Dial telegraph. 19th-century artwork of a dial telegraph. The dial (top) is turned to generate and transmit the telegraph signal for the letter selected. Several electric telegraph systems were developed from the 1830s and 1840s onwards. This artwork is from 'History,Theory,and Practice of the Electric Telegraph' (1860) by US telegraph engineer George Bartlett Prescott (1830-1894) | |
Licence : | Droits gérés |
Crédit: | Science Photo Library / King's College London |
Taille de l’image : | 3706 px × 4746 px |
Model Release : | Non requis |
Property Release : | Non requis |
Restrictions : | - |