Telegraph is the earliest reliable instant long-distance communication method to transmit information by electricity, which was developed in Britain and the United States in the 1930s from 65438 to 2009. Telegraph information is sent in the form of electrical signals through special exchange lines. This signal uses a code instead of words and numbers, and the commonly used code is Morse code.
Brief introduction of telegram
Early telegrams could only be transmitted by land lines. The earliest wires belong to single-wire type, which need to be looped through the ground, and the transmission distance is limited, not to mention crossing the ocean. By 1850, the first submarine cable crossed the English Channel, connecting Britain and the European continent. The first transatlantic telegraph cable was laid in 1857.
However, due to technical reasons, this transoceanic cable broke down after only a few days of use. The first Atlantic submarine telegraph cable will not be successfully put into use until nine years later, that is, 1866. As for the submarine cable across the Pacific Ocean, it will not be completed until 1902. By 19' s, telegrams were still transmitted by wire in various places.
Nikola tesla and other scientists began to study sending telegrams by radio at this time. 1895, Italian Guillermo Marconi successfully sent and received wireless telegrams for the first time. Four years later, 1899, he successfully transmitted from England to France. 1902 is the first communication across the Atlantic by radio.
Baidu Encyclopedia-Telegraph