WEBVTT Kind: captions; Language: en 00:00:19.000 --> 00:00:23.001 [...] 00:00:23.001 --> 00:00:29.001 [...] 00:00:36.001 --> 00:00:38.001 [...] 00:00:38.001 --> 00:00:42.001 [...] 00:00:42.001 --> 00:00:48.000 [...] to be a glass of [...] 00:00:48.000 --> 00:00:48.000 [...] 00:00:48.000 --> 00:00:49.001 [...] 00:00:49.001 --> 00:00:54.001 What I want to say. Oh, say hello when the chief clerk answers and then say we'll 00:00:54.001 --> 00:00:57.000 say whatever you please. Hello. 00:00:58.001 --> 00:01:05.000 Hello. Hello. 00:01:06.000 --> 00:01:11.001 Hello is this the office. I can't hear much of anything. 00:01:13.000 --> 00:01:17.000 Sounds like someone crying. Oh, but my dear, you mustn't be so critical. 00:01:17.000 --> 00:01:20.001 Of course it sounds strange at first. The advertisement says it will. 00:01:21.000 --> 00:01:24.001 Well, I don't think much of it. No one will ever use it. 00:01:25.000 --> 00:01:29.000 You mark my words, dear. The time will come when we will all use it. 00:01:29.000 --> 00:01:32.001 Well, we may even talk with distance cities. With distance cities. 00:01:33.000 --> 00:01:36.000 Oh, John, you're such a dreamer. 00:03:11.000 --> 00:03:15.000 Oh, far speaking is not simply a matter of stringing wires on poles. 00:03:15.000 --> 00:03:17.001 It is primarily a problem of transmission. 00:03:18.001 --> 00:03:21.001 The electric waves which carry the voice along the wires are like other waves. 00:03:21.001 --> 00:03:23.001 The farther they go, the weaker they become. 00:03:24.000 --> 00:03:28.001 The loading coil introduced in 1901 helps their energy to be better maintained 00:03:28.001 --> 00:03:31.001 and so improve the efficiency of the telephone circuit. 00:03:33.001 --> 00:03:38.000 To understand the term loading as used in telephony, let us consider a string 00:03:38.000 --> 00:03:39.001 along which waves are traveling. 00:03:40.000 --> 00:03:43.001 If the free end of the string is snapped up and down rhythmically, the waves 00:03:43.001 --> 00:03:46.001 along the string become weaker as they travel toward the fixed end. 00:03:47.000 --> 00:03:50.000 If however, small weights or loads are placed along the string at regular 00:03:50.000 --> 00:03:55.000 distances, those cells better. In a somewhat analogous manner, loaded telephone 00:03:55.000 --> 00:03:57.001 circuits are more efficient than unloaded circuits. 00:03:58.000 --> 00:04:01.000 Consequently, the electric waves carrying the voice can travel farther. 00:04:02.001 --> 00:04:06.001 But in 1912, a new instrumentality came to telephone engineers for development 00:04:06.001 --> 00:04:12.000 that was to revolutionize the art of telephony, the vacuum tube, to make possible 00:04:12.000 --> 00:04:15.000 calls across the country, calls to distant countries, radio 00:04:15.000 --> 00:04:16.001 programs from a hundred stations. 00:04:17.001 --> 00:04:19.001 By 1914, it was in commercial service. 00:04:20.000 --> 00:04:23.000 Ten years later, more than 10,000 were installed on telephone lines. 00:04:23.001 --> 00:04:26.001 In another decade, there were 350,000. 00:04:27.000 --> 00:04:30.001 On a conversation between New York and Los Angeles, for example, some 00:04:30.001 --> 00:04:32.001 200 vacuum tubes are involved. 00:04:33.000 --> 00:04:36.001 The majority of the tubes are used as amplifiers or repeaters. 00:04:37.000 --> 00:04:42.000 They are installed in repeater stations, of which there are some 475 in the 00:04:42.000 --> 00:04:44.001 United States today to amplify the voice currents. 00:04:45.000 --> 00:04:49.001 So expertly are the repeaters made and installed that a whisper at one end of the 00:04:49.001 --> 00:04:51.001 circuit can be heard at the other end. 00:04:51.001 --> 00:04:53.000 There are other functions too. 00:04:53.001 --> 00:04:57.001 Some of the tubes are used in carrier systems, where they step up the pitch or 00:04:57.001 --> 00:05:01.000 frequency of the voice currents, so that a circuit may carry several 00:05:01.000 --> 00:05:04.001 conversations, each at a separate control pitch or frequency, 00:05:04.001 --> 00:05:06.001 and hence without interference. 00:05:07.000 --> 00:05:10.001 Other tubes at the end of the line, of course, must step down these 00:05:10.001 --> 00:05:12.000 pitches to the original frequencies. 00:05:12.001 --> 00:05:16.001 The loading coil, as we have seen, reduces the loss of electrical energy in the 00:05:16.001 --> 00:05:19.000 wires, but some loss still remains. 00:05:19.001 --> 00:05:23.001 It is the vacuum tube repeater, which compensates for the remaining loss, and at 00:05:23.001 --> 00:05:28.000 the same time, permits the delicate inflections of the human voice, or the wide 00:05:28.000 --> 00:05:32.000 range of orchestral tone, to be carried by wires thousands of miles without 00:05:32.000 --> 00:05:33.001 loss of character or volume. 00:05:43.000 --> 00:05:47.001 The modern engineer needs many types of vacuum tubes for many purposes, some no 00:05:47.001 --> 00:05:50.001 bigger than your finger, some of enormous power for talking across oceans. 00:05:51.000 --> 00:05:53.001 The vacuum tube is the magic bottle of telephony. 00:05:54.000 --> 00:05:57.001 It is the Aladdin's lamp that brought into being far speaking. 00:07:06.001 --> 00:07:36.001 [...] 00:07:55.001 --> 00:08:13.000 [...] Now who could be calling us at this time of night I don't know I'm not 00:08:13.000 --> 00:08:26.001 expecting any calls. This is Mr Reynolds resident. Yes yes he's here. Japan. Just 00:08:26.001 --> 00:08:35.000 a minute [...] My journey. Come on mother. 00:08:37.001 --> 00:08:44.000 Hello yes this is Mr Reynolds. 00:08:46.001 --> 00:08:51.001 [...] but the mom I wish they'd hurry. Hello yes. 00:08:54.000 --> 00:09:00.001 [...] hello Marjorie how are you honey. It's marvelous to hear your voice 00:09:00.001 --> 00:09:06.001 your voice sounds just the same as ever grandpa. Oh it was lovely of you and 00:09:06.001 --> 00:09:11.000 grandmama to give us this trip we were only too glad we could do it there. 00:09:13.001 --> 00:09:17.001 Oh she splendid way here she 00:09:17.001 --> 00:09:22.000 is. Hello dear. 00:09:25.000 --> 00:09:31.000 Bless your heart for calling us. Yes yes 00:09:31.000 --> 00:09:32.001 we both feel fine. 00:09:35.001 --> 00:09:42.000 Are you having a good trip. We certainly miss you. All 00:09:42.000 --> 00:09:44.001 right. You do that. 00:09:45.001 --> 00:09:52.001 Goodbye dear. Just imagine hearing her 00:09:52.001 --> 00:09:57.000 voice so clearly and she's halfway around the world. 00:09:58.001 --> 00:10:05.000 It's it's well it's impossible. Yet you've talked with her and she with you 00:10:05.000 --> 00:10:12.000 I know but Japan it's uncanny but it's true. 00:10:13.001 --> 00:10:19.000 Mother do you remember what you said about first telephone in the old 00:10:19.000 --> 00:10:21.001 house. You remember. 00:10:23.001 --> 00:10:30.000 What did I say you said no one will ever use it you mark my words 00:10:30.000 --> 00:10:34.000 dear the time of government we will all use it but we may have been talked with 00:10:34.000 --> 00:10:40.001 this and said he's with this and said oh John you're such a dreamer why. 00:10:41.001 --> 00:10:47.001 I couldn't have said that I thought it had a wonderful future you were the one 00:10:47.001 --> 00:10:54.000 that didn't believe in it and said that it would never be you. Well all right 00:10:54.000 --> 00:11:01.000 mother let's play another game. Who's the leader. Thought it had a wonderful.