406 POPULAR LECTURES AND ADDRESSES. 



the quarter-second flash recurring every two seconds 

 will be very much more easily and surely picked up 

 practically at sea than a flash of one second recur- 

 ring every eight seconds. 



Before passing from this subject of flashing lights, 

 I may be allowed to say that I first received my 

 impression of the vital importance of quickness in 

 a light from a very practical man the man who, in 

 1866, showed us within a quarter of a mile, in mid- 

 ocean, where to find the cable which had been laid 

 and lost in 1865 Captain Moriarty, R.N. I well 

 remember when on one occasion, either in 1858 or 

 1865, I do not know which, in making the Irish 

 coast in dirty weather, he said 



"Those lighthouses should flash out their 

 characters like your electric signals ; every light- 

 house should flash, and flash, and flash, many times 

 in a minute, showing you which lighthouse it is 

 every time. That long minute of the revolving 

 light has often seemed to me like an age, when I 

 have been anxious to make out where we were in a 

 gale of wind and rain." 



