446 



PHYSIOLOGICAL PHYSICS, ichap. xxxm. 



covering the aperture in the pipe. To the front of the 

 box are connected two narrow tubes, to one of which 

 an indiarubber tube, conveying gas, is 

 attached, to the other a small _J -shaped 

 tube terminating at the upper extremity 

 in a fine point m. Gas enters the little 

 chamber by one tube and leaves by the 

 other, at which it is lighted, and a fine 

 tongue of flame is produced. Now at 

 the centre of the pipe, sounding its 

 fundamental note, the greatest changes 

 in density will occur. When the density 



Fig. 193. Organ . , J , ., . -,. ,, n ,-, J 



Pipe. is greatest the mdiarubber wall or the 



gas chamber will be forced outwards 

 from the organ-pipe, and when, the density is least it 

 will be forced inwards by the pressure of the outer 

 air. Agitations of the gas in the chamber will be pro- 

 duced, and agitations of the flame. Experiment con- 

 firms this, for the flame may be extinguished when 

 the note of the pipe is sounded. If other gas 

 chambers be connected with the pipe towards either 

 extremity, the flames will be affected, but not nearly 

 to the same extent. 



The analysis of sound. By means of such 

 gas jets as have been described, and with the aid of 

 resonators of Hehnholtz, an analysis of a complex 

 sound may be made. Fig. 194 shows Koenig's appa- 

 ratus for the analysis of a compound tone, by means 

 of manometric flames. It consists of eight resonators, 

 the largest vibrating with 256 vibrations per second, 

 ut 2 (do 2 ) ; and of the first seven of its harmonics, 

 numbers 1 (ut 3 ), 2, 3, 4, etc. From the narrow 

 aperture of each resonator a narrow indiarubber tube 

 leads to a small chamber divided into two by an 

 indiarubber partition. The air on one side of this 

 partition is in communication with the air in the 

 resonator. On the other side of the partition is gas, 



