THE FLAME-MANOMETER. 



395 



In Tand. Z>, the mouth passage is suddenly barred by 

 the application of the point of the tongue to the teeth, 

 or to the front part of the palate; while in K and G 

 (hard, as in go), the middle and back of the tongue are 

 similarly forced against the back part of the palate. 



An interesting contrivance for rendering visible the 

 difference of the vowel sounds, and also for other 

 acoustic experiments, is the gas-flame manometer. The 



FIG. 234 (A real size]. 



most essential part of the apparatus is a capsule, KK, 

 fig. 234, which is composed of two parts. Its interior 

 is divided into two cavities, separated by a very thin 

 membrane, A; into one leads a tube, , to which an 

 india-rubber tube may be attached for conveying sound 

 into the interior; into the other cavity illuminating gas 

 can be conducted by the pipe b ; it issues again from 

 the small tube c, and may be ignited at the extremity 

 of the latter tube. When sonorous vibrations are pass- 



