ayed there all the morning poring over the
map and asking further questions of the rugged miner, but at that
moment the nurse came in and declared that the injured man must have
quiet.

And so there, for the present, the matter rested. The professor
departed for his home greatly excited over the events of the morning,
but his excitement was a little allayed by the fear that he would be
late for his mid-day meal with dire results from Miss Melissa.

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 reca