As they had hoped, the deadly new ray stabbed out from somewhere on the side of the fort. It was not within the fort. "Which means," pointed out Morey, "that they can't make stuff to stand that. Probably the projector would be vulnerable." But a barrage of heat rays which immediately followed had no apparent effect. The little radio-controlled molecular beam projector lay on the rock under the melted ice, blazing incandescent with the rapidly released energy of the relux. "Now to try the real test we came here for," Morey clambered back to the power room, and turned on the controls of the magnetic beam. The ship was aligned, and then he threw the last switch. The great mass of the machine jerked violently, and plunged forward as the beam attracted the magnetic core of the Earth. Morey could not see it, but almost instantly the shimmer of the molecular screen on the fort died out. The deadly ray sprang out from the Thessian projector--and went dead. Frantically the Thessians tried weapon after weapon, and found them dead almost as soon as they were turned on--which was the natural result in the terrific magnetic field. And these men had iron bones, their very bones were attracted by the beam; they plunged upward toward the ship as the beam touched them, but, accustomed to the enormous gravitation accelerations of an enormous world, most of them were not killed. "Ah--!" exclaimed Arcot. He picked up the transmitter and spoke again to the Squadron Commander. "Squadron Commander Tharnton, what relux thickness does your ship carry?" "Inch and a quarter," replied the surprised voice of the commander. "Any of the other ships carry heavier?" "Yes, the special solar investigator carries five inches. What shall we do?" "Tell him to lower his screen, and let loose at once on all operating forts. His relux will stand for the time needed to shut them down for their own screens, unless some genius decides to fight it out. As soon as the other ships can lower their screens, tell them to do so, and tell them to join in. I'll be able to help then. My relux has been burned, and I'm afraid to lower the screen. It's mighty thin already." The squadron commander was smiling joyously as he relayed the advice as a command. Almost at once a single ship, blunt, an almost perfect cylinder, lowered its screen. In an instant the opalescence of the transformation showed on it, but its dozen ray projectors were at work. Fort after fort glowed opalescent, then flashed into protective ionization of screening. Quickly other ships lowered their screens, and joined in. In a moment more, the forts had been forced to raise their screens for protection.