The castaway, who had had his hair cut, and who had shaved himself, being attired in a spare suit of the professor’s, looked at the red spot.
“That is undoubtedly a radium burn,” he said quickly. “How did it happen?”
“It must have been when I sat down to rest,” explained Bob. “On the hill out there. I felt something sting me, and——”
“It was the radium!” cried Mr. Bentwell. “Where is the place? Let us go to it at once!”
“We can’t find it in the dark,” objected Jerry, but the professor and the castaway hurried out on the deck of the airship leading Bob with them.
“Point out, as nearly as you can, where it was,” begged Uriah Snodgrass.
Bob raised his hand, and, as he did so, he uttered a cry.
“Look! Look!” he gasped. “The ghosts! The ghosts again!”
There, floating down toward the airship, were tall whitish objects, wrapped in a bluish haze, like the tall forms of willowy beings shrouded in mist.