During this period of conversation we skirted the richly colored bluff with a rapid motion, and at last shot beyond it, as with a flash, into seeming vacancy. I was sitting with my gaze directed toward the bluff, and when it instantly disappeared, I rubbed my eyes to convince myself of their truthfulness, and as I did so our boat came gradually to a stand on the edge of what appeared to be an unfathomable abyss. Beneath me on the side where had risen the bluff that disappeared so abruptly, as far as the eye could reach, was an absolute void. To our right, and before and behind us, stretched the surface of that great smooth lake on whose bosom we rested. To our left, our boat brushing its rim, a narrow ledge, a continuation of the black, glass-like material, reached only a foot above the water, and beyond this narrow brink the mass descended perpendicularly to seemingly infinite depths. Involuntarily I grasped the sides of the boat, and recoiled from the frightful chasm, over which I had been so suddenly suspended, and which exceeded anything of a similar description that I had ever seen. The immeasurable depth of the abyss, in connection with the apparently frail barrier that held the great lake in its bounds, caused me to shudder and shrink back, and my brain reeled in dizzy fright. An inexplicable attraction, however, notwithstanding my dread, held me spell-bound, and although I struggled to shut out that view, the endeavor failed. I seemed to be drawn by an irresistible power, and yet I shuddered at the awful majesty of that yawning gulf which threatened to end the world on which I then existed. Fascinated, entranced, I could not help gazing, I knew not how long, down, down into that fathomless, silent profundity. Composing myself, I turned a questioning glance on my guide. He informed me that this hard, glass-like dam confined the waters of the slowly rising lake that we were sailing over, and which finally would rise high enough to overflow the barrier. [Illustration: "THE WALL DESCENDED PERPENDICULARLY TO SEEMINGLY INFINITE DEPTHS."] "The cycle of the periodic overflow is measured by great intervals," he said; "centuries are required to raise the level of the lake a fraction of an inch, and thousands of years may elapse before its surface will again reach the top of the adamantine wall. Then, governed by the law that attracts a liquid to itself, and heaps the teaspoon with liquid, the water of the quiet lake piles upon this narrow wall, forming a ledge along its summit. Finally the superimposed surface water gives way, and a skim of water pours over into the abyss." He paused; I leaned over and meditated, for I had now accustomed myself to the situation. "There is no bottom," I exclaimed.