Carbon microphone, invented in 1878 by David Edward Hughes, 1890. The apparatus was said to be so sensitive that a fly walking on the sounding-board could be heard by an observer on a telephone several miles away. Image published in 1869. | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library / Collection Abecasis |
Bildgröße: | 3307 px × 2864 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |