Part of the "monkey" business is that these are nicknamed "monkey
organs" or "monkey grinder organs," there being no popular alternative
term.  Similarly, a street piano is often called a "hurdy-gurdy."
Neither term was used in the days of popularity of these instruments.

As to "nickelodeon," Farny Wurlitzer said to him it _always_ meant a
theatre that charged a nickel for admission.  The first time he heard
it applied to a piano was in the modern tune, "Put Another Nickel In."

Dave Bowers

 [ MMDigest (me) advocates these definitions:
 [
 [   hurdy-gurdy -- a hand-cranked wheel violin, played by a musician
 [   crank-organ -- a hand-cranked self-playing organ
 [   street organ -- a self-playing organ seen on the streets
 [   nickelodeon (I concede!) -- a coin-operated self-playing piano
 [
 [ See http://www.mmdigest.com/Archives/KWIC/H/hurdy_gurdy.html 
 [
 [ -- Robbie