"Kinney's Arena" is a hundred feet in diameter, and is fifty feet high.
"Proctor's Arcade" is one hundred feet in width and three quarters of a mile in length. The walls, which are about forty-five feet high, are nearly perpendicular throughout the whole length of the arcade, joining the roof nearly at right angles, and are so smooth that they look like hammer-dressed stone.
"Silliman's Avenue" is a mile and a half in length and about forty feet in height, its width varying from twenty to two hundred feet.
"Shelby's Dome" and the pit beneath it are two hundred and thirty-five feet in height, and about twenty-five in diameter.
"Mammoth Dome" is two hundred and fifty feet high, and nearly one hundred in diameter.
"Lucy's Dome," the highest in the cave, is sixty feet in diameter, and three hundred in height.
Nine miles from the entrance of the cave is the "Maelström," a dry pit or well, one hundred and seventy-five feet deep, and about twenty in diameter; and from the bottom of this shaft may be seen the openings to three other avenues, which lead farther into this Plutonian labyrinth than mortal foot has ever trod.
Although the distance of nine miles is about as far as tourists usually get from the entrance, that is by no means the measure of its extent, but only the extent of the direct route; there being a number of other tunnels branching off from it on either side, some of which connect with it again at a distance of several miles, and some of which have not been explored to their connection, if they have any.
The total length of all the explored avenues is estimated at over one hundred miles. If a single day's experience in the cave were sufficient ground for offering an opinion, I should say that this was a large over-estimate; but I have no doubt that, like all other great works of both art and nature, it grows upon the sense of the beholder. But even setting down its extent at half the foregoing estimate, none can tread these hollow chambers, thinking of others unexplored, and extending not only from that distant nine-mile-station, but on every hand, into the unknown, without a feeling of awe and fear.
Thus on and on through the echoing avenues, where the reverberation of our footsteps seemed to follow stealthily far behind us, through chamber and hall, where my guide in the advance flung up his lights, revealing for an instant the grim and distant vaults,—through "Star Chamber," five hundred feet long, seventy in width, and sixty in height, "Cloud Room," a quarter of a mile in length, sixty feet in height, "Deserted Chamber," "River Hall," "Revellers' Hall," "The Great Walk,"—through all these, and a dozen more, we wandered, until, after two hours' walk, and at a distance of four and a half miles from the entrance to the cave, I paused upon the muddy banks of the "Styx," and, stooping, dipped up in my hands a draught from its cold, sunless waters.