354 
APPENDIX. VI. 
scholar. Every year also now produces greater 
and greater prodigies upon other instruments, 
im point of execution. 
I have before observed, that by attending to 
a nightingale, as well as a robin which was edu- 
cated under him, I always found that the notes 
reducible to our intervals of the octave were 
precisely the same; which is another proof that 
birds sing always in the same key. 
In this circumstance, they differ much fronr 
the human singer; because they who are not 
able to sing from the notes, often begin a song 
either above or below the compass of their 
voice, which they are not therefore able to ga 
through with. As birds, however, form the 
same passages with the same notes, at all times, 
this mistake of the pitch can never happen in 
them. 
Few singers again can continue their own 
part, whilst the same passages are sung by 
another in a different key; or if other passages 
are played, though they may agree both in har- 
mony and time. 
As birds, however, adhere so stedfastly to 
the same precise notes in the same passages, 
though they never trouble themselves about 
what is called tame or harmony in music; it 
