CHAP. IV.] 



WIND INSTRUMENTS. 



169 



to the lengths of the pipes. This is true with regard to closed pipes 

 those called the bourdons in the organ as well as open pipes. 

 Only in two pipes of the same length, the fundamental note in the 

 open pipe is an octave higher than tlmt produced by a closed one. 



With the fundamental note, when increased intensity is given 

 to the current of air, successive harmonic notes represented by the 



FIG. 115. Organ pipes with flute mouthpiece. 



FIG. 116. Flute-a-bec. 

 Section of mouthpiece. 



numbers 1, 2, 3, 4, etc., in open pipes, and the uneven harmonics, 

 1, 3, 5, in closed pipes, are also produced. 



This statement of the laws is sufficient to enable us to understand 

 the phenomena of musical acoustics produced in wind instruments, 

 and the principles to be borne in mind in the construction of each 

 of them. The form and the substance of which the pipes are formed, 

 the mouthpiece and the way in which it is used, modify the tone, 

 intensity, and sweetness of the sounds produced, not to mention 



