Two rebuilding questions

[Richard Brekne]

Hi

I have a couple questions about older pianos vs new.  In many (grands)
pianos of the 1800's you see the bent side of the soundboard left
unglued. Often enough half of the tail section is also unglued and the
other half floating... with or without an additional mass added at that
point.

My questions...

first :  What difference would gluing the these sections make to the
<<vibrational-ability>> of the soundboard assuming the mouldings that
are nailed down hold it just as strongly coupled (at least vertically)
to the rim ?  Presumably the unglued idea was to allow the panel to
expand sideways with climate changes .... perhaps this was an idea to
increase tuning stability ????

Second.. this mass addition at the tail.  I've seen various modern
schemes pictured on the list lately... veneers to add stiffness at the
tail... etc.  What is the perceived advantage of taking half the tail
section and floating it with an extra thick piece of wood glued to the
both sides of the panel. ? (I've only seen this done on the tail half
adjacent the bent side corner)

Any thoughts on the matter are very much appreciated.

Cheers
RicB