Time was pressing us now and McIvers wouldn’t let me forget it. We had made only about three hundred twenty miles in six driving periods, so we were about a hundred miles or even more behind schedule. “We’re not going to make it,” McIvers would complain angrily. “That Sun’s going to be out to aphelion by the time we hit the Center—” “Sorry, but I can’t take it any faster,” I told him. I was getting good and mad. I knew what he wanted, but didn’t dare let him have it. I was scared enough pushing the Bug out on those ledges, even knowing that at least _I_ was making the decisions. Put him in the lead and we wouldn’t last for eight hours. Our nerves wouldn’t take it, at any rate, even if the machines would. Jack Stone looked up from the aluminum chart sheets. “Another hundred miles and we should hit a good stretch,” he said. “Maybe we can make up distance there for a couple of days.” The Major agreed, but McIvers couldn’t hold his impatience. He kept staring up at the Sun as if he had a personal grudge against it and stamped back and forth under the sunshield. “That’ll be just fine,” he said. “_If_ we ever get that far, that is.” We dropped it there, but the Major stopped me as we climbed aboard for the next run. “That guy’s going to blow wide open if we don’t move faster, Peter. I don’t want him in the lead, no matter what happens. He’s right though, about the need to make better time. Keep your head, but crowd your luck a little, okay?” “I’ll try,” I said. It was asking the impossible and Mikuta knew it. We were on a long downward slope that shifted and buckled all around us, as though there were a molten underlay beneath the crust; the slope was broken by huge crevasses, partly covered with dust and zinc sheeting, like a vast glacier of stone and metal. The outside temperature registered 547° F. and getting hotter. It was no place to start rushing ahead. I tried it anyway. I took half a dozen shaky passages, edging slowly out on flat zinc ledges, then toppling over and across. It seemed easy for a while and we made progress. We hit an even stretch and raced ahead. And then I quickly jumped on my brakes and jerked the Bug to a halt in a cloud of dust. I’d gone too far. We were out on a wide, flat sheet of gray stuff, apparently solid—until I’d suddenly caught sight of the crevasse beneath in the corner of my eye. It was an overhanging shell that trembled under me as I stopped. McIvers’ voice was in my ear. “What’s the trouble now, Claney?” “Move back!” I shouted. “It can’t hold us!” “Looks solid enough from here.” “You want to argue about it? It’s too thin, it’ll snap. Move back!” I started edging back down the ledge. I heard McIvers swear; then I saw his Bug start to creep _outward_ on the shelf. Not fast or reckless, this time, but slowly, churning up dust in a gentle cloud behind him. I just stared and felt the blood rush to my head. It seemed so hot I could hardly breathe as he edged out beyond me, further and further—