And then a miracle happened--a miracle and a tragedy. The setting sun at last escaped from the cloud that covered it and its ruddy rays, coming over the summit of a nearby Andean peak, fell upon the mass of crystal at the western edge of the valley. A beam of bluish light, like the reflection from the glossy scales of a black serpent and more evilly gorgeous than the slumbering fires of a thousand opals, leaped from it. The ray struck Calhoun squarely. He staggered to his feet, uttered a choking cry, and crumpled lifeless to the earth! A few moments later the sun dropped behind the mountains and "The Devil's Nest" was again in shadow. Ready for Battle Six more weeks rolled by and, now the Asiatic Air Fleet advancing up the Mississippi Valley was only five hundred miles from Chicago. Should this last big city of the Occident be destroyed, all hope for further resistance would immediately crumble; for here were situated the munition factories and here was the government that kept the dwindling energies of the United States organized. Surrender was useless to the Americans. The blood lust of their foes had grown to such proportions that they had proclaimed that only the complete extermination of Occidentals would satisfy them. In a few more days, when the needed reinforcements had arrived from China, there would be a battle surpassing in magnitude and horrors all previous struggles. Then the men from the East would dump tons of chemicals upon the American metropolis; her twenty million inhabitants would suffer a moment of intense agony and, in a few minutes, she would be left silent and empty. So, at least, thought Tsu Tsin Ho, "The Wizard of the East," and many another wise head among the invaders; for the air fleet of the United States was outnumbered three to one. But there was one thing that the brilliant Orientals did not know of. In Whitley Park, Chicago's most important pleasure ground, an unusual engineering operation was in progress. Four slender, two-thousand-foot towers of steel, seemingly as frail as spider web, were rising as if by magic. They were arranged in a square and between them skillful workmen were fastening a maze of fine wires. In the center of the rectangle formed by the towers two enigmatic machines were being assembled. One was a huge apparatus, very similar in appearance to a gas engine of the twentieth century. Fully a hundred feet its eight bulky cylinders reared, gleaming with a glossy black sheen. There was something sinister and awesome about it--a suggestion that within its slumbering frame there lurked sufficient power to send the earth hurtling from its orbit. Beside the engine a great drum-like contrivance was slowly taking form beneath the hammers and riveters of the construction crew. It was a generator that would soon supply energy to the mass of wires overhead.