No one moved to stop me. Bill held out the papers, his thumbs marking a certain line. I saw that the margins were filled with his spidery writing. "Take that top sheet. Now, look at those readings. Has he reached them yet?" The figures looked familiar. Of course they were the settings at which Dampier had drawn his little red lines. "He's past them," I cried. "On all but two." "On all, my friend." Nebel turned again to the dials. "Bluffing does not work in a game for men." As he moved Bill sprang. Not at Nebel--not at the machine--but at the two great copper bars that came in through the wall. His lean body fell like a stretched spear across them. There was a burst of flame, the stench of burning flesh, but my eyes had left him. For as he leaped Nebel turned the dials. [Illustration: _Sparks crashed in a crescendo as he threw his body across the giant power cables, in a human short-circuit!_] A roar of subterranean thunders shook the room. Vast energies poured into the shining zone. It changed. It was a great mirror of utter blackness, its shimmering silver sheen gone leaving a shell of strange transparency out of which creatures of another world leered crookedly at us. And it began to grow! Momentum carried it. I know that now. The looped coils were swept aside. The apparatus beneath it buckled and split. Beyond it, Nebel's highborn gunmen gaped aghast. They vanished behind its sleek circumference, but Wilhelm Nebel was not of their stupid breed. With a roar he flung his huge body high across the swelling arc of the sphere's circumference. A moment he slithered on its top, sprawled like a toad, his great face crimson--then it crashed him against the ceiling like a toad under a giant's heel. Fragments of concrete began to fall. I was up the stair, the remaining sheet of Dampier's equations in my hand. I was at the outer door as the walls buckled and fell in ruin. I was running across the littered lawn, staring over my shoulder at the giant silver globe that towered a hundred feet above me. Then it burst! The force of the explosion hurled me a hundred yards across the fields. I lay gasping in the wet grass, staring glassy-eyed at the column of violet flame that plumed into the sky. I got shakily to my feet and stared into the smoking pit where Dampier's fortress had been. At last I remembered the scrap of crumpled paper in my hand. The margins of Dampier's paper were full of Bill's penciled notes. At the end he had added five neat equations, and below them the remaining space was filled with his closely written lines.