Flag semaphore
From Wikipedia, the free encyclopedia
Flag semaphore is a system for conveying information at a distance by means of visual signals with hand-held flags, rods, disks, paddles, or occasionally bare or gloved hands. Information is encoded by the position of the flags; it is read when the flag is in a fixed position. Semaphores were adopted and widely used (with hand-held flags replacing the mechanical arms) in the maritime world in the early 1800s. Semaphore signals were used, for example, at the Battle of Trafalgar. This was the period in which the modern naval semaphore system was invented. This system uses hand-held flags. It is still accepted for emergency communication in daylight or, using lighted wands instead of flags, at night. See also flag signals.
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[edit] Wig-wag flags
Wig-wag signalling (or wigwagging) uses one flag for signalling, in a method similar to semaphore. It was used in US Civil War times. A signal corpsman commonly stood on a platform about 6-10 feet off the gound, signalling to other units. The bright orange red and white flag made a primary target for the enemy.
[edit] Modern semaphore
The newer flag semaphore system uses two short poles with square flags, which a flagman holds in different positions to signal letters of the alphabet and numbers. The flagman holds one pole in each hand, and extends each arm in one of eight possible directions. Except for in the rest position, the flags cannot overlap. The flags are coloured differently based on whether the signals are sent by sea or by land. At sea, the flags are coloured red and yellow (the Oscar flag), while on land, they are white and blue.
[edit] Characters
The following semaphore characters are presented as one would face the flagman:
 Rest / Space |
 Numerals |
 Error |
 Cancel |
 A / 1 |
 B / 2 |
 C / 3 |
 D / 4 |
 E / 5 |
 F / 6 |
 G / 7 |
 H / 8 |
 I / 9 |
 J |
 K / 0 |
 L |
 M |
 N |
 O |
P |
 Q |
 R |
 S |
 T |
 U |
 V |
 W |
 X |
 Y |
 Z |
[edit] Japanese semaphore
The Japanese merchant marine and armed services have adapted the flag semaphore system to the Japanese language, as shown in Japanese here. Because their writing system involves a syllabary of about twice the number of characters in the Latin alphabet, most characters take two displays of the flags to complete; others need three and a few only one.
The flags are specified as a solid white square for the left hand and a solid red one for the right. The display motions chosen are not like the "rotary dial" system used for the Latin alphabet letters and numbers; rather, the displays represent the angles of the brush strokes used in writing in the katakana syllabary and in the order drawn.
For example, the character for "O" [オ], which is drawn first with a horizontal line from left to right, then a vertical one from top to bottom, and finally a slant between the two; follows that form and order of the arm extensions. It is the right arm, holding the red flag, which moves as a pen would, but in mirror image so that the observer sees the pattern normally. As in telegraphy, the katakana syllabary is the one used to write down the messages as they are received.
Also, the Japanese system presents the number 0 by moving flags in a circle, and those from 1 through 14 using a sort of the "rotary dial" system.
[edit] References in popular culture
An episode of Monty Python's Flying Circus depicts a supposed dramatic production of Wuthering Heights in flag semaphore.
In the same episode of Monty Python's Flying Circus, they use an aldis lamp in a parody of Shakespeare's Julius Caesar, with Caesar signaling, "E tu brute!"
In the short story for kids, "The Mystery of the Seven Wrong Clocks" (published in Alfred Hitchcock's Solve-Them-Yourself Mysteries, edited by Robert Arthur, Jr., Random House 1963), a soon-to-be murder victim identifies his murderer using the hands of clocks set in semaphore positions.
An episode of Due South features the use of semaphore communication between two Royal Canadian Mounted Police (RCMP) officers during a hostage crisis. They did not use flags.
In the book Winter Holiday by Arthur Ransome, Nancy sends secret messages to the other children by means of a picture in which the people's arm positions represent semaphore letters.
In a strip, the webcomic Sam and Fuzzy portrays one of the two titular characters, Fuzzy, using flag-based semaphore to convey a message he has been expressly (and legally) forbidden to repeat.
The Beatles' album cover Help! (1965), according to photographer Robert Freeman, was originally going to show the Beatles signaling the word HELP in semaphore. However, if read according to the code, George signals an "N" or maybe an "R" or "S", John a "U", Paul a "J", and Ringo a "D", "V", or "Cancel". The images on the US album are out of order, and all of the pictures are mirror-reversed. In the UK order, and reversed, the message appears to spell "LPUS." Freeman has stated that the letters "H-E-L-P" did not look good, graphically. Apparently "LPUS" ("help us") was used as a better-looking substitute (see Freeman, The Beatles: a Private View, p.62).
The peace symbol is a combination of the semaphoric letters N and D, standing for "nuclear disarmament."
In the April 1 RFC of 2007, the IETF proposed a way to transmit Internet traffic via semaphores, thus connecting the "Victorian Internet" and the current-day one.
In the movie "The Last Detail" starring Jack Nicholson and Randy Quaid, Nicholson plays a signalman in the US Navy who teaches semaphore to Quaid while escorting him to military prison. Quaid signals: "Bravo Yankee, Bravo Yankee, end of message" before attempting an escape.
[edit] See also
- Flagging dance
- Heliograph
- International maritime signal flags
- Railway signalling
- Semaphore line
- Signal lamp
- Semaphore Flag Signaling System
[edit] External links
- RFC 4824 The Transmission of IP Datagrams over the Semaphore Flag Signaling System (SFSS)
