INTRODUCTION. xix 



in those, where the organ is disclosed, the nerves, which take 

 their origin from it, are far from being so numerous, so large, 

 or so expanded as in the quadrupeds. We may therefore 

 regard touch in man, smell in the quadruped, and ^4"^/// in 

 birds, as respectively the three most perfect senses which 

 exercise a general influence on the character. 



After sight, the most perfect of the senses in birds appears 

 to be hearing, which is even superior to that of the quadru- 

 peds, and scarcely exceeded in the human species. We per- 

 ceive with what facility they retain and repeat tones, successions 

 of notes, and even words ; we delight to listen to their un- 

 wearied songs, to the incessant warbling of their tuneful affec- 

 tion. Their ear and throat are more ductile and powerful 

 than in other animals, and their voice more capacious and 

 generally agreeable. A Crow, which is scarcely more than the 

 thousandth part the size of an ox, may be heard as far, or 

 farther ; the Nightingale can fill a wider space with its music 

 than the human voice. This prodigious extent and power of 

 sound depend entirely on the structure of their organs ; but 

 the support and continuance of their song result solely from 

 their internal emotions. 



The windpipe is wider and stronger in birds than in any 

 other class of animals, and usually terminates below in a large 

 cavity that augments the sound. The lungs too have greater 

 extent, and communicate with internal cavities which are 

 capable of being expanded with air, and, besides lightening 

 the body, give additional strength to the voice. Indeed, the 

 formation of the thorax, the lungs, and all the organs connected 

 with these, seems expressly calculated to give force and dura- 

 tion to their utterance. 



Another circumstance, showing the great power of voice in 

 birds, is the distance at which they are audible in the higher 

 regions of the atmosphere. An Eagle may rise at least to the 

 height of seventeen thousand feet, for it is there just visible. 

 Flocks of Storks and Geese may mount still higher, since, not- 

 withstanding the space they occupy, they soar almost out of 

 sight ; their cry will therefore be heard from an altitude of 



