The New Student's Reference Work/Semaphore

Sem′aphore. This is an apparatus for visible telegraphy by means of flags, lanterns or similar signals. It is employed in connection with the block-system (q. v.) on railroads and at sea by means of flags. Different combinations of the flags, lanterns or movements of signal-arms may serve to indicate the different letters of the alphabet. Sometimes they are used to indicate numbers. Semaphores are of importance not only to indicate the movements of trains and shipping; but in war-signaling, when special codes are employed.