As for the boys, they could talk of nothing else.  The idea of that lonely island, lying at the bottom of an unscalable canyon in the midst of a burning, desolate desert, appealed powerfully to their imaginations.  Their minds were in a whirl over the strange coincidence that had brought them in contact with a man who knew where possibly inexhaustible supplies of the mysterious Z.2.X. lay ready for the taking, provided it could be reached.

“I’d give a whole lot to be able to fix up an expedition to go out there and get that stuff,” said Jack with a sigh.

“So would I,” agreed Tom.  “But I guess, as Zeb Cummings said, it will be a long time before anyone sets foot on Rattlesnake Island.”

CHAPTER XVII.

In the laboratory.

That afternoon Jack broached to his father the events of the morning.  Mr. Chadwick’s enthusiasm may be imagined as his son told him of the professor’s hasty analysis of the contents of Zeb Cumming’s glass vial.

But there remained the insuperable obstacle of the remoteness of the island where the deposits lay, and the difficulties—­in fact, almost the impossibilities—­that barred the way.  For the time being, however, the matter was set aside while further experiments with the radio telephone were conducted.  As a means of increased transmitting power, Mr. Chadwick had in mind a series of sending devices attached to one mouthpiece.  In this way he believed he could at least partially overcome the resistance of the atmosphere, and get a higher percentage of current.

He had been working on the idea all the morning and was anxious for a test.  The Wondership was, therefore, wheeled out, and before long the boys were in the air once more.  As before, they sailed in the direction of Rayburn.  As they passed above the farm where they had met with their adventure the day before, they turned to each other with a laugh.

Below them they could see men working on the damaged roof of the barn and Tom burst into an uncontrollable fit of laughter as he recalled the queer sight the farmer presented dangling from the grapnel high above his broad acres.

“That reminds me,” said Jack.  “We must send him some money for that roof.”

“How about his personal feelings?” grinned Tom.

“I guess he wiped that score out when he blazed away at the balloon bag.”

“Just the same, I think we’d better go pretty high up,” advised Tom.  “He might fancy trying another shot at us.”

“That’s so,” agreed Jack, studying the men moving about far below.

He pulled a lever and the Wondership began to rise.  It was as well he did so perhaps, for as they shot upward they could see that their presence had been noted.  They watched the men scurrying about and pointing upward.  But whether the Wondership was too high, or his animosity had cooled after his involuntary ascension, the farmer made no hostile demonstration, and they were soon out of Perkins’ sight.