Swift as were the great cubes ahead, though, our great cruisers of the Interstellar Patrol, speediest of all the galaxy's ships, were proving now to be swifter, since slowly, steadily, we had begun to overhaul those fleeing shapes. I heard Gor Han's deep voice, excited as always in battle, from the speech-instruments, heard Jurt Tul's calm comments as we drove nearer the flying cubes, heard Najus Nar's eager cries. The cubes were passing out now from over the great coma, on over the vast tail, to my puzzlement. I had thought they were striving to gain the interior of the comet, but instead they were racing away from it, while with every moment we were drawing nearer to them. Then, just when it seemed that another moment's flight would bring us upon them, they halted abruptly in space, hovering above the faint, vast-streaming tail, and then plunged straight down into the mighty currents of the tail, and were moving back, _inside_ that tail, toward the great coma behind us! "The tail!" cried Najus Nar. "They're going up the tail itself and into the coma's heart!" But I too had seen and had understood all in that moment, had understood what I had not dreamed before, that the only opening through the great coma to the hollow at its heart lay at the coma's rear, and could be reached only by struggling up to it through the awful currents of the tail! These mighty cubes, I saw, had been constructed in that shape especially to resist and endure those terrible, back-sweeping ether-currents set up by the comet's rush through the void, terrific currents glowing with the electrical energy shot backward and dissipated in driving the comet on. The cubes thus specially constructed could brave those colossal currents where weaker craft would be battered to fragments. All this I understood and weighed, in that tense moment, and then had made decision and was shouting back into the instrument before me. "Down with our ships, too, then!" I cried. "_We're going up the tail after them!_"