^86 itEPOKT — 1884. 



Triple flashing. 



Quadruple flashing. 



Double flashing — 1 white and 1 red. 



Triple flashing — 2 white and 1 red. 



Quadruple flashing — 3 white and 1 red. 



Quintuple flashing — 4 white and 1 red. 



It would appear to be doubtful whether so limited a code would be 

 found to be sufficient for efficiently covering any important extent of coast, 

 and especially where opposite coasts and mid-channel shoals are required 

 to be lighted. 



For the most efficient lighting of a coast, the revolving, or more 

 properly named flashing, class of lights demand the first consideration, 

 on account of their superior intensity and penetrative power as compared 

 with the fixed or occulting class. The fact of being able to obtain from 

 three to seven times the intensity of light with the same expenditure of 

 the illuminating material is of itself a very important consideration, 

 even when judged on its economic merits ; but, when considered in its 

 aspect of relative efficiency for the benefit of the mariner, it is impossible 

 to over-estimate its real value, although hitherto its importance does not 

 appear to have been fairly recognised. The number of coast signals 

 throughout the world is about 4,900. Of these about 80 per cent, arc- 

 fixed lights, 19 per cent, only are flashing lights, and 1 per cent, only 

 are occulting lights. On the extensive sea coasts of the Dominion of 

 Canada there are about 371 coast light signals : of these about 78 per 

 cent, are fixed lights, 20 per cent, flashing lights, and 2 per cent, 

 occulting lights. With regard to the signal lights on the coast of 

 England under the control of the Trinity House, if we except the double 

 fixed lights used as leading lights and for distinction, the fixed lights 

 represent only 16 per cent., while the flashing lights represent 64 per 

 cent, and the occulting lights 20 per cent, of the whole. It is probable 

 that in the course of another year there will not remain a single fixed 

 light in the service of the Trinity House. 



On Plate V. are shown two alphabetical codes of flashing lights, 

 nearly all of which can be produced by existing forms of optical ap- 

 paratus, which is an important consideration. It will be observed that 

 short and long flashes are adopted in the first code, and white and red 

 flashes in the second code. The signals A, M, O, R, and T, in the first 

 code, and the signals A, T, and U in the second code, have been adopted 

 by the Trinity House. With these signals a pei'iod of half a minute has 

 been adopted, as shown on the diagram, and this period is found to be 

 generally satisfactory to the mariner. It has the important advantage 

 over shorter periods of a greater intensity of the flashes accumulated 

 during the longer eclipse ; and it is to be remembered that the optical 

 apparatus of large coast lights should not be rotated faster than is 

 absolutely necessary, for two reasons : first, to avoid unnecessary wear 

 and tear ; and second, to reduce as far as practicable the labour required 

 of the light-keeper in winding up the driving clockwork, which, with 

 some of the largest apparatus, forms the heaviest portion of his duty. 



It is an important requirement of any coast signal that the flash or 

 group of flashes given in quick succession occupy not less than 6 to 10 

 seconds, to enable a mariner, on first sighting the light, to determine 

 on the instant his correct position by a compass bearing. In the proposed 

 codes the mean duration of the groups of flashes is about 10 seconds. It 



