DUANE— SIGHT AND SIGNALLING IN THE NAVY. 401 



are emploved. These elements are combined according to the In- 

 ternational Morse System to form letters ; and a succession of such 

 letters may form an arbitrary combination to be interpreted by the 

 Nav}' Code. 



Methods of Signalling. 

 The methods used in navy signalHng are as follows : 



(a) Motions. 

 Wig-wag (movement of flag, torch, search-light, or other object 

 from side to side). 



{h) FlasJics of Light. 

 Flash lantern and winker light. 



(c) Colors, Fixed or Moving. 

 Display of colored and white lights (usually several in one display) 



(Ardois Method). 

 Projection into the air of rockets or red and green stars (Very 



Method). 

 Coston and other lights. 



{d) Forms. 

 Cone, top, and drum. 

 Square flag, pennant, and ball. 

 Semaphore. 



{e) Forms and Colors. 

 Hoists of colored flags. 



(/) Sounds. 

 Steam whistle, bell, gunfire. 

 Telegraph (usually wireless). 



Systems of Signalling. 



The systems commonly used in naval signalling are these : 



Dot-Dash System. — Comprises two or usually three elements,^ 



viz.. right, left, and front motions (Wig-wag) ; short, long, and 



extra long flashes (Winker Light, Heliograph) ; red and white lights 



(Ardois) ; red and green stars and rocket (Very Method) ; short, 



long, and extra long (or single, double, and triple) sounds (Sound 



1 Really in these systems there is a time interval (between letters) wliich 

 constitutes a fourth element. 



