In response to Jim Crank's request on the particulars of the Automatic
Tempo System, I offer the following information.

Before the tracker bar is "turned on", five upper holes, the Swell row,
are assigned the task of reading and setting the tempo.

The scheme works this way.  With no input, the roll speed will be tempo
30.  Opening any combination of four holes will add to this base tempo
30.  The fifth control hole locks the tempo, and transfers the function
of the five control holes back to reading notes.

  Swell hole for note 16 yields tempo 5
  Swell hole for note 18 yields tempo 10
  Swell hole for note 20 yields tempo 20
  Swell hole for note 22 yields tempo 40
  Swell hole for note 24 locks in the tempo and returns all
  to note function.

An accordion pneumatic (fan, hinged at one end) with proportional
sized chambers is collapsed by the above holes.  The collapse of this
pneumatic directly moves a control rod on the air motor governor.  So
with increments of 5, any tempo between 30 and 105 may be set.

Not all rolls came perforated for automatic operation.  Concertola
owners were given a template so that they could add the necessary
holes.  This duty, I am sure, was delegated to someone on the household
staff!

Bob Taylor