From Harlem Tunnel we came into Cataract Hall, also of great length, and remarkable for containing a small opening extending to an unknown distance within the mountain, since it apparently cannot be explored.  Applying the ear to this opening, the sound of an immense cataract becomes audible, pouring over the rocks far within the recesses of the mountain, where the Creator alone, who meted out those unseen, sunless waters, can behold its beauty and its terror.

Crossing the Pool of Siloam, whose babbling waters sparkled into beauty as we held our lamps above them, we entered Franklin Hall.  Here the roof, although high enough in some places, is uncomfortably low in others; whereupon Bob bade us give heed to the caution of Franklin, ‘Stoop as you go, and you will miss many hard thumps.’

We arrived next at Flood Hall, where a party of explorers were once put in great peril by a sudden freshet in the stream.  They barely saved themselves by rapid flight, the water becoming waist-deep before they gained the entrance.  We had no reason to doubt the truth of this story, as there were evidences of the rise and fall of water all about us.

Congress Hall now awaited us, but I will omit a description of it, as Musical Hall, which immediately succeeded, contains so much more that is interesting.  On entering, our attention was first directed to an aperture wide enough for the admission of a man’s head.  Any sound made in this opening is taken up and repeated by echo after echo, till the very spirit of music seems awakened.  Wave after wave of melodious sound charms the ear, even if the first awakening note has been most discordant.  If the soul is filled with silent awe while listening to the unseen waterfall in Cataract Hall, it is here wooed into peace by a harmony more perfect than any produced by mortal invention.  A temple-cavern vaster than Ellora with a giant ‘lithophone’ for organ!

The second wonder of Musical Hall is a lake of great extent, and from ten to thirty feet in depth.  The smooth surface of these crystal waters, never ruffled by any air of heaven, and undisturbed save by the dip of our oars as we were ferried across, the utter darkness that hid the opposite shore from our straining sight, the huge rocks above, whose clustering stalactites, lighted by our glimmering lamps, sparkled like a starry sky, the sound of the far-off waterfall, softened by distance into a sad and solemn music, all united to recall with a vivid power, never before felt, the passage of the ‘pious AEneas’ over the Styx, which I had so often read with delight in my boyhood.  I half fancied our Yankee Bob fading into a vision of the classic Charon, and that the ghosts of unhappy spirits were peering at us from the darkness.

At the end of the lake is Annexation Rock, a huge limestone formation in the shape of an egg.  It stands on one end, is twenty-eight feet in diameter, and over forty in height.