"Thank Heaven!" I breathed; and I answered:
"Here, Harry boy, here."
"But where?"
"I don't know. On a ledge of rock at the edge of the water. Where are you?"
"Same place. Which side are you on?"
"The right side," I answered with heartfelt emphasis. "That is to say, the outside. If it weren't for this infernal darkness—Listen! How far away does my voice sound?"
But the innumerable echoes of the cavern walls made it impossible to judge of distance by sound. We tried it over and over; sometimes it seemed that we were only a few feet apart, sometimes a mile or more.
Then Harry spoke in a whisper, and his voice appeared to be directly in my ear. Never have I seen a night so completely black as that cavern; we had had several hours, presumably, for our eyes to adjust themselves to the phenomenon; but when I held my hand but six inches in front of my face I could not get even the faintest suggestion of its outline.
"This is useless," I declared finally. "We must experiment. Harry!"
"Yes."