NAVIGATION. 125 



signals, by providing that every vessel shall not 

 merely sound her steam whistle or fog-horn, but 

 shall do so according to a carefully arranged code 

 of signals, so as to give certain definite useful in- 

 formation as to any change of course she (if a 

 steamer) may be making or be on the point of 

 making, and (if a sailing ship) so as to show the 

 tack on which she is sailing. 



66. This brings me, almost in conclusion, to 

 speak of the communication of information, or 

 orders from ship to ship, by signals. The methods 

 chiefly used are : 



(1) Signalling by flags. This, when worked by 

 very skilful signalmen, as in the Royal Navy, is the 

 most effective method at present in use for signal- 

 ling by day from ship to ship in clear weather. 



(2) For signalling in clear weather by night, 

 Captain Colomb's method by short and long flashes 

 has been successfully used in the British Navy for, 

 I believe, nearly twenty years. It has also been 

 largely used on land by our army, as in the 

 Abyssinian war. It is curious to find in military 

 operations of the nineteenth century a return to a 



