"Because earthmen have to get mad to fight," returned Lonny, "and you can't get mad here somehow. Oh, shut up! I don't know how to explain it. Earthmen just don't feel violent emotions here on Uranus. They don't get mad at anything! They don't fall in love! They're just sapped dry of everything." His head was aching. It was a good thing his body had recovered from its exposure to the heavy pressure area. He climbed the rampway for the upper deck, and stood motionless, breaking upon a surprising scene. * * * * * All of the compartments had been searched, and he saw his cache of Uranusian pearls open to view. The wall safe hung ajar--apparently the deft fingers of Link Raeburn had encountered no great difficulty in finding the combination. His eyes were glittering with fascination, and the girl, too, seemed unable to wrench her eyes from the inviting spectacle. "That's enough," gasped Link Raeburn, "to set a fellow up for life." "Yeh, and here we are," returned the girl hollowly, "stuck deep in the mud of Uranus." "Maybe you forget who they belong to," snorted Lonny, stalking into their midst and slamming his treasure back into its hiding place. "The indicator says we're at six thousand five hundred and forty-one feet." "Then we've stopped," said Raeburn. "It read the same five minutes ago." Lonny stood watching the gauges and found that the other was right. The mud-submarine had indeed come to a halt. It meant that some sort of an equilibrium was being established in the barometric storm center that raged above. "I'll start the motors and try jarring the ship around a little," he said, seating himself before the mechanisms. At a touch of his finger, dial bulbs lighted up, and from the lower depths came the whine of machinery. Almost instantly they felt a sidewise lurch, and then a slow climbing motion. "It looks good, anyway," said Link Raeburn. "We're going up again." "Thank Heaven for small favors," breathed Lana thankfully, and watched attentively as Lonny began juggling the controls alarmedly. Link's eyes watched the indicator, and began to show new amazement. "We're not ascending now," said Lonny grimly. "I don't know what's the matter. The motor-drive is okay, but we're making a crazy circle, over and over, and not getting any higher." "You're nuts!" burst out Raeburn, stalking forward, waving his arms. Yet the yellow pallor of his face showed that he too had noticed the mud-ship's erratic behavior. "It's just not possible! Uranus is all mud--just plain fluid mud!" "Or that's what we've thought, up to now," said Lonny significantly. "What do you mean?" demanded Lana. "You can't mean that we're trapped here with a fortune just in our grasp." The whine of the lower motors mounted, and as a result the mud-submarine began spinning around like a top. Yet the depth pointer had not moved.