[Illustration: _The fury of the beams rebounded in scintillating torrents, shot off in blinding streamers_--] Nor was that superbly disguised citadel designed for defense alone. Knowing now that the last faint hope of continuing in business upon Bronseca was gone, and grimly determined to take full toll of the hated Patrol, the defenders in turn loosed their beams. Five of them shot out simultaneously, and five of the panels of mobile screen flamed instantly into eye-tearing violet. Then black. These were not the comparatively feeble, antiquated rays which Haynes had expected, but were the output of up-to-the-minute, first-line space artillery! Defenses down, it took but a blink of time to lick up the caterpillars. On, then, the destroying beams tore, each in a direct line for a remote-control station. Through tremendous edifices of masonry and steel they drove, the upper floors collapsing into the cylinders of annihilation only to be consumed almost as fast as they could fall. "All screen-control stations, back, fast!" Haynes directed crisply. "Back, dodging! Put your screens on automatic block until you get back beyond effective range. Spy-ray men! See if you can locate the enemy observers directing fire!" But no matter how far back they went, Boskonian beams still sought them out in grimly persistent attempts to slay. Their shielding fields blazed white, their refractories wavered in the high blue as the overdriven refrigerators strove mightily to cope with the terrific load. The operators, stifling, almost roasting in their armor of proof, shook sweat from the eyes they could not reach as they drove themselves and their mechanisms on to even greater efforts; cursing luridly, fulminantly the while at carrying on a space war in the hotly reeking, the hellishly reflecting and heat-retaining environment of a metropolis!