Something old, something new.

[A440A@AOL.COM]

Greetings list, 
    Here is today's Steinway quiz.........
I recently set up a piano's action for a studio.  It is a 1910 model D, which,
according to the factory, was used in the C&A division from 1910 until 1950, (
I think, it was definitely longer than the normal span today). 
    What puzzled me was some of the plate writing, and I hope someone here can
tell me what it meant.  In raised, cast, letters, on the plate, in the middle
treble section was the phrase "Ring Bridge- pat. Dec 30, 1889". 
Hmmm,  the owner asked me what that meant, and dang if I didn't have to say
those awful words, "I don't know".  
   So,  someone that does will hopefully tell me whether that refers to the
wrap-around bridge, or the aliquot sections, matrimonial procedures of the
family, etc........ 
Anyone? 
Thanks,
Ed Foote