Wire recording device, a rotor telegraphone (also called a rotor wire telephonograph) for recording speech on steel wires, from the Paris World Exhibition in 1900

After discovering the principle of magnetic recording in 1898, Valdemar Poulsen moved to Berlin in May 1900 to continue developing the phonograph cylinder with Mix & Genest. In June 1900, Poulsen exhibited his devices to the public at the "Aktieskelsabet Telegrafonen" booth at the Paris World Expo, while Mix & Genest prepared demonstrations for invited attendees and press representatives. The telephonograph was one of the devices they showcased.