■105 



Guye's Iiearing apparatus tested in the camera silenta (its 

 reinforcement compared with a funnel whose width is nine 

 times smaller). 



average 18 



N.B. Considering the size of the receiver of Guye's apparatus 

 we could have looked only for a ninefold reinforcement. 

 The actual reinforcement, however, is eighteenfold. This 

 is accounted for partly by the shorter distance from the 

 sound-generator to the measuring apparatus, to a great 

 extent it is attributable also to resonance. 



Reinforcing influence of German hearing-apparatus (pleophone 



nO. 2). The receiver has- the same width as the comparison 



funnel. (21 cm2). 



Measurement in an ordinary room. 



N.B. Average reinforcement 7,8 times. However, not nearly so 

 regular as in Guye's apparatus. 



