 This is you who are about to talk. Ha ha! Very good. That does look like me. When you talk, your transmitter diaphragm vibrates correspondingly. This produces electric waves on the wire which conform to the vibrations your voice has caused. The electric current makes the receiver diaphragm vibrate. These vibrations are similar to those of the transmitter diaphragm. They are reconverted into sound. And that's what the man at the receiver hears. I understand all that. It seems very simple. But if the electric waves reach Chicago, why not San Francisco? They will, but the speech would not be intelligible. You see, the electric waves which represent your voice grow weak with distance. Then they get smothered by the other waves on the wire. What are the waves? Oh, electrical disturbances and other things. We call it noise. When your speech level gets down to the noise level, the man at the other end of the wire won't hear it. So that's it. That's the situation. What we need is a device that will take the electric current when it becomes weak, restore it to its original strength, and keep unchanged the wave pattern that represents your speech. Sounds like a fine idea. Oh, we have the idea, but we haven't found the device. When we do, we'll have better lines. The only alternative is to increase the size of the wires and space them farther apart. Oh, why not do that? And a wire used on the new circuit to Chicago. What we call the number eight size. This means 800 and 70 pounds of copper to the mile. The two wires must be spaced about 12 inches apart. At certain intervals, they are transposed. Transposed? Yes. That helps to overcome induction. Induction. That's what causes the noise I was telling you about. Now, we could string wires all the way across the country, but they'd have to be larger than these number eights and with wider spacing. Probably, oh, 24 inch spacing would do the job. Well, if you can do it, I think you should do it. I want to use those wires. It's a matter of economics, sir. A circuit like that would need thousands of pounds of copper per mile. To support the added weight, more poles would be needed or else heavier ones. With the wider spacing, fewer wires could be carried on the cross arms. The investment would be tremendous, so you can imagine what the rate would be. Maybe $100. Would you want to pay that? No, of course not. Still, at times it might be worth more than $100. Well, there's the fundamental problem. To make wires tough and to make it worth your while to use them. I see. I see. Well, I guess you folks know what you're doing. I saw Mr. Bell's invention at the Centennial in 76. You've gone a long way since then. I suppose I should be grateful for what we have. Well, thank you very much. Goodbye, sir. Goodbye. I hope you'll recommend the service to your friends. I'm doing that all the while. I suppose someday you'll have a lot of wires to Chicago and pack them in one of those cables I see around town. No cable to Chicago, I'm afraid. You can talk through cables less than 100 miles. Guess we'll stick to these number 8s up on poles where we can watch them. Good day, sir. Goodbye. Oh, cable to Chicago thought the engineers of 1892. There was no scientific experience that could foresee it. But there is such a cable, and in the picture record of its completion is the presence of some of those same engineers watching the ceremony of the final splice. And this cable, as we heard foretold a moment ago, is packed with wire circuits so that the pulsing interrelated life of great urban communities may be expressed in speech over the miles. In the record, too, is a still more significant reminder of progress. A type of cable with only four conductors providing channels for hundreds of simultaneous conversations. And while glancing at these exhibits of development, let us mark still another achievement. It is the grouping in a single sheeting of 4,242 strands of insulated wire that may be buried so confidently beneath the city streets as channels for the speech of its citizens. Certainly, an exciting transmission problem that of making cable circuits conform to the needs of changing times. Yet it's intriguing histories, but one of a thousand chapters in the telephone story, each replete with the thrills of discovery, of technical application, of development and change to match progress in a thousand directions. It is a record that reveals the astonishing ramifications of scientific persistency. There's a half-century of history for you installers to read if you would know about the hundred and more types of transmitters and receivers preceding the instruments that today you put to work so skillfully and you with switching mechanisms in your care, a vast literature awaits you if you would retrace the path leading back to the beginning of intercommunication. You manage the cables and open wires who build the lines and keep them efficient for the flying speech of this modern day. Look in the record if you would know what went before the writing of your present manuals of technique. And you guardians of the amplifiers that helped to make a whisper recognizable around the world. There's historic drama for you in the record of engineering and laboratory adventuring that gave you your tools of today. Deduct from the telephone art what the search of this record will disclose and you have left as you all know nothing but the first crude instrument. The temptation to explore that record here is strong indeed but there is time to pause at but a few of the pages that refer to this anniversary story. Our narrative is still in the early 90s. There were 300,000 telephones in the nation. From all important population centers the lines were spreading to suburban areas. A system of long distance lines was growing but its limited range is revealed in a special directory of that day. A book listing all the telephones in America that were connected with this system by all metal circuits. It was called a national directory. Yet the telephones that listed were only 14 states and a thousand miles was still the limit for talking. But men were thinking, men were experimenting and at the beginning of the century there came to telephone engineers a device that would preserve weakened energy on long circuits. It was the loading coil. To understand the loading principle we can think of energy being applied at one end of a rope. A wave pattern is created but it soon disappears because of the rope's resistance. But if the rope is loaded with weights at proper intervals the initial energy is not so quickly lost. Thus the wave pattern is maintained for a longer distance. There was another development of the period that bears upon this anniversary resume. This was the possibility of arranging two circuits in such a way that a third circuit for conversation would be created. This third circuit is what you call a phantom circuit. The engineers who plan for these invisible carriers of speech know best the millions of miles of copper wire that the phantom principle has saved. As experience was gained in the scientific loading off circuits hundreds of miles were added to the range of the spoken word. Historic advertisements told that an unlimited range was the hope but limits still remain. And from the circuit map came the challenge of the gaps yet to be bridged not just by wires but by wires that would talk. I walked in. That's all right. We'll just sit down. Thank you. I'm after some information about your service. I'm rather a large user. In fact my firm uses several of your private wires. You probably should talk with the commercial manager. I'm an engineer. That reminds me sir. I talked with one of your engineers nearly 20 years ago. He said something about waves. Said you needed something that would make the long distance wires talk farther. You must have met a repeating device or an amplifier something of that sort. Now that was it. I'm glad you found it. Oh we've been developing repeaters for several years but we haven't solved the problem by any means. I thought you had. Why down at the office we often talk to. St. Louis Omaha service is pretty good too. And now this statement by your president in the morning paper says we soon have service to the coast. Oh he doesn't say soon does he. No he just believes that universal service is on the way. Well I'm afraid I read it hastily. But what is the difficulty. You say you'll have those repeated things. Yes but they've got to be better. Much better. We're in a peculiar position. We know definitely what we need and it doesn't even exist. That puts it right up to us doesn't it. I just can't grasp the problem. The problem is to get the telephone waves to the distant end with volume enough without distortion and without picking up a lot of noise. Now the lines we're using are loaded with loaded. With what. Well loading in telephony is rather difficult to explain to the layman. But it means that calls of wire like this round line calls are introduced into the line every few miles. They don't add additional energy but they do conserve what we have. They make the entire length of telephone line more efficient. What are these things you call repeated. They are also devices which are introduced into the line but much farther apart than loading coils. They actually introduce new energy into the line to restore the electrical current when it becomes weakened. Well can't you use your coils and your repeaters together.