There seemed no cause for these ripplings. But there were powerful gravitational fields in the void, so powerful as to warp space and bend the starlight passing through them. These gravity-fields moved with an incredible speed. There were ten of them, circling in a complex pattern which was spread out as an invisible unit which moved faster than the light their space-twisting violence distorted. They seemed absolutely undetectable, because even such minute light-ripplings as they made were left behind them. The ten ships which created these monstrous force-fields were unbelievably small. They were no larger than cargo ships on the oceans of one planet in the solar system toward which they sped. They were less than dust particles in infinity. They would travel for only a few more days, now, and then would flash through the solar system which was their target. They should reach its outermost planet--four light-hours away--and within eight minutes more swing mockingly past and through the inner worlds and the sun. They would cross the plane of the ecliptic at nearly a right angle, and they should leave the planets and the yellow star Sol in flaming self-destruction behind them. Then they would flee onward, faster than the chaos they created could follow. The living creatures on the world to be destroyed would have no warning. One instant everything would be as it had always been. The next, the ground would rise and froth out flames, and more than two thousand million human beings would hardly know that anything had occurred before they were destroyed. There was no purpose to be served by notifying the world that it was to die. The rulers of the nations had decided that it was kinder to let men and women look at each other and rejoice, thinking they had all their lives before them. It was kinder that children should be let play valorously, and babies wail and instantly be tended. It was better for humanity to move unknowing under blue and sunshine-filled skies than that they should gaze despairingly up at white clouds, or in still deeper horror at the shining night stars from which devastation would presently come. In the one place where there was foreknowledge, no attention at all was paid to the coming doom. Burke went raging about brightly lighted corridors, shouting horrible things. He cried out to Sandy to answer him, and defied whatever might have seized her to dare to face him. He challenged the cold stone walls. He raged up and down the gallery in which she had vanished, and feverishly explored beyond it, and returned to the place where she had disappeared, and pounded on solid rock to see if there could be some secret doorway through which she had been abducted. It seemed that his heart must stop for pure anguish. He knew such an agony of frustration as he had never known before.