4 THE ROYAL SOCIETY OF CANADA 



Since 1913 I have been engaged on the problem of applying the 

 science of measurement to the production of sound by various types 

 of fog signal apparatus. Recent work has been carried out under the 

 auspices of the Honorary Advisory Council for Scientific Research. 

 In Bulletin No. 2, published by this body in 1918, I have summarized 

 recent achievements in this direction as follows : — 



"To sum up the results achieved by the tests referred to above, it 

 may be stated that methods of measuring sound quantitatively and 

 qualitatively have been developed and tested in practice. The 

 acoustic characteristics of a siren may now be determined with fair 

 accuracy in absolute measure, whereas, previous to these experiments, 

 an almost complete ignorance existed on these points. Measurements 

 of the intensity of the master tone may now be carried out at distances 

 of several miles and the influence of meteorological condition on the 

 propagation of sound may be studied in the light of accurate data. 

 These achievements conclude an important chapter in practical 

 acoustic engineering. The next step is to bring these results to bear 

 on the improvement of fog-signal machinery. In spite of war con- 

 ditions, several inquiries from engineering firms and makers of fog- 

 signal apparatus have been received by the writer for information 

 on points connected with the measurement of sound. It is evident, 

 however, that rapid progress in the design of such apparatus can be 

 made only by the organization of a well-equipped experimental station 

 or laboratory under Government auspices. Not only could the actual 

 construction of new sound-generating apparatus be undertaken along 

 lines suggested by the results of tests on existing sirens, but the 

 machines and designs of various makers could be subjected to com- 

 parative tests and recommendations made with a view to their amelio- 

 ration. It has been stated that development of the diaphone in 

 recent years in the matter of power has already led to a noticeable 

 diminution in the annual loss of lives due to fog at points where the 

 more modern types have been installed. There is no reason why 

 further progress should not be made in this direction. 



"It has been proposed to issue fog-signal warnings by submarine 

 acoustic signals, and the results achieved in this direction in the 

 United States lend support to the view that audible signals may be 

 generated more efficiently and will travel with more certainty and to 

 greater distances in water than in air. The attention paid to the 

 development of anti-submarine devices as a result of the war, has led 

 to the invention of extremely sensitive receiving microphones. As 

 soon as these achievements in submarine acoustics shall have been made 

 public, their application to navigational problems of all kinds should 



