He shuddered; then he began to explore the dome of the building for a means of entrance. * * * * * There was no opening in the roof. A solid sheet of reddish metal, like a titanic half-eggshell, it glittered under him in an unbroken piece. He crept down its increasingly precipitous edge till he reached a sort of cornice that formed a jutting circle of stone around it. There he leaned far over and saw, about ten feet below him, a round opening like a big port-hole. From it were streaming waves of warm, foul air, from which he judged it to be a ventilator outlet. He scrambled over the edge of the cornice, hung at arm's length, and swung himself down into the opening. And there, perched high up under the roof, he looked down at an enigmatic, eery scene. That the structure was indeed a strange sort of power-house was instantly made evident. But what curious, mysterious, and yet bewilderingly simple machinery it held! In the center was a titanic coil of reddish metal formed by a single cable nearly a yard through. Around this, at the four corners of the compass, were set coils that were identical in structure but a trifle smaller. From the smaller coils to the larger streamed, unceasingly, blue waves of light like lightning bolts. Along a large arc of the wall was a stone slab set with an endless array of switches and insulated control-buttons. Gauges and indicators of all kinds, whose purpose could not even be guessed at, were lined above and below, all throbbing rhythmically to the leap of the electric-blue rays between the monster coils. * * * * * Almost under Brand's perch a great square beam of metal came through the building wall from outside, to be split into multitudinous smaller beams that were hooked up with the bases of the coils. Across from him, disappearing out through the opposite wall, was an identical beam. "The terminals for the metal plate system that extends over the whole red spot," murmured Brand. "This building _is_ important. But what can I do to throw sand in the gears before I'm caught and killed...?" He surveyed the great round room below him more thoroughly. Now he saw, right in the center of the huge control board, a solitary lever, that seemed a sort of parent to all the other levers and switches. It was flanked by a perfect army of gauges and indicators; and was covered by a glass bell which was securely bolted to the rock slab. "That looks interesting," Brand told himself. "I'd like to see that closer, if I can climb down from here without being observed.... Why"--he broke off--"where is everybody!"