[Transcriber's note: equation in figure is long division of 1552.41 divided by 1.141]
Kraag stared at it, carrying out the rest of the simple mathematics in his head. The answer was 1101. But what was the problem?
The figure "1.41" was familiar enough. It was the square root of two, carried to two decimal places. But what was Jonner dividing by it, and why?
He frowned in concentration. There was something familiar about the numbers, something that had to do with him and Jonner, and Jonner wouldn't be working arithmetic just for amusement.
He saw Jonner moving on the horizon, just his head visible against the black sky, his body hidden by the curve of the planet. Jonner was circling.
The sudden realization of danger wiped other thoughts from his mind. Until he saw the epitaph Jonner had written for Stein, Kraag had thought Jonner looked at this as he did: one man against the other, and winner take all. But Jonner intended to win even if he lost, because Jonner was not fighting just for Jonner's survival but for due process of law.
Jonner was trying to make certain that, even if Kraag killed him, Martian law would punish Kraag for Stein's death. And if Jonner got into the sphere, he could get his message to Marsport or the rescue ship simply by turning on the radio.
Kraag turned and raced back to the sphere. He arrived, panting heavily. Jonner was nowhere in sight, but he knew Jonner, circling, could not have gotten there ahead of him.
He must kill Jonner before nightfall, if he could, but he must not get far enough from the sphere to let Jonner slip in behind him. He was not ready, yet, to destroy the radio to keep Jonner from it.
He walked around the sphere. There was Jonner on the other side, only his head above the horizon, moving clockwise. The sun flashed and gleamed from Jonner's helmet.
There was no sense in shooting at so small a target as a head. A mile away, Jonner's whole body was a small enough target. A carefully gauged leap carried Kraag to the top of the sphere. Here, 40 feet higher, his range of view was increased considerably. He could see Jonner well.
Jonner could see him, too. Jonner stopped to hurl a stone. It took a while for the missile to cover the distance. It passed below Kraag's level, some distance away from him.
"Why don't you give it up, Jonner?" asked Kraag. "You can't hurt me with a rock, at this distance."
"Why should I?" retorted Jonner. "All I have to do is wait till night."
"Sure, wait. But I'm not waiting, Jonner. One of us is going to win this thing before night, or I'm going to blast the radio so you can't reach Marsport. If I have to do that, I'll track you down tomorrow—and I think I can stay outside and fight you away from the sphere tonight."
"Getting desperate enough to fight like a man now, aren't you, Kraag? If you want a showdown today, I'm willing."
Kraag's mind was clear now. He had the situation under control. He glanced around the landscape at the scattered portions of the wrecked ship. There was the cargo hull, burst open, where Jonner had gotten his sledge hammer and the pick to bury Stein. Over there was a red sphere, ripped by the jagged gash of the meteor collision—one of the two hydrazine fuel tanks. The yellow sphere 30 degrees away from it was an oxygen fuel tank.
Kraag leveled Jonner's gun and fired at the yellow sphere. The kick knocked him off the sphere, but as he somersaulted backwards he saw the projectile hit the ground. Still low and to one side. But he noticed something on the gun, he hadn't seen before.
There were ridges for sighting along the barrel of Jonner's pistol. Regaining his position atop the sphere, Kraag pressed his back against the observatory dome, to brace himself against the gun's backlash. He aimed carefully at the yellow sphere and fired again.
The yellow tank jumped—not from the impact, but from the spout of freed, expanding oxygen through the hole the bullet made. It moved and wobbled about in the weak gravity, like a dying balloon. When it stopped, Kraag knew he had destroyed half of Jonner's oxygen supply.
"Good shot, Kraag," congratulated Jonner, with fatalistic irony in his tone. "Of course, I'm not as big a target as the tanks."
"Each target in its own time," replied Kraag triumphantly, and looked around for the other yellow sphere.
He had been afraid it might be one of the parts that had fallen over the horizon, but it wasn't. It was behind him, a little closer than the first. He hit it with one shot.
Now Jonner had only the oxygen in his spacesuit tanks.
Jonner had made no effort to move farther away. He was still visible on the horizon, from the knees up, moving in a great circle around the personnel sphere.
Kraag aimed carefully and fired. He did not know the projectile's speed, but certainly it would be much faster than Jonner's rocks. After half a minute had passed, he knew he had missed.
There was only one thing to do. He settled himself and fired again, trying to lead Jonner slightly. Again he missed.
Methodically, taking his time, Kraag fired. Jonner walked on unconcernedly, circling. Kraag tried to fire so the path of his projectile would strike at the top of Jonner's strides, for then Jonner rose several feet into the air and his whole body was visible.
Occasionally, Jonner would stop and hurl a stone at Kraag. One man was as inaccurate as the other. Jonner's stones went wide at that distance, and Kraag obviously had not hit Jonner with a bullet.
At last Jonner stopped. He seemed to be fiddling with something that was right on the ground, below Kraag's line of vision. Then a tremendous stone, bigger than Kraag's head, came hurtling toward the sphere. Kraag ducked instinctively, but the missile passed 10 feet above him, still going well.
"What in the devil!" exclaimed Kraag.
"A little innovation of mine, to make things more interesting," said Jonner. "In case you ever want to use the idea, I made me a super-slingshot out of two of the jeep inner tubes from the cargo, and a couple of crowbars I could drive into crevices. Fixed it up yesterday for bombardment purposes."
The duel went on.
There came the time when the hammer of the pistol clicked on an empty chamber.
"How do you refuel this thing, Jonner?" asked Kraag pleasantly. The sun was still high. He could retreat to the interior of the sphere and figure it out if he had to.
"It's pretty hard to do with spacesuit hooks," replied Jonner. "Be glad to demonstrate, if you'll toss me the gun."
Kraag laughed, a laugh with more triumph in it than humor, because in his fumbling he had just hit the button that ejected the magazine. To push in a fresh one was the matter of a moment.
He had hoped Jonner would move in closer when he knew the pistol was empty, but no such luck. Jonner stayed put.
Kraag's first effort with the new magazine brought no results, for he had neglected to prime the weapon by pushing the outer covering back on the barrel. He did this, and resumed his methodical firing.
As the time wore on, Kraag began to appreciate the difficulties involved in hitting a moving target, even a slowly moving one, when the marksman was as inexperienced as he was. The trouble was that, at that distance, he could not see where the bullets were striking and had no way of knowing how wide of his mark he was shooting.
He was on the fourth magazine and the sun had passed the meridian when he felt the sphere vibrate faintly and momentarily beneath him. He twisted around, alarmed. He could see nothing. It wasn't one of Jonner's rocks, because a big one had just missed.
His eye detected a shining streak that stretched a few inches along the curve of the sphere's meteor shield, at about the level of his feet. He bent to examine it. Something had struck it at high speed, a glancing blow.
It couldn't be one of Jonner's rocks. Small meteor?
A jagged hole suddenly appeared in the observatory dome near him. Kraag moved up and examined it closely. It had been made by some small object. Through the glassite he could see a similar hole in the other side of the dome.
Did Jonner have some sort of new weapon? He couldn't. Even Jonner wasn't resourceful enough to invent a high-powered weapon with the innocuous cargo they were carrying for the Titan colony.
Something struck Kraag a powerful blow in the left chest, a blow that hurled him sideways, to tumble off the sphere and fall slowly to the ground below. There was a great pain in his chest, and he released his hand-hooks in agony, so that the pistol fell away from him.
Kraag gasped for breath as he struck the ground and bounced. He coughed up blood.
He fell slowly again, and bounced again. The third time he settled jarringly, prone on his back.
He couldn't understand what had happened to him. He pulled his right arm inside the suit with an effort and probed the painful area on his chest. He felt the hot wetness of flowing blood.
He would have to get to the sphere. He tried to move. He couldn't get off his back. He lay there and writhed in pain.
Jonner's voice was in his ears, saying something.
"I knew it would get you," Jonner said. "It was my only chance. But it got you at last, Kraag."
"Come help me, Jonner," whimpered Kraag weakly. "I've been hit by ... I don't know. It must have been a meteor."
"I'm coming as fast as I can, Kraag, but it was no meteor. It was my gun."
"Gun?" repeated Kraag wonderingly.
"I warned you about that gun of mine, Kraag. If you'd looked at the figures on the barrel, the muzzle velocity of those .45-calibre bullets is 1100 feet a second. With Ceres' escape velocity, that's almost exactly the circular velocity at the asteroid's surface."
Jonner was standing over him, and then was lifting him gently, to carry him to the sphere.
"I deliberately got just out of your range of vision, from the ground, so you'd climb to a high spot," said Jonner. "You had to be high, so the bullet would clear the irregularities on the planet's surface, and I knew that sooner or later you'd shoot a bullet or two high enough not to hit the ground.
"When you were firing at me, your bullets weren't describing a trajectory and falling to the surface, as they would on Earth or Mars. They were taking an orbit that brought them all the way around the planet to the same spot, to hit you from the other side two hours later."
Kraag tried to look up at him. Something was going wrong with his sight, and everything outside his face plate was a blur. Must be the oxygen ... maybe his suit didn't seal the bullet hole properly.
"I thought...." Kraag began, and choked. He coughed, slowly and painfully, then tried again: "I thought that ... problem on the rocks ... looked familiar."
"You've always done it with a slide rule. That's probably why the long division didn't register," said Jonner. "The equation is one every spaceman knows: the circular velocity equals the escape velocity divided by the square root of two."