Semaphore line

A semaphore line is an installation used to send optical signals. It is also known as optical telegraph. Common system include signal towers with special installations on them or hand-held flags. The meaning of the signal is determined by the position of the elements, for example the flags. The signal can be read when it is in a stable position. In modern usage, it refers to signalling with a set of flags.

Signal towers came before the electric telegraph. They were faster than sending out post riders with the information.

• 
  Optical telegraph of Claude Chappe on the Litermont near Nalbach, Germany.
• 
  Diagram of person holding 2 semaphore flags as letter "P"
• 
  A Chappe semaphore tower near Saverne, France
• 
  A Chappe semaphore telegraph at Louvre, France

Characters

The following semaphore characters are presented as one would face the flagman:

• 
  Rest / Space
• 
  Numerals
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  Error
• 
  Cancel
• 
  A / 1
• 
  B / 2
• 
  C / 3
  Acknowledge
• 
  D / 4
• 
  E / 5
• 
  F / 6
• 
  G / 7
• 
  H / 8
• 
  I / 9
• 
  J
  Letters
• 
  K / 0
• 
  L
• 
  M
• 
  N
  Negative
• 
  O
• 
  P
• 
  Q
• 
  R
• 
  S
• 
  T
• 
  U
• 
  V
• 
  W
• 
  X
• 
  Y
• 
  Z

Related articles

• Railway semaphore signal