Telegraphy

The electrical telegraph, or more commonly just 'telegraph', superseded optical semaphore telegraph systems, such as those designed by Claude Chappe for the French military, and Friedrich Clemens Gerke for the Prussian military, thus becoming the first form of electrical telecommunications. In a matter of decades after their creation, electrical telegraph networks permitted people and commerce to almost instantly transmit messages across both continents and oceans, with widespread social and economic impacts.

Colour photograph of a telegraph key. A simple metal lever-like switch on a small wooden base connected with a wire disappearing out of frame.
Telegraphy