"Why, the stump turns up in the pool a thousand feet below, and so must the river! You see, after entering the fissure, it twists back underground, to emerge down there at the bottom of the cliff."
"Of course," said Compton, eagerly; "and that body must have followed the same course."
"Exactly."
"That accounts for the appearance of the pool and of the dead man, but it does not explain the trickery."
"Perhaps it does," said Venning, who, now that he saw a cause for things, recovered his nerve and his spirit. "There is a subterranean passage. The formation here is volcanic. The valley is an extinct crater, the hills are the walls. Well, in volcanic formations, there are usually enormous caverns. Now, then, how do we know that the Okapi has not been taken into one of those caverns opening on to the pool?"
"Good; go on to the trickery."
"The person who hid the boat, if it is hidden, would probably be on the watch to scare off any who tried to find out what had become of it. Well, then, if we admit that, it is easy to admit the rest— that a good swimmer could play the trick played on us."
"Let me find him," said Compton, angrily.
"Yes—yes," muttered Mr. Hume; "there's a lot in that, and we'll follow it up, but not without a good plan."
He filled his pipe, and stared into the fire for some time.