and J^istrilmtion of Sound. 305 



that D, E, F, G were effective sources of sound, and were in 

 tact more powerful than the open ends A, B, as was to be 



Flo-. 2. 



Sect/ ON throc/gh G 



IVooo 



expected. The half wave-length of the actual sound was 

 8 inches, showing that the '' openness ^^ of the pipe at D, E, 

 F, G was rather imperfect, owing to the smallness of the 

 holes. Still the apparatus afforded a combination of six 

 sources of sound, all in the same phase and at about half a 

 wave-length apart. 



The observations were made upon a lawn ; and, as the 

 sound was rather feeble, a very moderate distance sufficed. 

 When A B was vertical, the sources cooperated and the 

 maximum sound was heard. But when A B was moved 

 away, so as no longer to be perpendicular to the (horizontal) 

 line of observation, the sound was less, a de^dation of 30° 

 causing a very great falling off. The effect was as if the 

 sound had suddenly gone away to a great distance. The 

 success of the experiment no doubt depended a good deal 

 upon the absence of over-tones, a condition of things favoured 

 by the feebleness of the sound and also by the high pitch. 

 Terling Place, Witham, 

 July 21, 1903. 



FUl. Mag, IS. 6. Vol. 6. No. 33. Se^t. 1903. X 



