230 



Professor Silvanus P. Thompson 



[June 13, 



each is opposite the crest of the wave of its own wave-disk ; all the 

 slits being simultaneously closed. This corresponds in Dr. Koenig's 

 nomenclature to a phase of |; minimum flow of air occurring 



Fig. 9. 



Positions of the Slits in front of the Wave-disks for combining the Sounds 

 with Phase-difference f . 



Fig. 10. 



Position of the Slits for Phase-difference \. 



Fig. 11. 



Position of the Slits for Phase-difference J. 



simultaneously for all the components. Suppose now it is desired to 

 change the phase so that the slits shall all be open simultaneously, 

 all that is necessary is to move forward the slits of alternate 



