Surrounded by her four guards, she hastened to the laboratory of the Merlin Research Institute; and, requiring solitude for efficient work, busied herself from dawn to dusk and even through the early hours of daylight to perfect her invention. Formerly she had expected to be able to finish the contrivance at her leisure. But now with what feverish haste she labored, scarcely taking time to eat, to sleep, to think except of one thing only! At first the fear haunted her that the Saturnians would break in, and steal her away despite her bodyguard. But was it that the one lucky shot, which had spilled the golden-orange blood of her attacker, had deterred the invaders? More probably, they did not think her worth bothering about--what could she, one poor feeble woman, do to avert the doom that had been so well plotted, and that was so soon to descend? The heat, as she worked, had risen to furnace intensity. Temperatures below a hundred were now rarely found near sea level in the so-called temperate regions; all breezes, except those engendered by electric fans, were memories of the dear departed days; while so many areas were parched and browned, so many people were perishing on all sides, that bureau of statistics no longer kept records. That the long-awaited Day of Judgment was at hand; that the destruction of the earth and all its inhabitants was a matter but of weeks or at most of months, was now the theme of preachers and laymen alike; millions, ceasing to hope, passed their days amid a long mumbling of lamentations and prayers. * * * * * Meanwhile few knew or cared about the young woman who, with eyes red and strained, with fingers deft yet nervously hurried, with skin and apron mottled with chemicals, yet with a spirit that refused to give up, labored amid the motors and ray-spouting tubes, the flasks and crucibles of the steamy hot laboratory. Nearly five days had gone by before she had put her machine into working order--five days which, in view of the time lost under the spell of the hypodermic drug, should bring her beyond the deadline set by Dunbar. Already, perhaps, he had turned over the containers of compressed air to the Saturnians! Already they were making their last deadly assault! Already it was too late--too late to save the earth! Nevertheless, if but one chance in ten thousand remained, that chance must not be tossed aside. Her machine, when ready, was a monstrous-looking affair, somewhat resembling a siege-gun in appearance. The fifteen-foot steel snout, shooting upward like a spire from the central mass of lenses, prisms and radio-like tubes, was attached by wires to several huge dynamos. A telescope, fastened to the side of the main tube, connected with the range finder; while the whole could be moved hither and thither on wheels, a little like a great gun on its carriage.