Slowly the conjectures already pieced together in his mind during early days on the island came back to him.
The skeleton of an Englishman lying there among the bushes near the well; the Golgotha of the poison-filled hollow; the mining tools, both Chinese and European; the plan on the piece of tin--ah, the piece of tin! Mechanically the sailor produced it from the breast-pocket of his jersey.

At last the mysterious sign "32/1" revealed its significance.

Measure thirty-two feet from the mouth of the tunnel, dig one foot in depth, and you came upon the mother-lode of this gold-bearing rock.

This, then, was the secret of the cave.
The Chinese knew the richness of the deposit, and exploited its treasures by quarrying from the other side of the hill.

But their crass ignorance of modern science led to their undoing.