Seasonal pitch change:

[Ron Nossaman]

> Do people notice tiny discrepencies of lever pressure on tuning pins?  
> We never can get all of them perfect. My suspicion is that some of the 
> unison problem is simply the fact we are never perfect tuners, and as 
> the piano "flexes", when it settles back those discrepencies "come to 
> the surface".......  There are so many factors at work in tuning 3 
> strings together..... It's a miracle, to me, anything stays.
> les bartlett

I have no doubt this is a factor, as I've noticed the result 
in my own, and other's tunings. The last string tuned in the 
unison is the most likely to be out, being revisited and 
verified least. While that may account for some of the little 
stuff, it's not a major factor in tuning instability unless 
the tuner just has no clue whatsoever. That's short term. In 
the long term, the shorter overall string length will react 
the most to humidity induced changes however skilled the tuner 
was.

Since the role in soundboard rise and fall has apparently 
suddenly and miraculously been discovered to be relatively 
inconsequential to the process, I expect that shortly after 
the flurry of rim and plate movement, rotating pin block, 
rolling bridge, and warping continent theories dies down for 
lack of rational connection, the observation that string path 
length changes with strings being moved up and down bridge 
pins slanted in apposing directions by humidity induced cap 
dimensional changes will be equally suddenly and miraculously 
discovered as being a likely candidate, to the edification of 
- some, maybe. That is, if anyone actually runs some physical 
tests and thinks about it.

Hey, it could happen someday.
Ron N