But Eidson’s phonograph was no trick. The “record” was a sheet of tinfoil wrapped around a metal cylinder. A disc with a needle in it was set vibrating by the sound of the human voices, causing the needle to make grooves of varying depths in the tinfoil as the cylinder rotated. A second disc-and-needle unit was employed to play back the sound; as the second needle traveled over the same grooves, its disc vibrated, recreating the sound.
Eidson charged admission to people who wanted to hear his early phonographs play”Yankee Doodle”, and sold several hundred tinfoil phonographs. But he considered them oddities, and concentrated on other projects. Alexander Graham Bell, inventor of the telephone, improved on Edison’s idea, introducing wax-covered cylinders. Recorded disks, or “records,” were the idea of German inventor Emile Berliner. Millions of records could be stamped from a single master disk. They were first marketed in the United States in 1893. And Americans were soon cranking up phonographs to listen to their favorite singers and dance to the newest tune.