"Funny that he should pa.s.s out like that," commented Strong, sniffing the air. "I _still_ don't smell anything."

Kit looked up at Strong and grinned. "He's not ga.s.sed. He's asleep."

"Asleep!" exclaimed Walters.

The enlisted s.p.a.ceman standing on guard at the door stepped forward and saluted smartly. "Captain Howard hasn't slept for the last five days,"

he said. "He's been working night and day."

Walters smiled. "All right, Sergeant, take him to his quarters." Then he held up his hand. "No, let him stay where he is." He turned to Steve.

"Come on, Steve. You too, Kit. Let's see if we can't get a report from the electronics section before we speculate any further."

The three men left the control-tower office under the watchful eyes of a squad of s.p.a.ce Marines. Trouble had already started at the s.p.a.ceport when a crowd of excited miners had charged a detachment of enlisted men guarding Solar Guard cruisers. The crowds were growing panicky as the deadly gas filled the city, unchecked.

Strong, Walters, and Kit Barnard climbed into a waiting jet car, amid the hoots and catcalls from the waiting miners, and hurtled away to the giant building housing the electronic "brain" that controlled the force-field screens.

Walters' face was grim. Beside him, Strong and Kit were silent as they raced through the empty streets. If there was no positive discovery by the electronics section of the huge screening operations, then it would have to be a.s.sumed that Commander Walters was right in his theory of overpopulation. To remedy that situation would require complete reconstruction of the satellite settlement and temporary abandonment of t.i.tan. Millions of dollars would be lost and thousands of people thrown out of work. It would be a severe blow to the Solar Alliance.

The jet car slowed to a stop. They were in front of the electronics building and the three men climbed out wearily. They would know in a few minutes now.

CHAPTER 13

"You're afraid of your own shadow!" Miles snarled over his shoulder to Charley Brett who followed him out of the room. Brett was adjusting his oxygen mask with one hand and gripping a paralo-ray gun tightly with the other.

"Never mind the cracks," snapped Brett, his voice m.u.f.fled by the mask.

"I tell you I heard someone moving around in here."

Miles laughed again and walked straight to the middle of the room. With their backs pressed to the wall beside the door, Tom and Astro saw Miles bend over and lift a trap door in the middle of the floor.

The two men flashed a light down into the opening and climbed down, pulling the trap door closed after them.

No sooner was it shut than Tom and Astro jumped forward to examine it cautiously. Astro started to pull it open but Tom held out a warning hand. He turned and pointed toward the room that Miles and Brett had left. Astro nodded and they walked quickly back to the door. Sliding it open, they stepped inside.

"By the rings of Saturn!" cried Astro.

"Well, blast my jets!" Tom exclaimed.

The air in the room was clear, completely free of the misty whirling methane ammonia of death that swirled around them outside. Recovering from his surprise quickly, Astro closed the door and walked to the center of the room, looking around curiously. Tom had already slipped off his mask and was examining the equipment lying on the floor. Astro bent over an oddly shaped machine that looked somewhat like an ancient compressed-air drill, with a long bar protruding from one end. He examined the bar closely and then turned slowly to Tom.

"Do you know what this machine is?" he asked in almost a whisper.

Tom looked at it and then shook his head.

"I haven't seen one of these since I left Venus, and then only when I was a kid hanging around the s.p.a.ceports where the s.p.a.ce rats used to blast off for the asteroids looking for uranium."

"You mean you hunt uranium with that thing?" asked Tom.

"No, you dig it out with this."

Tom gazed at the machine thoughtfully. "Why would it be here?" he mused.

"It's already been used," said Astro, standing up. "Look, the drill head is dull."

"That trap door!" Tom exclaimed. "It leads to a mine. Miles and Brett have discovered high-grade uranium right here on t.i.tan where everyone thought there was nothing but _crystal_!"

Astro nodded grimly. "And that isn't all. This room is free of ammonia gas."

"But how in the star-blazing d.i.c.kens can they keep it out of here when everything else outside is flooded with it?" asked Tom.

Astro spun around and began to examine the walls. "Just as I thought!"

he exclaimed. "This room is airtight! Sealed! Oxygen is being pumped in here."

"From where?"

"Might be from somewhere below," replied the big Venusian. "Down that trap where Miles and Brett went."

Tom put his mask back on and headed for the door. Astro followed him.

They opened it a little and peered into the swirling mist.

"Then it's being pumped in directly," Tom a.s.serted. "Through a duct leading directly up into this room from somewhere below."

Astro nodded. "Then there's only one thing left to do. Go down through that trap door and see what we can find." He stepped forward.

"Wait a minute, Astro," said Tom, stopping him. "Let me check our oxygen. There might not be any down there. Remember, Miles and Brett wore _their_ masks."

Making a quick check of their oxygen supply, Tom patted Astro on the back and started forward. "It's O.K. We've got another four hours left.

Come on!"

They moved toward the trap door slowly.

"I still wish I had a ray gun," whispered Tom.

"As long as I can use these"--Astro balled his hamlike hands into fists--"we're O.K."

When they reached the trap door, Tom got down on his knees and felt around for the opening. He found a small ring bolt, motioned to Astro to step back, and pulled. The trap door swung back easily and a shaft of white light gleamed in his face. The young cadet leaned down and looked through the opening. What he saw made him gasp.

"What is it?" demanded Astro.

[Ill.u.s.tration: _Tom got down on his knees and felt around for an opening_]

Tom motioned for him to get down and look. The big cadet dropped lightly to his knees to peer through the opening. "By the moons of Jupiter," he exclaimed, "it's a--a mining shaft!"

"Just what we thought it was," whispered Tom. "Come on. Let's go down and find out where it leads."

"Maybe we'd better go back and tell Captain Strong about this first,"

Astro said speculatively.