DUAXE— SIGHT AND SIGNALLING IN THE NAVY. 403 



ing as letters, but would denote the message "Ship disabled; will 

 you tow me ? " 



The following codes are used : 



Alphabetic Codes. — Unless notice by special signal is given to 

 the contrary, all messages sent by wig-wag, Ardois, telegraph, winker 

 light, and semaphore are spelling messages. All of these are inter- 

 preted by the International ]\Iorse Code except the semaphore, and 

 this is read by the semaphore code. In certain cases the flags of 

 the International System may also have their alphabetic meaning 

 and be used to form spelling messages. 



Signal-Book Codes. — All messages sent by flag hoist, shapes, 

 steam-whistle, and Very stars, and occasionally- messages sent by 

 other methods are code messages, to be interpreted by special signal 

 codes. These signal codes are the — 



Intenmtional Code used with the International Flag Hoist. It 

 includes the slightly variant code used with shapes for sending In- 

 ternational Distance Signals. 



Navy Code used with flag hoist, shapes, steam whistle, and Very 

 stars. The regular Navy Code includes battle signals, general sig- 

 nals, boat and deck signals, and speed signals. To these may be 

 added the towing, running, and riding lights (International), buoy 

 and lighthouse signals (U. S.), storm signals, and the various offi- 

 cers' and national flags. 



Of course a message, whether a spelling or code message, may 

 be transformed by cipher, previously agreed upon or denoted by the 

 signal sent. 



What a Signalman Has to Do. 



The signalman must have an intimate working knowledge of 

 eight difl:'erent methods of signalling (by wig-wag, light flash, Ar- 

 dois, Very stars, sounds, shapes, semaphore, and flag hoist) to be 

 used according to six different systems. He must know with abso- 

 lute certainty the signification (often multiple in each case) of some 

 30 combinations of right and left movements, 30 combinations of 

 red and white lights displayed over one another, 30 combinations of 

 red and green stars projected into the air, 30 combinations of short 

 and long flashes or of short and long sounds, 30 different positions 



-When preceded hy the special call meaning "signals follow." 



