Traffic became high enough to spur the development of automated systems- teleprinters and punched tape transmission. Telegrams became a popular means of sending messages once telegraph prices had fallen sufficiently. Wireless telegraphy developed in the early 20th century became important for maritime use, and was a competitor to electrical telegraphy using submarine telegraph cables in international communications. The heliograph was standard military equipment as late as World War II. The most extensive heliograph network established was in Arizona and New Mexico during the Apache Wars. It was mainly used in areas where the electrical telegraph had not been established and generally used the same code. The heliograph is a telegraph system using reflected sunlight for signalling. The Morse system was adopted as the international standard in 1865, using a modified Morse code developed in Germany in 1848. The electric telegraph was slower to develop in France due to the established optical telegraph system, but an electrical telegraph was put into use with a code compatible with the Chappe optical telegraph. This was quickly followed by a different system developed in the United States by Samuel Morse. It was first taken up in Britain in the form of the Cooke and Wheatstone telegraph, initially used mostly as an aid to railway signalling. The electric telegraph started to replace the optical telegraph in the mid-19th century. The system was used extensively in France, and European nations occupied by France, during the Napoleonic era. The earliest true telegraph put into widespread use was the optical telegraph of Claude Chappe, invented in the late 18th century. Possible messages were fixed and predetermined and such systems are thus not true telegraphs. Ancient signalling systems, although sometimes quite extensive and sophisticated as in China, were generally not capable of transmitting arbitrary text messages. Thus flag semaphore is a method of telegraphy, whereas pigeon post is not. Telegraphy is the long-distance transmission of messages where the sender uses symbolic codes, known to the recipient, rather than a physical exchange of an object bearing the message.
Replica of Claude Chappe's optical telegraph on the Litermont near Nalbach, Germany
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