Engraving by G Bartlett showing the two-needle telegraph, a descendant of the five-needle telegraph, invented in 1837 by William Fothergill Cooke (1806-1879) and Charles Wheatstone (1802-1875). Unlike its direct-reading predecesor, the two-needle telegraph needed a skilled operator, but gave faster signalling with lower installation costs. It was first used on the Great Western Railway's extension from West Drayton (on the outskirts of London) to Slough in Berkshire in 1843. In 1845, this instrument received a mesage that led to the arrest of a notorious murderer and gave the telegraph widespread publicity. By 1845, several other railway companies had begun installing their own telegraph systems.
© Science Museum / Science & Society Picture Library