This went on for a while, since the dreadful thing did not travel fast notwithstanding the frightful speed of its revolutions. I should doubt indeed if it advanced more quickly than a man could walk; at any rate so it seemed to us. But we had no means of judging its real rate of progress whereof we knew as little as we did of the course it followed in the bowels of the earth. Perhaps that was spiral, from the world’s deep heart upwards, and this was the highest point it reached. Or perhaps it remained stationary, but still spinning, for scores or hundreds of years in some central powerhouse of its own, whence, in obedience to unknown laws, from time to time it made these terrific journeys. No one knows, unless perhaps Oro did, in which case he kept the information to himself, and no one will ever know. At any rate there it was, travelling towards us on its giant butt, the peg of the top as it were, which, hidden in a cloud of friction-born sparks that enveloped it like the cup of a curving flower of fire, whirled round and round at an infinite speed. It was on this flaming flower that the search-light played steadily, doubtless that Oro might mark and measure its monstrous progress. “He is going to try to send the thing down the right-hand path,” I shouted into Bickley’s ear. “Can’t be done! Nothing can shift a travelling weight of tens of millions of tons one inch,” Bickley roared back, trying to look confident. Clearly, however, Yva thought that it could be done, for of a sudden she cast down her shield and, throwing herself upon her knees, stretched out her hands in supplication to her father. I understood, as did we all, that she was imploring him to abandon his hellish purpose. He glared at her and shook his head. Then, as she still went on praying, he struck her across the face with his hand and pushed her to her feet again. My blood boiled as I saw it and I think I should have sprung at him, had not Bickley caught hold of me, shouting, “Don’t, or he will kill her and us too.” Yva lifted her shield and returned to her station, and in the blue discharges which now flashed almost continuously, and the phosphorescent glare of the advancing mountain, I saw that though her beautiful face worked beneath the pain of the blow, her eyes remained serene and purposeful. Even then I wondered—what was the purpose shining through them. Also I wondered if I was about to be called upon to make that sacrifice of which she had spoken, and if so, how. Of one thing I was determined—that if the call came it should not find me deaf. Yet all the while I was horribly afraid.