402 POPULAR LECTURES AND ADDRESSES. 



which there is an interval of eighteen seconds of 

 darkness. These are, no doubt, very admirable and 

 thoroughly distinctive lights ; but it would be very 

 much better if they were made three times as fast, 

 which, with the existing machinery, could, I believe, 

 be easily done. If this were done they would 

 show their flashes each in two-thirds of a second, 

 and with only a second of time between. Thus, 

 the three flashes completed in four seconds would 

 be instantly recognised as a group of three, without 

 the necessity of any counting either of flashes or of 

 numbers of seconds of time in the intervals between 

 the flashes ; and, instead of having to wait in 

 darkness for eighteen seconds, the sailor would 

 only have to wait six seconds for a repetition of 

 the triple flash. 



The Royal Sovereign, the Seven Stones, the 

 Newarp (near Yarmouth, on the east coast), and 

 the Saltees (off the south coast of Ireland), all 

 lightships supplied within the last few years with 

 the Triple Flashing Light, are each of them of one 

 minute period, of which there is thirty-six seconds 

 of darkness, and twenty-four seconds of flashing. 



