vi On the Songs of Birds 127 



The figure B represents the musical instrument of 

 a bird. It may be a Book's, or it may be a Nightin- 

 gale's; there is no difference in the make of the 

 instrument, and the difference in the voice depends 

 simply on the size of the instrument and the skill of 

 the performer. The sound is produced in the same 

 way by all our songsters, and on the same principle 

 as in the oboe. The bird breathes from its lungs 

 into two bronchial tubes ; at the point where these 

 two tubes combine into one there is fixed a tiny 

 elastic membrane, 1 which serves the same purpose as a 

 reed, and sets the air vibrating in the pipe which 

 corresponds to the pipe in the oboe, i.e. the bird's 

 windpipe. We are apt to fancy that the bird sings 

 with his bill or his tongue, but this is altogether a 

 mistake. It is possible that these may have some 

 kind of influence upon the sound, but that sound is 

 produced far down in the bird's throat, at the thin 

 end of the tube, just as it is in the oboe. 



The two instruments are thus really alike; yet 

 there is a difference, not only in the material of which 

 they are made, but in the way in which they are 

 used. Or, to put it another way, the difference of 

 material makes it inevitable that the methods of 

 playing upon them should also be different. In the 

 oboe the tube is of wood, and therefore hard and 

 inelastic ; of itself it cannot alter the pitch of the 



1 See Appendix and plate at end of volume. 



