Section III, 1918 [I6i] Trans. R.S.C. 



The Analysis of Photographs of Fog Signals Obtained with the Phonodeik 



By Daytox C. Miller, D.Sc, Professor of Physics, Case School 

 OF Applied Science, Cleveland 



Presented by Professor Louis \'. King, D.Sc. ,F. R.S.C. 



(Read May Meeting, 1918) 



In September, 1913, t.he acoustic efficiency of fog-signal machinery 

 was investigated by Professor Louis V. King of McGill L'niversity, 

 at Father Point, Quebec. In September, 1917, these investigations 

 were continued under a grant from the Advisory Council for Scientific 

 and Industrial Research, with the co-operation of the Department 

 of Marine and Fisheries of the Canadian Government.^ On the latter 

 occasion, upon invitation of Professor King, the writer joined the 

 temporary staff of five members at the Father Point Station for the 

 purpose of making photographs of fog-signals with the "Phonodeik." 

 This instrument is an apparatus devised by the writer in 1908 in which 

 the wave form corresponding to a sound may be photographically 

 recorded in a form suitable for quanti tati\'e analysis; it has been fully 

 described in "The Science of Musical Sounds,"- and consists essentialh- 

 of a sensitive diaphragm, with a collecting horn. The vibra- 

 tions of the diaphragm are mechanically transmitted to a small 

 mirror and recorded by a spot of light on a moving photographic film. 

 The apparatus can be made very sensitive by tuning the resonance of 

 the horn, but in these observations there was no such tuning, and 

 only a moderate sensitiveness was used. 



Twenty-three photographs of sound waves were obtained, which 

 form the basis of this report; fourteen of these are of the sound from 

 the regular fog-signal, a 4-inch Diaphone, taken at points over the 

 Avater at Aarious distances directly in front of the horn, that is, on 



^On the Acoustic Efficiency of Fog Signal Machinery: Louis V. King, Journal 

 oj the Franklin Institute, March, 1917, pp. 259-286. 



^The photographic study of sound waves: Dayton C. Miller, "The Science of 

 Musical Sounds," New York (1916); the Phonodeik, pp. 78-88; practical analysis 

 and synthesis, pp. 92-141, bibliography on analysis and synthesis, pp. 272-277; 

 correcting records of sound waves, pp. 142-166; graphic presentation of analyses, 

 pp. 166-174. Brief accounts of the phonodeik are given in Proceedings of the British 

 Association for the Advancement of Science, Winnipeg (1909) p. 414, and Dundee 

 (1912) p. 419, and of the methods of correcting analyses for resonance in Proceed- 

 ings of the Fifth International Congress of Mathematicians, Cambridge (1912), 11, 

 pp. 245-249. 



