402 DUANE— SIGHT AND SIGNALLING IN THE NAVY. 



Signals). Two of the elements are combined to form letters accord- 

 ing to the International Morse Code, and if there is a third, this is 

 used to form an interval or make some special signal. 



Semaphore System. — Comprises 8 elements, viz., the eight posi- 

 tions of each of the two arms of the semaphore (or the two arms of 

 a man). Combinations of these according to a special code form 

 the various letters of the alphabet and special signals. 



International Hoist. — Comprises 27 elements (flags denoting 26 

 letters of the alphabet and one answ^ering or code pennant). 



Naz'v Hoist. — Comprises 45 elements, viz., the 26 alphabetic flags 

 of the International System and 19 others (repeaters, guide, recall, 

 position, etc.) 



International Distance System. — Comprises 4 elements, viz. cone, 

 top (inverted cone), drum, ball. (A square flag may be used for 

 cone, pennant for top, a pennant tied back to halHards or a flag tied 

 in the middle for a drum.) These combined according to a special 

 system form letters and special signals. 



Naz'v Distance System. — Comprises 3 elements, viz., cone, top, 

 and drum. These combined according to a special system form 

 letters and special signals interpreted by the Navy Code. 



Signal Codes. 



Signal codes are divided into two great classes. Alphabetic and 

 Signal-Book Codes. In an Alphabetic Code the letters or digits in- 

 dicated by the special system employed have their actual value as 

 letters or digits, and are further combined to form words and num- 

 bers just as they are in ordinary writing — to form,. in other words, 

 what we may call spelling messages. In a Signal-Book Code, the 

 letters indicated by combining the elements in the system used are 

 mere indexes referring to special messages or words contained in a 

 code-book. Thus the elements i, 2, 3, of the dot-dash system, when 

 used in its ordinary way as an alphabetic code, would if combined 

 thus, 22 2122 3, denote the actual letters M Y, spelling the word 

 ]\IY. But the same letters whether sent by the Dot-Dash System, 

 the International Flag System, or the International Distance Sys- 

 tem would, if interpreted by the International Code, have no mean- 



