"Solved what?" demanded Walter in amazement.
"This," cried his chum excitedly, extending the square of doe-skin with its red ink tracings. "It's really absurdly simple," he continued. "According to the captain, the chief talked about leaving me riches of some sort. I took that circumstance for my key and tried to think what a race as poor as the chief and his people would consider as riches. The picture of that bird answered the question. Plumes are their only form of wealth, hence plumes must be the treasure of which he spoke."
"Reasoned like a detective," approved Walter, scarcely less excited than his chum.
"The rest was simple. The picture of the tree was to show where it was hidden and the object at its base is intended as a shovel to tell that I would have to dig for the treasure, but," and his face fell, "how are we to find that identical tree?"
"There's only one palm on the island," Walter assured him.
"Then all we have to do is to go there and dig and we'll find the treasure," Charley declared. "But we must wait for the captain, we must all be present when it is unearthed."
The morning slipped away quickly, the boys amusing themselves by exploring their little island, fishing from the bank, and loafing in the shade of the solitary palm, at whose base was supposed to lie the buried treasure.
Dinner time came and the meal was eaten without the captain, who had not returned. As the afternoon wore away without any sign of the old sailor, the boys began to feel a vague uneasiness which increased as the sun set and night began to fall. Walter, who alone knew the real object of the captain's trip, was greatly worried. Long after the others had retired to the wigwam for the night, he sat alone straining eye and ear for sight or sound that would herald the absent one's return. As the night wore away, anxiety deepened into certainty with the troubled lad. Something must have happened to the captain. Impatiently the lad waited for daylight, determined to set off at the first break of dawn in search of the missing one. Suddenly, the lad started up from the reclining position weariness had caused him to assume. Full and deep upon the still night air rang out the tolling of the mysterious bell. To the anxious watcher, its tones no longer rang full and sweet as upon the previous evening, but sounded slow and threatening, as if freighted with an ominous meaning.
A step sounded behind him and the overwrought lad sprang to his feet, every nerve a-tingle.
"Where are you, Walt?" called Charley's voice from out of the darkness.