On This Day…

On the 10th June 1837 the electric Five Needle Telegraph was patented

The electric Five Needle Telegraph was patented in London by Charles Wheatstone and William Fothergill Cooke. Cooke and Wheatstone, who had previously invented the concertina, produced the first practical electric telegraph system: the Five-Needle Telegraph. Electric currents travelled from a battery via combinations of 5 wires to electromagnets at the receiving end. These caused pairs of needles to deflect and point at individual letters, and so allowed a message to be sent and read. The Wheatstone telegraph soon evolved to use Morse Code.

Initially the transmitter comprised two telegraph keys. Pressing one sent a current in one direction around an electrical circuit and pressing the other sent a current in the opposite direction. These currents activated electromagnets at the receiver and deflected a single needle to the left or right, indicating dot and dash signals respectively. Although several other types of telegraph evolved, the single-needle telegraph continued in use well into the 20th century, particularly for railway signalling. Later manual telegraphs usually used a single telegraph key.