onverted into waves, and the
receiving station, as you see here, with its aerial on the roof, its
detector, its 'phone and its tuner, gets these waves and turns them
again into sound. That is the outline of the thing, which you will
understand better 'after' than 'before using.'

"The technical construction of the radio receiving set is neither
difficult nor expensive; it is described fully in several books on the
subject and I shall be glad to give any of you hints on the making and
the operation of a receiving set. The 'phone receivers and the crystal
detector will have to be purchased as well as some of the accessories,
such as the copper wire, pulleys, battery, switches, binding posts, the
buzzer tester and so forth. With proper tools and much ingenuity some of
these appliances may be home-made.

"The making of the tuner, the wiring, the aerial and the assembling are
all technicalities that may be mastered by a careful study of the
subject and the result will be a simple and inexpensive set having a
limited range. With more highly perfected appliances, as a vacuum, or
audion tube, and an aerial elevated from sixty to over a hundred feet,
you may receive radio energy thousands of miles away.

"Now, this talk we are about to hear comes to us from the broadcasting
station WUK at Wilmerding, a distance of three hundred miles, and this
outfit of mine is such as to get the words loudly and clearly enough to
be audible through a horn. The talks are in series; there have been
three on modern poets, two on the history of great railroad systems and
now this will be the first of several on great inventors, beginning with
Edison, in four parts. The next will be on Friday and I want you all to
be here. Time is up; there will be a preliminary-ah, there it is: a
cornet solo by Drake."

CHAPTER II

AN UNUSUAL LAD

Professor Gray turned to the box and began moving the metal switch arms
back and forth, thus tuning in more perfectly as indicated by the
increased and clearer sound and the absence of interference from other
broadcasting stations, noticed at first by a low buzzing. In a moment
the music came clear and sweet, the stirring tune of "America." When the
sound of the cornet ceased, there followed this announcement:

"My subject is the early life of Thomas Alva Edison."

Everyone settled down most contentedly and Gus saw Bill hug himself in
anticipatory pleasure; the lame boy had always been a staunch admirer