Several private responses to my humidity application question
implored me to investigate the "Dampp-Chaser" system.  The company
is now sending me literature on their BSV9PS model (Backside Vertical
9-Part System) which they claim will fit in my tightly-packed 1917
Autopiano; we'll see when I review it's dimensional specifications.

The only concern I have of this system is if it's heating action
will unduly accelerate the deterioration/hardening of rubberized cloth.
I gather that proper humidity is more important than temperature;
is it advisable to leave the heater portion of the Dampp-Chaser system
unplugged and only use the humidifying portion of the system, or are
the two integral to the system's stability?  I'm more concerned with
winter dryness.

Until I make a purchasing decision I'll experiment by placing two
pie plates of water in the piano's bottom and see what the portable
humidity gage left inside reads after a day.  The treadle linkage is
raw metal that has started to rust already, and I'm cautious about
accelerating this process too.  Using a whole-room humidifier would
cause condensation during the thermostat set-back periods.

Karl Ellison
Salem, Massachusetts U.S.A.