MANCE, SIR HENRY CHRISTOPHER

born 1840, London, Eng. died April 21, 1926, Oxford, Oxfordshire British scientist and engineer who invented the heliograph, a signaling device that employs two mirrors to gather sunlight and send it to a prearranged spot as a coded series of short and long flashes. Mance joined the Persian Gulf Telegraph Department of the government of India in 1863 and helped lay the first submarine telegraph cables in the Persian Gulf. He also invented the Mance method of detecting and localizing defects in submarine cables. After his heliograph was successfully used during the second Anglo-Afghan War (187880), it was adopted generally by the British army and was widely used in India. It also found extensive use by the U.S. Army in campaigns against American Indians in the southwestern United States. Mance was knighted upon his retirement in 1885.