Edison's head is like a running machine, which can spark inspiration in generate. He is always searching for various phenomena that have not happened, and at the same time thinking and studying various phenomena and problems that have appeared. There are countless inventions in his life, one of which is the phonograph.
In p>1876, Bell invented the telephone, and Edison was entrusted to improve it because of its low sound. One day in 1877, when Edison was testing the telephone, he found that the diaphragm in the microphone was vibrating with the voice. He wanted to know the vibration amplitude of the diaphragm, so he found a steel needle and fixed it on the diaphragm. At the other end, he gently pressed it with his hand. When Edison spoke to the microphone, he suddenly felt that the finger touching the diaphragm needle had a corresponding vibration. What's even more amazing is that the voice tone is high, the vibration is fast, and the vibration is slow when the tone is low. If the sound is loud, its vibration is strong, and if the sound is small, its vibration is weak. This accidental discovery excited Edison, who had long wanted to invent a machine that could repeat sounds. From this, he reasoned that the stylus can stimulate fingers, so it should also draw a continuous notch on the surface of materials such as tin foil; If the stylus on the diaphragm moves along this notch for recording sound, it is believed that the original sound will be obtained. He wrote in his notebook: "I pointed a piece of diaphragm with a stylus at the rapidly rotating wax paper, and the vibration of the voice was clearly engraved on the wax paper." Experiments have proved that it is completely possible to store all human voices and automatically release them at any time when needed in the future. "
Edison was full of confidence and set about designing and manufacturing this "machine that reproduces people's speech". After several failures, Edison drew a sketch and gave it to the foreman of the machinery workshop. A few days later, John Crusi, the assistant, recreated a strange machine composed of a crank, a big cylinder and two small metal tubes according to the pattern. On November 29, 1877, the laboratory was crowded with people. After sitting at the table and carefully examining the machine, Edison took out a flat tin foil from the drawer and laid it on the cylinder. Then he shook the crank handle and the cylinder rotated evenly. He aimed at the small metal tube with a film inside and placed a stylus pointing to the cylinder, and sang aloud: "Mary has a lamb/snowball like a fur/wherever Mary goes/it always runs behind ..." When the screw mechanism rotates the cylinder and will slowly move along the horizontal direction, the stylus will carve a groove on the tin foil paper, which is the trace left by the sound. After singing this song, Edison gently pulled out a small mechanical spring, touched the needle away from the cylinder, shook the handle in the opposite direction, and then shook the curved handle again after the cylinder returned to its original position. The whole room held its breath and stared intently, expecting a miracle. At this time, with the rotation of the cylinder machine, the drum with the horn gently sang: "Mary has a little lamb …" People were shocked, which was exactly the same as what Edison had just sung. John Crusi paused for half a ring before saying a word: "My God, it is really a talking machine!" At this moment, people in the whole room laughed, and the first phonograph in human history was born. Edison applied for a patent in February 1878.
The news of the birth of the talking machine caused a sensation all over the world. In December 1877, Edison publicly performed the phonograph, and public opinion immediately praised him as Napoleon in science, one of the three most exciting inventions in the 19th century. The upcoming Paris World Expo immediately put it on display as a new exhibit, and even then US President Hayes walked around the phonograph for more than two hours.
ten years later, Edison improved the large cylinder and small crank on the phonograph into a clockwork-like device, and the phonograph was widely popularized when a thin wax disk was driven by a motor.