MYSTERIOUS FORCES
The boys broke out in roars of laughter in which the doctor joined
heartily.
"You see how it is," he said, as the song came to an end. "There's
hardly anything you can think of that you can't hear over the wireless
telephone. It takes you anywhere you want to go in a fraction of a
second. In the last few minutes, we've covered quite a section of the
United States, and with a still stronger instrument we could go right
out to the Pacific coast and hear the barking of the sea lions at the
Golden Gate."
"Wonder if we could hear the barking of the hot dogs at Coney Island,"
whispered the irrepressible Herb, who would have his joke.
Bob nudged him sharply and Herb subsided.
"And you can pick out any kind of entertainment you want," the doctor
went on. "The great stations from which this music was sent out have
programs which are published every day, together with the exact time
that the selections will be given. At a given minute you can make your
adjustment and listen to a violin solo, a band concert, a political
speech, a sermon, or anything else that you want. If it doesn't please
you, you can shut it off at once, which is much easier and pleasanter
than getting up and going out from an audience.
"We'll have some more selections later on in the evening," he
continued, "but now I want to explain to you how this thing is done.
I can't hope to do much more than touch the surface of the subject
to-night, for I don't want to tire you out, and there'll be plenty of
other nights and days when I hope you boys will call upon me for any
information that you want and I can give.
"Of course the whole thing is based on electricity, the most wonderful
thing that perhaps there is in the whole physical world. Nobody knows
what electricity is--Mr. Edison himself doesn't know. We only know
that it is a wonderful fluid and that the ether is full of it. But
though we don't know what it is, scientific men have learned how to
develop and use its energy, and among other things they have harnessed
it in the service of the wireless telephone.
"Take for instance a quiet lake. It may seem absolutely still, but
if you throw a stone in it you start a number of ripples that keep
spreading further and further out until they break on the shore. So
if you hit a drum with a stick, sound waves are stirred up that keep
spreading out very much like the ripples on the lake.
"Now electricity is something like that. It doesn't begin to act until
you do something to it. The impulse to ripple is in the quiet lake all
the time, but it doesn't ripple until you throw the stone in it. The
sound quality is in the drum, but you don't hear it until you hit the
drum with a stick. So you've got to put into the ether something that
disturbs the electricity in it, something that stirs it up, and then
this disturbance makes waves that travel on, just as the waves on the
lake follow one another and just as the sound waves from the drum keep
pushing each other along.
"A man named Hertz discovered a way of stirring up this energy,
snapping it, you might say, as a man snaps a whip. It was found that
these waves could be made long enough and strong enough to go all
the way across the Atlantic Ocean, in fact to go around the world.
"Around the world!" murmured Jimmy, and again he was tempted to ask
somebody to pinch him, but remembered his previous experience and
stopped just in time.
"Now," continued the doctor, "you may ask what this has to do with
the voice, for it is with the voice that one talks over the 'phone.
The whole principle of the wireless telephone is based on the fact
that sound can be transformed into electricity and then can be
transformed back into sound again. I know," he said, with a smile,
"that that sounds very much like saying that you can make eggs into
an omelet and then get the omelet back into separate eggs again"--here
there was an audible snicker from the boys--"but that is very
much like what is done by the wireless, although it doesn't exactly
fit the case.
"Now see what a wonderful increase in power you get the moment the
sound waves are changed into electric waves. Sound goes at the rate
of one thousand and ninety feet a second. Electrical energy travels
at the rate of one hundred and eighty-six thousand miles a second.
In other words it could go around the world more than seven times
in a single second.
"When you speak into a telephone, unless you are greatly excited,
you don't use more than a fiftieth part of the power of your voice.
But by the time that sound has been caught up and churned, as it
were, into electrical energy it is more than a hundred thousand
times as loud and strong.
"Suppose now, just as an illustration, that you were going to
telephone to Europe. You'd pick up the 'phone and give your message.
That sound would go in the form of a tiny electrical impulse into one
of the great sending stations on the Atlantic Coast, we'll say, and
there it would be caught up by a powerful lot of electrical machines,
amplifiers, alternators, and others, that would keep making it
stronger and stronger until finally it was flung out into space from
the ends of the great wires or antennae. Out and out it would go until
it struck a lot of wires on the other side of the ocean. Then it would
go through another process that would gradually change the electrical
impulse back into sound again, and the man at the other end of the
telephone would hear your voice, just as one does now when you 'phone
to any one in this town."
He paused for a moment, and there was a long drawn breath on the part
of his auditors that testified to the rapt attention with which they
had followed him into this fairyland of science.
"So much for the theory and principle of the wireless," resumed the
doctor. "Of course I've only scratched the surface, and if I talked
to you all night there'd be still lots left to say. But we only need
to know a little about it to put it to practical use. And it is the
practical use of the wireless telephone that I'm especially interested
in for the sake of you boys. I'm satisfied that there's hardly
anything that could give you more pleasure or more benefit than for
each of you to have one of these contrivances in your own home. It's
a wonderful educator, it helps to develop your interest in science,
and what will perhaps appeal to you most of all, you can have more
fun with it than anything else I know of."
Here Bob put in a question that was in the minds of many of
the others.
"Does it cost very much, Doctor?" he asked.
"Not very much," the doctor replied. "Of course, some of the more
powerful ones with vacuum tubes and other high class improvements run
into the hundreds of dollars. But some very good receiving sets--and
that's all you could use at the start, for it takes considerable time
and you have to get a license before you are permitted to transmit--cans
be bought for from twenty-five to seventy-five dollars."
There was a little gasp at this, some of which was due to a feeling of
disappointment. It seemed beyond the range of what they could save up
from their pocket money, and while the parents of some of them were
well to do, others came from simple and frugal homes where every
dollar had to be carefully counted.
The doctor was quick to note the expression on many faces, and took
pains at once to remove any feeling of discouragement.
"But don't let that bother you at all," he said, "for with a little
thought and planning any one of you will be able to build a telephone
receiving set for himself at hardly any cost at all. In fact, I'd much
rather have you build one than buy one, for in that way you'll get an
understanding of the whole thing that otherwise you might not get at
all. You'd be surprised perhaps if I told you that this set here was
built by me and I wouldn't exchange the experience I've had in putting
it together for a good deal of money."
"But you knew how to do it," put in Joe, "while we don't know the
first thing about it. We wouldn't know how to start, even, let alone
finish one."
"I was coming to that," returned Dr. Dale, smiling. "As some of you
know, I've fitted up a workshop in the barn behind this house where
I do a good deal of tinkering in my spare hours. Now I'm going to ask
you boys to come out there next Saturday and see me build a wireless
receiving set from A to Z. You'll be surprised to see how much can be
done with a few things that cost very little money and with a lot of
things that don't cost any money at all. How about it, boys?"
It was almost with a whoop that the invitation was accepted by his
eager hearers, and the minister smiled with gratification at their
enthusiasm.
"Now that's all the talking I'm going to do tonight," he said. "And
as talking's rather dry work, I'm going to have a little refreshment.
Will you boys join me?"
Would they join him? They would and they did, and the havoc they
wrought on the sandwiches and cake and ice-cream that were brought in
and passed around was something to be remembered. Jimmy in particular
ate until his eyes bulged and fully sustained his previous reputation.
And while they ate, the doctor turned on one lively selection after
another, finishing with a selection from a jazz band that sent them
into a frenzy of laughter.
They were still tingling with it as they finally said good-night
to the doctor and started on their way home.
"Oh, you wireless telephone!" exclaimed Herb.
"Isn't it a wonder?" ejaculated Joe.
"Wonder!" repeated Bob. "It's a miracle!"