Ibach whazzit

[A440A at aol.com]

Greetings,  
      OK, I give up.  I don't have a clue what this thing is, and am hoping 
maybe someone familiar with Ibach pianos knows.   This is a rather old, small 
grand.  Three bridges with the last 7 or 8 notes on a separate bridge with tall 
"stilts" holding a brass bar on the lower bridge.  
        There is a spring loaded button in the top of the treble side music 
desk support.  It operates a small lever located down below the support, but it 
is not connected to anything I can see.  It has a small concave surface on 
the top, but pushing on it does nothing but flex the spring it is connected to. 
Anybody seen one of these and know what it is for?  There may be something 
missing, as this piano has been rebuilt. 
Thanks, 

Ed Foote RPT 
http://www.uk-piano.org/edfoote/index.html
www.uk-piano.org/edfoote/well_tempered_piano.html
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