"No; but I had an idea we should find this after we made our second trip."
"What did you see?"
"Nothing but what Harry brought to me."
"What was that?" both exclaimed, eagerly.
"The slab of carbonate which Harry brought me for the marking tablet, and on which we made the chart of the cave."
"What did you find on it?"
"If you will recall, I brought it with me. It is now in the boat." Harry dashed down to the boat and brought it back, turning it over and over on the way.
The slab referred to was about two inches thick, a foot long, and probably ten inches wide, a little irregular in formation.
"When we returned home that evening, after the trip referred to, I took the slab and transferred the chart we had made to a board. In doing so, I noticed that the lime had been chipped away from one side, but that did not cause me to make any investigation at the time.
"Some days afterwards I again took it up, and could see plainly through the carbonate what appeared to be the shadows of some characters, and it at once occurred to me that, owing to the sunlight and the comparatively dry atmosphere in which it had been kept after its removal, that the lime would turn or change its color, but the lime on this background did not change in the same degree where the characters had been placed, and when we get into the sunlight you will be able to see just what I saw."