Back and forth through space they talked for quite a time. The boys
were jubilant. The despair of many inventors, the wireless or radio
telephone appeared to be an accomplished fact. But they didn't dream
how much yet remained to be done. At length Mr. Chadwick told them to
"hang-up" and come back to the workshop.

The boys were glad to do this for they were extremely anxious to learn
something of the forces controlling this aërial method of
conversation. So far, they had not the least understanding, beyond a
general idea, of how the thing was done. Of the details by which Mr.
Chadwick had worked out this radical departure in telephony, they knew
nothing.

"Well, what did you think of it, boys?" asked Mr. Chadwick when they
returned to the workshop.

"Wonderful, beyond anything I could have imagined," declared Jack.

"How far will it work?" asked Tom.

"That's just the point," said Mr. Chadwick. "That's where I'm at sea.
I need a metal of greater conductivity than any attainable to get real
results. The carbon that I am using does not throw off enough radio
activity to produce a sufficient number of electric impulses to the
atmosphere."

Jack and Tom looked puzzled.

"You don't understand me I see," said Mr. Chadwick.