would be one of the most elementary developments of man."
"It is clearly some sort of script," said Challenger.
"Looks like a guinea puzzle competition," remarked Lord John, craning his neck to have a look at it. Then suddenly he stretched out his hand and seized the puzzle.
"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 hill-side 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.
