s mind was a blank on that point. But one
thing he told me that is important. For twenty years he had lived among
the Gallas in a village fifty miles to the south of Harar, and it was a
few years after he had been brought there that he nearly succeeded in
making his escape.

"He had often heard from the natives of an underground river that was
said to exist, and which emptied either into the River Juba or into the
sea. The tales concerning the river were many and strange, but the chief
of the Gallas assured him that at one time a tribe of natives had lived
in the mouth of a huge cavern which gave access to the river."

"I have heard something of that myself," interrupted Melton. "An Arab at
Zanzibar told me, but I never had any faith in the story."

"That river exists," said Canaris solemnly. "The Englishman found it."

"What!" cried Guy and Melton in one breath. "He found the underground
river?"

"Yes, he discovered it," resumed Canaris. "He found it one day while
hunting in a concealed cavern. He ventured down and came to a great
sandy beach, past which flowed swiftly a broad stream. On the beach lay
half a dozen strong canoes with paddles. All this he saw by the light
that streamed in from narrow crevices overhead. He went back to the
village and began to lay aside provisions for the journey, for he
intended making his escape by the river. In a week all was ready. He had
concealed near the cavern supplies for a long voyage. The very day fixed
for his escape he was sold to a Galla chief who lived twenty miles
distant. In the years that followed he made many attempts to escape, but
on every occasion was captured and brought back. At last he was given as
tribute to the Emir by this Galla chief, and here in this dungeon, on
the spot you are sitting on now, he breathed his last."

Canaris paused and helped himself to a glass of water.

"A strange story, indeed," said Guy; "but what has it got to do with
us?"

"I will tell you," responded Canaris, with a slight tremor in his voice.
"It may have nothing to do with any of us, and it may be of the greatest
importance to us all."

"Did the old man tell you where to find the cavern?" asked Guy.

"No," answered Canaris, "but before he died he gave me this," and,
pulling a folded bit of linen from his pocket he handed it to Guy.

"Can you read that?" he asked in strange excitement. "I have never been
able to make anything out of it."

Guy pulled it carefully open an