388 REED-PIPES. 



used in these instruments differ essentially in their mode 

 of action from the strong elastic tongues applied in other 

 instruments, for instance in the concertina, the accordion, 

 the harmonium, or the reed-pipes of the organ. These 

 metal tongues are thin, long, narrow rectangular plates of 

 hardened brass or german-silver, fixed by their thicker 

 ends upon a plate of metal, usually of zinc, so as nearly 

 to close a rectangular slit in the plate. In fig. 233, A 



FIG. 233 (A, an. proj. ; A and , real size). 



represents the exterior, B a section of such a tongue. 

 The plate with the tongue fixed upon it is called a 

 4 reed ; ' it is fastened so as to form one side of a small 

 box into which air can be forced through an opening; 

 that side of the plate upon which the tongue is fixed 

 is turned towards the inside of the box, and, as the 

 current of air escapes from it, it presses the tongue 

 in the direction of the small arrow into the slit of the 

 plate, into the position indicated by the dotted line; 

 the slit is thus for an instant more completely closed 

 than before, and the current of air almost entirely 

 interrupted. Consequently the elasticity of the tongue 

 immediately causes it to return to its first position ; a 

 passage is thus again opened for the air; the current is 

 re-established and carries the tongue with it, as before, 

 so as again to obstruct its own path; the tongue then 

 springs back once more, and so the action is continually 



