ny such word as 'always' in radio," returned Bob. "I
shouldn't wonder if in the next twenty or thirty years we shall be able,
by means of appliances like this new power vacuum tube, to get our power
from the ordinary lighting circuit."

"And that would do away entirely with generators," added Joe
triumphantly.

"Well, I wouldn't say anything was impossible," said Herb doubtfully.
"But that seems to me like a pretty large order."

"It is a large order," agreed Bob, adding with conviction: "But it isn't
too large for radio to fill."

"Speaking of lodging all apparatus in one fair-sized room," Joe went on.
"I don't see why that can't really be done in a few years. Why, they say
that this new power vacuum tube which handles fifty K. W. is not any
larger than a desk drawer."

"I see the day of the vest-pocket radio set coming nearer and nearer,
according to you fellows," announced Herb. "Pretty soon we'll be getting
our apparatus so small we'll need a microscope to see it."

"Laugh if you want to," said Bob. "But I bet in the next few years we're
going to see greater things done in radio than have been accomplished
yet."

"And that's saying something!" exclaimed Joe, with a laugh.

"I guess," said Jimmy thoughtfully, "that there have been more changes
in a short time in radio than in any other science."

"I should say so!" Herb took him up. "Look at telephone and telegraph
and electric lighting systems. There have been changes in them, of
course, but beside the rapid-fire changes of radio, they seem to have
been standing still."

"There haven't been any changes to speak of in the electric lighting
systems for the last fifteen years or more," said Bob. "And the
telephone has stayed just about the same, too."

"There's no doubt about it," said Joe. "Radio has got 'em all beat as
far as a field for experiment is concerned. Say," he added fervently,
"aren't you glad you weren't born a hundred years ago?"

The boys stopped in at Adam McNulty's cabin to see how the old fellow
was getting along. They found him in the best of spirits and, after
"listening in" with him for a while and laughing at some of his Irish
jokes, they started toward home.

"I wish," said Bob, "that we could have gotten a line on Dan Cassey. It
seems strange that we haven't been able to pick up some real clue in all
this time."

For, although the boys had caught several other mysterious messages
uttered in the stuttering voice of Dan Cassey,