Charles Wheatstone#Cooperation with Cooke

The needle telegraph is a historic telegraph apparatus, which was developed for use as a compatible device in 1837 by Charles Wheatstone and William Fothergill Cooke. First preliminary work made ​​1835 Paul Ludwig Schilling of Cannstatt and Georg Wilhelm Munke whose structures but found no practical use. The needle telegraph represents one of the first reliable telegraph equipment and was first used in 1838 on the 21 km long railway line of the Great Western Railway between London and West Drayton.

Construction

The needle telegraph is a precursor to two years later developed by Wheatstone and Cooke pointer telegraph dar. It consists of five horizontally mounted needles and has a diamond-shaped display panel, as shown in the right figure. The five needles are driven from the transmitting station from a plurality of individually switch: In the rest position, the needles are aligned vertically, by positive or negative current pulses, a needle of about 30 degrees to the right or left side are rotated. There are always two needles at the same time controlled, the intersection of the imaginary extension line of the needles is the transmitted letters represent: it can ensure that the 20 most common letters are telegraphed from the alphabet. For the transmission of the letter A, the left needle is rotated to the right and rotated the right needle to the left: The intersection of the imaginary extension is then up to the letter A at the top position of the display panel.