“By George!” he cried, “I believe I’ve got it. The boy guessed right the very first time. See here! How many marks are on that paper? Eighteen. Well, if you come to think of it there are eighteen cave openings on the hillside above us.”
“He pointed up to the caves when he gave it to me,” said I.
“Well, that settles it. This is a chart of the caves. What! Eighteen of them all in a row, some short, some deep, some branching, same as we saw them. It’s a map, and here’s a cross on it. What’s the cross for? It is placed to mark one that is much deeper than the others.”
“One that goes through,” I cried.
“I believe our young friend has read the riddle,” said Challenger. “If the cave does not go through I do not understand why this person, who has every reason to mean us well, should have drawn our attention to it. But if it does go through and comes out at the corresponding point on the other side, we should not have more than a hundred feet to descend.”
“A hundred feet!” grumbled Summerlee.
“Well, our rope is still more than a hundred feet long,” I cried. “Surely we could get down.”
“How about the Indians in the cave?” Summerlee objected.
“There are no Indians in any of the caves above our heads,” said I. “They are all used as barns and storehouses. Why should we not go up now at once and spy out the land?”
There is a dry bituminous wood upon the plateau—a species of araucaria , according to our botanist—which is always used by the Indians for torches. Each of us picked up a faggot of this, and we made our way up weed-covered steps to the particular cave which was marked