Before Mrs. Quayle could protest further, Miranda seized her by the throat, hauling at the massive necklace in an effort to find the clasp that held it in place. The task proved difficult and promised to develop features that savored more of surgery than anything else. The trouble was not so much from the defensive tactics employed by Mrs. Quayle--who contrived to elude Miranda's grasp with surprising agility--as it was with the necklace itself. Never was a simple piece of jewelry more rebellious. It slipped through the doctor's fingers and jumped about and tugged at its victim's neck in the most baffling and erratic manner. But Miranda, growing more eager and determined, triumphed at last. Holding the snakelike coil in both hands as in an iron vise, he tore the chain apart with a masterly jerk. And then an odd thing happened. Bounding to his feet, elated with his success, and holding the necklace towards his companions as if it were a hard-won trophy, Miranda suddenly spun around like a top, his arms shot straight out in front of him, and in this posture, before any one knew what he was about, he fairly raced towards the ominous apparatus at the end of the corridor and hurled himself on the oblong stone beneath it. XIV THE BLACK MAGNET For once Doctor Miranda had nothing to say. To the eager queries of those about him he returned a grimace and a scowl of rage. Then he asked savagely for Mrs. Quayle. "There is her neckalace," he said indignantly, letting go his hold on that extraordinary piece of jewelry and scrambling to his feet with as much dignity as was left to him. "Will you tell me what all this means?" demanded Leighton sternly. "How I know?" retorted Miranda, glaring venomously at him. "I pull the neckalace from the neck, and it fly from me. When I follow, it fly more fast--and it get stronger and it fly harder every time until it touch the rock. Then it stop and not come loose." Sure enough, on the greenish-black rock over which they were bending, the necklace was spread out to its full length. With a quick jerk, Leighton dislodged one of the ends from its resting place. Letting it go, it returned to its original position with the sharp snap of a steel spring. "A magnet! The most amazing magnet ever heard of!" exclaimed Leighton. "A magnet that pull gold!" scoffed Miranda. "That is the foolishness!"