4 Telephone sets, after Bell; in box

The patent for the invention of the telephone is in the name of Alexander Graham Bell (1847-1922). In 1876 he lodged his patent application only a few hours before the second inventor, Elisha Gray (1835-1901). Therefore, the ‘Bell Telephone Company’ could conquer the market. In both designs the air vibrations of a voice were converted into a varying electric current. The sound of a voice sets a membrane, to which a small magnet is attached, into vibration. In a coil the vibrating magnet generates an induced current, which is led through a wire to a receiver. In the receiver a reverse process sets a membrane into vibration, which reproduces the recorded sound. The four telephone sets in this box were made by the well-known firm of Siemens & Halske from Berlin.