,086 



iiKl'oitT — 1H84. 



\ 



-Iff 



Triple flashing. 



(Quadruple flasliin<;. 



i)oTiblo ttasliini^ — I white ami 1 red. 



Triple flashing — 2 white and 1 red. 



Quadruple flashing — :» white and 1 red. 



(Quintuple HaHhing — |. white and I red. 



It would appear to bo doubtful whether so limited a code would he 

 found to be snllieient for ellieiently covering any iniporlant extent of const, 

 and es{)ecially where opposite coiists and niid-cliannel shoals are required 

 to b(! lighted. 



For the most eflicient lighting of a coast, tho revolving, or more 

 properly named flashing, class of lights demand tiie flrst consideration, 

 on account of their sujierior intensity and penetrative power as compared 

 ■witii the fixed or occulting class, 'hie fact of being able to obtain (rom 

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

 the illuminating material is of itself a very important consideration, 

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

 aspect of relative efficiency for the benefit of tho mariner, it is impossibk; 

 io over-estimate its real vidue, although hitherto its importance does not 

 appear to have been fairly rceognis(;d. 1'he number of coast signals 

 throughout the world is about -IjilOO. Of tliese about 80 per cent, arc 

 fixed lights, 1\) per cent, only are flashing lights, and 1 per cent, only 

 are (jcculting lights. On the extensive sea coasts of the Dominion of 

 Canada there are abont '.i71 coast light .signals : of tliese about 78 per 

 cent, aro 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 J louse, if wo except the double 

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

 represent oidy IG per cent., while the flashing lights represent 04 jicr 

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

 that in the course of another year there will not i-emain a single fixed 

 light in the service of tho Trinity House. 



On Plate V. aro shown two al]»habctical codes of flashing lights, 

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

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

 short and long flashes aro adopted in the first code, and wiiite and rtd 

 flashes in the second code. The signals A, ^I, O, R, and T, in the first- 

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

 by tho Trinity House. With the.se sigiuils a period of half a minute has 

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

 generally satisfactoiy to the mariner. It has the imjiortant advantagi; 

 over shorter periods of a greater intensity of the flashes accumulated 

 during the longer eclipse ; and it is lo bo remembered that the optical 

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

 absolutely necessarj% for two reasons : first, to avoid unnecessary wear 

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

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

 some of the largest appai-atus, 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 sit^hting 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 abont 10 seconds. It 



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