26 AKT. Kl. T. TERADA. 



to the distance between the middle section of the diaj)hragm and 

 tlie open end of the glass pipe. 



Another way of studying the effect of diaphragms is as 

 follows. Inside an ordinary organ pipe a diaphragm is so inserted 

 that its position may be adjusted in any desired way ; the pipe 

 is blown by means of a regulated bellows ; and the pitch of the 

 pipe for different positions of the diaphragm is determined. The 

 organ j)ipe used in my experiment was a wooden one with a 

 rectangular section, giving a^ for the fundamental tone. The 

 diaphragm was made of wood, fitting tightly in the inside of the 

 pipe and perforated with a channel having a rectangular section. 

 The lateral side of the diaphragm was covered with cloth in 

 order to secure close contact with the inner wall of the pipe. 

 The diaphragm could be brought to any position by means of two 

 thin rods of steel which were fixed to the diaphragm diagonally 

 opposite to each other. If the diaphragm is gradually pushed 

 into the pipe wdiile it is being blown with a constant pressure, the 

 pitch of the note gradually rises till a maximum is attained at 

 the node of the pipe ; whence the pitch falls gradually with the 

 further position of the diaphragm. The results of the experiment 

 are quite analogous to those in the former experiment. 



For the case when the section of a nearly cylindrical pipe 

 varies slightly, Kayleigh obtained 



X> 27: 

 ro.s -^ 



,, , 27:x AS J 



On 



where J( is the correction of the length due to the irregularity ; 

 / the length between the consecutive loop and node ; JS the small 

 variation of the section givjen as a function of x measured from 

 the node along the length of the p\i)e ; and So the mean section. 



