In a way he was. Mercurian surface gravity was almost precisely equal to Martian surface gravity, and it was something he was at home with thoroughly. His cool, gray eyes, watching sharply, noticed every sway in Urteil's body, every knotting of a sudden muscle as he worked to keep erect.

Small misjudgments even in merely keeping one's balance were inevitable when working in a gravity to which one was unaccustomed.

Bigman moved in suddenly, springing from foot to foot and side to side in a broken motion that was at once amusingly dancelike and completely confusing.

"What is this?" growled Urteil in exasperation. "A Martian waltz?"

"Kind of," said Bigman. His arm lunged outward, and his bare knuckles slammed into Urteil's side with a resounding thwack, staggering the big fellow.

There was a gasp from the audience and one yell of "Hey, boy!"

Bigman stood there, arms akimbo, waiting for Urteil to recover his balance.

Urteil did so in a matter of five seconds, but now there was an angry red splotch on his side and a similar and angrier one on each cheekbone.

His own arm shot out powerfully, his right palm half open as though a slap would be sufficient to fling this stinging insect out of his way forever.

But the blow continued, dragging Urteil about. Big-man had ducked, leaving a fraction of an inch to spare, with the sure judgment of a perfectly co-ordinated body. Urteil's efforts to stop his follow-through left him teetering wildly, back to Bigman.

Bigman placed his foot on the seat of Urteil's pants and shoved gently. The recoil sent him hopping easily backward on the other foot, but Urteil went slowly forward on his face in grotesque slow motion.

There was sudden laughter from the side lines.

One of the spectators called out, "Changed my mind, Urteil. I'm betting."

Urteil made no gesture of hearing this. He was facing Bigman again, and from the corner of his thick lips a viscid drop of saliva made its way down the corner of his chin.

"Up the gravity!" he roared hoarsely. "Get it to normal!"

"What's the matter, tubbo?" mocked Bigman. "Isn't forty pounds in your favor enough?"

"I'll kill you. I'll kill you," Urteil shouted.

"Go ahead!" Bigman spread his arms in mock invitation.

But Urteil was not entirely beyond reason. He circled Bigman, hopping a little in ungainly fashion. He said, "I'll get my gravity legs, bug, and once I grab you anywhere, that piece gets torn off you."

"Grab away."

But there was an uneasy silence among the men who watched now. Urteil was a stooping barrel, his arms sweeping out and wide, his legs spread. He was keeping Ms balance, catching the rhythm of the gravity.

Bigman was a slender stalk in comparison. He might be as graceful and self-assured as a dancer, yet he looked pitifully small.

Bigman seemed unworried. He hopped forward with a sudden stamp of his feet that sent him shooting high in the air, and when Urteil lunged at the rising figure, Bigman lifted his feet and went down behind Ms adversary before the other could turn around.

There was loud applause, and Bigman grinned.

He performed what was almost a pirouette as he ducked under one of the great arms that threatened him, reaching out and bringing the side of Ms hand sharply down against the biceps.

Urteil restrained a cry and whirled again.

Urteil maintained a dreadful calm to all these grandstanding provocations now. Bigman, on the other hand, tried in every way he could to taunt and sting Urteil into a wild motion that would send him shooting off balance.

Forward and away; quick, sharp blows, which for all their flicking qualities carried a sting.

But a new respect for Urteil was growing in the small Martian's mind. The cobber was taking it. He was maintaining his ground like a bear warding off the attack of a hunting dog. And Bigman was the hunting dog which could only hover at the outskirts, snap, snarl, and keep out of the reach of the bear's paws.

Urteil even looked like a bear with Ms large, hairy body, Ms small, bloodshot eyes, and his jowly, bristly face.

"Fight, cobber," jeered Bigman. "I'm the only one giving the customers a show."

Urteil shook his head slowly. "Come closer," he said.

"Sure,' said Bigman lightly, dashing in. With flashing movements, he caught Urteil on the side of the jaw and was under his arm and away in almost the same movement.

Urteil's arm half moved, but it was too late and the motion wasn't completed. He swayed a little. "Try it again," he said.

Bigman tried it again, twisting and diving under his other arm this time and finishing with a little bow to accept the roars of approval.

"Try it again," said Urteil thickly.

"Sure," said Bigman. And he dashed.

This time Urteil was thoroughly prepared. He moved neither head nor arms, but his right foot shot forward.

Bigman doubled, or tried to, in mid-air and didn't quite make it. His ankle was caught and pinned brutally for a moment by Urteil's shoe. Bigman yelped at the pressure.

Urteil's rapid movement carried him forward, and Bigman, with a quick, desperate shove at the other's back, accelerated that movement.

This time Urteil, more accustomed to the gravity, was not thrown forward as far and recovered more quickly, while Bigman, with his ankle on fire, moved about with a frightening clumsiness.

With a wild shout Urteil charged and Bigman, pivoting on his good foot, was not fast enough. His right shoulder was caught in one hamlike fist. His right elbow was caught in the other. They went down together.

A groan went up almost in concert from the spectators and Cook, watching ashen-faced, cried out, "Stop the fight" in a croaking voice that went completely unheeded.

Urteil got to his feet, his grip firm on Bigman, lifting the Martian as though he were a feather. Bigman, face twisted in pain, writhed to get a footing of his own.

Urteil muttered into the little fellow's ear. "You thought you were wise, tricking me into fighting under low gravity. Do you still think so?"

Bigman wasted no time in thought. He would have to get at least one foot on the floor... Or on Urteil's kneecap, for his right foot rested momentarily on Urteil's knee and that would have to do.

Bigman pushed down hard and lunged his body backward.

Urteil swayed forward. That was not dangerous for Urteil in itself, but his balancing muscles overshot the mark in the low gravity, and in righting himself he swayed backward, And as he did so, Bigman, expecting that, shifted his weight and pushed hard forward.

Urteil went down so suddenly that the spectators could not see how it was accomplished. Bigman wrenched half free.

He was on his feet like a cat, with his right arm still pinned. Bigman brought his left arm down on Urteil's wrist and brought up his knee sharply against the other's elbow.

Urteil howled and his grip on Bigman loosened as he shifted position to keep his own arm from being broken.

Bigman took his chance with the quickness of a jet's ignition. He wrenched his pinned hand completely loose while maintaining his grip on Urteil's wrist. His freed hand came down upon Urteil's arm above the elbow. He had a two-handed grip now on Urteil's left arm.

Urteil was scrabbling to his feet, and as he did so, Bigman's body bowed and his back muscles went down hard with effort. He lifted along the line of Urteil's own motion of rising.

Bigman's muscles, combined with the action of Urteil's lift, carried that large body free of the ground in a slow motion, impressive display of what could be done in a low gravity field.

With his muscles near to cracking, Bigman whipped Urteil's torso still farther upward, then let go, watching it as it went flailing in a parabolic arc that seemed grotesquely slow by Earth standards.

They all watched and were all caught in the sudden change of gravity. Earth's full gravity snapped on with the force and speed of a blaster bolt, and Bigman went to his knees with a painful wrench on his twisted ankle. The spectators also went down in a chorus of confused cries of pain and astonishment.

Bigman caught only the merest glimpse of what happened to Urteil. The change in gravity had caught him almost at the high point of the parabola, snapping him downward with sharp acceleration. His head struck a protecting stanchion of one of the generators a sharp, cracking blow.

Bigman, rising painfully to his feet, tried to shake sense into his addled brains. He staggered and was aware of Urteil sprawled limply, of Cook kneeling at Urteil's side.

"What happened?" cried Bigm'an. "What happened to the gravity?"

The others echoed the question. As nearly as Bigman could tell, Cook was the only one on his feet, the only one who seemed to be thinking.

Cook was saying, "Never mind the gravity. It's Urteil."

"Is he hurt?" cried someone.

"Not any more," said Cook, getting up from his kneeling position. "I'm pretty sure he's dead."

They made an uneasy circle about the body.

Bigman said, "Better get Dr. Gardoma." He scarcely heard himself say it. A great thought had come to him.

"There's going to be trouble,' said Cook. "You killed him, Bigman."

"The change in gravity did that," said Bigman.

"That'll be hard to explain. You threw him."

Bigman said, "I'll face any trouble. Don't worry."

Cook licked his lips and looked away. "I'll call Gardoma."

Gardoma arrived five minutes later, and the shortness of his examination was proof enough that Cook had been correct.

The physician rose to his feet, wiping his hands on a pocket handkerchief. He said gravely, "Dead. Fractured skull. How did it happen?"

Several spoke at once, but Cook waved them down.

He said, "A grudge fight between Bigman and Urteil... "

"Between Bigman and Urteil!" exploded Dr. Gardoma. "Who allowed that? Are you crazy, expecting Bigman to stand up... "

"Easy there," said Bigman. "I'm in one piece."

Cook said in angry self-defense, "That's right, Gar-doma, it's Urteil that's dead. And it was Bigman who insisted on the fight. You admit that, don't you?"

"I admit it all right," said Bigman. "I also said it was to be under Mercurian gravity."

Dr. Gardoma's eyes opened wide. "Mercurian gravity? Here?" He looked down at his feet as though wondering if his senses were playing him tricks and he were really lighter than he felt.

"It isn't Mercurian gravity any more," said Bigman, "because the pseudo-grav field snapped to full Earth gravity at a crucial time. Bam! Like that! That's what killed Urteil, not yours truly."

"What made the pseudo-grav snap to Earth levels?" asked Gardoma.

There was silence.

Cook said feebly, "It might have been a short... "

"Nuts," said Bigman, "the level is pulled up. It didn't do that by itself."

There was a new silence and an uneasy one.

One of the technicians cleared his throat and said, "Maybe in the excitement of the fight someone was moving around and shoved it up with his shoulder without even realizing it."

The others agreed eagerly. One of them said, "Space! It just happened!"

Cook said, "I'll have to report the entire incident. Bigman... "

"Well," said the small Martian calmly, "am I under arrest for manslaughter?"

"N-no," said Cook uncertainly. "I won't arrest you, but I have to report, and you may be arrested in the end."

"Uh huh. Well, thanks for the warning." For the first time since returning from the mines, Bigman found himself thinking of Lucky. This, he thought, is a fine peck of trouble for Lucky to find waiting for him when he comes back.

And yet there was an odd stir of excitement in the little Martian, too, for he was sure he could get out of the trouble... and show Lucky a thing or two in the process.

A new voice broke in. "Bigman!"

Everyone looked up. It was Peverale, stepping down the ramp that led from the upper levels. "Great Space, Bigman, are you down there? And Cook?" Then almost pettishly, "What's going on?"

No one seemed to be able to say anything at all. The old astronomer's eyes fell on the prone body of Urteil, and he said with mild surprise, "Is he dead?"

To Bigman's astonishment, Peverale seemed to lose interest in that. He didn't even wait for his question to be answered before turning to Bigman once more.

He said, "Where's Lucky Starr?"

Bigman opened his mouth but nothing came out. Finally, he managed to say weakly, "Why do you ask?"

"Is he still in the mines?"

"Well... "

"Or is he on Sun-side?"

"Well... "

"Great Space, man, is he on Sun-side?"

Bigman said, "I want to know why you're asking."

"Mindes," said Peverale impatiently, "is out in his flitter, patrolling the area covered by Ms cables. He does that sometimes."

"So?"

"So he's either mad or he's correct in saying he's seen Lucky Starr out there."

"Where?" cried Bigman at once.

Dr. Peverale's mouth compressed in disapproval.

"Then he is out there. That's plain enough. Well, your friend Lucky Starr was apparently in some trouble with a mechanical man, a robot-- "

"A robot!"

"And according to Mindes, who has not landed but who is waiting for a party to be sent out, Lucky Starr is dead!"