But in a little while a danger developed which we had not thought of. It arose from the existence of other caverns whose mouths opened upon the plain. To have precipitated the sleds into these would have been fatal. Luckily, shafts of light issued from all of them, and warned by these, we managed to avoid the danger. But it was not entirely passed before we had traveled at least a hundred miles. It was like an immense city of prairie dogs without mounds. The cavern that we had discovered on our arrival was evidently situated on the outskirts of the group, and now we were passing through the center of it. Occasionally we saw a huge white form disappear in one of the holes as we swiftly approached, but that was all we beheld of the inhabitants. But the spectacle of the shafts of light rising all around us was amazing. When we were in the midst of it Edmund hesitated for a moment, muttering that we had been too hasty and should have remained longer to study the peculiarities of this wonderful world of night; but finally he decided to keep on, and soon afterwards we saw the last of the caverns. Then, as there appeared to be no obstructions of any kind, the speed was worked up to a hundred miles an hour. Going straight ahead as we did, there was no danger of the sleds being overturned. Having, as Edmund had calculated, about five thousand miles to go before reaching the edge of the sun-illuminated hemisphere, it was evident that, at our present rate of progress, we should arrive there in a little over two days by the calendar clock. We guided our course by the stars, and for me one of the most interesting things was to see the earth sinking toward the horizon, accompanied by the stars, as if the heavens were revolving in a direction opposed to our line of travel. We smoked and talked and ate and slept in the old way, while the marvelous mouths in the wall resumed their strange deglutition. Thus the time passed, without ennui, until, unexpectedly, a new phenomenon captured our attention. Ahead, through the peephole, Edmund had descried again the flaming spires which had so astonished us on our approach to Venus. But now their appearance was splendid and imposing beyond words. Above them rose an arc of pearly light which grew higher every hour. And with the arc of light rose the flames also. At the same time they seemed to spread to the right and the left, until they were simultaneously visible from both of the side windows of the car. Their colors were wonderful--red, green, purple, orange--all the hues of the prism.