"You killed merely an assistant who had disobeyed my orders. Had I not decreed his death, he would be alive to-day. I could kill you as you stand there; resolve you into nothingness; but I do not choose to do so--yet. Other attempts I have made you have frustrated, but this time I shall succeed. I will institute a reign of terror which will bring your rich, foolish country to its knees. Listen, while I give you a taste of my power. The city of Charleston is about to be destroyed." A thunderous roaring filled the air. Crash followed crash in rapid succession. It sounded as though all the noise of the universe had been concentrated in the cavern. The earth shook and rocked like a restless sea. From above came cries of terror. The three men in the cavern were thrown to the ground. Shaken by the fall and deafened by the tumult, they hung onto irregularities of the rock on which they lay. Gradually the tumult and the shaking subsided. The cries from above became more apparent. Silence finally reigned in the cavern and the metallic Voice spoke again. "Go back now and look at Charleston and you will see what to expect. The rest of your cities will soon share the same fate. Beware of trying to trace my movements, for your lives are in the hollow of my hand." * * * * * The voice died away in silence. From the edge of the hole came a cry. A Fort Moultrie officer was peering down at them. "Are you all right down there?" he hailed. "Right as hops," called Dr. Bird cheerfully. "What happened up above?" "I don't know, Doctor. There seems to be a lot of smoke and fire over in the direction of the city. I expect the quake shook them up a little this time. What shall we do now?" "We're ready to come up. First I'm going to send up a wheelbarrow full of yellow powder. Rig a crane to lift it, for it's too heavy to try to hoist with ropes." With the aid of Carnes and Dr. Lassen, Dr. Bird collected a few cubic inches of the yellow powder from the ridges in the rock. He made the wheelbarrow containing it fast to the wire cables of the crane and gave the signal. Slowly it was raised to the surface. When it had safely reached there he turned to his companions. "Grab a rope and let's go," he said. In a few moments they were on the upper level. With the efforts of half a dozen men, the body of the wheelbarrow was lifted into the car. With a few final words of instruction to the colonel, Dr. Bird and his companions entered the car and were whisked away to the city. A spectacle of destruction and ruin awaited them. Fully one-fourth of the city had sunk thirty feet into the ground. The sinking was not even nor uniform. The sunken ground was rolled into huge waves while buildings which had collapsed lay in confused heaps on all sides. From a dozen places in the area, columns of fire rose in the air. * * * * *