Telegraphing is a way of sending messages using wires and an electric current. At one end, the sender naps out a word with a switch. Each tap completes the circuit and allows electricity to flow. The electricity flows down wires to the receiver, where it powers an indicator dial or pointer, enabling the operator to observe the message coming in.
Early forms of the telegraph were based on electrolysis, in which electricity passes through a liquid to produce a visual effect. Samuel Thomas von Sommering'S early electrolysis telegraph consisted of thirty wires immersed in acidic water, one for each letter of the German alphabet. As the letters were tapped and the circuit completed, an electrochemical reaction produced a flow of hydrogen bubbles. The message was easily deciphered by watching which wire produced the bubbles.
Baron Pavel Schilling (c. 1780-1836) decided to collaborate with von Sommering to invent a more practical device. Around 1830, Schilling found that coiling electrical wire around a magnetized needle would make it swing one way or the other. The effect was based on electromagnetism, in which electricity flowing through a wire creates a magnetic field. If the wire is coiled, the field is amplified and is strong enough to swing the needle. He incorporated this phenomenon into the telegraph by using horizontally mounted needles to indicate letters.
The electromagnetic telegraph, first demonstrated in 1832, represented the first major use of electricity for communication. Four years later, Charles Wheatstone and William Fothergill Cooke patented their electrical telegraph, and in May 1844 Samuel Morse's first single-wire telegraph line was opened.
