“Everything points to that, certainly,” answered Sorrel, “and Rollsborough here will tell us all about it.” And as several others came up at the news and crowded round, Rollsborough proceeded,—“It seems more than possible that we shall come to an illumined world; the luminiferous ether permeates everything, and given an air free from solid matter that could obstruct, absorb, or divert the rays of light (and every mile of descent the air is becoming clearer), there is no reason why we should not have light below, for light is, in effect, the same as sound and follows many of the same laws, and if two luminous waves encounter each other at opposites, each extinguishes the other and total darkness results; but on the other hand, if two light-rays run parallel to each other, then the light is doubled. An effect of this is seen in the twinkling stars, from which two unequally vibrating rays will coincide at certain points, when their light will be doubled, but at all their vibrations that do not coincide there is no light of any kind, but instead, total darkness. This—darkness and light following in rapid succession as the unequal rays coincide and miss one another—gives us the twinkling of the stars; the altering humidity and density of the air on Earth through which the light-rays must pass also contribute largely to the effect of scintillation. “It is, therefore, judging from the present progress, probable that as we descend we shall come to a world which is self-lighting, and on which the luminiferous ether has so many of its rays in coincidence that every ray is augmented by its next ray, and not a single light-ray is lost, thus making this unknown world, if not brilliant, at least light; probably very light, as is the case with many of the stars.” Needless to say, this conversation did not conduce to calmness in their already exciting position, and Godfrey remarked,—“Folk say that scientists conduct their work without sentiment, and are all matter-of-fact, but, upon my word, we all of us need a good thrashing to compel us to go on with our own business! I never knew it so difficult to work steadily on and wait patiently for what is coming!” All the same, every one knew he was working well and seriously with every nerve concentrated on what he had in hand. And if it had been suggested that they should rush down to solve their doubts, he would have been one of the first to say, “No, we must not be too enthusiastic; we must examine step by step, and get a true record of every stratum through which we pass.” He, however, did but express the general feeling, and none were sorry when the time came to sink lower.