Soon we went on. The shining mountain rose before us like a great cone of fire. It must have been three thousand feet high, and about that in diameter at the bottom. Its walls were as smooth and straight as though turned from milky rock crystal in a gigantic lathe. It shone with a steady, brilliantly white radiance. "That's no natural hill!" Ray grunted beside me as we limped on. We were less than a mile from the foot of the cone of fire. Soon we observed another remarkable thing about it. It seemed that a straight band of silvery metal rose from the snow about its foot. "Has it a wall around it?" I exclaimed. "Evidently," said Ray. "Looks as if it's built on a round metal platform. But by whom? When? Why?" * * * * * We approached the curious wall. It was of a white metal, apparently aluminum, or a silvery alloy of that metal. In places it was twenty-five feet high, but more usually the snow and ice was banked high against it. The smooth white wall of the gleaming mountain stood several hundred yards back from the wall. "Let's have a look over it." Ray suggested. "We can get up on that hummock, against it. You know, this place must have been built by men!" We clambered up over the ice, as he suggested, until our heads came above the top of the wall. "A lake of fire!" cried Ray. Indeed, a lake of liquid fire lay before us. The white aluminum wall was hardly a foot thick. It formed a great circular tank, nearly a mile across, with the cone of white fire rising in the center. And the tank was filled, to within a foot of the top, with shimmeringly brilliant white fluid, bright and luminous as the cone--liquid light! Ray dipped a hand into it. The hand came up with fingers of fire, radiant, gleaming, with shining drops falling from them. With a spasmodic effort, he flung off the luminous drops, rubbed his hand on his garments, and got it back into its fur mitten. "Gee, it's cold!" he muttered. "Freeze the horns off a brass billy-goat!" "Cold light!" I exclaimed. "What wouldn't a bottle of that stuff be worth to a chemist back in the States!" "That cone must be a factory to make the stuff." Ray suggested, hugging his hand. "They might pump the liquid up to the top, and then let it trickle down over the sides: that would explain why the cone is so bright. The stuff might absorb sunlight, like barium sulphide. And there could be chemical action with the air, under the actinic rays." "Well, if somebody's making cold light, where does he use it?" "I'd like to find out, and strike him for a hot meal," Ray said, grinning. "It's too cold to live on top of the ground around here. They must run it down in a cave." "Then let's find the hole." "You know it's possible we won't be welcome. This mountain of light may be connected with the vanishing of all the aviators. We'd better take along the rifle." * * * * *