John "Make it cheap - make it quick" Kleinbauer wrote about piano wire
fingers to read music rolls.  That is exactly the arrangement used in
the Mills Violanos and pianos.

Mills made quite a feeder and reader using this method.  Each note
had two piano wire "hairs" soldered to a small clip.  The wires poked
through the holes in the roll and touched a steel roller which was
attached to the motor-speed governor.  The clip was notched and fit
inside a hollow threaded rod.  The notch would slip under an adjusting
nut.  By turning the nut, you could lengthen the wire as the 100-volts
direct current arcing burnt the tip off.

Now, with all the arcing and ozone generated by the high voltage, this
system worked great, although it did consume these little brush wires
after time, and perhaps more than one Violano was set afire by the
thing.  On lower voltages, you might have a problem with sufficient
pressure to make good contact.

The reroll mechanism would pop the entire brush assembly clear of the
roll.  I've read that their high speed duplicating perforating machine
used the same mechanism for reading rolls in real time.

Ed Gloeggler
Long Beach, NY