.
"You ever see any nuclear bombing, Miss Quinton?" the young man with the hairy legs asked, offering her his candy bag.
"Only by telecast, back Sol-side," she replied, helping herself. "Test-shots at the Federation Navy proving-ground on Mars. I never even heard of nuclear bombs being used for mining till I came here, though."
"Well, if this turns out as well as the other job, three months ago, it'll be something to see," he promised. "These volcanoes have been dormant for, oh, maybe as long as a thousand years; there ought to be a pretty good head of gas down there. And the magma'll be thick, viscous stuff, like basalt on Terra. Of course, this won't be anything like basalt in composition—it'll be intensely compressed metallic fluorides, with a very high metal-content. The volcanoes we shot three months ago yielded a fine flow of lava with all sorts of metals—nickel, beryllium, vanadium, chromium, indium, as well as copper and iron."
"What sort of gas were you speaking about?" she asked.
"Hydrogen. That's what's going to make the fireworks; it combines explosively with fluorine. The hydrogen-fluorine combination is what passes for combustion here; the result is hydrofluoric acid, the local equivalent of water. See, the metallic core of this planet is covered, much less thickly than that of Terra, with fluoride rock—fluorspar, and that sort of thing. There's nothing like granite here, for instance. That's why those big dunes, out there, are the best Niflheim has in the way of mountains. The subsurface hydrogen is produced when the acid filters down through the rock, combines with pure metals underneath."
"Dr. Murillo's inside, now," the radioman said. "Just came out of the inner airlock. He'll be up as soon as he gets out of his pressure-suit."
"As soon as he gets here, I'll touch it off," the bearded man said. "Everything set, de Jong?"
"Everything ready, Dr. Gomes," one of his assistants assured him.
The door at the rear of the control-cabin opened, and Juan Murillo, the seismologist, entered, followed by an assistant. Murillo was a big man, copper-skinned, barrel-chested; he looked like a third-or fourth-generation Martian, of Andes Indian ancestry. He came forward and stood behind Gomes' chair, looking down at the instruments. His assistant stopped at the door. This assistant was not human. He was a biped, vaguely humanoid, but he had four arms and a face like a lizard's, and, except for some equipment on a belt, he was entirely naked.
He spoke rapidly to Murillo, in a squeaking jabber. Murillo turned.
"Yes, if you wish, Gorkrink," he said, in the English-Spanish-Afrikaans-Portuguese mixture that was Sixth Century, A.E., Lingua Terra. Then he turned back to Gomes as the Ulleran sat down in a chair by the door.
"Well, she's all yours, Lourenço, shoot the works."
Gomes stabbed the radio-detonator button in front of him. A voice came out of the 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?" Lourenço 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 there."
"Here she comes!" the chief engineer called. "Watch the base of the column!"
The pillar of fiery smoke and dust, still boiling up from where the bombs had gone off far underground, was being violently agitated at the bottom. A series of new flashes broke out, lifting and spreading the incandescent radioactive gasses, and then a great gush of flame rose. A column of pure hydrogen must have rushed up into the vacuum created by the explosion; the next blast of flame, in a lateral sheet, came at nearly ten thousand feet above the ground, and great rags of fire, changing from red to violet and back through the spectrum to red again, went soaring away to dissipate in the upper atmosphere. Then geysers of hot ash and molten rock spouted upward; some of the white-hot debris landed almost at the acid river, half-way to the armor-tender.
"We've started a first-class earthquake, too," the Hispano-Indian Martian Murillo said, looking at the instruments. "About six big cracks opening in the rock-structure. You know, when this quiets down and cools off, we'll have more ore on the surface than we can handle in ten years, and more than we could have mined by ordinary means in fifty."
About four miles from the original blast, another eruption began with a terrific gas-explosion.
"Well, that finishes our work," the large young man said, going to a kitbag in the corner of the cabin and getting out a bottle. "Get some of those plastic cups, over there, somebody; this one calls for a drink."
"That's right," Gomes said. "You do something once, it may be an accident; you repeat the performance, and it's a success." He began pushing papers aside on his desk, and the girl in the too-ample coveralls brought drinking cups.
The Ulleran, in the background, rose quickly and squeaked apologetically. Murillo nodded. "Yes, of course, Gorkrink. No need for you to stay here." The Ulleran went out, closing the door behind him.
"That taboo against Ullerans and Terrans watching each other eat and drink," Murillo said. "What is that, part of their religion?"
"No, it's their version of modesty," the girl replied. "Like some of our sex-inhibitions, which they can't even begin to understand.... But you were speaking to him in Lingua Terra; I didn't know any of them understood it."
"Gorkrink does," Murillo said, uncorking the bottle and pouring into the plastic cups. "None of them can speak it, of course, because of the structure of their vocal organs, any more than we can speak their languages without artificial aids. But I can talk to him in Lingua Terra without having to put one of those damn gags in my mouth, and he can pass my instructions on to the others. He's been a big help; I'll be sorry to lose him."
"Lose him?"
"Yes, his year's up; he's going