st as one of themselves. Apart, too,
from the thorough liking they had for him as a man, they were
exceedingly grateful to him for the help he had been to them in radio
matters. He was their mentor, guide and friend.

"I knew I'd find you busy with the radio," he said, with a genial smile.

"We can't be torn away from it," replied Bob. "We think it's just the
greatest thing that ever happened. Just now we've been listening to
Larry Bartlett give his imitations of animals. You remember Larry?"

"I certainly do," replied Dr. Dale. "And I remember how you boys helped
him get his present position. It was one of the best things you ever
did. He's certainly a finished artist. I heard him on his opening night,
and I've laughed thinking of it many times since. He's a most amusing
entertainer."

It was the first opportunity the boys had had to tell the doctor of the
night when Bob found that he was a human aerial, and he listened to the
many details of the experiment with absorbed interest.

"It's something new to me," he said. "You boys have reason to be
gratified at having had a novel experience. That's the beauty of radio.
Something new is always cropping up. Many of the other sciences have
been more or less fully explored, and while none of them will ever be
exhausted, their limits have been to some extent indicated. But in radio
we're standing just on the threshold of a science whose infinite
possibilities have not even been guessed. One discovery crowds so
closely on the heels of another that we have all we can do to keep track
of them.

"I've just got back from a little trip up in New York State," he went
on, as he settled himself more comfortably in his chair, "and I stopped
off at Schenectady to look over the big radio station there. By great
good luck, Marconi happened to be there on the same day----"

"Marconi!" breathed Bob. "The father of wireless!"

"Yes," smiled Dr. Dale. "Or if you want to put it in another way, the
Christopher Columbus who discovered the New World of radio. I counted it
a special privilege to get a glimpse of him. But what attracted my
special attention in the little while I could spend there was a small
tube about eighteen inches long and two inches in diameter which many
radio experts think will completely revolutionize long distance radio
communication."

"You mean the Langmuir tube," said Joe. "I was reading of it the other
day, and it seems to be a dandy."

"It's a wonderful thi