The face of Dalis went suddenly white, but he nodded, his eyes burning redly. Jaska moved closer to the men, who stood near the table of the vari-colored lights. "You needed my father's father," said Sarka softly, "because the secret of your scheme rested here in this laboratory, which is the highest point in the world! You pretended to need him in your scheme; but you did not need my father's father, though you _did_ need his laboratory, and some of the facts of science that _he_ discovered. So you came to him with your scheme, discovered that he believed, though he denied it, your scheme was possible--because he refused to aid you in it! Then, as an excuse to re-enter this laboratory, you told him you would return within two days! Now, shall I tell you your secret?" * * * * * The lips of Dalis were moving soundlessly. His right hand started to rise, as though he would make it signal the negative he was unable for a moment to speak. But even as he stood there, swaying slightly on his feet, Sarka dashed to the lights on the table, disconnecting them one by one; to the Revolving Beryl, which then ceased to revolve for the first time in centuries--whirled when he had finished, and stepped to the very center of the room. "Now," he whispered, "your secret, Dalis!" Still the hand upraised, still Dalis tried to speak, and could not. Sarka spoke, in a hoarse, almost terrified whisper, four words: "The Beryl! The Ovoids!" Gasps of surprise from the other two Sarkas, whose eyes for a second flashed to the huge Beryl, which now was still, silent--and blind. Dawning comprehension was evident in their faces. "The success of the Revolving Beryl," whispered Sarka, "which sees all that transpires in this world, depends on one fact: that its revolving is proportionately timed to infinite exactness with the revolution of the Earth about its axis! This Beryl is the Master Beryl of the Earth, which was why Dalis needed this Beryl, and could use no other!" * * * * * "Suppose that for a period of two days, uniformly progressive, this Beryl were forced to revolve in sharp jerks at an increasing rate of speed! With all connections in place, and all the world's Beryls attuned to the speed of this one--what would happen? What would happen if a single Gens were marshalled in warlike array atop the area of the Gens, and kept up a steady, rhythmic march for a period of hours?" "In a few hours," whispered Sarka the First, "the roof of the Gens area would begin to vibrate, to vibrate throughout all the area, and even into all surrounding Gens areas--and in time the roof would collapse!"