284 A. M. Mayer — Sensations of interrupted tones. 



A brass tube. T, of 125 cms interior diameter and l-8 cms long 

 is cemented in a bole in the bottom of the glass flask, A ; 

 which is a common form of flask, used by chemists. When 

 the tube, T, is closed the air in the flask resounds powerfully 

 to the sound of an UT 3 fork, F; but when this tube is open 

 the resonator resounds so feebly as to be just audible at the 

 distance of several feet from the flask. 



If the tube be closed and opened several times in a second 

 we shall have short loud sounds with faint interposed sounds. 

 The opening and closing of the tube is effected by a perforated 

 disk, D, revolving on a rotator, R. The tube, T, is placed in 

 the circular path of the 16 holes which perforate the disk, with 

 the mouth of the tube quite close to surface of the disk. A 

 short tube, B, with flanges on it, slides neatly over the tube, 

 T, and the flange of B is pressed against the surface of the 

 disk, D, by the helical spring, S. By this arrangement the 

 tube, T, is full} 7 opened when a hole in the disk coincides with 

 the opening of the tube, T, and is entirely closed when the 

 flange of B is between the holes in the disk and gently press- 

 ing against its surface. 



On slowly rotating the disk, while the fork is kept in vibra- 

 tion by an electro-magnet, we have the perception of power- 



