nd do nothing but ask fool questions," he explained. "But when I get
some one who knows the subject and can understand what I'm showing him,
that's a different matter."

He showed them over the sending station from the studio to the roof. The
boys listened with the keenest interest as he described to them the
methods by which the broadcasting was carried on, which every night
delighted hundreds of thousands of people within range of the station.

In a little room close to the roof they saw the sending apparatus which
really did the work. There was a series of five vacuum bulbs through which
the current passed, receiving a vastly greater amplification from each,
until from the final one it climbed into the antenna and was flung into
space. To the casual onlooker they would have seemed like simply so many
ordinary electric bulbs arranged in a row and glowing with, perhaps,
unusual brilliance.

But the boys knew that they were vastly more than this. Where the electric
light tube would have contained only the filament, these tubes at which
they were looking contained also a plate and a grid--the latter being that
magical invention which had worked a complete revolution in the science of
radio and had made broadcasting possible. From the heated filament
electrons were shot off in a stream toward the plate, and by the
wonder-working intervention of the grid were amplified immeasurably in
power and then passed on to the other tube, which in turn passed it on to
a third, and so on until the sound that had started as the ordinary tone
of a human voice had been magnified many thousands of times. This little
series of tubes was able to make the crawl of a fly sound like the tread
of an elephant and there is no doubt that a time will come when through
this agency the drop of a pin in New York City can be heard in San
Francisco.

The boys were so fascinated with the possibilities contained in the
apparatus that it was only with reluctance that they left the roof and
went to the studio. This they found to be a long, rather narrow room,
wholly without windows, and with the floors covered with the heaviest of
rugs. The reason for this, as their guide explained, was to shut out all
possible sound except that which it was desired to transmit over the
radio.

"What is the idea of having no windows?" asked Bob.

"So there shall be no vibration from the window panes," replied Mr. Reed.
"I tell you, boys, this broadcasting hasn't been