By this time the moon had risen and its clipped light shone full upon the slab. I saw faint gleams pass over it as of fleeting phosphorescence--but so faint were they that I could not be sure of the truth of my observation. We set the ladders in place. Olaf I assigned to stand before the door and watch for the first signs of its opening--if open it should. The Becquerels were set within three-inch tripods, whose feet I had equipped with vacuum rings to enable them to hold fast to the rock. I scaled one ladder and fastened a condenser over the boss; descended; sent Larry up to watch it, and, ascending the second ladder, rapidly fixed the other in its place. Then, with O'Keefe watchful on his perch, I on mine, and Olaf's eyes fixed upon the moon door, we began our vigil. Suddenly there was an exclamation from Larry. "Seven little lights are beginning to glow on this stone!" he cried. But I had already seen those beneath my lens begin to gleam out with a silvery lustre. Swiftly the rays within the condenser began to thicken and increase, and as they did so the seven small circles waxed like stars growing out of the dusk, and with a queer--curdled is the best word I can find to define it--radiance entirely strange to me. Beneath me I heard a faint, sighing murmur and then the voice of Huldricksson: "It opens--the stone turns--" I began to climb down the ladder. Again came Olaf's voice: "The stone--it is open--" And then a shriek, a wail of blended anguish and pity, of rage and despair--and the sound of swift footsteps racing through the wall beneath me! I dropped to the ground. The moon door was wide open, and through it I caught a glimpse of a corridor filled with a faint, pearly vaporous light like earliest misty dawn. But of Olaf I could see--nothing! And even as I stood, gaping, from behind me came the sharp crack of a rifle; the glass of the condenser at Larry's side flew into fragments; he dropped swiftly to the ground, the automatic in his hand flashed once, twice, into the darkness. And the moon door began to pivot slowly, slowly back into its place! I rushed toward the turning stone with the wild idea of holding it open. As I thrust my hands against it there came at my back a snarl and an oath and Larry staggered under the impact of a body that had flung itself straight at his throat. He reeled at the lip of the shallow cup at the base of the slab, slipped upon its polished curve, fell and rolled with that which had attacked him, kicking and writhing, straight through the narrowing portal into the passage! Forgetting all else, I sprang to his aid. As I leaped I felt the closing edge of the moon door graze my side. Then, as Larry raised a fist, brought it down upon the temple of the man who had grappled with him and rose from the twitching body unsteadily to his feet, I heard shuddering past me a mournful whisper; spun about as though some giant's hand had whirled me--