[king] fog signal researches 113 



to be the only satisfactory one in practice. From a thermal test 

 combined with an analysis of a phondeik record complete information 

 as to the performance of a fog-alarm may now be obtained. For 

 instance, it is possible to state in horse-power or watts the total 

 acoustic output of a siren as well as to compute the relative proportions 

 of power contained in the master tone and in the overtones. That this 

 may be done as a shop testis of great importance, as a designer will now 

 be able to predetermine the behaviour of fog-signal apparatus without 

 depending on tests carried out with the equipment installed at great 

 cost at some station by the sea. It is to be expected that, with such 

 methods of testing available, the development and improvement of 

 fog-sirens will be much more rapid than in the past. 



It is evident from these results that improvement in the design 

 of aerial sound generators offers large field for scientific effort, not 

 only with regard to economy of power, but also in the provision of 

 less costly and more numerous fog-signal installations as additional 

 aids to navigation in the neighbourhood of fog-infested shores. 



Although submarine sound-signalling and automatic methods of 

 radio-telegraphic signalling are rapidly being introduced as aids to 

 navigation near rocky coasts, the need for powerful and efficient aerial 

 fog-signals will be felt for many years to come in the interests of small 

 ships unprovided with means of availing themselves of the first two 

 methods. In the writer's opinion, scientific concentration on these 

 problems with adequate facilities for experimental work at sea would 

 in a few decades more than repay the expenditure incurred through a 

 reduction of the yearly toll in lives and property resulting from acci- 

 dents at sea. 



