Flag semaphore

Flag semaphore is a visual communication system used to convey information over long distances. The name comes from the Ancient Greek words for "sign" and "bearer." It works by using hand-held flags, rods, disks, or paddles to create signals. Information is encoded through the specific positions of these objects. A receiver reads the message when the flags are held in fixed positions. This method is vital when sound cannot travel easily, such as across large bodies of water or through mountains.

The mechanism of the current flag semaphore system is quite precise. A signal person holds one short pole with a square flag in each hand. The signaler can extend each arm in one of eight possible directions. To ensure the message is clear, the flags do not overlap unless they are in the rest position. The colors of the flags change depending on the environment. At sea, the "Oscar flag" uses red and yellow colors. On land, the "Papa flag" uses white and blue. These bright colors make the characters much easier to see from a distance.

Communicating a full message requires following a specific protocol of signals. To start, the sender uses an "Attention" signal to ask for permission to transmit. The receiver must then grant permission by raising both flags vertically overhead and dropping them to the rest position once. To signal letters, the sender first signals the letter "J." To signal numbers, they must first signal "Numerals." Once the message is finished, the sender uses a "Ready to receive" signal. The receiver can then reply with an "Attention" signal, at which point the two people swap roles.

History shows that flag semaphore was an adaptation of older technology. It originated in 1866 as a handheld version of the optical telegraph system. Home Riggs Popham used an earlier land-based system consisting of fixed stations. Those stations used large, moveable arms pivoted on upright members. Because those mechanical arms were difficult to install on ships, the handheld flag version was created. Charles Pasley later provided improvements to these telegraph systems. Some evidence suggests Popham based his original telegraph on French coastal stations used for ship-to-shore communication.

Different cultures have adapted the system to fit their specific languages. The Japanese merchant marine and armed services use a version of semaphore for the Japanese language. Because the Japanese writing system uses a syllabary with about twice as many characters as the Latin alphabet, the signals are more complex. Most characters require two flag displays, while others need three. Some only require one. In this system, the left flag is a solid white rectangle and the right flag is solid red. Instead of a "rotary dial" motion, the arm movements represent the angles and order of brush strokes used in katakana writing.

For example, the Japanese character for "O" [オ] follows the specific order of its written form. It is drawn with a horizontal line, then a vertical line, and finally a slant. The signaler mimics this by moving the right arm, which holds the red flag, as if it were a pen. The observer sees the pattern normally because the movements are a mirror image. While the Latin alphabet uses a rotary system for numbers, the Japanese system uses a different method. For instance, the number 0 is signaled by moving the flags in a circle.

Beyond military and maritime use, semaphore has left a mark on art and culture. The famous peace symbol was designed in 1958 by artist Gerald Holtom. He used the semaphore positions for the letters "N" and "D," which stood for "nuclear disarmament." This symbol was first carried on a protest march in April 1958. Semaphore has also appeared in popular media. The Beatles' 1965 album *Help!* almost featured the band members spelling the title in semaphore. It is also used in literature, such as the *Swallows and Amazons* series by Arthur Ransome. Today, the US Navy still uses semaphore, and it remains a subject of study for Scouts.