"Can philosophers more than speculate about that which they have not experienced if they have no data from which to calculate? Name the student in science who has reached this depth in earth, or has seen a man to tell him of these facts?" "I can not." "Then why should you have expected any of them to describe our surroundings? Misguided men will torture science by refuting facts with theories; but a fact is no less a fact when science opposes." [Illustration: "SEATED HIMSELF ON A NATURAL BENCH OF STONE."] I recognized the force of his arguments, and cordially grasped his hand in indication of submission. We continued our journey, and rapidly traveled downward and onward. The light gradually increased in intensity, until at length the cavern near about us seemed to be as bright as diffused daylight could have made it. There was apparently no central point of radiation; the light was such as to pervade and exist in the surrounding space, somewhat as the vapor of phosphorus spreads a self-luminous haze throughout the bubble into which it is blown. The visual agent surrounding us had a permanent, self-existing luminosity, and was a pervading, bright, unreachable essence that, without an obvious origin, diffused itself equally in all directions. It reminded me of the form of light that in previous years I had seen described as epipolic dispersion, and as I refer to the matter I am of the opinion that man will yet find that the same cause produces both phenomena. I was informed now by the sense of sight, that we were in a cavern room of considerable size. The apartment presented somewhat the appearance of the usual underground caverns that I had seen pictured in books, and yet was different. Stalactites, stalagmites, saline incrustations, occurring occasionally reminded me of travelers' stories, but these objects were not so abundant as might be supposed. Such accretions or deposits of saline substances as I noticed were also disappointing, in that, instead of having a dazzling brilliancy, like frosted snow crystals, they were of a uniform gray or brown hue. Indeed, my former imaginative mental creations regarding underground caverns were dispelled in this somber stone temple, for even the floor and the fragments of stone that, in considerable quantities, strewed the floor, were of the usual rock formations of upper earth. The glittering crystals of snowy white or rainbow tints (fairy caverns) pictured by travelers, and described as inexpressibly grand and beautiful in other cavern labyrinths, were wanting here, and I saw only occasional small clusters of quartz crystals that were other than of a dull gray color. Finally, after hours or perhaps days of travel, interspersed with restings, conversations, and arguments, amid which I could form no idea of the flight of time, my companion seated himself on a natural bench of stone, and directed me to rest likewise. He broke the silence, and spoke as follows: CHAPTER XVI.