A disc of artificial matter ten feet across suddenly appeared beside the _Ancient Mariner_. It advanced with terrific speed, struck the great dome of the fort, and the dome caved, bent in, bent still more--but would not puncture. The disc retreated, became a sharp cone, and drove in again. This time the point smashed through the relux, and made a small hole. The cone seemed to change gradually, melting into a cylinder of twenty foot diameter, and the hole simply expanded. It continued to expand as the cylinder became a huge disc, a hundred feet across, set in the wall. Suddenly it simply dissolved. There was a terrific roar, and a mighty column of white rushed out of the gaping hole. Figures of Thessians caught by the terrific current came rocketing out. The inside was at last visible. The terrific pressure was hurling the outside line of ships about like thistledown. The _Ancient Mariner_ reeled back under the tremendous blast of expanding gas. The snow that fell to the boiling water below was not water, _in toto_; some was carbon dioxide--and some oxygen chilled in the expansion of the gas. It was snowing within the dome. The falling forms of Thessians were robbed of the life-giving air pressure to which they were accustomed. But all this was visible for but an instant. Then a small, thin sheet of artificial matter formed beside the fort, and advanced on the dome. Like a knife cutting open an orange, it simply went around the dome's edge, the great dome lifted like the lid of a teapot under the enormous gas pressure remaining--then dropped under its own weight. The artificial matter was again a huge disc. It settled over the exact center of the dome--and went down. The dome caved in. It was crushed under a load utterly inestimable. Then the great disc, like some monstrous tamper, tamped the entire works of the Thessians into the bed-rock of the island. Every ship, every miniature fort, every man was caught under it--and annihilated. The disc dissolved. A terrific barrage of heat beams played over the island, and the rock melted, flowed over the ruins, and left only the spumes of steam from the Arctic ice rising from a red-hot: mass of rock, contained a boiling pool. The Battle of the Arctic was done. Chapter XI "WRITE OFF THE MAGNET" "Squadron commander Tharnton speaking: Squadron 73-B of Planetary Guard will follow orders from Dr. Arcot directly. Heading south to Antarctica at maximum speed," droned the communicator. Under the official tone of command was a note of suppressed rage and determination. "And the squadron commander wishes Dr. Arcot every success in wiping out Antarctica as thoroughly and completely as he destroyed the Arctic base."