162 THE ROYAL SOCIETY OF CANADA 



the "acoustic axis" of the horn, and three were taken out of the axis, 

 at the wharf. Six photographs were obtained of the sounds from a 

 2-inch diaphone operating under various pressures of air and with 

 and without its resonating trumpet. 



Through the courtesy of Lieutenant Colonel W. P. Anderson, 

 Chief Engineer of the Department of Marine and Fisheries, the regular 

 diaphone fog-signal of the Father Point Station was operated as desired 

 for experimental purposes in clear weather, and the pilot boat ^^ Eureka' 

 was made available to carry the phonodeik to the various stations 

 at sea. The Captain and other officers of the ''Eureka' and the 

 engineer in charge of the fog-signal station gave all possible assistance 

 which was most highly appreciated. 



At the time of each phonodeik record at sea. Professor King made 

 observations with the phonometer, and Lieutenant E. S. Bieler made 

 sextant observations for distance. During the observations at sea, 

 Mr. J. Patterson and Dr. A. Norman Shaw made complete meteor- 

 ological observations at the Experimental Station. The operation 

 of the phonodeik, the provision of special facilities, and the photo- 

 graphic operations required much labor in which all of the gentlemen 

 named rendered most enthusiastic and efficient assistance, which is 

 gratefully acknowledged. A general account of the work is given in 

 reports by Professor King and other members of the staff, ^ the fol- 

 lowing report being confined to the anah'tical study of the photo- 

 graphic records of the fog-signals. 



All of the wave forms obtained with the phonodeik ha\'e been 

 completely analyzed and synthesized by the harmonic method, to 

 twenty components, and for the more complex waves, to thirty 

 components. The resonance characteristics of the recording appar- 

 atus as used in the experiments have been determined for the range 

 of frequencies considered, from 87 to 2610, and each separate compon- 

 ent has been corrected for these effects. The results of the analysis 

 are: (1) the actual amplitudes, in millimeters on the photographic 

 film, of each of the twenty (or thirty) harmonic components of the 

 twenty-three curves: (2) the corrected values of these amplitudes, 

 that is, the relative amplitudes of the actual sound waves in air un- 

 affected by the resonance of the phonodeik: (3) the relative phases of 

 these components: and (4) the relative intensities (loudness) of the 

 components, the intensity being àssum.ed as proportional to the square 

 of the product of the amplitude and frequency. (5) Each analysis 



^On the Propagation of Sound in the Free Atmosphere and the Acoustic Efficiency 

 of Fog Signal Machinery: an account of Experiments carried out at Father Point, 

 Quebec, September, 1913. Read before the Roy. Soc, London, June 14ih, 1917. 

 Publication delayed owing to war conditions. 



