"Yes," replied my uncle, in a tone of pardonable pride; "the Central Sea. No future navigator will deny the fact of my having discovered it; and hence of acquiring a right of giving it a name."

It was quite true. A vast, limitless expanse of water, the end of a lake if not of an ocean, spread before us, until it was lost in the distance. The shore, which was very much indented, consisted of a beautiful soft golden sand, mixed with small shells, the long-deserted home of some of the creatures of a past age. The waves broke incessantly—and with a peculiarly sonorous murmur, to be found in underground localities. A slight frothy flake arose as the wind blew along the pellucid waters; and many a dash of spray was blown into my face. The mighty superstructure of rock which rose above to an inconceivable height left only a narrow opening—but where we stood, there was a large margin of strand. On all sides were capes and promontories and enormous cliffs, partially worn by the eternal breaking of the waves, through countless ages! And as I gazed from side to side, the mighty rocks faded away like a fleecy film of cloud.

It was in reality an ocean, with all the usual characteristics of an inland sea, only horribly wild—so rigid, cold and savage.

One thing startled and puzzled me greatly. How was it that I was able to look upon that vast sheet of water instead of being plunged in utter darkness? The vast landscape before me was lit up like day. But there was wanting the dazzling brilliancy, the splendid irradiation of the sun; the pale cold illumination of the moon; the brightness of the stars. The illuminating power in this subterranean region, from its trembling and Rickering character, its clear dry whiteness, the very slight elevation of its temperature, its great superiority to that of the moon, was evidently electric; something in the nature of the aurora borealis, only that its phenomena were constant, and able to light up the whole of the ocean cavern.

The tremendous vault above our heads, the sky, so to speak, appeared to be composed of a conglomeration of nebulous vapors, in constant motion. I should originally have supposed that, under such an atmospheric pressure as must exist in that place, the evaporation of water could not really take place, and yet from the action of some physical law, which escaped my memory, there were heavy and dense clouds rolling along that mighty vault, partially concealing the roof. Electric currents produced astonishing play of light and shade in the distance, especially around the heavier clouds. Deep shadows were cast beneath, and then suddenly, between two clouds, there would come a ray of unusual beauty, and remarkable intensity. And yet it was not like the sun, for it gave no heat.

The effect was sad and excruciatingly melancholy. Instead of a noble firmament of blue, studded with stars, there was above me a heavy roof of granite, which seemed to crush me.

Gazing around, I began to think of the theory of the English captain who compared the earth to a vast hollow sphere in the interior of which the air is retained in a luminous state by means of atmospheric pressure, while two stars, Pluto and Proserpine, circled there in their mysterious orbits. After all, suppose the old fellow was right! In truth, we were imprisoned—bound as it were, in a vast excavation. Its width it was impossible to make out; the shore, on either hand, widening rapidly until lost to sight; while its length was equally uncertain. A haze on the distant horizon bounded our view. As to its height, we could see that it must be many miles to the roof. Looking upward, it was impossible to discover where the stupendous roof began. The lowest of the clouds must have been floating at an elevation of two thousand yards, a height greater than that of terrestrial vapors, which circumstance was doubtless owing to the extreme density of the air.

I use the word "cavern" in order to give an idea of the place. I cannot describe its awful grandeur; human language fails to convey an idea of its savage sublimity. Whether this singular vacuum had or had not been caused by the sudden cooling of the earth when in a state of fusion, I could not say. I had read of most wonderful and gigantic caverns—but, none in any way like this.