ANNALS OF BIRD LIFE. 



tion, and then as imperceptibly dies away again, 

 like the swelling volume of melody from some 

 stupendous organ-pipes, commencing in low and 

 fitful strains, then rolling out in grand, majestic 

 cadence, then fading away again as gradually as it 

 rose. The following table may therefore prove of 

 interest to the student of natural phenomena, and 

 serve as a guide to more elaborate observations. 

 It has been compiled from my note-books, extend- 

 ing over a long series of years, and some nineteen 

 species of birds have been selected as examples : 



