Treble Resonator

[Dave Nereson]

Piano Frame
C.F.T. Steinway [Charles F. Theodor Steinway]
Pat. #314,740
May 31, 1885

Principles:  Structural stability and freedom in the transfer of energy

"Treble Bell"
"The tension of the strings exerts a lifting action on the treble portion of the metallic string-frame [plate] of the piano, so that the same assumes the shape of a flattened longitudinal arch.  It is therefore of the utmost importance to give the treble portion of the string-frame an exterior support, whereby the frame is better adapted to resist the strains of the strings and to impart thereby to the treble strings an increased singing quality of tone." 
    "The annular base-rim a and the tapering tongue a' support the bell-shaped bracket D rigidly on the rims C, C', so that the vibrations of the rims are propagated in longitudinal direction through the hollow bell-shaped bracket D, without being interrupted or impeded thereby."

    --from "The Steinway Patents"


    In other words, the bolt through the plate into the bell keeps the plate from trying to arch up in the high treble. [I don't see why it would try to arch up more in that area than elsewhere on the plate.]  But the resonator part of it I don't quite "get", i.e., once the vibrations of the rims [why plural?] are propagated through the bell in a longitudinal direction [which direction is that?  from the base to the apex?  why is that "longitudinal" as opposed to "latitudinal"?], where do they go -- up the bolt to the plate?  Why would they want the vibrations to end up there?  Or does the high treble sound tend to "collect" there, and the bell conducts it out to the rim?    
    Several years ago, a rep from Steinway explained this in the "Steinway patents" class at the National in Albuquerque or Kansas City, but I forget the particulars.
    --David Nereson, RPT