
has made the greatest contribution to the entire invention of Edison than the phonograph. Because most other inventions were made major improvements based on predecessors, while phonographs were completely different. In the long river of human history, "storing voices" was never considered before Edison.

This invention was created by chance. In order to improve a device on the telegram, Edison accidentally touched the needle tip on the telegram device to the sliding telegram tape. The needle tip quickly swipes over the symbols engraved with wires and dots, making a music-like hum. This unexpected discovery aroused Edison's great interest. He thought: If this pattern matches the human voice, will the human voice be reproduced?
Edison survived many sleepless nights for this problem. He rotated the cylinder with tin foil in a horizontal direction, pressed the needle mounted on the diaphragm on the cylinder, and then spoke loudly to the diaphragm, and the needle drew a mark on the tin foil. After repeated trials, the phonograph was finally successfully tested! Edison sang loudly at the diaphragm, and slowly left engravings on the cylinder's tin foil. When he put the needle back on the cylinder and rotated the cylinder again, the sound reappeared. The reappearing sound was exactly the same as Edison's. Edison couldn't help but feel happy when faced with this major invention.