The telegraph and Morse code

In 1835, inventors Joseph Henry and Edward Davey independently demonstrated electromagnetic relay, where a weak electrical signal can be amplified and transmitted across long distances. Cooke and Wheatstone invented the telegraph shortly after.

A few years later, Samuel Morse developed a version that sent signals from Washington D.C. to Baltimore. Afterwards, he developed a system of signal-induced indentations that correlated to numbers, special characters, and letters of the alphabet, known as the Morse code.