172 THE APPLICATIONS OF PHYSICAL FORCES. [BOOK n 



of the pipe. It is free to vibrate through this aperture, the vibration 

 being of equal amplitude : this is the principal difference between a 

 free reed and a beating one, its tones being harder and shriller. 



FIG. 120. Clarionet. 

 Ssction of mouthpiece. 



c 



FIG. 121. Hautboy. 

 Front and side view of reed, 



What then produces the tone in the reed ? It is not the vibra- 

 tions of the metal substance which composes it, but those produced 



