t appealed to Gus, the lame boy had often proved that he had a
native wit and a tongue that could give as good as was ever given him.

"Here we are, Gus, and how can I ever get square with you?" Bill said,
his crutch and loot thumping the steps as the boys gained the doorway.

In answer to the bell, a sweet-faced lady opened the door, greeted the
boys by name and ushered them into a book-lined study where already
several other boys and girls of about the same age were gathered about
their school teacher.

Professor James B. Gray, although this was vacation time, was the sort
of man who got real and continued pleasure out of instruction,
especially concerning his hobbies. Thus his advanced classes, here
represented, had come into much additional knowledge regarding the
microscope and the stereopticon and had also greatly enjoyed the
Professor's moving-picture apparatus devoted to serious subjects. The
latest wonder, and one worthy of intense interest, was a newly installed
radio receiver.

"Come in, come in, David and Jonathan,--I mean William and Augustus!"
greeted Professor Gray. "Find chairs, boys. I'm glad you've come. Now,
then, exactly in nine minutes the lecture starts and it will interest
you. The announcement, as sent out yesterday, makes the subject the life
and labors of the great scientist and inventor, Thomas Alva Edison, and
it begins with his boyhood. Don't you think that a fitting subject upon
an occasion where electricity is the chief factor? But before the time
is up, let me say a few words concerning our little boxed instrument
here, out of which will come the words we hope to hear. Some of you, I
think, have become pretty familiar with this subject, but for those who
have not given much attention to radio, I will briefly outline the
principles upon which these sounds we shall hear are made possible.

"It would seem that our earth and atmosphere," continued the Professor,
"and all of the universe, probably, is surcharged with electrical energy
that may be readily set in motion through the mechanical vibrations of a
sensitive diaphragm much as when one speaks into a telephone. This
motion is transmitted in waves of varying intensity and frequency which
are sent into space by the mechanism of the broadcasting station, which
consists of a sound conducting apparatus induced by strong electrical
currents from generators or batteries and extensive aerial or antennas
wires high in the air. Thus sound is c