Far off, there seemed a lake of fire; a cloud of black gas hung over it; rolled slowly upward, and away. The nearer jagged rocks here on the rim were painted with the lurid red. It hung like a mist everywhere--a monstrous red shadow of it slanted up into the void overhead. The heavy choking smell of sulphur was in the air; a black coil of smoke was drifting up from one side, slanting off on an air-current, a suction toward the further distance. A scene infernal. Slumbering forces. Restless. Stirring. Nature infernal, here in leash. A slumbering giant down here, breathing uneasily. And when, throwing off his bonds, the giant rose? Honeycomb passages, breaking upward with his lungs! His surging breath--we at the surface then would call this a volcano. Or if, still far underground, the porous rock strata broke sidewise; shivered, trembled and broke--an earthquake then, to dash a tidal wave against our coasts, to engulf our islands--or with a trembling, quaking earth-surface, to bring down our cities in ruins. This slumbering giant! CHAPTER XVI. UNMASKING THE TRAITOR. As Tad listened, standing on the caldron’s rim, he heard yet another sound, unnatural and fearsome. It seemed to come through a rift in the side wall here--a cañon rift slashed like a huge black gash. A sound very far away, but gigantic; a dim, monstrous surge--the roar of tumbling water! He turned. “Entt, what is that?” Nereid answered him. “The water coming through the flood-gates.” Ah, and when, backed up with its pressure, or breaking through the walls, it reached here? There was human activity here--sights and sound and movement. On the broad, nearer slope from this upper rim to the red level where the fire began, stone buildings were set in terraces. It was the main industrial village of the Middge. Great pipes led up, bringing the heat for power, to the factories, not active now. They stood with windows dark, their outlines edged with red. But there was one large building, a mile away, with rows of lights. Figures moved about it, and the open rocky plateau beside it was busy with human activity. This was the Middge scientific workshop. Nereid pointed it out. It was the laboratory and arsenal where the Middge were now assembling their equipment of war. There was a broad, mile-long ledge, near at hand on the downward slope. It was thronged with Middge; several hundred young men seated in orderly array, and nearly as many young girls, like Nereid, of flowing robes and tawny hair. The pick of the youth of the Middge were here, small, slender, white-skinned, come here to be told what to do. There were older men moving around among them. Tad was drawn away. Middge leaders came up to greet Fen--small men of middle age, alert, solemn. The party went down the slope, mingled with the crowd on the ledge. The _arras_ were left at the summit, half-blinded by the glare, chained to the rocks.