VII. MUSICAL INSTRUMENTS. 191 



For the action of heated air, the rectangular chamber is turned upside 

 down upon its support, and the heated air from six gas jets allowed to stream 

 in through six narrow openings across the sound waves. The air thus 

 rendered heterogeneous has the effect of immediately rendering the sensitive 

 flame quiescent. Phil. Trans., 1874. 



739. Diagrams and Apparatus illustrating the reflection 

 and refraction of sound-bearing waves, as exhibited to a class by- 

 means of a sensitive flame. Prof. W. F. Barrett. 



The arrangement shows a suitable source of sound, a good form of gas 

 pillar for yielding a tranquil flow of gas to the burner, and the best shape 

 and size of steatite burner for the flame, together with a useful form of gas-- 

 holder for giving steady pressure of gas larger than that usually given by the 

 street mains. 



These experiments \vere first shown by the exhibitor in connexion with a 

 paper read by him before the Royal Dublin Society in Jan. 1868. See 

 Quarterly Journal of Science, Jan. 1870. 



VI. RESONATORS. 



740. Resonator of adjustable pitch. Lord Rayleigh 



Resonator, whose pitch can be rapidly adjusted to the various notes of a 

 harmonic scale A';> , a[? , e;> , a't? , e". The smallest hole is made first and 

 adjusted until the resonator responds a[> . The second hole is then made and 

 adjusted, until, with both holes open, the note is dj . Similarly with three holes 

 the note is a'^ , and with four holes e". When the note Aj? is sounded on the 

 piano or harmonium, and the resonator is suitably fingered, the various 

 overtones are heard with great distinctness, and the phenomenon is more 

 marked than usual in consequence of the contrast afforded by the rapid 

 transition. 



740a. Sonorous Tubes, by Dulong. 



Polytechnic School, Paris* 



741. Six Resonators of glazed cardboard, for the sounds: 

 c' (256 vibrations), e 7 (320 vibrations), g' (384 vibrations), 

 c"(512 vibrations), e" (640 vibrations), g" (768 vibrations). 



Gustav Schubring, Erfurt. 



VII. MUSICAL INSTRUMENTS. 



742. Enharmonic Harmonium, with generalised key- 

 board ; 84 keys in each octave ; compass, 4-| octaves. 



R. H. M. Bosanquct. 



This instrument is tuned according to the division of the octave into 53 

 equal intervals, a system sensibly identical with a system of perfect fifths. 



