How Does the Telegraph Work?

The telegraph was the first long-distance communications breakthrough and laid the foundation for current devices like the telephone, fax machine and even the Internet. Samuel Morse is credited with developing the telegraph in the 1830s and 1840s, securing all of the device’s patents in his name, but he had a great deal of help from “unnamed” inventors. An October 2013 article in Smithsonian Magazine credits Leonard Gale, a chemistry teacher from NYU, Joseph Henry, an electromagnetics expert, and Albert Vail, Morse’s assistant, as key contributors to the telegraph’s creation in the United States.

Pushbutton Morse
The telegraph revolutionized communications.
credit: james63/iStock/Getty Images

The Groundwork

The telegraph would not have been possible if not for two vital electronic discoveries in the early 19th century. outlines the technologies needed to bring the telegraph to life. In 1800, Alessandro Volta invented the battery, so electric current could be stored and used in a controlled environment. In 1820, Hans Christian Oersted successfully demonstrated the link between electricity and magnetism by moving a magnetic needle with an electric current. Other early inventors (in addition to the Morse group) instrumental to telegraph development include English researchers Sir William Cooke and Sir Charles Wheatstone.

Early Adaptations

The British team of Cooke and Wheatstone developed a system used for railroad signaling in Britain as featured in the article. Their system consisted of five magnetically charged needles that could be moved around a panel of numbers and letters when charged with electricity. The Morse system was based on single-circuit technology that worked by completing the electronic circuit between the sending station and the receiving station connected by lines or wires.

How It Works

The operator at the sending station pushes down an operator key that closes the electronic circuit and sends a signal through the telegraph lines or wires to the receiver. When the signal reaches the receiver, it activates a magnet that pulls down the key at the receiver station completing the circuit. Pushing and then releasing the key on the sender’s side allows current to flow or be interrupted in pulses. This series of pulses is called Morse Code. Morse Code assigns a specific pattern of dots and dashes to letters of the alphabet. The most easily recognized example of Morse Code is dot-dot-dot, dash-dash-dash, dot-dot-dot, or SOS. provides a key to the International Morse Code system.

Beginning of the End

The telegraph succeeded in connecting the nation and contributed greatly to western expansion. The device even helped President Lincoln communicate with his generals during the Civil War, as outlined in a story on By the late 1860s, the Western Union Telegraph Company purchased most of the telegraph patents and controlled a good part of the telegraph and telegram industry for the next century and a half. Western Union played a vital role in the development of other technologies that sprang from the telegraph, as posted on the company website. A few of these accomplishments include the transcontinental telegraph network in 1861, the stock ticker in 1865, and the first commercial inter-city microwave communications system in 1943.

In July 2013, India shut down its state-controlled Bharat Sanchar Nigam, Ltd. (BSNL) telegraph network, as reported on This was the last known wired telegraph system in the world. The telegraph is certainly a technology from a bygone era, but many of the communication devices we now take for granted wouldn’t have been possible without those dots and dashes.