An electrical telegraph was a point-to-point text messaging system, used from the 1840s until better systems became widespread. It used coded pulses of electric current through dedicated wires to transmit information over long distances. It was the first electrical telecommunications system, the most widely used of a number of early messaging systems called telegraphs, devised to send text messages more rapidly than written messages could be sent. This system allowed for communication to occur without the necessity of physical transportation. Prior to this, beacons, smoke signal, flag semaphore, and optical telegraphs used visual signals to communicate over distances of land.
An electrical telegraph consisted of two or more geographically separated stations (often called telegraph offices) connected by wires, usually supported overhead on utility poles. There were many different electrical telegraph systems invented, but the ones that became widespread fit into two broad categories. The first category consists of needle telegraphs in which a needle pointer is made to move electromagnetically with a pulse of electric current from a battery or dynamo down the telegraph line. Early systems used multiple needles requiring multiple wires. The first commercial system, and the most widely used needle telegraph, was the Cooke and Wheatstone telegraph, invented in 1837. Early equipment sets used five needles to point to the letter being transmitted, but the cost of installing wires was more economically significant than the cost of training operators so a single-needle system with a code that had to be learned became the norm.
The second category consists of armature systems in which the pulse activates a telegraph sounder which makes a click. The archetype of this category was the Morse system, invented by Samuel Morse in 1838, using a single wire. At the sending station, an operator would tap on a switch called a telegraph key, spelling out text messages in Morse code. Originally, the armature was intended to make marks on paper tape, but operators learned to interpret the clicks and it was more efficient to write down the message directly. In 1865, the Morse system became the standard for international communication with a modified code developed for German railways. However, some countries continued to use established national systems internally for some time afterwards.
In the 1840s the electrical telegraph superseded optical telegraph systems (except in France), becoming the standard way to send urgent messages. By the latter half of the century, most developed nations had created commercial telegraph networks with local telegraph offices in most cities and towns, allowing the public to send messages called telegrams addressed to any person in the country, for a fee. Beginning in 1854 submarine telegraph cables allowed for the first rapid communication between continents. Electrical telegraph networks permitted people and commerce to transmit messages across both continents and oceans almost instantly, with widespread social and economic impacts. In the early 20th century the telegraph was slowly replaced by teletype networks. More details
The second category consists of armature systems in which the pulse activates a telegraph sounder which makes a click. The archetype of this category was the Morse system, invented by Samuel Morse in 1838, using a single wire. At the sending station, an operator would tap on a switch called a telegraph key, spelling out text messages in Morse code. Originally, the armature was intended to make marks on paper tape, but operators learned to interpret the clicks and it was more efficient to write down the message directly. In 1865, the Morse system became the standard for international communication with a modified code developed for German railways. However, some countries continued to use established national systems internally for some time afterwards.
