The Radio Boys First Wireless | Page 9

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,