Another Noth vessel had been sunk. There were only three barges left afloat, and they were in distress. Many of their swimming dogs lay dead in harness. Aboard all three of them, figures were fighting the flames. They clustered in a group near the center of the channel. Loto had withdrawn his forces, reduced now to half their original number. With ammunition almost exhausted, they hovered out of range above their adversaries. The wounded were still straggling back through the air; a few of them had already arrived at the cavern. Again Fahn ordered his army down. It would be the last attempt. In the cavern room, Fahn had not moved from his seat for hours. Often he could not see the battle plainly, for Loto, disobeying orders, had many times cast himself into the thick of it. But now Loto was aloft; by the moonlight and the glare of the rockets and bombs, Fahn saw that another Noth vessel had appeared--a very small barge. It was close to shore, coming swiftly forward and little objects of gleaming silver were mounting from it. One after the other they came sailing up. Fahn rasped an order; Loto's voice roared it out. The men and girls who were descending to the attack halted, circling about, wondering what had happened. The first of the white objects came sailing slowly horizontally across the channel. It seemed to be a whirling white disc some foot or two in diameter. Loto was still some distance away from it when a group of girls passed between him and the disc. The thing seemed to turn toward them. One of the girls became confused; it struck her and she fell. The disc, its rotation halted, fell also. Loto saw then what it was: broad, thin, crossed blades of steel, inclined to each other like the blades of a propeller. It had risen up and sustained itself in the air by rotation. Loto remembered the defeat of the flying thunderbolt platforms which Fahn had sent northward to Toroh's encampment. These whirling knives were what had destroyed them! The newly arrived barge was now sending up, in every direction, a slow but steady stream of the whirling knives. They seemed so easy to avoid that the aerial army at first paid them little heed. Loto's warning from Fahn rang out, but it came almost too late. The knives sought out the figures in the air. They began falling--cut, mangled by the whirling blades. There was confusion. The army mounted higher, but other knives had been sent straight upward and were floating down. Uncannily, they seemed to single out their victims. Fahn understood now. This was the weapon Toroh had procured from that time-world of the past. These whirling knives were strangely, powerfully magnetized; they followed the human bodies passing near them, seeking contact. The Scientist leader had ordered his fighters to the sea level; the knives, as they came lower, seemed to have spent themselves. They could be avoided. But nearly forty of the Anglese had met death before the lesson was learned.