The invention of the telephone
As a professor of phonetics, Bell pays close attention to the development of the times with the keenness of young people. At this time, the industrial revolution swept across the United States, science developed rapidly, and new technical means emerged one after another. Bell realized that his main direction of deepening phonetics research should be to help deaf people overcome difficulties with advanced scientific and technological means and began his scientific exploration.
Bell found in an accidental experiment that when the current is turned on or off, the spiral coil will make noise, which is very similar to the "tick" sound of the telegraph. Bell was greatly inspired: "If I can simulate the change of sound waves with the change of current intensity, can't I use electricity to transmit sound?"
Because of his doubts about his knowledge of electricity, Bell first told several people in the field of electricity, but all the audience laughed at him: "Study your deaf-mute problem, you don't know electricity, don't be whimsical!" Not discouraged, Bell decided to ask joseph henry, a great physicist at that time. Bell stated his findings to Henry and explained in detail the idea of transmitting sound by electricity. At the same time, I also talked about my own difficulty-lack of electromagnetic knowledge. He hesitated, whether to express his ideas for others to do, or to work hard to achieve them himself?
Great scientist Henry affirmed Bell's idea and asked Bell to "master it" in electromagnetic knowledge. Bell is determined to enrich his knowledge first. Many years later, Bell recalled, "I would never have invented the telephone without the inspiring word' master it'."
Bell returned to Boston and began to study electromagnetism seriously. To this end, he resigned as a professor at Boston University. He also needs equipment to integrate electromagnetism and acoustics into one furnace, and he also needs assistants. By chance, Bell met a young electrical engineer named Watson. He firmly believed in Bell's ideal and said that he would go all out to help Bell. In this way, the two became lifelong comrades.
The development of the times doomed the invention of the telephone. At that time, after Morse invented the telegraph, because of its fast transmission speed, it was quickly paid attention to by all countries and was widely used. But at that time, many people of insight realized that some telegrams needed to be drafted in advance, and some had to be translated into codes by looking up the code books and then handed over to the telegraph office for filming. You have to wait for a call back, and you have to go through such a process. It takes a long time to go back and forth. So people began to feel dissatisfied with the telegram. People think that since telegrams transmit signals through on-off current, can we use the principle of on-off current to transmit human voice?
1860, the german inventor Les successfully transmitted a melody-like sound with current for the first time. Although it is not human voice, it is also a great invention. He named his device "telephone", which became the name of "telephone" and has been in use ever since.
Bell's exploration met the needs of social development at that time. Bell and Watson designed practical machinery while studying the principle of electroacoustic conversion.
In an experiment, Watson and Bell do experiments in two rooms. They are connected by wires between two devices. A reed on Watson's machine was stuck by a magnet, so he pulled it away. At this moment, Bell suddenly found that the reed on his machine was vibrating and making a sound.
This discovery aroused Bell's great interest and triggered new ideas. He believes that the voice of human speech is a kind of air vibration. If you talk to the thin iron diaphragm, it will make the diaphragm vibrate; If an electromagnet is placed behind the diaphragm, the vibration of the diaphragm will change the distance from the electromagnet, so that the magnetic field lines of the electromagnet will change, and the corresponding changing current will be induced in the electromagnet coil. This current is transmitted to the electromagnet coil of the same device along the wire, which will change the magnetic field lines of the electromagnet and attract the diaphragm in front, thus making a sound.
Bell told Watson the idea. Watson agreed to his idea, and they immediately started research and development, and made the simplest "telephone" on June 3rd, 1875. This kind of phone can only transmit a single tone, but it can't transmit the complete words of people, but they think the development idea is right, but the difference is that the technology is too rough.
Soon, after repeated trials and improvements, they finally made a breakthrough. At that time, the two of them were very tired after several days and nights of continuous experiments. Watson was resting in another room with headphones on. Bell accidentally spilled sulfuric acid on his leg while operating the machine in the room. Because of the pain, Bell couldn't help shouting into the microphone, "Mr. Watson, come quickly!" " I need your help! "Watson clearly heard the cry of Bell from the earphone. He excitedly ran to Bell's room, hugged Bell regardless and said, "You know, we did it! " "
That night, Bell wrote to his mother excitedly and said, "Today is a big day for me, and our ideal has finally come true! I think the day is coming when we put wires in the house, and friends can talk to each other without leaving home ... "
That night, Bell's neighbors were very strange. Why didn't they shout today? For more than two years, well-meaning neighbors have been silently enduring their fruitless cries. Today, two enterprising young people are finally able to gratefully invite their neighbors to share the joy of their success.
As a deaf person, Mabel Hubbard, Bell's wife, has helped Bell make a lot of contributions to phonetics. Although she couldn't hear the voice on the phone today, she saw her neighbors scrambling to listen and talk by the phone. She happily told Bell in sign language: "I'm so happy, congratulations!" "
Bell constantly improved the prototype, and after half a year, the prototype can be used in practice. 1876 In February, Bell applied for a patent for his invention with the patent number 174465.
Today, this machine is still very simple and can only send information in one direction. Although it is inconvenient to use, it is much more convenient to send a message in time than to send a telegram. At that time, Bell and Watson conducted a call test with a distance of tens of kilometers on the line borrowed from the telegraph (the telegraph was still wired at that time), which verified the reliability of the telephone.