"Don't venture out there till you are fully equipped for the job," said the professor. "Serious results might ensue. In the meantime, I am going to analyze this sample in order to be doubly sure."
Jack gave a deep sigh of relief. After all, it was not a dream. They had found the valuable earth. It was now only a question of transportation. His father's fortunes were saved. The radio-'phone would be rushed to perfection and placed on the market within a short time of their return home.
While Jack lay back and indulged in daydreams, the others watched the professor as he tested the black sand over a portable assaying furnace and made all sorts of experiments to determine its value and the proportion of the different precious metals contained in it.
There was a slight rustling in the bushes behind him. Jack, whose nerves had been rather on edge since the occurrences of the preceding night and that morning, faced round quickly.
The next instant he uttered a loud shout.
Peering out of the bushes was a hideous, hairy face, more like an ape's than a human being's. From it glowed two wild, piercing eyes, like those of a beast of prey.
As Jack shouted and the others started toward him, the face vanished like a flash.