"It's water."
"Water?"
"Yes. H2O."
"Water? I'm from Missouri. You'd better see that your revolver is handy. Who ever heard water make a shivery sound like that?"
"You'll see that I'm right, Bill, though I think that you'll hear first."
Ere long there could be no doubt about it: Milton was right; it was the sound of falling water. I was not in a hurry, however, to admit the fact. I had to let myself down gracefully. At length, though, it was impossible to hold out any longer.
"Must be at quite a distance," I said; "sounds carry a long way in tubes, and that is what this tunnel is."
Steadily we made our way along and down, and, just as steadily, the sound increased in volume. The gallery made several sharp turns, and then of a sudden the sound rose from a loud growl to a roar, and we fetched up and an exclamation burst from us.
It is impossible to convey to the reader the eerie effect of that sudden, strange transition. One moment we were in the gallery; the next we had issued from it and stood in a most tremendous cavern, or, rather, we stood on a ledge or a shelf high up on one of the walls of that cavern.
The opposite side was but dimly visible. The roof swept across a hundred feet or more above our heads. And the bottom? I gazed at the edge of the rock-shelf on which we stood, out and down into that yawning abyss, and I felt a shudder run through me and one through my heart. The roar of the falling waters came from our right. We turned the rays of our lights in that direction, but nothing was visible there, save the dark limestone rock and Cimmerian blackness.