Chicago stood as dead and silent as though the Asiatics had already dumped their poisonous vapors upon her. Her unlighted skyscrapers loomed up wanly under the blinking stars and her streets were gorges of Stygian shadow. Scarcely a speck of radiance was left to betray her location to the enemy. The inhabitants had shut themselves indoors. A few wept quietly, but otherwise there was no inordinate display of emotion. These people had lost much of their terror of war by constant contact with it. The Crystal Ray In the glow of floodlights, a thousand workmen were laboring like demons on some giant machine that gleamed dimly in the faint radiance. Far, far aloft, supported by four slender towers, was a vast network of wires. Plainly the finishing touches to the engine were in progress. A hundred men were fastening cables to a two-hundred ton cylinder-head which would in a moment be hoisted into place by an electric crane. Other workers were inspecting and oiling the giant machine. At one end of the strange titan was a control board bearing many levers, switches and dials; and before it stood the gaunt figure of a man who shouted orders through an amplifier system. It was Pelton; but how greatly changed from the plump young aviator of two months before! His hair was wildly disheveled, and sweat streamed down his shrunken face which, in the wan light, looked almost like a parchment mask hiding the visage of a skull. Lack of sleep and endless hours of labor had wrought this startling change. In spite of his worn condition, there was something magnetic about him that could not help but inspire confidence. "Crew One, see to the lubrication of the cylinder valves and other parts," he cried; "use the L. F. liquid. Crew Two, examine all the connections of the Z wires. Crew Three, fill the main fuel tanks with the liquid _terrorium_ preparation; Crews Four and Five will take care of the cylinder-head. Are all the cables securely fastened? We can't afford another mishap, you know. Good! Now start the crane." Every man realized that it was vitally important that he should perform his task to the best of his ability in the shortest possible time; and every man responded to the will of his chief with the promptness of a well-oiled machine. In a moment the mass of aluminum alloy soared upward and settled into position. To the south, and high in the air, a vast oval patch of white light, looking like the head of some enormous comet, had appeared. It had drifted ominously near, and from it there came a subdued roar. In it thousand of insect-like specks flitted, and from them tiny points of radiance leaped as though they were fireflies. It was the battle. As they fought the two contesting fleets had done their best to get above each other, to gain the advantage of position. As a result their altitude was prodigious. They must have been fully twenty miles above the earth.