The stream of electrons caught the front face of our main building in a six foot circle. It held a few seconds, vanished, then stabbed again, and still again. Three bolts. A total, I suppose, of nine or ten seconds. I was standing with Grantline at a front window. We had rigged an oblong of insulated fabric like a curtain; we stood peering, holding the curtain cautiously aside. The ray struck some twenty feet away from us. "Harmless!" The men shouted it with derision. But Grantline swung on them: "Don't get that idea!" An interior signal panel was beside Grantline. He called the duty men in the instrument room. "It's over. What are your readings?" The bombarding electrons had passed through the outer shell of the building's double wall, and been absorbed in the rarefied, magnetized aircurrent of the Erentz circulation. Like poison in a man's veins, reaching his heart, the free alien electrons had disturbed the motors. They accelerated, then retarded. Pulsed unevenly, and drew added power from the reserve tanks. But they had normalized at once when the shot was past. The duty man's voice sounded from the grid in answer to Grantline's question: "Five degrees colder in your building. Can't you feel it?" The disturbed, weakened Erentz system had allowed the outer cold to radiate through a trifle. The walls had had a trifle extra explosive pressure from the air. A strain--but that was all. "It's probably their most powerful single weapon, Gregg," said Grantline. I nodded, "Yes, I think so." I had smashed the real giant, with its ten mile range. The ship was only two miles from us, but it seemed as though this projector were exerted to its distance limit. I had noticed on the deck only one of this type. The others, paralyzing rays and heat rays, were less deadly. Grantline commented: "We can withstand a lot of that bombardment. If we stay inside--" That ray, striking a man outside, would penetrate his Erentz suit within a few seconds, we could not doubt. We had, however, no intention of going out unless for dire necessity. "Even so," said Grantline, "a hand shield would hold it off for a certain length of time." We had an opportunity a moment later to test our insulated shields. The bolt came again. It darted along the front face of the building, caught our window, and clung. The double window shelves were our weakest points. The sheet of flashing Erentz current was transparent; we could see through it as though it were glass. It moved faster, but was thinner at the windows than the walls. We feared the bombarding electrons might cross it, penetrate the inner shell and, like a lightning bolt, enter the room. We dropped the curtain corner. The radiance of the bolt was dimly visible. A few seconds, then it vanished again, and behind the shield we had not felt a tingle. "Harmless!" But our power had been drained nearly an aeron, to neutralize the shock to the Erentz current. Grantline said: