"There is the old mystery again," exclaimed Edmund, "and I can no more explain it now than I could when we first saw it on nearing the planet. The arc of light above is natural enough; it's simply the dawn. The sun never rises on this side of Venus, but it will rise for us because we are approaching it, and the light is the first indication that we are getting near enough to the border between day and night for some of the sun's rays to be bent over the horizon by refraction. But those flames! See how steady they are as a whole, and yet how they change color like a slowly turning prism." "Don't, for God's sake, run us into a conflagration," said Jack. "I'm ready to believe anything of this topsy-turvy old planet, and I shouldn't be surprised if the other side is all fire as this one is all frost. I can stand these hairy beasts, but I'll be hanged if I want to be introduced among salamanders." "That's not real fire," said Edmund. "When we get a little nearer we can see what it is. In the meantime I'll try to think it out." The result of Edmund's meditations, when he announced it to us, an hour later, awoke as much amazement in our minds as anything that had yet occurred. He had been sitting silent in his corner, occasionally taking a glimpse through the peephole, or one of the windows, when suddenly he slapped his thigh, and springing to his feet, exclaimed: "They're mountains of crystal!" "Mountains of crystal!" we echoed. "Nothing else in the world, and I am ashamed not to have foreseen the thing. It's plain enough when you come to think about it. Remember that Venus being a world lying half in the daylight and half in the night, is necessarily as hot on one side as it is cold on the other. All of the clouds and floating vapors are on the day side, where the sunbeams act. The heated air charged with moisture rises over the sunward hemisphere, and flows off above, on all sides, toward the night side, while from the latter cold air flows in beneath to take its place. Along the junction of the two hemispheres the clouds and moisture are condensed by the intense cold, and fall in ceaseless snowstorms. This snow descending for ages has piled up in mountainous masses whose height may be increased in some places by real mountain ranges buried beneath. The atmospheric moisture cannot pass very far into the night hemisphere without being condensed, and so it is all arrested within a ring, or band, extending completely around the planet, and marking the division between perpetual day and perpetual night. The appearance of gigantic flames is produced by the sunbeams striking these mountains of ice and snow from behind and breaking into prismatic fire." We listened to this explanation, so simple and yet so wonderful, with mingled feelings of astonishment and admiration. And then we turned again to regard the phenomenon, which now, with our nearer approach, had become splendid and awful beyond description.