There was only—the ball! It was the answer.

Through the observation port, he could see the circular ship. It was getting ready to attack again. The sphere was moving leisurely toward its already crippled prey, getting ready to deliver the final stroke. It would answer all questions of this crew, answer them unmistakably. It leered at them.

Wham!

The ship vibrated to a sudden gust of sound. Something lashed out from the vessel. Hargraves did not see it go because it, too, went faster than the eye could follow. But he knew what it was. The sound told him. He saw the hole appear in the sphere. A round hole that opened inward. Dust puffed outward.

Wham, wham, wham!

The negatron! The blood brother of the defense screen, its energies concentrated into a pencil of radiation. Faster than anyone could see it happen, three more holes appeared in the sphere, driving through its outer shell, punching into the machinery at its heart.

The sphere shuddered under the impact. It turned. Light spewed out of it, beaming viciously into this alien sky without direction. Smoke boiled from the ball. Turning it seemed to roll along the sky. It looked like a huge burning snowball rolling down some vast hill.

Ron Val lifted a white face from the sighting 'scope of the negatron.

"Did—did I get him?"

"I'll say you did!" Hargraves heard somebody shout exultantly. He was surprised to discover his own voice was doing the shouting. The sphere was finished, done for. It was out of the fight, rolling down the vast hill of the sky, it would smash on the planet below.

They were following it.

There was still no answer from the engine room.

"Space suits!" Hargraves ordered. "Nielson, you stay here. Ron Val, you others, come with me."

CHAPTER II

Vegan World

The engine room was crammed to the roof with machinery. The bulked housings of the atomics, their heavy screens shutting off the deadly radiations generated in the heart of energy seething within the twin domes, were at the front. They looked like two blast furnaces that had somehow wandered into a space ship by mistake and hadn't been able to find their way out again. The fires of hell, hotter than any blast furnace had ever been, seethed within them.

Behind the atomics were the Kruchek drivers, twin brawny giants chained to the treadmill they pushed through the skies. Silent now. Not grumbling at their task. Loafing. Like lazy slaves conscious of their power, they worked only when the lash was on them.

Between the drivers was the control panel. Ninety-nine percent automatic, those controls. They needed little human attention, and got little. There were never more than three men on duty here. This engine room almost operated itself.

It had ceased to operate itself, Jed Hargraves saw, as he forced open the last stubborn air-tight door separating the engine room from the rest of the ship. Ceased because—Involuntarily he cried out.

He could see the sky.

A great V-shaped notch straddled the back of the ship. Something, striking high on the curve of the hull, had driven through inches of magna steel, biting a gigantic chunk out of the ship. The beam from the sphere! That flashing streak of light that had driven through the defense screen. It had struck here.

"Jed! They're dead!"

That was Ron Val's voice, choking over the radio. One of the men in this engine room had been Hal Sarkoff, a black-browed giant from somewhere in Montana. Engines had behaved for Sarkoff. Intuitively he had seemed to know mechanics.

He and Ron Val had been particular friends.

"The air went," Hargraves said. "When that hole was knocked in the hull, the air went. The automatic doors blocked off the rest of the ship. The poor devils—"

The air had gone and the cold had come. He could see Sarkoff's body lying beside one of the drivers. The two other men were across the room. A door to the stern compartment was there. They were crumpled against it.

Hargraves winced with pain. He should have ordered everyone into space suits. The instant Nielson reported the approach of the sphere, Hargraves should have shouted, "Space suits" into the mike. He hadn't.

The receiver in his space suit crisped with sound.

"Jed! Have you got into that engine room yet? For cripes sake, Jed, we're falling."

That was Nielson, on the bridge. He sounded frantic.

Sixteen feet the first second, then thirty-two, then sixty-four. They had miles to fall, but their rate of fall progressed geometrically. They had spent many minutes fighting their way through the air tight doors. One hundred and twenty-eight feet the fourth second. Jed's mind was racing.

No, by thunder, that was acceleration under an earth gravity. They didn't know the gravity here. It might be less.

It might be more.

Ron Val had run forward and was kneeling beside Sarkoff.

"Let them go," Hargraves said roughly. "Ron Val, you check the drivers. You—" Swiftly he assigned them tasks, reserving the control panel for himself.

They were specialists. Noble, the blond youth, frantically examining the atomics, was a bio-chemist. Ushur, the powerfully built man who had stood at Ron Val's right hand on the negatron, was an archeologist.

They were engineers now. They had to be.

"Nothing seems to be wrong here." That was Ron Val, from the drivers.

"The atomics are working." That was Noble reporting.

"Then what the hell is wrong?" At the control panel, Hargraves saw what was wrong. The damned controls were automatic, with temperature and air pressure cut-offs. When the air had gone from the engine room, that meant something was wrong. The controls had automatically cut off the drivers. The ship had stopped moving.

A manual control was provided. Hargraves shoved the switch home. An oil-immersed control thudded. The loafing giants grunted as the lash struck them, roared with pain as they got hastily to work on their treadmill.

The ship moved forward.

"We're moving!" That was Red Nielson shouting. The controls on the bridge were responding now. "I'm going to burn a hole in space getting us away from here."

"No!" said Hargraves.

"What?" There was incredulous doubt in Nielson's voice. "That damned sphere came from this planet."

"Can't help it. We've got to land."

"Land here, now!"

"There's a hole as big as the side of a house in the ship. No air in the engine room. Without air, we can't control the temperature. If we go into space, the engine room temperature will drop almost to absolute zero. These drivers are not designed to work in that temperature, and they won't work in it. We have to land and repair the ship before we dare go into space."

"But—"

"We land here!"

There was a split second of silence. "Okay, Jed," Nielson said. "But if we run into another of those spheres—"

"We'll know what to do about it. Ron Val. Ushur. Back to the bridge and man the negatron. If you see anything that even looks suspicious, beam it."

Ron Val and Usher dived through the door that led forward.

"Stern observation post. Are you alive back there?"

"We heard you, Jed. We're alive all right."

Back of the engine room, tucked away in the stern, was another negatron.

"Shoot on sight!" Hargraves said.

The Third Interstellar Expedition was coming in to land—with her fangs bared.

Jed Hargraves called a volunteer to hold the switch—it had to be held in by hand, otherwise it would automatically kick out again—and went forward to the bridge. Red Nielson gladly relinquished the controls to him.

"The sphere crashed over there," Nielson said, waving vaguely to the right.

Not until he stepped on the bridge did Jed Hargraves realize how close a call they had had. The fight had started well outside the upper