A. M. Mayer — Researches in Acoustics. 



13 



disk of the siren and by opening one or another of the various 

 circles of holes in the drum. A, I had the means of obtaining 

 a considerable range in the numbers of interruptions of sounds 

 per second. 



The results given by this apparatus were the same as those 

 obtained with (A), but the objection to its action is the produc- 



^> ft 



n 



Fig. 10. 



tion of sounds by the apparatus itself, caused by the rotation 

 of the perforated disk. These sounds distracted the attention 

 from the phenomenon of the continuous sensation produced 

 by the interruptions of the sound from the fork and so masked 

 it that I consider this apparatus the least efficient of any I 

 have described. 



These experiments on the blending of interrupted sounds 

 are not pleasant to make. The ear soon becomes fatigued and 

 the perception of sound is dulled. After an experiment the 

 ear has to be rested during a considerable time before the 

 experiment can be repeated satisfactorily. Thus much time is 

 consumed and these experiments cannot be made in a few 

 days, but weeks are required to arrive at satisfactory measures ; 

 also considerable time is consumed in gaining mastery over 

 the apparatus. To make these experiments less tedious, fatigue 

 of the ear is to be avoided. This is done b}^ not allowing the 

 interrupted sounds to enter the ear longer than during two or 

 three seconds, then a rest of 5 to 6 seconds is taken while the 



