G 



A. 31. Mayer — Researches in Acoustics. 



ears was permanently impaired by the experiments I made 

 with this apparatus nineteen years ago. 



In the apparatus, presently to be described, the fork vi- 

 brates in front of the mouth of the resonator and the inter- 

 ruptions in the flow of sound are caused by the perforated 

 disk revolving in front of the small opening in the nipple of 

 the resonator, as shown in fig. 7. 



Discussion of the effects. of the relative sizes of the openings in 

 the revolving dish and of the opening in the tube conveying the 

 sound to the disk. 



First case. — Suppose that the opening of the nipple of the 

 resonator and the openings in the disk have the same diam- 

 eter. In the actual experiments these openings were l cm in 

 diameter. The nipple of the resonator had a tube of that 

 diameter adapted to it. 



Fig. 4. 



Fig. 4 is the graphic representation of the results of com- 

 puting the varying areas of the opening of the tube of the 

 resonator as an opening in the disk passes in front of it. This 

 diagram is to be studied in connection with tig. 2. The entire 

 length on the axis of abscissas, OX, gives the space A to B of 

 fig. 2, divided into 16 parts. The ordinates of the curve give 

 the relative areas of opening for corresponding positions on 

 the axis of abscissas. The ordinate marked 8Y shows the full 

 area of opening when the circles of the tube of the resonator 

 and of the disk coincide. It will be observed that the tube is 

 opened and closed slowly and is only instantaneously fully 

 opened at 8. 



Second Case. — The openings in* the disk remain l cm in diam- 

 eter, but the opening in the nipple of the resonator is J cm in 

 diameter. Fig. 5 shows the relations between the areas of 

 opening of the nipple of the resonator and the path A to B 

 (tig. 6), of this opening, R, as it is supposed to move across the 

 opening D in the disk. Fig. 5 is to be studied in connection 

 with fig. 6. Fig. 5 shows that the opening and closing of the 



