Walking continuously through the gloom, one loses to some extent the idea of progression. Here he can get no look ahead, no backward view. He is the centre of a little circle of light, beyond which is immeasurable darkness, whence objects seem to come to him like apparitions, changing form as the first and last rays of light fall upon them, as though the shape in which they appear under the full light of the lamp were only some disguise of assumed innocence, which they cast off as they glide silently into the dark again, to take on some semblance too awful for mortal eyes. Farther and farther we went along these arched, crypt-like ways; passing frequently through lofty chambers where the roof could not be discovered, each with some fanciful and often inappropriate name assigned to it, until we came at length to what looked like a window in the side wall of the cave. Peering through this, and holding my lamp high over my head, I could see neither roof nor sides nor bottom,—only the wall in which was the window through which I looked. Upward it was lost in the darkness, and from my breast it descended, perpendicular as a plummet line, until it vanished in the gulf below, from which arose a sound of dripping water. This, my guide informed me, was "Gorin's Dome." Taking then from his haversack a Bengal light, he ignited it and threw it into the dark void. The sulphurous light shot up and up into a dome unlike anything built by human hands, unless it might be the interior of some tremendous tower, eighty feet in width, and nearly two hundred in height, which the beholder viewed from without, looking inwards through a window placed at two thirds of the entire height from the bottom.
The inaccessible floor of this place is nearly level, and the walls strictly perpendicular from base to summit; the whole cavern having been hollowed out by the constant dripping of water holding carbonic acid in solution, which cuts the rock as ordinary water channels the ice of a glacier or the mural face of an iceberg into a semblance of columns, and sometimes into the folds of an immense curtain.
The brief light fell upon the distant floor; flashed up once, bringing into strong relief every salient angle in the wonderful walls, and then died out; the awful prospect vanishing like a nightmare vision, and leaving nothing to the sense but the sound of the water dripping into the depths below. The light had burned only half a minute; but so strange was the scene, that this glimpse sufficed to photograph it indelibly in my memory.
Gorin's Dome is not the largest of this class of sub-cavities in the cave, being smaller than Mammoth Dome; but it is the first of its class that the tourist sees, and it is viewed from so singular a stand-point that it makes the most startling impression.
Five minutes' farther walk brought us to a wooden footbridge,—a narrow, shaky contrivance, with a treacherous footing and a slender hand-rail. Here the bottom of the cave seemed to have dropped out, and the roof to have gone in search of it; and but for the dim glimpse of the rock on the other side one might have suspected that this bridge would launch him into that ungeographical locality called, in the old Norse mythology, "Ginnunga Gap,"—a place where there was neither side, edge, nor bottom to anything.
The vault overhead is called "Minerva's Dome"; the gulf below is called the "Side-Saddle Pit," though I failed to discover any degree of appropriateness in the odd name.
Standing in the middle of the bridge, my guide flung one of his Bengal lights far upward, in the midst of the slow-falling drops that had already carved out this tremendous well and were still making it larger. The light turned them for an instant into a shower of diamonds; then down it fell, down, down! As in its descent it passed the bridge on which we stood, the shadows of our two figures rushed up the opposite wall, like a pair of demons scared out of their abode by the hissing flame; and Nick, the guide, as he leaned over, looking downward after it,—every one of the innumerable wrinkles in his black face made more distinct, with his white beard and mustache, and the whites of his eyes seeming to glow in the blue elfish light,—was a caricature, half grotesque, almost terrible, of Satan himself.
Minerva's Dome and Side-Saddle Pit, both being one place and formed by the same dripping water, correspond to Gorin's Dome and the pit beneath it; that part which has been hollowed out above the roof of the cave being called the dome, and the part below the floor of the cave the pit. The only difference between the two is that in the case of Gorin's Dome the dripping waters have bored their huge shaft on one side of the track of the cave, only just piercing the wall of it in one spot, to make the window through which it is viewed; while in the case of the Side-Saddle Pit the vertical shaft cuts directly across the track of the cave, or, to speak more correctly, across the tunnel which was once the bed of a subterranean river, but which is now a broad, smooth, dry path.
The topography of this underground realm may be divided into three departments, as follows:—
First,—as being greatest in extent,—the "avenues," or tunnels, which present conclusive evidence of having once been the channels of a subterranean stream, whose waters, having some peculiar solvent property, wore their bed lower and lower in the rock, until they cut through into some lower opening, through which they were drawn off, leaving the old channels dry. Imagine one of the narrow, crooked streets in the old part of Boston, spanned by a continuous stone archway from the summits of the buildings on either hand; then close with solid masonry every window and loop-hole by which a ray of light could struggle in, and you have for proportions and sinuosity not a bad semblance of these tunnels, which constitute four fifths of the extent of the Mammoth Cave.