Telegraph

An example of a telegraph

A telegraph is a device which functions as part of an electric communication system. A telegraph allows for messages to be sent electronically over long distances through wires.

Function

A telegraph works by using a hand-operated key to break and complete an electric circuit, sending short and long pulses of electricity along a wire to a receiver. These electrical signals activate an electromagnet at the receiving end, which stays down until the circuit on the other end is broken. A human operator then translates the series of short and long pulses with a binary code such as Morse Code into a message, or "telegram."