In response to Christopher Proudfoot's notes and question of the
Nightingale box [171107 MMDigest].  A handful have been observed over
the years, and I have personally inspected a hand cranked example along
with a more complex clockwork example with a series of cams that could
be selected on an individual basis that changed the bird song ("chant").

My guess at the primary purpose of these machines would be in teaching
a caged songbird to warble a melody conducive to something that he
would learn in his natural environment.  In the wild, he would learn
this song from his contemporaries, and try to out do them for obvious
reasons.  Any young male caged bird will try and replicate the audio
information as presented.

Back in 1980 a friend's family bought a young canary; his only daytime
stimulation in his caged environment was the "Brrr Brrr" call tone of
an early and unanswered electronic phone.  So accurate was his imitation,
that when the house filled again in the evening, everyone reached for
the phone.  I did notice this unfortunate little creature was disposed
of at some point shortly thereafter, due to his initially amusing song
becoming an irritation.

Mark Singleton