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The telegraph—the precursor of radio technology—was invented in the United States in the 1840s and was the first technology to enable messages to move faster than human travel. Through the telegraph, messages (such as news) could be transmitted from coast to coast within minutes, rather than the days required by ships and other modes of conveyance. American artist and inventor Samuel Morse initially developed this practical system of sending electrical impulses from a transmitter through a cable to a reception device. To send messages, telegraph operators used what became known as Morse code—a series of dots and dashes that stood for letters in the alphabet and that interrupted the electrical current along a wire cable. By 1844, Morse had set up the first telegraph line, which linked Washington, D.C., and Baltimore, Maryland. By 1861, telegraph lines stretched coast-to-coast. Just five years later, the first transatlantic cable, capable of transmitting about six words a minute, ran between Newfoundland and Ireland along the ocean floor.

Though revolutionary, the telegraph had significant limitations. For one thing, it couldn’t transmit the human voice. Moreover, because it depended on wires, it was no help for anyone seeking to communicate with commercial or military ships at sea. The world needed a telegraph without wires. A promising theory came from James Maxwell, a Scottish physicist who in the mid-1860s postulated the existence of radio waves that could be harnessed to send signals from a transmission point to a reception point. In the 1880s, German physicist Heinrich Hertz tested Maxwell’s theory—with interesting results. Hertz conducted an experiment using electrical sparks that emitted electromagnetic waves, invisible electronic impulses similar to light. The experiment was the first recorded transmission and reception of radio waves, and would dramatically advance the development of wireless communication.