Optical communications. 19th-century illustration of the French military communicating using an optical system of lights and mirrors. The French military developed a number of such systems, including an advanced optical telegraphy system, before the widespread use of telegraphy and telephones. This illustration is from 'Physique Populaire' (Emile Desbeaux, 1891). | |
Lizenzart: | Lizenzpflichtig |
Credit: | Science Photo Library |
Bildgröße: | 4178 px × 4182 px |
Modell-Rechte: | nicht erforderlich |
Eigentums-Rechte: | nicht erforderlich |
Restrictions: | - |