This appears to be a tracking system that had all of the vertical
slots connected together and connected to a large pneumatic that was
fed vacuum through a bleed.

When the paper went too far to the right, more air was allowed in
through the various playing note holes and reduced the vacuum level
in the pneumatic.  When the paper was too far left, little air was
admitted and the vacuum in the pneumatic increased. I doubt that the
system worked very well, and I can understand why it would have been
disconnected.  There is probably a dusty patent lying around somewhere
for this system.

That tracker bar should go into a "museum of oddities" and a new
standard one should go into the piano.  Imagine how much dust the old
system would have collected.  Perhaps it was also a roll cleaner, too!

Gordon Ramsey - Ramsey Music Service