Knowra Flag semaphore Flag semaphore Flag semaphore is a visual signaling system in which a person holds two flags at distinct angles to represent letters, numbers, or operational messages.
Semaphore alphabet : A set of flag positions, usually arranged around a signaler’s body, that encodes letters and numerals. Its angular positions are the basic symbols used to spell flag-semaphore messages.
Chappe semaphore : A late-eighteenth-century French optical telegraph that transmitted messages using movable arms on towers. It belongs to the broader semaphore tradition from which hand-flag signaling drew its name and principle.
Naval signaling : The exchange of information among ships or between ships and shore using agreed signals. Flag semaphore is one visual method used to pass messages between vessels.
Wigwag signaling : A military visual signaling method that uses one flag moved in different directions to encode symbols. It uses one flag and directional motions, unlike semaphore’s two flags held at set angles.
Optical telegraph : A long-distance communication system that transmits messages through visible signals relayed between stations. Flag semaphore carries the same principle of encoded visual signals, but usually without fixed relay towers.
Claude Chappe : A French inventor who developed an optical telegraph network during the French Revolution. His tower-based system established a prominent model for visual message transmission before modern telecommunications.
Maritime communication : The transmission of information among ships, shore stations, and maritime authorities. Semaphore operates within this broader communication environment, especially for short-range visual exchange.
Maritime signal flags : Flags displayed singly or in combinations to convey standardized maritime meanings. These signals rely on flag identity and combinations, not a person’s arm positions.
Line of sight : An unobstructed straight path between two points, required for direct visual communication. A flag signal cannot reach its intended observer when terrain or buildings block the view.
Royal Navy : The United Kingdom’s naval warfare service, with a history extending to the sixteenth century. Naval fleets adopted flag signaling to exchange orders between ships at sea.
Show all 19