3479983 Cooke & Wheatstone\'s double needle telegraph, 1850; (add.info.: Cooke & Wheatstone\'s double needle telegraph. The letters of the alphabet and a variety of conventional signals; were indicated by single and combined movements of the galvanometer needles. The operator worked the instrument by manipulating the two handles at the bottom and an alarm bell was housed in the upper casing and was used to signal the beginning of a message.); Universal History Archive/UIG; out of copyright.