Needle telegraph
The needle telegraph is a historical telegraph device which was developed as a usable device in 1837 by Charles Wheatstone and William Fothergill Cooke . Paul Ludwig Schilling von Cannstatt and Georg Wilhelm Munke carried out the first preparatory work in 1835 , but their designs were not used in practice. The needle telegraph is one of the first reliable telegraph apparatus 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 forerunner of the pointer telegraph developed two years later by Wheatstone and Cooke . It consists of five horizontally attached needles and has a rhombus-shaped display plate , as shown in the illustration on the right. The five needles are controlled individually from the transmitter station using several buttons: In the rest position, the needles are aligned vertically; positive or negative current pulses can turn a needle by approx. 30 degrees to the right or left. Two needles are always activated at the same time, the intersection of the imaginary extension line of the needles represents the transferred letter: The 20 most common letters from the alphabet can be telegraphed with it. To transmit the letter A , the left needle is turned to the right and the right needle is turned to the left: The intersection of the imaginary extension is then at the letter A at the top position of the display panel.
Individual evidence
- ↑ Cooke and Wheatstone five-needle telegraph ( Memento of the original from July 5, 2012 in the Internet Archive ) Info: The archive link was inserted automatically and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. , Science Museum, London, engl.
literature
- Anonymous: Varley's needle telegraph with induced magnetic needle. In: Polytechnisches Journal . 199, 1871, p. 175.
