Hands-free telephone. This telephone represented an advance on earlier models as it included headphones. It was known as a bi-telephone. The operator is writing down a message as it is spoken to her through the headphones. The first practical telephones were developed in the 1870s. Artwork from the ninth volume (first period of 1892) of the French popular science weekly 'La Science Illustree' | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library |
Bildgröße: | 3926 px × 5362 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |